[Libreoffice-commits] online.git: 9 commits - kit/Delta.hpp kit/Kit.cpp loleaflet/src net/Ssl.cpp net/Ssl.hpp test/data test/DeltaTests.cpp test/Makefile.am wsd/LOOLWSD.cpp wsd/TileDesc.hpp

Michael Meeks michael.meeks at collabora.com
Wed Nov 22 15:55:23 UTC 2017


 kit/Delta.hpp                         |  219 ++++++++++++++++++++++++++++++++++
 kit/Kit.cpp                           |   10 +
 loleaflet/src/core/Socket.js          |   20 ++-
 loleaflet/src/layer/tile/TileLayer.js |   96 ++++++++++++++
 net/Ssl.cpp                           |   10 +
 net/Ssl.hpp                           |    8 -
 test/DeltaTests.cpp                   |  209 ++++++++++++++++++++++++++++++++
 test/Makefile.am                      |    1 
 test/data/delta-text.png              |binary
 test/data/delta-text2.png             |binary
 wsd/LOOLWSD.cpp                       |    6 
 wsd/TileDesc.hpp                      |    1 
 12 files changed, 568 insertions(+), 12 deletions(-)

New commits:
commit 92379ffbf2a52d3430eb7f693f64850413a1f347
Author: Michael Meeks <michael.meeks at collabora.com>
Date:   Wed Nov 22 15:54:42 2017 +0000

    Make the WSD SSL cipher list configurable.
    
    Change-Id: If79b9efc9438cf0a2345b8e81385adafef63ce22

diff --git a/net/Ssl.cpp b/net/Ssl.cpp
index 5a9f8280..cd28f53b 100644
--- a/net/Ssl.cpp
+++ b/net/Ssl.cpp
@@ -26,11 +26,14 @@ extern "C"
     };
 }
 
+#define DEFAULT_CIPHER_SET "ALL:!RC4:!SEED:!ADH:!LOW:!EXP:!MD5:@STRENGTH"
+
 std::unique_ptr<SslContext> SslContext::Instance(nullptr);
 
 SslContext::SslContext(const std::string& certFilePath,
                        const std::string& keyFilePath,
-                       const std::string& caFilePath) :
+                       const std::string& caFilePath,
+                       const std::string& cipherList) :
     _ctx(nullptr)
 {
     const std::vector<char> rand = Util::rng::getBytes(512);
@@ -107,7 +110,10 @@ SslContext::SslContext(const std::string& certFilePath,
         }
 
         SSL_CTX_set_verify(_ctx, SSL_VERIFY_NONE, nullptr /*&verifyServerCallback*/);
-        SSL_CTX_set_cipher_list(_ctx, "ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH");
+        std::string ciphers(cipherList);
+        if (ciphers.empty())
+            ciphers = DEFAULT_CIPHER_SET;
+        SSL_CTX_set_cipher_list(_ctx, ciphers.c_str());
         SSL_CTX_set_verify_depth(_ctx, 9);
 
         // The write buffer may re-allocate, and we don't mind partial writes.
diff --git a/net/Ssl.hpp b/net/Ssl.hpp
index b6fc0427..90ba4f44 100644
--- a/net/Ssl.hpp
+++ b/net/Ssl.hpp
@@ -29,10 +29,11 @@ class SslContext
 public:
     static void initialize(const std::string& certFilePath,
                            const std::string& keyFilePath,
-                           const std::string& caFilePath)
+                           const std::string& caFilePath,
+                           const std::string& cipherList = "")
     {
         assert (!Instance);
-        Instance.reset(new SslContext(certFilePath, keyFilePath, caFilePath));
+        Instance.reset(new SslContext(certFilePath, keyFilePath, caFilePath, cipherList));
     }
 
     static void uninitialize();
@@ -47,7 +48,8 @@ public:
 private:
     SslContext(const std::string& certFilePath,
                const std::string& keyFilePath,
-               const std::string& caFilePath);
+               const std::string& caFilePath,
+               const std::string& cipherList);
 
     void initDH();
     void initECDH();
diff --git a/wsd/LOOLWSD.cpp b/wsd/LOOLWSD.cpp
index 7ff87b79..102670e7 100644
--- a/wsd/LOOLWSD.cpp
+++ b/wsd/LOOLWSD.cpp
@@ -927,11 +927,15 @@ void LOOLWSD::initializeSSL()
     const auto ssl_ca_file_path = getPathFromConfig("ssl.ca_file_path");
     LOG_INF("SSL CA file: " << ssl_ca_file_path);
 
+    const auto ssl_cipher_list = getPathFromConfig("ssl.cipher_list");
+    LOG_INF("SSL Cipher list: " << ssl_cipher_list);
+
 #if ENABLE_SSL
     // Initialize the non-blocking socket SSL.
     SslContext::initialize(ssl_cert_file_path,
                            ssl_key_file_path,
-                           ssl_ca_file_path);
+                           ssl_ca_file_path,
+                           ssl_cipher_list);
 #endif
 }
 
commit 74f44251b782e5cab42960d1e328102a1538e72f
Author: Michael Meeks <michael.meeks at collabora.com>
Date:   Mon Oct 23 20:59:10 2017 +0100

    Deltas - collapse multiple rows to a single row.
    
    Change-Id: Ia2a617c2adbbc4e66b7c773c2280ec609aead16e

diff --git a/kit/Delta.hpp b/kit/Delta.hpp
index 82f871bb..e1890370 100644
--- a/kit/Delta.hpp
+++ b/kit/Delta.hpp
@@ -64,6 +64,7 @@ class DeltaGenerator {
 
         // How do the rows look against each other ?
         size_t lastMatchOffset = 0;
+        size_t lastCopy = 0;
         for (int y = 0; y < prev._height; ++y)
         {
             // Life is good where rows match:
@@ -78,12 +79,25 @@ class DeltaGenerator {
                 if (prev._rows[match].identical(cur._rows[y]))
                 {
                     // TODO: if offsets are >256 - use 16bits?
+                    if (lastCopy > 0)
+                    {
+                        char cnt = output[lastCopy];
+                        if (output[lastCopy + 1] + cnt == (char)(match) &&
+                            output[lastCopy + 2] + cnt == (char)(y))
+                        {
+                            output[lastCopy]++;
+                            matched = true;
+                            continue;
+                        }
+                    }
 
-                    // hopefully find blocks of this.
                     lastMatchOffset = match - y;
-                    output.push_back('c'); // copy-row
+                    output.push_back('c');   // copy-row
+                    lastCopy = output.size();
+                    output.push_back(1);     // count
                     output.push_back(match); // src
-                    output.push_back(y); // dest
+                    output.push_back(y);     // dest
+
                     matched = true;
                     continue;
                 }
diff --git a/loleaflet/src/layer/tile/TileLayer.js b/loleaflet/src/layer/tile/TileLayer.js
index a1ac27f9..5f0ba440 100644
--- a/loleaflet/src/layer/tile/TileLayer.js
+++ b/loleaflet/src/layer/tile/TileLayer.js
@@ -1306,13 +1306,20 @@ L.TileLayer = L.GridLayer.extend({
 
 			// FIXME; can we operate directly on the image ?
 			var imgData = ctx.getImageData(0, 0, canvas.width, canvas.height);
-			var oldData = new Uint8ClampedArray(imgData);
+			var oldData = new Uint8ClampedArray(imgData.data);
+
 			var delta = img;
 			var pixSize = canvas.width * canvas.height * 4;
 			var offset = 0;
 
 			console.log('Applying a delta of length ' + delta.length + ' pix size: ' + pixSize + '\nhex: ' + hex2string(delta));
 
+			// Green-tinge the old-Data ...
+//			for (var i = 0; i < pixSize; ++i)
+//			{
+//				oldData[i*4 + 1] = 128;
+//			}
+
 			// wipe to grey.
 //			for (var i = 0; i < pixSize * 4; ++i)
 //			{
@@ -1325,15 +1332,19 @@ L.TileLayer = L.GridLayer.extend({
 				switch (delta[i])
 				{
 				case 99: // 'c': // copy row
-					var srcRow = delta[i+1];
-					var destRow = delta[i+2]
-					i+= 3;
-					console.log('copy row ' + srcRow + ' to ' + destRow);
-					var src = srcRow * canvas.width * 4;
-					var dest = destRow * canvas.width * 4;
-					for (var i = 0; i < canvas.width * 4; ++i)
+					var count = delta[i+1];
+					var srcRow = delta[i+2];
+					var destRow = delta[i+3];
+					i+= 4;
+					console.log('copy ' + count + ' row(s) ' + srcRow + ' to ' + destRow);
+					for (var cnt = 0; cnt < count; ++cnt)
 					{
-						imgData.data[dest + i] = oldData[src + i];
+						var src = (srcRow + cnt) * canvas.width * 4;
+						var dest = (destRow + cnt) * canvas.width * 4;
+						for (var j = 0; j < canvas.width * 4; ++j)
+						{
+							imgData.data[dest + j] = oldData[src + j];
+						}
 					}
 					break;
 				case 100: // 'd': // new run
@@ -1351,7 +1362,8 @@ L.TileLayer = L.GridLayer.extend({
 					imgData.data[offset - 2] = 256; // debug - blue terminator
 					break;
 				default:
-					console.log('Unknown code ' + delta[i]);
+					console.log('ERROR: Unknown code ' + delta[i] +
+						    ' at offset ' + i);
 					i = delta.length;
 					break;
 				}
diff --git a/test/DeltaTests.cpp b/test/DeltaTests.cpp
index 705b7d3e..66868523 100644
--- a/test/DeltaTests.cpp
+++ b/test/DeltaTests.cpp
@@ -84,15 +84,19 @@ std::vector<char> DeltaTests::applyDelta(
         {
         case 'c': // copy row.
         {
-            int srcRow = (uint8_t)(delta[i+1]);
-            int destRow = (uint8_t)(delta[i+2]);
-
-            std::cout << "copy row " << srcRow << " to " << destRow << "\n";
-            const char *src = &pixmap[width * srcRow * 4];
-            char *dest = &output[width * destRow * 4];
-            for (size_t j = 0; j < width * 4; ++j)
-                *dest++ = *src++;
-            i += 3;
+            int count = (uint8_t)(delta[i+1]);
+            int srcRow = (uint8_t)(delta[i+2]);
+            int destRow = (uint8_t)(delta[i+3]);
+
+//            std::cout << "copy " << count <<" row(s) " << srcRow << " to " << destRow << "\n";
+            for (int cnt = 0; cnt < count; ++cnt)
+            {
+                const char *src = &pixmap[width * (srcRow + cnt) * 4];
+                char *dest = &output[width * (destRow + cnt) * 4];
+                for (size_t j = 0; j < width * 4; ++j)
+                    *dest++ = *src++;
+            }
+            i += 4;
             break;
         }
         case 'd': // new run
@@ -102,7 +106,7 @@ std::vector<char> DeltaTests::applyDelta(
             size_t length = (uint8_t)(delta[i+3]);
             i += 4;
 
-            std::cout << "new " << length << " at " << destCol << ", " << destRow << "\n";
+//            std::cout << "new " << length << " at " << destCol << ", " << destRow << "\n";
             CPPUNIT_ASSERT(length <= width - destCol);
 
             char *dest = &output[width * destRow * 4 + destCol * 4];
commit fa86ba9ec5ecb418bd025c0bc7bbea8456409c07
Author: Michael Meeks <michael.meeks at collabora.com>
Date:   Fri Sep 29 18:05:03 2017 +0100

    Convert Javascript to row deltas.
    
    Change-Id: I2ec612c2bc047dc36f86c2935178c964f9feae11

diff --git a/loleaflet/src/layer/tile/TileLayer.js b/loleaflet/src/layer/tile/TileLayer.js
index 6d1077cb..a1ac27f9 100644
--- a/loleaflet/src/layer/tile/TileLayer.js
+++ b/loleaflet/src/layer/tile/TileLayer.js
@@ -1306,6 +1306,7 @@ L.TileLayer = L.GridLayer.extend({
 
 			// FIXME; can we operate directly on the image ?
 			var imgData = ctx.getImageData(0, 0, canvas.width, canvas.height);
+			var oldData = new Uint8ClampedArray(imgData);
 			var delta = img;
 			var pixSize = canvas.width * canvas.height * 4;
 			var offset = 0;
@@ -1319,38 +1320,43 @@ L.TileLayer = L.GridLayer.extend({
 //			}
 
 			// Apply delta.
-			for (var i = 1; i < delta.length &&
-			     offset < pixSize;)
+			for (var i = 1; i < delta.length;)
 			{
-//				var span = delta[i];
-//				var isChangedRun = span & 64;
-//				if (span >= 128)
-//				{
-				// first char is a control code.
-				var isChangedRun = delta[i++] & 64;
-				span = delta[i++];
-				span += delta[i++] * 256;
-//				}
-				if (isChangedRun) {
-					console.log('apply new span of size ' + span + ' at offset ' + i + ' into delta at byte: ' + offset);
+				switch (delta[i])
+				{
+				case 99: // 'c': // copy row
+					var srcRow = delta[i+1];
+					var destRow = delta[i+2]
+					i+= 3;
+					console.log('copy row ' + srcRow + ' to ' + destRow);
+					var src = srcRow * canvas.width * 4;
+					var dest = destRow * canvas.width * 4;
+					for (var i = 0; i < canvas.width * 4; ++i)
+					{
+						imgData.data[dest + i] = oldData[src + i];
+					}
+					break;
+				case 100: // 'd': // new run
+					var destRow = delta[i+1];
+					var destCol = delta[i+2];
+					var span = delta[i+3];
+					var offset = destRow * canvas.width * 4 + destCol * 4;
+					i += 4;
+					console.log('apply new span of size ' + span + ' at pos ' + destCol + ', ' + destRow + ' into delta at byte: ' + offset);
 					span *= 4;
+					imgData.data[offset + 1] = 256; // debug - greener start
 					while (span-- > 0) {
 						imgData.data[offset++] = delta[i++];
 					}
 					imgData.data[offset - 2] = 256; // debug - blue terminator
-				} else {
-					console.log('apply unchanged span of size ' + span + ' at offset ' + i + ' into delta at byte: ' + offset);
-					offset += span * 4;
-					imgData.data[offset - 3] = 256; // debug - green terminator
+					break;
+				default:
+					console.log('Unknown code ' + delta[i]);
+					i = delta.length;
+					break;
 				}
 			}
 
-			while (offset < pixSize) // debug
-			{
-				imgData.data[offset] = 256; // redden the remaining section.
-				imgData.data[offset+3] = 256; // with some alpha
-				offset += 4;
-			}
 			ctx.putImageData(imgData, 0, 0);
 
 			tile.oldWireId = tile.wireId;
commit 5efb59db50a49374bcf53198f7c0a1e120754cc9
Author: Michael Meeks <michael.meeks at collabora.com>
Date:   Thu Sep 28 09:45:46 2017 +0100

    Make delta-builder row-based.
    
    Change-Id: Ic59324535c4f412abc4e83774073eb8f57290704

diff --git a/kit/Delta.hpp b/kit/Delta.hpp
index 95f6a1f1..82f871bb 100644
--- a/kit/Delta.hpp
+++ b/kit/Delta.hpp
@@ -21,106 +21,149 @@
 /// A quick and dirty delta generator for last tile changes
 class DeltaGenerator {
 
+    struct DeltaBitmapRow {
+        uint64_t _crc;
+        std::vector<uint32_t> _pixels;
+
+        bool identical(const DeltaBitmapRow &other) const
+        {
+            if (_crc != other._crc)
+                return false;
+            return _pixels == other._pixels;
+        }
+    };
+
     struct DeltaData {
         TileWireId _wid;
-        std::shared_ptr<std::vector<uint32_t>> _rawData;
+        int _width;
+        int _height;
+        std::vector<DeltaBitmapRow> _rows;
     };
-    std::vector<DeltaData> _deltaEntries;
+    std::vector<std::shared_ptr<DeltaData>> _deltaEntries;
 
     bool makeDelta(
-        const DeltaData &prevData,
-        const DeltaData &curData,
+        const DeltaData &prev,
+        const DeltaData &cur,
         std::vector<char>& output)
     {
-        std::vector<uint32_t> &prev = *prevData._rawData.get();
-        std::vector<uint32_t> &cur = *curData._rawData.get();
-
-        // FIXME: should we split and compress alpha separately ?
-
-        if (prev.size() != cur.size())
+        // TODO: should we split and compress alpha separately ?
+        if (prev._width != cur._width || prev._height != cur._height)
         {
-            LOG_ERR("mis-sized delta: " << prev.size() << " vs " << cur.size() << "bytes");
+            LOG_ERR("mis-sized delta: " << prev._width << "x" << prev._height << " vs "
+                    << cur._width << "x" << cur._height);
             return false;
         }
 
         output.push_back('D');
-        LOG_TRC("building delta of " << prev.size() << "bytes");
-        // FIXME: really lame - some RLE might help etc.
-        for (size_t i = 0; i < prev.size();)
+        LOG_TRC("building delta of a " << cur._width << "x" << cur._height << " bitmap");
+
+        // row move/copy src/dest is a byte.
+        assert (prev._height <= 256);
+        // column position is a byte.
+        assert (prev._width <= 256);
+
+        // How do the rows look against each other ?
+        size_t lastMatchOffset = 0;
+        for (int y = 0; y < prev._height; ++y)
         {
-            int sameCount = 0;
-            while (i + sameCount < prev.size() &&
-                   prev[i+sameCount] == cur[i+sameCount])
-            {
-                ++sameCount;
-            }
-            if (sameCount > 0)
+            // Life is good where rows match:
+            if (prev._rows[y].identical(cur._rows[y]))
+                continue;
+
+            // Hunt for other rows
+            bool matched = false;
+            for (int yn = 0; yn < prev._height && !matched; ++yn)
             {
-#if 0
-                if (sameCount < 64)
-                    output.push_back(sameCount);
-                else
-#endif
+                size_t match = (y + lastMatchOffset + yn) % prev._height;
+                if (prev._rows[match].identical(cur._rows[y]))
                 {
-                    output.push_back(0x80 | 0x00); // long-same
-                    output.push_back(sameCount & 0xff);
-                    output.push_back(sameCount >> 8);
+                    // TODO: if offsets are >256 - use 16bits?
+
+                    // hopefully find blocks of this.
+                    lastMatchOffset = match - y;
+                    output.push_back('c'); // copy-row
+                    output.push_back(match); // src
+                    output.push_back(y); // dest
+                    matched = true;
+                    continue;
                 }
-                i += sameCount;
-                LOG_TRC("identical " << sameCount << "pixels");
             }
+            if (matched)
+                continue;
 
-            int diffCount = 0;
-            while (i + diffCount < prev.size() &&
-                   (prev[i+diffCount] != cur[i+diffCount]))
+            // Our row is just that different:
+            const DeltaBitmapRow &curRow = cur._rows[y];
+            const DeltaBitmapRow &prevRow = prev._rows[y];
+            for (int x = 0; x < prev._width;)
             {
-                ++diffCount;
-            }
-
-            if (diffCount > 0)
-            {
-#if 0
-                if (diffCount < 64)
-                    output.push_back(0x40 & diffCount);
-                else
-#endif
+                int same;
+                for (same = 0; same + x < prev._width &&
+                         prevRow._pixels[x+same] == curRow._pixels[x+same];)
+                    ++same;
+
+                x += same;
+
+                int diff;
+                for (diff = 0; diff + x < prev._width &&
+                         (prevRow._pixels[x+diff] == curRow._pixels[x+diff] || diff < 2) &&
+                         diff < 254;)
+                    ++diff;
+                if (diff > 0)
                 {
-                    output.push_back(0x80 | 0x40); // long-diff
-                    output.push_back(diffCount & 0xff);
-                    output.push_back(diffCount >> 8);
-                }
+                    output.push_back('d');
+                    output.push_back(y);
+                    output.push_back(x);
+                    output.push_back(diff);
+
+                    size_t dest = output.size();
+                    output.resize(dest + diff * 4);
+                    memcpy(&output[dest], &curRow._pixels[x], diff * 4);
 
-                size_t dest = output.size();
-                output.resize(dest + diffCount * 4);
-                memcpy(&output[dest], &cur[i], diffCount * 4);
-                LOG_TRC("different " << diffCount << "pixels");
-                i += diffCount;
+                    LOG_TRC("different " << diff << "pixels");
+                    x += diff;
+                }
             }
         }
+
         return true;
     }
 
-    std::shared_ptr<std::vector<uint32_t>> dataToVector(
+    std::shared_ptr<DeltaData> dataToDeltaData(
+        TileWireId wid,
         unsigned char* pixmap, size_t startX, size_t startY,
         int width, int height,
         int bufferWidth, int bufferHeight)
     {
+        auto data = std::make_shared<DeltaData>();
+        data->_wid = wid;
+
         assert (startX + width <= (size_t)bufferWidth);
         assert (startY + height <= (size_t)bufferHeight);
 
-        auto vector = std::make_shared<std::vector<uint32_t>>();
-        LOG_TRC("Converting data to vector of size "
+        LOG_TRC("Converting pixel data to delta data of size "
                 << (width * height * 4) << " width " << width
                 << " height " << height);
 
-        vector->resize(width * height);
+        data->_width = width;
+        data->_height = height;
+        data->_rows.resize(height);
         for (int y = 0; y < height; ++y)
         {
+            DeltaBitmapRow &row = data->_rows[y];
             size_t position = ((startY + y) * bufferWidth * 4) + (startX * 4);
-            memcpy(&(*vector)[y * width], pixmap + position, width * 4);
+            int32_t *src = reinterpret_cast<int32_t *>(pixmap + position);
+
+            // We get the hash ~for free as we copy - with a cheap hash.
+            uint64_t crc = 0x7fffffff - 1;
+            row._pixels.resize(width);
+            for (int x = 0; x < width; ++x)
+            {
+                crc = (crc << 7) + crc + src[x];
+                row._pixels[x] = src[x];
+            }
         }
 
-        return vector;
+        return data;
     }
 
   public:
@@ -143,17 +186,15 @@ class DeltaGenerator {
         if (_deltaEntries.size() > 6) // FIXME: hard-coded ...
             _deltaEntries.erase(_deltaEntries.begin());
 
-        // FIXME: assuming width etc. are all constant & so on.
-        DeltaData update;
-        update._wid = wid;
-        update._rawData = dataToVector(pixmap, startX, startY, width, height,
-                                       bufferWidth, bufferHeight);
+        std::shared_ptr<DeltaData> update =
+            dataToDeltaData(wid, pixmap, startX, startY, width, height,
+                            bufferWidth, bufferHeight);
         _deltaEntries.push_back(update);
 
         for (auto &old : _deltaEntries)
         {
-            if (oldWid == old._wid)
-                return makeDelta(old, update, output);
+            if (oldWid == old->_wid)
+                return makeDelta(*old, *update, output);
         }
         return false;
     }
diff --git a/test/DeltaTests.cpp b/test/DeltaTests.cpp
index 3532931e..705b7d3e 100644
--- a/test/DeltaTests.cpp
+++ b/test/DeltaTests.cpp
@@ -57,61 +57,85 @@ class DeltaTests : public CPPUNIT_NS::TestFixture
         const std::vector<char> &delta);
 
     void assertEqual(const std::vector<char> &a,
-                     const std::vector<char> &b);
+                     const std::vector<char> &b,
+                     int width, int height);
 };
 
 // Quick hack for debugging
 std::vector<char> DeltaTests::applyDelta(
     const std::vector<char> &pixmap,
-    png_uint_32 /* width */, png_uint_32 /* height */,
+    png_uint_32 width, png_uint_32 height,
     const std::vector<char> &delta)
 {
     CPPUNIT_ASSERT(delta.size() >= 4);
     CPPUNIT_ASSERT(delta[0] == 'D');
 
-//    std::cout << "apply delta of size " << delta.size() << "\n";
+    std::cout << "apply delta of size " << delta.size() << "\n";
 
+    // start with the same state.
     std::vector<char> output = pixmap;
-    CPPUNIT_ASSERT_EQUAL(output.size(), pixmap.size());
-    size_t offset = 0;
-    for (size_t i = 1; i < delta.size() &&
-             offset < output.size();)
+    CPPUNIT_ASSERT_EQUAL(output.size(), size_t(pixmap.size()));
+    CPPUNIT_ASSERT_EQUAL(output.size(), size_t(width * height * 4));
+
+    size_t offset = 0, i;
+    for (i = 1; i < delta.size() && offset < output.size();)
     {
-        bool isChangedRun = delta[i++] & 64;
-        CPPUNIT_ASSERT(i < delta.size());
-        uint32_t span = (unsigned char)delta[i++];
-        CPPUNIT_ASSERT(i < delta.size());
-        span += ((unsigned char)delta[i++])*256;
-        CPPUNIT_ASSERT(i < delta.size() ||
-                       (i == delta.size() && !isChangedRun));
-        span *= 4;
-//        std::cout << "span " << span << " offset " << offset << "\n";
-        if (isChangedRun)
+        switch (delta[i])
+        {
+        case 'c': // copy row.
+        {
+            int srcRow = (uint8_t)(delta[i+1]);
+            int destRow = (uint8_t)(delta[i+2]);
+
+            std::cout << "copy row " << srcRow << " to " << destRow << "\n";
+            const char *src = &pixmap[width * srcRow * 4];
+            char *dest = &output[width * destRow * 4];
+            for (size_t j = 0; j < width * 4; ++j)
+                *dest++ = *src++;
+            i += 3;
+            break;
+        }
+        case 'd': // new run
         {
-            CPPUNIT_ASSERT(offset + span <= output.size());
-            memcpy(&output[offset], &delta[i], span);
-            i += span;
+            int destRow = (uint8_t)(delta[i+1]);
+            int destCol = (uint8_t)(delta[i+2]);
+            size_t length = (uint8_t)(delta[i+3]);
+            i += 4;
+
+            std::cout << "new " << length << " at " << destCol << ", " << destRow << "\n";
+            CPPUNIT_ASSERT(length <= width - destCol);
+
+            char *dest = &output[width * destRow * 4 + destCol * 4];
+            for (size_t j = 0; j < length * 4 && i < delta.size(); ++j)
+                *dest++ = delta[i++];
+            break;
+        }
+        default:
+            std::cout << "Unknown delta code " << delta[i] << "\n";
+            CPPUNIT_ASSERT(false);
+            break;
         }
-        offset += span;
     }
-    CPPUNIT_ASSERT_EQUAL(pixmap.size(), output.size());
-    CPPUNIT_ASSERT_EQUAL(output.size(), offset);
+    CPPUNIT_ASSERT_EQUAL(delta.size(), i);
     return output;
 }
 
 void DeltaTests::assertEqual(const std::vector<char> &a,
-                             const std::vector<char> &b)
+                             const std::vector<char> &b,
+                             int width, int /* height */)
 {
     CPPUNIT_ASSERT_EQUAL(a.size(), b.size());
     for (size_t i = 0; i < a.size(); ++i)
     {
         if (a[i] != b[i])
         {
-            std::cout << "Differences starting at byte " << i;
+            std::cout << "Differences starting at byte " << i << " "
+                      << (i/4 % width) << ", " << (i / (width * 4)) << ":\n";
             size_t len;
-            for (len = 0; a[i+len] != b[i+len] && i + len < a.size(); ++len)
+            for (len = 0; (a[i+len] != b[i+len] || len < 8) && i + len < a.size(); ++len)
             {
-                std::cout << std::hex << (int)((unsigned char)a[i+len]) << " ";
+                std::cout << std::hex << (int)((unsigned char)a[i+len]) << " != ";
+                std::cout << std::hex << (int)((unsigned char)b[i+len]) << "  ";
                 if (len > 0 && (len % 16 == 0))
                     std::cout<< "\n";
             }
@@ -157,7 +181,7 @@ void DeltaTests::testDeltaSequence()
 
     // Apply it to move to the second frame
     std::vector<char> reText2 = applyDelta(text, width, height, delta);
-    assertEqual(reText2, text2);
+    assertEqual(reText2, text2, width, height);
 
     // Build a delta between text & text2Wid
     std::vector<char> two2one;
@@ -169,7 +193,7 @@ void DeltaTests::testDeltaSequence()
 
     // Apply it to get back to where we started
     std::vector<char> reText = applyDelta(text2, width, height, two2one);
-    assertEqual(reText, text);
+    assertEqual(reText, text, width, height);
 }
 
 void DeltaTests::testRandomDeltas()
commit 42d264eeb00fc14bb89104c7dc8b3bcd53897e30
Author: Michael Meeks <michael.meeks at collabora.com>
Date:   Sat Sep 16 17:32:20 2017 +0100

    Start of Delta unit-tests.
    
    Change-Id: I1a25f5347c0d7430000146bb585a041d363bcf37

diff --git a/kit/Delta.hpp b/kit/Delta.hpp
index b2b6a13e..95f6a1f1 100644
--- a/kit/Delta.hpp
+++ b/kit/Delta.hpp
@@ -10,8 +10,10 @@
 #define INCLUDED_DELTA_HPP
 
 #include <vector>
+#include <assert.h>
+#include <Log.hpp>
 
-#ifdef TILE_WIRE_ID
+#ifndef TILE_WIRE_ID
 #  define TILE_WIRE_ID
    typedef uint32_t TileWireId;
 #endif
@@ -125,7 +127,7 @@ class DeltaGenerator {
     DeltaGenerator() {}
 
     /**
-     * Creates a delta if possible:
+     * Creates a delta between @oldWid and pixmap if possible:
      *   if so - returns @true and appends the delta to @output
      * stores @pixmap, and other data to accelerate delta
      * creation in a limited size cache.
diff --git a/test/DeltaTests.cpp b/test/DeltaTests.cpp
new file mode 100644
index 00000000..3532931e
--- /dev/null
+++ b/test/DeltaTests.cpp
@@ -0,0 +1,181 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include "config.h"
+
+#include <cppunit/extensions/HelperMacros.h>
+
+#include "Delta.hpp"
+#include "Util.hpp"
+#include "Png.hpp"
+#include "helpers.hpp"
+
+/// Delta unit-tests.
+class DeltaTests : public CPPUNIT_NS::TestFixture
+{
+    CPPUNIT_TEST_SUITE(DeltaTests);
+
+    CPPUNIT_TEST(testDeltaSequence);
+    CPPUNIT_TEST(testRandomDeltas);
+
+    CPPUNIT_TEST_SUITE_END();
+
+    void testDeltaSequence();
+    void testRandomDeltas();
+
+    std::vector<char> loadPng(const char *relpath,
+                              png_uint_32& height,
+                              png_uint_32& width,
+                              png_uint_32& rowBytes)
+    {
+        std::ifstream file(relpath);
+        std::stringstream buffer;
+        buffer << file.rdbuf();
+        file.close();
+        std::vector<png_bytep> rows =
+            Png::decodePNG(buffer, height, width, rowBytes);
+        std::vector<char> output;
+        for (png_uint_32 y = 0; y < height; ++y)
+        {
+            for (png_uint_32 i = 0; i < width * 4; ++i)
+            {
+                output.push_back(rows[y][i]);
+            }
+        }
+        return output;
+    }
+
+    std::vector<char> applyDelta(
+        const std::vector<char> &pixmap,
+        png_uint_32 width, png_uint_32 height,
+        const std::vector<char> &delta);
+
+    void assertEqual(const std::vector<char> &a,
+                     const std::vector<char> &b);
+};
+
+// Quick hack for debugging
+std::vector<char> DeltaTests::applyDelta(
+    const std::vector<char> &pixmap,
+    png_uint_32 /* width */, png_uint_32 /* height */,
+    const std::vector<char> &delta)
+{
+    CPPUNIT_ASSERT(delta.size() >= 4);
+    CPPUNIT_ASSERT(delta[0] == 'D');
+
+//    std::cout << "apply delta of size " << delta.size() << "\n";
+
+    std::vector<char> output = pixmap;
+    CPPUNIT_ASSERT_EQUAL(output.size(), pixmap.size());
+    size_t offset = 0;
+    for (size_t i = 1; i < delta.size() &&
+             offset < output.size();)
+    {
+        bool isChangedRun = delta[i++] & 64;
+        CPPUNIT_ASSERT(i < delta.size());
+        uint32_t span = (unsigned char)delta[i++];
+        CPPUNIT_ASSERT(i < delta.size());
+        span += ((unsigned char)delta[i++])*256;
+        CPPUNIT_ASSERT(i < delta.size() ||
+                       (i == delta.size() && !isChangedRun));
+        span *= 4;
+//        std::cout << "span " << span << " offset " << offset << "\n";
+        if (isChangedRun)
+        {
+            CPPUNIT_ASSERT(offset + span <= output.size());
+            memcpy(&output[offset], &delta[i], span);
+            i += span;
+        }
+        offset += span;
+    }
+    CPPUNIT_ASSERT_EQUAL(pixmap.size(), output.size());
+    CPPUNIT_ASSERT_EQUAL(output.size(), offset);
+    return output;
+}
+
+void DeltaTests::assertEqual(const std::vector<char> &a,
+                             const std::vector<char> &b)
+{
+    CPPUNIT_ASSERT_EQUAL(a.size(), b.size());
+    for (size_t i = 0; i < a.size(); ++i)
+    {
+        if (a[i] != b[i])
+        {
+            std::cout << "Differences starting at byte " << i;
+            size_t len;
+            for (len = 0; a[i+len] != b[i+len] && i + len < a.size(); ++len)
+            {
+                std::cout << std::hex << (int)((unsigned char)a[i+len]) << " ";
+                if (len > 0 && (len % 16 == 0))
+                    std::cout<< "\n";
+            }
+            std::cout << " size " << len << "\n";
+            CPPUNIT_ASSERT(false);
+        }
+    }
+}
+
+void DeltaTests::testDeltaSequence()
+{
+    DeltaGenerator gen;
+
+    png_uint_32 height, width, rowBytes;
+    const TileWireId textWid = 1;
+    std::vector<char> text =
+        DeltaTests::loadPng("data/delta-text.png",
+                            height, width, rowBytes);
+    CPPUNIT_ASSERT(height == 256 && width == 256 && rowBytes == 256*4);
+    CPPUNIT_ASSERT_EQUAL(size_t(256 * 256 * 4), text.size());
+
+    const TileWireId text2Wid = 2;
+    std::vector<char> text2 =
+        DeltaTests::loadPng("data/delta-text2.png",
+                            height, width, rowBytes);
+    CPPUNIT_ASSERT(height == 256 && width == 256 && rowBytes == 256*4);
+    CPPUNIT_ASSERT_EQUAL(size_t(256 * 256 * 4), text2.size());
+
+    std::vector<char> delta;
+    // Stash it in the cache
+    CPPUNIT_ASSERT(gen.createDelta(
+                       reinterpret_cast<unsigned char *>(&text[0]),
+                       0, 0, width, height, width, height,
+                       delta, textWid, 0) == false);
+    CPPUNIT_ASSERT(delta.size() == 0);
+
+    // Build a delta between text2 & textWid
+    CPPUNIT_ASSERT(gen.createDelta(
+                       reinterpret_cast<unsigned char *>(&text2[0]),
+                       0, 0, width, height, width, height,
+                       delta, text2Wid, textWid) == true);
+    CPPUNIT_ASSERT(delta.size() > 0);
+
+    // Apply it to move to the second frame
+    std::vector<char> reText2 = applyDelta(text, width, height, delta);
+    assertEqual(reText2, text2);
+
+    // Build a delta between text & text2Wid
+    std::vector<char> two2one;
+    CPPUNIT_ASSERT(gen.createDelta(
+                       reinterpret_cast<unsigned char *>(&text[0]),
+                       0, 0, width, height, width, height,
+                       two2one, textWid, text2Wid) == true);
+    CPPUNIT_ASSERT(two2one.size() > 0);
+
+    // Apply it to get back to where we started
+    std::vector<char> reText = applyDelta(text2, width, height, two2one);
+    assertEqual(reText, text);
+}
+
+void DeltaTests::testRandomDeltas()
+{
+}
+
+CPPUNIT_TEST_SUITE_REGISTRATION(DeltaTests);
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/test/Makefile.am b/test/Makefile.am
index aa54e0cb..98426f72 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -47,6 +47,7 @@ wsd_sources = \
 test_base_source = \
 	TileQueueTests.cpp \
 	WhiteBoxTests.cpp \
+	DeltaTests.cpp \
 	$(wsd_sources)
 
 test_all_source = \
diff --git a/test/data/delta-text.png b/test/data/delta-text.png
new file mode 100644
index 00000000..3d48d9bf
Binary files /dev/null and b/test/data/delta-text.png differ
diff --git a/test/data/delta-text2.png b/test/data/delta-text2.png
new file mode 100644
index 00000000..d05b897c
Binary files /dev/null and b/test/data/delta-text2.png differ
commit 78398d4482a5a39c87d7c0ec88fc9d357f73408c
Author: Michael Meeks <michael.meeks at collabora.com>
Date:   Sat Sep 16 17:27:31 2017 +0100

    Move the Delta generator out into its own file.
    
    Change-Id: I7f7553c292970b1a52879b6d6c14e67172022310

diff --git a/kit/Delta.hpp b/kit/Delta.hpp
new file mode 100644
index 00000000..b2b6a13e
--- /dev/null
+++ b/kit/Delta.hpp
@@ -0,0 +1,162 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+#ifndef INCLUDED_DELTA_HPP
+#define INCLUDED_DELTA_HPP
+
+#include <vector>
+
+#ifdef TILE_WIRE_ID
+#  define TILE_WIRE_ID
+   typedef uint32_t TileWireId;
+#endif
+
+/// A quick and dirty delta generator for last tile changes
+class DeltaGenerator {
+
+    struct DeltaData {
+        TileWireId _wid;
+        std::shared_ptr<std::vector<uint32_t>> _rawData;
+    };
+    std::vector<DeltaData> _deltaEntries;
+
+    bool makeDelta(
+        const DeltaData &prevData,
+        const DeltaData &curData,
+        std::vector<char>& output)
+    {
+        std::vector<uint32_t> &prev = *prevData._rawData.get();
+        std::vector<uint32_t> &cur = *curData._rawData.get();
+
+        // FIXME: should we split and compress alpha separately ?
+
+        if (prev.size() != cur.size())
+        {
+            LOG_ERR("mis-sized delta: " << prev.size() << " vs " << cur.size() << "bytes");
+            return false;
+        }
+
+        output.push_back('D');
+        LOG_TRC("building delta of " << prev.size() << "bytes");
+        // FIXME: really lame - some RLE might help etc.
+        for (size_t i = 0; i < prev.size();)
+        {
+            int sameCount = 0;
+            while (i + sameCount < prev.size() &&
+                   prev[i+sameCount] == cur[i+sameCount])
+            {
+                ++sameCount;
+            }
+            if (sameCount > 0)
+            {
+#if 0
+                if (sameCount < 64)
+                    output.push_back(sameCount);
+                else
+#endif
+                {
+                    output.push_back(0x80 | 0x00); // long-same
+                    output.push_back(sameCount & 0xff);
+                    output.push_back(sameCount >> 8);
+                }
+                i += sameCount;
+                LOG_TRC("identical " << sameCount << "pixels");
+            }
+
+            int diffCount = 0;
+            while (i + diffCount < prev.size() &&
+                   (prev[i+diffCount] != cur[i+diffCount]))
+            {
+                ++diffCount;
+            }
+
+            if (diffCount > 0)
+            {
+#if 0
+                if (diffCount < 64)
+                    output.push_back(0x40 & diffCount);
+                else
+#endif
+                {
+                    output.push_back(0x80 | 0x40); // long-diff
+                    output.push_back(diffCount & 0xff);
+                    output.push_back(diffCount >> 8);
+                }
+
+                size_t dest = output.size();
+                output.resize(dest + diffCount * 4);
+                memcpy(&output[dest], &cur[i], diffCount * 4);
+                LOG_TRC("different " << diffCount << "pixels");
+                i += diffCount;
+            }
+        }
+        return true;
+    }
+
+    std::shared_ptr<std::vector<uint32_t>> dataToVector(
+        unsigned char* pixmap, size_t startX, size_t startY,
+        int width, int height,
+        int bufferWidth, int bufferHeight)
+    {
+        assert (startX + width <= (size_t)bufferWidth);
+        assert (startY + height <= (size_t)bufferHeight);
+
+        auto vector = std::make_shared<std::vector<uint32_t>>();
+        LOG_TRC("Converting data to vector of size "
+                << (width * height * 4) << " width " << width
+                << " height " << height);
+
+        vector->resize(width * height);
+        for (int y = 0; y < height; ++y)
+        {
+            size_t position = ((startY + y) * bufferWidth * 4) + (startX * 4);
+            memcpy(&(*vector)[y * width], pixmap + position, width * 4);
+        }
+
+        return vector;
+    }
+
+  public:
+    DeltaGenerator() {}
+
+    /**
+     * Creates a delta if possible:
+     *   if so - returns @true and appends the delta to @output
+     * stores @pixmap, and other data to accelerate delta
+     * creation in a limited size cache.
+     */
+    bool createDelta(
+        unsigned char* pixmap, size_t startX, size_t startY,
+        int width, int height,
+        int bufferWidth, int bufferHeight,
+        std::vector<char>& output,
+        TileWireId wid, TileWireId oldWid)
+    {
+        // First store a copy for later:
+        if (_deltaEntries.size() > 6) // FIXME: hard-coded ...
+            _deltaEntries.erase(_deltaEntries.begin());
+
+        // FIXME: assuming width etc. are all constant & so on.
+        DeltaData update;
+        update._wid = wid;
+        update._rawData = dataToVector(pixmap, startX, startY, width, height,
+                                       bufferWidth, bufferHeight);
+        _deltaEntries.push_back(update);
+
+        for (auto &old : _deltaEntries)
+        {
+            if (oldWid == old._wid)
+                return makeDelta(old, update, output);
+        }
+        return false;
+    }
+};
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/kit/Kit.cpp b/kit/Kit.cpp
index dfdf276e..df2d6ce5 100644
--- a/kit/Kit.cpp
+++ b/kit/Kit.cpp
@@ -66,6 +66,7 @@
 #include "Unit.hpp"
 #include "UserMessages.hpp"
 #include "Util.hpp"
+#include "Delta.hpp"
 
 #include "common/SigUtil.hpp"
 #include "common/Seccomp.hpp"
@@ -285,141 +286,6 @@ namespace
 #endif
 }
 
-/// A quick and dirty delta generator for last tile changes
-struct DeltaGenerator {
-
-    struct DeltaData {
-        TileWireId _wid;
-        std::shared_ptr<std::vector<uint32_t>> _rawData;
-    };
-    std::vector<DeltaData> _deltaEntries;
-
-    bool makeDelta(
-        const DeltaData &prevData,
-        const DeltaData &curData,
-        std::vector<char>& output)
-    {
-        std::vector<uint32_t> &prev = *prevData._rawData.get();
-        std::vector<uint32_t> &cur = *curData._rawData.get();
-
-        // FIXME: should we split and compress alpha separately ?
-
-        if (prev.size() != cur.size())
-        {
-            LOG_ERR("mis-sized delta: " << prev.size() << " vs " << cur.size() << "bytes");
-            return false;
-        }
-
-        output.push_back('D');
-        LOG_TRC("building delta of " << prev.size() << "bytes");
-        // FIXME: really lame - some RLE might help etc.
-        for (size_t i = 0; i < prev.size();)
-        {
-            int sameCount = 0;
-            while (i + sameCount < prev.size() &&
-                   prev[i+sameCount] == cur[i+sameCount])
-            {
-                ++sameCount;
-            }
-            if (sameCount > 0)
-            {
-#if 0
-                if (sameCount < 64)
-                    output.push_back(sameCount);
-                else
-#endif
-                {
-                    output.push_back(0x80 | 0x00); // long-same
-                    output.push_back(sameCount & 0xff);
-                    output.push_back(sameCount >> 8);
-                }
-                i += sameCount;
-                LOG_TRC("identical " << sameCount << "pixels");
-            }
-
-            int diffCount = 0;
-            while (i + diffCount < prev.size() &&
-                   (prev[i+diffCount] != cur[i+diffCount]))
-            {
-                ++diffCount;
-            }
-
-            if (diffCount > 0)
-            {
-#if 0
-                if (diffCount < 64)
-                    output.push_back(0x40 & diffCount);
-                else
-#endif
-                {
-                    output.push_back(0x80 | 0x40); // long-diff
-                    output.push_back(diffCount & 0xff);
-                    output.push_back(diffCount >> 8);
-                }
-
-                size_t dest = output.size();
-                output.resize(dest + diffCount * 4);
-                memcpy(&output[dest], &cur[i], diffCount * 4);
-                LOG_TRC("different " << diffCount << "pixels");
-                i += diffCount;
-            }
-        }
-        return true;
-    }
-
-    std::shared_ptr<std::vector<uint32_t>> dataToVector(
-        unsigned char* pixmap, size_t startX, size_t startY,
-        int width, int height,
-        int bufferWidth, int bufferHeight)
-    {
-        assert (startX + width <= (size_t)bufferWidth);
-        assert (startY + height <= (size_t)bufferHeight);
-
-        auto vector = std::make_shared<std::vector<uint32_t>>();
-        LOG_TRC("Converting data to vector of size "
-                << (width * height * 4) << " width " << width
-                << " height " << height);
-
-        vector->resize(width * height);
-        for (int y = 0; y < height; ++y)
-        {
-            size_t position = ((startY + y) * bufferWidth * 4) + (startX * 4);
-            memcpy(&(*vector)[y * width], pixmap + position, width * 4);
-        }
-
-        return vector;
-    }
-
-    // Creates a bespoke delta file-format ...
-    bool createDelta(
-        unsigned char* pixmap, size_t startX, size_t startY,
-        int width, int height,
-        int bufferWidth, int bufferHeight,
-        std::vector<char>& output,
-        TileWireId wid, TileWireId oldWid)
-    {
-        // First store a copy for later:
-        if (_deltaEntries.size() > 6) // FIXME: hard-coded ...
-            _deltaEntries.erase(_deltaEntries.begin());
-
-        // FIXME: assuming width etc. are all constant & so on.
-        DeltaData update;
-        update._wid = wid;
-        update._rawData = dataToVector(pixmap, startX, startY, width, height,
-                                       bufferWidth, bufferHeight);
-        _deltaEntries.push_back(update);
-
-        for (auto &old : _deltaEntries)
-        {
-            if (oldWid == old._wid)
-                return makeDelta(old, update, output);
-        }
-        return false;
-    }
-};
-
-
-
 /// A quick & dirty cache of the last few PNGs
 /// and their hashes to avoid re-compression
 /// wherever possible.
diff --git a/wsd/TileDesc.hpp b/wsd/TileDesc.hpp
index a4c61636..7e738f64 100644
--- a/wsd/TileDesc.hpp
+++ b/wsd/TileDesc.hpp
@@ -20,6 +20,7 @@
 #include "Exceptions.hpp"
 #include "Protocol.hpp"
 
+#define TILE_WIRE_ID
 typedef uint32_t TileWireId;
 typedef uint64_t TileBinaryHash;
 
commit ed8807a1a5a613f54dfc5a204294e870969254e2
Author: Michael Meeks <michael.meeks at collabora.com>
Date:   Tue Sep 12 09:32:30 2017 +0100

    Insert pixels from 'new' not 'old'.
    
    Change-Id: I117348885073b740ed8b2df84d805854b2f00767

diff --git a/kit/Kit.cpp b/kit/Kit.cpp
index 5f9c9106..dfdf276e 100644
--- a/kit/Kit.cpp
+++ b/kit/Kit.cpp
@@ -357,7 +357,9 @@ struct DeltaGenerator {
                     output.push_back(diffCount >> 8);
                 }
 
-                output.insert(output.end(), (char *)&cur[i], (char *)&cur[i+diffCount]);
+                size_t dest = output.size();
+                output.resize(dest + diffCount * 4);
+                memcpy(&output[dest], &cur[i], diffCount * 4);
                 LOG_TRC("different " << diffCount << "pixels");
                 i += diffCount;
             }
@@ -401,16 +403,16 @@ struct DeltaGenerator {
             _deltaEntries.erase(_deltaEntries.begin());
 
         // FIXME: assuming width etc. are all constant & so on.
-        DeltaData reference;
-        reference._wid = wid;
-        reference._rawData = dataToVector(pixmap, startX, startY, width, height,
-                                          bufferWidth, bufferHeight);
-        _deltaEntries.push_back(reference);
+        DeltaData update;
+        update._wid = wid;
+        update._rawData = dataToVector(pixmap, startX, startY, width, height,
+                                       bufferWidth, bufferHeight);
+        _deltaEntries.push_back(update);
 
-        for (auto &it : _deltaEntries)
+        for (auto &old : _deltaEntries)
         {
-            if (oldWid == it._wid)
-                return makeDelta(reference, it, output);
+            if (oldWid == old._wid)
+                return makeDelta(old, update, output);
         }
         return false;
     }
commit b1124c05a89007bd00f29be3e1a42d7817458048
Author: Michael Meeks <michael.meeks at collabora.com>
Date:   Wed Aug 23 17:01:18 2017 +0100

    Deltas should be pixel based, add debugging.
    
    Change-Id: I3b47b738ee71d015911e3d77b59b5f3cb34ecd75

diff --git a/kit/Kit.cpp b/kit/Kit.cpp
index 67e7ac8e..5f9c9106 100644
--- a/kit/Kit.cpp
+++ b/kit/Kit.cpp
@@ -290,7 +290,7 @@ struct DeltaGenerator {
 
     struct DeltaData {
         TileWireId _wid;
-        std::shared_ptr<std::vector<char>> _rawData;
+        std::shared_ptr<std::vector<uint32_t>> _rawData;
     };
     std::vector<DeltaData> _deltaEntries;
 
@@ -299,8 +299,10 @@ struct DeltaGenerator {
         const DeltaData &curData,
         std::vector<char>& output)
     {
-        std::vector<char> &prev = *prevData._rawData.get();
-        std::vector<char> &cur = *curData._rawData.get();
+        std::vector<uint32_t> &prev = *prevData._rawData.get();
+        std::vector<uint32_t> &cur = *curData._rawData.get();
+
+        // FIXME: should we split and compress alpha separately ?
 
         if (prev.size() != cur.size())
         {
@@ -311,43 +313,59 @@ struct DeltaGenerator {
         output.push_back('D');
         LOG_TRC("building delta of " << prev.size() << "bytes");
         // FIXME: really lame - some RLE might help etc.
-        for (size_t i = 0; i < prev.size(); ++i)
+        for (size_t i = 0; i < prev.size();)
         {
             int sameCount = 0;
             while (i + sameCount < prev.size() &&
                    prev[i+sameCount] == cur[i+sameCount])
             {
-                if (sameCount >= 127)
-                    break;
                 ++sameCount;
             }
             if (sameCount > 0)
-                output.push_back(sameCount);
-            i += sameCount;
-            LOG_TRC("identical " << sameCount << "bytes");
+            {
+#if 0
+                if (sameCount < 64)
+                    output.push_back(sameCount);
+                else
+#endif
+                {
+                    output.push_back(0x80 | 0x00); // long-same
+                    output.push_back(sameCount & 0xff);
+                    output.push_back(sameCount >> 8);
+                }
+                i += sameCount;
+                LOG_TRC("identical " << sameCount << "pixels");
+            }
 
             int diffCount = 0;
             while (i + diffCount < prev.size() &&
-                   (prev[i+diffCount] != cur[i+diffCount] || diffCount < 3))
+                   (prev[i+diffCount] != cur[i+diffCount]))
             {
-                if (diffCount >= 127)
-                    break;
                 ++diffCount;
             }
 
             if (diffCount > 0)
             {
-                output.push_back(diffCount | 0x80);
-                for (int j = 0; j < diffCount; ++j)
-                    output.push_back(cur[i+j]);
+#if 0
+                if (diffCount < 64)
+                    output.push_back(0x40 & diffCount);
+                else
+#endif
+                {
+                    output.push_back(0x80 | 0x40); // long-diff
+                    output.push_back(diffCount & 0xff);
+                    output.push_back(diffCount >> 8);
+                }
+
+                output.insert(output.end(), (char *)&cur[i], (char *)&cur[i+diffCount]);
+                LOG_TRC("different " << diffCount << "pixels");
+                i += diffCount;
             }
-            LOG_TRC("different " << diffCount << "bytes");
-            i += diffCount;
         }
         return true;
     }
 
-    std::shared_ptr<std::vector<char>> dataToVector(
+    std::shared_ptr<std::vector<uint32_t>> dataToVector(
         unsigned char* pixmap, size_t startX, size_t startY,
         int width, int height,
         int bufferWidth, int bufferHeight)
@@ -355,16 +373,16 @@ struct DeltaGenerator {
         assert (startX + width <= (size_t)bufferWidth);
         assert (startY + height <= (size_t)bufferHeight);
 
-        auto vector = std::make_shared<std::vector<char>>();
+        auto vector = std::make_shared<std::vector<uint32_t>>();
         LOG_TRC("Converting data to vector of size "
                 << (width * height * 4) << " width " << width
                 << " height " << height);
 
-        vector->resize(width * height * 4);
+        vector->resize(width * height);
         for (int y = 0; y < height; ++y)
         {
             size_t position = ((startY + y) * bufferWidth * 4) + (startX * 4);
-            memcpy(&(*vector)[y * width * 4], pixmap + position, width * 4);
+            memcpy(&(*vector)[y * width], pixmap + position, width * 4);
         }
 
         return vector;
diff --git a/loleaflet/src/layer/tile/TileLayer.js b/loleaflet/src/layer/tile/TileLayer.js
index daca0b96..6d1077cb 100644
--- a/loleaflet/src/layer/tile/TileLayer.js
+++ b/loleaflet/src/layer/tile/TileLayer.js
@@ -13,6 +13,18 @@ if (typeof String.prototype.startsWith !== 'function') {
 	};
 }
 
+function hex2string(inData)
+{
+	hexified = [];
+	data = new Uint8Array(inData);
+	for (var i = 0; i < data.length; i++) {
+		hex = data[i].toString(16);
+		paddedHex = ('00' + hex).slice(-2);
+		hexified.push(paddedHex);
+	}
+	return hexified.join('');
+}
+
 L.Compatibility = {
 	clipboardGet: function (event) {
 		var text = null;
@@ -1283,7 +1295,6 @@ L.TileLayer = L.GridLayer.extend({
 		}
 		else if (tile && typeof(img) == 'object') {
 			// 'Uint8Array' delta
-			console.log('hit here with a delta');
 			var canvas = document.createElement('canvas');
 			canvas.width = 256;
 			canvas.height = 256;
@@ -1298,19 +1309,48 @@ L.TileLayer = L.GridLayer.extend({
 			var delta = img;
 			var pixSize = canvas.width * canvas.height * 4;
 			var offset = 0;
+
+			console.log('Applying a delta of length ' + delta.length + ' pix size: ' + pixSize + '\nhex: ' + hex2string(delta));
+
+			// wipe to grey.
+//			for (var i = 0; i < pixSize * 4; ++i)
+//			{
+//				imgData.data[i] = 128;
+//			}
+
+			// Apply delta.
 			for (var i = 1; i < delta.length &&
-			     offset < pixSize; ++i)
+			     offset < pixSize;)
 			{
-				var span = delta[i] & 127;
-				if (delta[i] & 128) { // changed run.
+//				var span = delta[i];
+//				var isChangedRun = span & 64;
+//				if (span >= 128)
+//				{
+				// first char is a control code.
+				var isChangedRun = delta[i++] & 64;
+				span = delta[i++];
+				span += delta[i++] * 256;
+//				}
+				if (isChangedRun) {
 					console.log('apply new span of size ' + span + ' at offset ' + i + ' into delta at byte: ' + offset);
+					span *= 4;
 					while (span-- > 0) {
-						imgData.data[offset++] = delta[++i];
+						imgData.data[offset++] = delta[i++];
 					}
+					imgData.data[offset - 2] = 256; // debug - blue terminator
 				} else {
-					offset += span;
+					console.log('apply unchanged span of size ' + span + ' at offset ' + i + ' into delta at byte: ' + offset);
+					offset += span * 4;
+					imgData.data[offset - 3] = 256; // debug - green terminator
 				}
 			}
+
+			while (offset < pixSize) // debug
+			{
+				imgData.data[offset] = 256; // redden the remaining section.
+				imgData.data[offset+3] = 256; // with some alpha
+				offset += 4;
+			}
 			ctx.putImageData(imgData, 0, 0);
 
 			tile.oldWireId = tile.wireId;
commit 0bfbbf98510f82eb9a8ff3dc44254bd848458d53
Author: Michael Meeks <michael.meeks at collabora.com>
Date:   Fri Jun 30 17:22:12 2017 +0100

    Start of delta creator.
    
    Change-Id: Idf186cda4f11e2418d9ff9f435825832c6b10294

diff --git a/kit/Kit.cpp b/kit/Kit.cpp
index 1a7d87c1..67e7ac8e 100644
--- a/kit/Kit.cpp
+++ b/kit/Kit.cpp
@@ -285,6 +285,121 @@ namespace
 #endif
 }
 
+/// A quick and dirty delta generator for last tile changes
+struct DeltaGenerator {
+
+    struct DeltaData {
+        TileWireId _wid;
+        std::shared_ptr<std::vector<char>> _rawData;
+    };
+    std::vector<DeltaData> _deltaEntries;
+
+    bool makeDelta(
+        const DeltaData &prevData,
+        const DeltaData &curData,
+        std::vector<char>& output)
+    {
+        std::vector<char> &prev = *prevData._rawData.get();
+        std::vector<char> &cur = *curData._rawData.get();
+
+        if (prev.size() != cur.size())
+        {
+            LOG_ERR("mis-sized delta: " << prev.size() << " vs " << cur.size() << "bytes");
+            return false;
+        }
+
+        output.push_back('D');
+        LOG_TRC("building delta of " << prev.size() << "bytes");
+        // FIXME: really lame - some RLE might help etc.
+        for (size_t i = 0; i < prev.size(); ++i)
+        {
+            int sameCount = 0;
+            while (i + sameCount < prev.size() &&
+                   prev[i+sameCount] == cur[i+sameCount])
+            {
+                if (sameCount >= 127)
+                    break;
+                ++sameCount;
+            }
+            if (sameCount > 0)
+                output.push_back(sameCount);
+            i += sameCount;
+            LOG_TRC("identical " << sameCount << "bytes");
+
+            int diffCount = 0;
+            while (i + diffCount < prev.size() &&
+                   (prev[i+diffCount] != cur[i+diffCount] || diffCount < 3))
+            {
+                if (diffCount >= 127)
+                    break;
+                ++diffCount;
+            }
+
+            if (diffCount > 0)
+            {
+                output.push_back(diffCount | 0x80);
+                for (int j = 0; j < diffCount; ++j)
+                    output.push_back(cur[i+j]);
+            }
+            LOG_TRC("different " << diffCount << "bytes");
+            i += diffCount;
+        }
+        return true;
+    }
+
+    std::shared_ptr<std::vector<char>> dataToVector(
+        unsigned char* pixmap, size_t startX, size_t startY,
+        int width, int height,
+        int bufferWidth, int bufferHeight)
+    {
+        assert (startX + width <= (size_t)bufferWidth);
+        assert (startY + height <= (size_t)bufferHeight);
+
+        auto vector = std::make_shared<std::vector<char>>();
+        LOG_TRC("Converting data to vector of size "
+                << (width * height * 4) << " width " << width
+                << " height " << height);
+
+        vector->resize(width * height * 4);
+        for (int y = 0; y < height; ++y)
+        {
+            size_t position = ((startY + y) * bufferWidth * 4) + (startX * 4);
+            memcpy(&(*vector)[y * width * 4], pixmap + position, width * 4);
+        }
+
+        return vector;
+    }
+
+    // Creates a bespoke delta file-format ...
+    bool createDelta(
+        unsigned char* pixmap, size_t startX, size_t startY,
+        int width, int height,
+        int bufferWidth, int bufferHeight,
+        std::vector<char>& output,
+        TileWireId wid, TileWireId oldWid)
+    {
+        // First store a copy for later:
+        if (_deltaEntries.size() > 6) // FIXME: hard-coded ...
+            _deltaEntries.erase(_deltaEntries.begin());
+
+        // FIXME: assuming width etc. are all constant & so on.
+        DeltaData reference;
+        reference._wid = wid;
+        reference._rawData = dataToVector(pixmap, startX, startY, width, height,
+                                          bufferWidth, bufferHeight);
+        _deltaEntries.push_back(reference);
+
+        for (auto &it : _deltaEntries)
+        {
+            if (oldWid == it._wid)
+                return makeDelta(reference, it, output);
+        }
+        return false;
+    }
+};
+
+
+
 /// A quick & dirty cache of the last few PNGs
 /// and their hashes to avoid re-compression
 /// wherever possible.
@@ -310,6 +425,7 @@ class PngCache
     size_t _cacheHits;
     size_t _cacheTests;
     TileWireId _nextId;
+    DeltaGenerator _deltaGen;
 
     std::map< TileBinaryHash, CacheEntry > _cache;
     std::map< TileWireId, TileBinaryHash > _wireToHash;
@@ -406,9 +522,15 @@ class PngCache
                                    int width, int height,
                                    int bufferWidth, int bufferHeight,
                                    std::vector<char>& output, LibreOfficeKitTileMode mode,
-                                   TileBinaryHash hash, TileWireId wid, TileWireId /* oldWid */)
+                                   TileBinaryHash hash, TileWireId wid, TileWireId oldWid)
     {
         LOG_DBG("PNG cache with hash " << hash << " missed.");
+        if (_deltaGen.createDelta(pixmap, startX, startY, width, height,
+                                  bufferWidth, bufferHeight,
+                                  output, wid, oldWid))
+            return true;
+
+        LOG_DBG("Encode a new png for this tile.");
         CacheEntry newEntry(bufferWidth * bufferHeight * 1, wid);
         if (Png::encodeSubBufferToPNG(pixmap, startX, startY, width, height,
                                       bufferWidth, bufferHeight,
diff --git a/loleaflet/src/core/Socket.js b/loleaflet/src/core/Socket.js
index 5adf34b8..36c75624 100644
--- a/loleaflet/src/core/Socket.js
+++ b/loleaflet/src/core/Socket.js
@@ -611,6 +611,7 @@ L.Socket = L.Class.extend({
 		else if (!textMsg.startsWith('tile:') && !textMsg.startsWith('renderfont:') && !textMsg.startsWith('dialogpaint:') && !textMsg.startsWith('dialogchildpaint:')) {
 			// log the tile msg separately as we need the tile coordinates
 			L.Log.log(textMsg, L.INCOMING);
+
 			if (imgBytes !== undefined) {
 				try {
 					// if it's not a tile, parse the whole message
@@ -628,12 +629,21 @@ L.Socket = L.Class.extend({
 		}
 		else {
 			var data = imgBytes.subarray(index + 1);
-			// read the tile data
-			var strBytes = '';
-			for (var i = 0; i < data.length; i++) {
-				strBytes += String.fromCharCode(data[i]);
+
+			if (data.length > 0 && data[0] == 68 /* D */)
+			{
+				console.log('Socket: got a delta !');
+				var img = data;
+			}
+			else
+			{
+				// read the tile data
+				var strBytes = '';
+				for (var i = 0; i < data.length; i++) {
+					strBytes += String.fromCharCode(data[i]);
+				}
+				var img = 'data:image/png;base64,' + window.btoa(strBytes);
 			}
-			var img = 'data:image/png;base64,' + window.btoa(strBytes);
 		}
 
 		if (textMsg.startsWith('status:')) {
diff --git a/loleaflet/src/layer/tile/TileLayer.js b/loleaflet/src/layer/tile/TileLayer.js
index 7ee9c90c..daca0b96 100644
--- a/loleaflet/src/layer/tile/TileLayer.js
+++ b/loleaflet/src/layer/tile/TileLayer.js
@@ -1281,6 +1281,44 @@ L.TileLayer = L.GridLayer.extend({
 				docType: this._docType
 			});
 		}
+		else if (tile && typeof(img) == 'object') {
+			// 'Uint8Array' delta
+			console.log('hit here with a delta');
+			var canvas = document.createElement('canvas');
+			canvas.width = 256;
+			canvas.height = 256;
+			var ctx = canvas.getContext('2d');
+
+			oldImg = new Image();
+			oldImg.src = tile.el.src;
+			ctx.drawImage(oldImg, 0, 0);
+
+			// FIXME; can we operate directly on the image ?
+			var imgData = ctx.getImageData(0, 0, canvas.width, canvas.height);
+			var delta = img;
+			var pixSize = canvas.width * canvas.height * 4;
+			var offset = 0;
+			for (var i = 1; i < delta.length &&
+			     offset < pixSize; ++i)
+			{
+				var span = delta[i] & 127;
+				if (delta[i] & 128) { // changed run.
+					console.log('apply new span of size ' + span + ' at offset ' + i + ' into delta at byte: ' + offset);
+					while (span-- > 0) {
+						imgData.data[offset++] = delta[++i];
+					}
+				} else {
+					offset += span;
+				}
+			}
+			ctx.putImageData(imgData, 0, 0);
+
+			tile.oldWireId = tile.wireId;
+			tile.wireId = command.wireId;
+			tile.el.src = canvas.toDataURL('image/png');
+
+			console.log('set new image');
+		}
 		else if (tile) {
 			if (command.wireId != undefined) {
 				tile.oldWireId = command.wireId;


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