[Libreoffice-commits] online.git: loolwsd/Png.hpp loolwsd/Util.cpp

[Caolán McNamara]

 loolwsd/Png.hpp  |   61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 loolwsd/Util.cpp |    2 +
 2 files changed, 63 insertions(+)

New commits:
commit 9803e2e448a8fc41b8f7ea1fdf5fcd20bdd4f350
Author: Caolán McNamara <caolanm at redhat.com>
Date:   Fri Nov 20 15:39:44 2015 +0000

    adapt to cairo data format
    
    Change-Id: I9b12ee4ab2ff8cd056ffbc907fb78c0bf3928e4c

diff --git a/loolwsd/Png.hpp b/loolwsd/Png.hpp
new file mode 100644
index 0000000..a2d27eb
--- /dev/null
+++ b/loolwsd/Png.hpp
@@ -0,0 +1,61 @@
+/* cairo - a vector graphics library with display and print output
+ *
+ * Copyright © 2003 University of Southern California
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it either under the terms of the GNU Lesser General Public
+ * License version 2.1 as published by the Free Software Foundation
+ * (the "LGPL") or, at your option, under the terms of the Mozilla
+ * Public License Version 1.1 (the "MPL"). If you do not alter this
+ * notice, a recipient may use your version of this file under either
+ * the MPL or the LGPL.
+ *
+ * You should have received a copy of the LGPL along with this library
+ * in the file COPYING-LGPL-2.1; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
+ * You should have received a copy of the MPL along with this library
+ * in the file COPYING-MPL-1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
+ * OF ANY KIND, either express or implied. See the LGPL or the MPL for
+ * the specific language governing rights and limitations.
+ *
+ * The Original Code is the cairo graphics library.
+ *
+ * The Initial Developer of the Original Code is University of Southern
+ * California.
+ *
+ * Contributor(s):
+ *        Carl D. Worth <cworth at cworth.org>
+ *        Kristian Høgsberg <krh at redhat.com>
+ *        Chris Wilson <chris at chris-wilson.co.uk>
+ */
+
+/* Unpremultiplies data and converts native endian ARGB => RGBA bytes */
+static void
+unpremultiply_data (png_structp /*png*/, png_row_infop row_info, png_bytep data)
+{
+    unsigned int i;
+
+    for (i = 0; i < row_info->rowbytes; i += 4) {
+        uint8_t *b = &data[i];
+        uint32_t pixel;
+        uint8_t  alpha;
+
+        memcpy (&pixel, b, sizeof (uint32_t));
+        alpha = (pixel & 0xff000000) >> 24;
+        if (alpha == 0) {
+            b[0] = b[1] = b[2] = b[3] = 0;
+        } else {
+            b[0] = (((pixel & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
+            b[1] = (((pixel & 0x00ff00) >>  8) * 255 + alpha / 2) / alpha;
+            b[2] = (((pixel & 0x0000ff) >>  0) * 255 + alpha / 2) / alpha;
+            b[3] = alpha;
+        }
+    }
+}
diff --git a/loolwsd/Util.cpp b/loolwsd/Util.cpp
index bf8be1f..1b42d86 100644
--- a/loolwsd/Util.cpp
+++ b/loolwsd/Util.cpp
@@ -26,6 +26,7 @@
 #include <Poco/Util/Application.h>
 
 #include "Util.hpp"
+#include "Png.hpp"
 
 // Callback functions for libpng
 
@@ -99,6 +100,7 @@ namespace Util
 
         png_write_info(png_ptr, info_ptr);
 
+        png_set_write_user_transform_fn (png_ptr, unpremultiply_data);
         for (int y = 0; y < height; ++y)
             png_write_row(png_ptr, pixmap + y * width * 4);