[PATCH evdev] Remove AUTO feature of middle mouse button emulation.

[Peter Hutterer]

The AUTO feature was the default, MB emulation was on until a middle mouse
button was pressed. MB emulation however results in a delay of the first
press, causing minor annoyances to the users.

Disable the feature by default unless the device has no middle button.
Note that the restrictions of the PS/2 protocol result in all mice having
the middle mouse button bit set, so it's not a particularly reliable
indicator whether the device needs the emulation.
There's not a lot of two-button mice around anymore though, so arguably we
should start caring about more important things.

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
 man/evdev.man |    5 ++---
 src/emuMB.c   |   56 ++++++++++++++++++++------------------------------------
 src/evdev.c   |    2 --
 src/evdev.h   |    2 +-
 4 files changed, 23 insertions(+), 42 deletions(-)

diff --git a/man/evdev.man b/man/evdev.man
index 49ab12c..bb8a83c 100644
--- a/man/evdev.man
+++ b/man/evdev.man
@@ -76,9 +76,8 @@ indicating that the next button pressed is to be
 .BI "Option \*qEmulate3Buttons\*q \*q" boolean \*q
 Enable/disable the emulation of the third (middle) mouse button for mice
 which only have two physical buttons.  The third button is emulated by
-pressing both buttons simultaneously.  Default: off for touchscreens, otherwise
-on until a middle mouse button event is registered. Property: "Evdev Middle
-Button Emulation".
+pressing both buttons simultaneously.  Default: off unless no middle
+button was detected. Property: "Evdev Middle Button Emulation".
 .TP 7
 .BI "Option \*qEmulate3Timeout\*q \*q" integer \*q
 Sets the timeout (in milliseconds) that the driver waits before deciding
diff --git a/src/emuMB.c b/src/emuMB.c
index c33ea8e..7528fbe 100644
--- a/src/emuMB.c
+++ b/src/emuMB.c
@@ -43,12 +43,6 @@
 
 #include <evdev-properties.h>
 
-enum {
-    MBEMU_DISABLED = 0,
-    MBEMU_ENABLED,
-    MBEMU_AUTO
-};
-
 #ifdef HAVE_PROPERTIES
 static Atom prop_mbemu     = 0; /* Middle button emulation on/off property */
 static Atom prop_mbtimeout = 0; /* Middle button timeout property */
@@ -232,11 +226,6 @@ EvdevMBEmuFilterEvent(InputInfoPtr pInfo, int button, BOOL press)
     if (!pEvdev->emulateMB.enabled)
         return ret;
 
-    if (button == 2) {
-        EvdevMBEmuEnable(pInfo, FALSE);
-        return ret;
-    }
-
     /* don't care about other buttons */
     if (button != 1 && button != 3)
         return ret;
@@ -310,21 +299,26 @@ void
 EvdevMBEmuPreInit(InputInfoPtr pInfo)
 {
     EvdevPtr pEvdev = (EvdevPtr)pInfo->private;
-
-    if (pEvdev->flags & EVDEV_TOUCHSCREEN)
-        pEvdev->emulateMB.enabled = MBEMU_DISABLED;
-    else
-        pEvdev->emulateMB.enabled = MBEMU_AUTO;
-
-    if (xf86FindOption(pInfo->options, "Emulate3Buttons"))
-    {
-        pEvdev->emulateMB.enabled = xf86SetBoolOption(pInfo->options,
-                                                      "Emulate3Buttons",
-                                                      MBEMU_ENABLED);
-        xf86Msg(X_INFO, "%s: Forcing middle mouse button emulation %s.\n",
-                pInfo->name, (pEvdev->emulateMB.enabled) ? "on" : "off");
-    }
-
+    int dflt;
+
+
+    /* the PS/2 protocol doesn't allow button detection so the kernel simply
+     * sets LMR as always present.
+     * On actual three-button mice this is annoying as the left mouse button
+     * will suffer from a delay until the middle mouse button is pressed.
+     *
+     * There's not a lot of two-button mice around anymore, so disable MB
+     * emulation by default for all devices that have a middle button (even
+     * though this _will_ give false positives).
+     */
+
+    dflt = !TestBit(BTN_MIDDLE, pEvdev->key_bitmask);
+
+    pEvdev->emulateMB.enabled = xf86SetBoolOption(pInfo->options,
+                                                  "Emulate3Buttons",
+                                                  dflt);
+    xf86Msg(X_INFO, "%s: Middle mouse button emulation %s.\n",
+            pInfo->name, (pEvdev->emulateMB.enabled) ? "on" : "off");
     pEvdev->emulateMB.timeout = xf86SetIntOption(pInfo->options,
                                                  "Emulate3Timeout", 50);
 }
@@ -352,16 +346,6 @@ EvdevMBEmuFinalize(InputInfoPtr pInfo)
 
 }
 
-/* Enable/disable middle mouse button emulation. */
-void
-EvdevMBEmuEnable(InputInfoPtr pInfo, BOOL enable)
-{
-    EvdevPtr pEvdev = (EvdevPtr)pInfo->private;
-    if (pEvdev->emulateMB.enabled == MBEMU_AUTO)
-        pEvdev->emulateMB.enabled = enable;
-}
-
-
 #ifdef HAVE_PROPERTIES
 static int
 EvdevMBEmuSetProperty(DeviceIntPtr dev, Atom atom, XIPropertyValuePtr val,
diff --git a/src/evdev.c b/src/evdev.c
index bd92d91..ac475b7 100644
--- a/src/evdev.c
+++ b/src/evdev.c
@@ -747,8 +747,6 @@ EvdevReadInput(InputInfoPtr pInfo)
     }
 }
 
-#define TestBit(bit, array) ((array[(bit) / LONG_BITS]) & (1L << ((bit) % LONG_BITS)))
-
 static void
 EvdevPtrCtrlProc(DeviceIntPtr device, PtrCtrl *ctrl)
 {
diff --git a/src/evdev.h b/src/evdev.h
index 8c89f83..8ed1299 100644
--- a/src/evdev.h
+++ b/src/evdev.h
@@ -80,6 +80,7 @@
 #define MAX_VALUATORS 36
 #endif
 
+#define TestBit(bit, array) ((array[(bit) / LONG_BITS]) & (1L << ((bit) % LONG_BITS)))
 
 #if GET_ABI_MAJOR(ABI_XINPUT_VERSION) < 5
 typedef struct {
@@ -214,7 +215,6 @@ void EvdevMBEmuBlockHandler(pointer, struct timeval**, pointer);
 void EvdevMBEmuPreInit(InputInfoPtr);
 void EvdevMBEmuOn(InputInfoPtr);
 void EvdevMBEmuFinalize(InputInfoPtr);
-void EvdevMBEmuEnable(InputInfoPtr, BOOL);
 
 /* Mouse Wheel emulation */
 void EvdevWheelEmuPreInit(InputInfoPtr pInfo);
-- 
1.6.5.2