1 files changed, 44 insertions, 0 deletions
diff --git a/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp b/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
index 730473b983..47702741e0 100644
--- a/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
@@ -1012,6 +1012,50 @@ void QXcbConnection::xi2HandleScrollEvent(void *event, ScrollingDevice &scrollin
 #endif // XCB_USE_XINPUT21
 }
 
+static int xi2ValuatorOffset(const unsigned char *maskPtr, int maskLen, int number)
+{
+    int offset = 0;
+    for (int i = 0; i < maskLen; i++) {
+        if (number < 8) {
+            if ((maskPtr[i] & (1 << number)) == 0)
+                return -1;
+        }
+        for (int j = 0; j < 8; j++) {
+            if (j == number)
+                return offset;
+            if (maskPtr[i] & (1 << j))
+                offset++;
+        }
+        number -= 8;
+    }
+    return -1;
+}
+
+bool QXcbConnection::xi2GetValuatorValueIfSet(const void *event, int valuatorNum, double *value)
+{
+    const xXIDeviceEvent *xideviceevent = static_cast<const xXIDeviceEvent *>(event);
+    const unsigned char *buttonsMaskAddr = (const unsigned char*)&xideviceevent[1];
+    const unsigned char *valuatorsMaskAddr = buttonsMaskAddr + xideviceevent->buttons_len * 4;
+    FP3232 *valuatorsValuesAddr = (FP3232*)(valuatorsMaskAddr + xideviceevent->valuators_len * 4);
+
+    int valuatorOffset = xi2ValuatorOffset(valuatorsMaskAddr, xideviceevent->valuators_len, valuatorNum);
+    if (valuatorOffset < 0)
+        return false;
+
+    *value = valuatorsValuesAddr[valuatorOffset].integral;
+    *value += ((double)valuatorsValuesAddr[valuatorOffset].frac / (1 << 16) / (1 << 16));
+    return true;
+}
+
+void QXcbConnection::xi2PrepareXIGenericDeviceEvent(xcb_ge_event_t *event)
+{
+    // xcb event structs contain stuff that wasn't on the wire, the full_sequence field
+    // adds an extra 4 bytes and generic events cookie data is on the wire right after the standard 32 bytes.
+    // Move this data back to have the same layout in memory as it was on the wire
+    // and allow casting, overwriting the full_sequence field.
+    memmove((char*) event + 32, (char*) event + 36, event->length * 4);
+}
+
 Qt::MouseButton QXcbConnection::xiToQtMouseButton(uint32_t b)
 {
     switch (b) {