Partial fix for bug 2726 - Win32 'mouse' events not applying 'SDL_TOUCH_MOUSEID'

This is a Win32-specific fix for bug 2726.  A WinRT fix for this bug was applied
separately, via https://hg.libsdl.org/SDL/rev/91f56dcad879

This fix applies SDL_TOUCH_MOUSEID to 'mouse' events coming from touch devices,
but only when relative-mouse-mode is turned OFF.  This bug is still present
when relative-mouse-mode is ON, however Microsoft does not provide documentation
on whether or not those input events (which come from WM_INPUT) can be
identified as touch-specific or not.  Unofficially, that data might be available
(via GetMessageExtraInfo()), however this patch only uses MS-documented APIs.

src/video/windows/SDL_windowsevents.c

@@ -45,6 +45,9 @@
 #include "wmmsg.h"
 #endif
 
+/* For processing mouse WM_*BUTTON* and WM_MOUSEMOVE message-data from GetMessageExtraInfo() */
+#define MOUSEEVENTF_FROMTOUCH 0xFF515700
+
 /* Masks for processing the windows KEYDOWN and KEYUP messages */
 #define REPEATED_KEYMASK    (1<<30)
 #define EXTENDED_KEYMASK    (1<<24)
@@ -196,7 +199,7 @@ WindowsScanCodeToSDLScanCode(LPARAM lParam, WPARAM wParam)
 
 
 void
-WIN_CheckWParamMouseButton(SDL_bool bwParamMousePressed, SDL_bool bSDLMousePressed, SDL_WindowData *data, Uint8 button)
+WIN_CheckWParamMouseButton(SDL_bool bwParamMousePressed, SDL_bool bSDLMousePressed, SDL_WindowData *data, Uint8 button, SDL_MouseID mouseID)
 {
     if (data->focus_click_pending && button == SDL_BUTTON_LEFT && !bwParamMousePressed) {
         data->focus_click_pending = SDL_FALSE;
@@ -204,9 +207,9 @@ WIN_CheckWParamMouseButton(SDL_bool bwParamMousePressed, SDL_bool bSDLMousePress
     }
 
     if (bwParamMousePressed && !bSDLMousePressed) {
-        SDL_SendMouseButton(data->window, 0, SDL_PRESSED, button);
+        SDL_SendMouseButton(data->window, mouseID, SDL_PRESSED, button);
     } else if (!bwParamMousePressed && bSDLMousePressed) {
-        SDL_SendMouseButton(data->window, 0, SDL_RELEASED, button);
+        SDL_SendMouseButton(data->window, mouseID, SDL_RELEASED, button);
     }
 }
 
@@ -215,15 +218,15 @@ WIN_CheckWParamMouseButton(SDL_bool bwParamMousePressed, SDL_bool bSDLMousePress
 *  so this funciton reconciles our view of the world with the current buttons reported by windows
 */
 void
-WIN_CheckWParamMouseButtons(WPARAM wParam, SDL_WindowData *data)
+WIN_CheckWParamMouseButtons(WPARAM wParam, SDL_WindowData *data, SDL_MouseID mouseID)
 {
     if (wParam != data->mouse_button_flags) {
         Uint32 mouseFlags = SDL_GetMouseState(NULL, NULL);
-        WIN_CheckWParamMouseButton((wParam & MK_LBUTTON), (mouseFlags & SDL_BUTTON_LMASK), data, SDL_BUTTON_LEFT);
-        WIN_CheckWParamMouseButton((wParam & MK_MBUTTON), (mouseFlags & SDL_BUTTON_MMASK), data, SDL_BUTTON_MIDDLE);
-        WIN_CheckWParamMouseButton((wParam & MK_RBUTTON), (mouseFlags & SDL_BUTTON_RMASK), data, SDL_BUTTON_RIGHT);
-        WIN_CheckWParamMouseButton((wParam & MK_XBUTTON1), (mouseFlags & SDL_BUTTON_X1MASK), data, SDL_BUTTON_X1);
-        WIN_CheckWParamMouseButton((wParam & MK_XBUTTON2), (mouseFlags & SDL_BUTTON_X2MASK), data, SDL_BUTTON_X2);
+        WIN_CheckWParamMouseButton((wParam & MK_LBUTTON), (mouseFlags & SDL_BUTTON_LMASK), data, SDL_BUTTON_LEFT, mouseID);
+        WIN_CheckWParamMouseButton((wParam & MK_MBUTTON), (mouseFlags & SDL_BUTTON_MMASK), data, SDL_BUTTON_MIDDLE, mouseID);
+        WIN_CheckWParamMouseButton((wParam & MK_RBUTTON), (mouseFlags & SDL_BUTTON_RMASK), data, SDL_BUTTON_RIGHT, mouseID);
+        WIN_CheckWParamMouseButton((wParam & MK_XBUTTON1), (mouseFlags & SDL_BUTTON_X1MASK), data, SDL_BUTTON_X1, mouseID);
+        WIN_CheckWParamMouseButton((wParam & MK_XBUTTON2), (mouseFlags & SDL_BUTTON_X2MASK), data, SDL_BUTTON_X2, mouseID);
         data->mouse_button_flags = wParam;
     }
 }
@@ -235,25 +238,25 @@ WIN_CheckRawMouseButtons(ULONG rawButtons, SDL_WindowData *data)
     if (rawButtons != data->mouse_button_flags) {
         Uint32 mouseFlags = SDL_GetMouseState(NULL, NULL);
         if ((rawButtons & RI_MOUSE_BUTTON_1_DOWN))
-            WIN_CheckWParamMouseButton((rawButtons & RI_MOUSE_BUTTON_1_DOWN), (mouseFlags & SDL_BUTTON_LMASK), data, SDL_BUTTON_LEFT);
+            WIN_CheckWParamMouseButton((rawButtons & RI_MOUSE_BUTTON_1_DOWN), (mouseFlags & SDL_BUTTON_LMASK), data, SDL_BUTTON_LEFT, 0);
         if ((rawButtons & RI_MOUSE_BUTTON_1_UP))
-            WIN_CheckWParamMouseButton(!(rawButtons & RI_MOUSE_BUTTON_1_UP), (mouseFlags & SDL_BUTTON_LMASK), data, SDL_BUTTON_LEFT);
+            WIN_CheckWParamMouseButton(!(rawButtons & RI_MOUSE_BUTTON_1_UP), (mouseFlags & SDL_BUTTON_LMASK), data, SDL_BUTTON_LEFT, 0);
         if ((rawButtons & RI_MOUSE_BUTTON_2_DOWN))
-            WIN_CheckWParamMouseButton((rawButtons & RI_MOUSE_BUTTON_2_DOWN), (mouseFlags & SDL_BUTTON_RMASK), data, SDL_BUTTON_RIGHT);
+            WIN_CheckWParamMouseButton((rawButtons & RI_MOUSE_BUTTON_2_DOWN), (mouseFlags & SDL_BUTTON_RMASK), data, SDL_BUTTON_RIGHT, 0);
         if ((rawButtons & RI_MOUSE_BUTTON_2_UP))
-            WIN_CheckWParamMouseButton(!(rawButtons & RI_MOUSE_BUTTON_2_UP), (mouseFlags & SDL_BUTTON_RMASK), data, SDL_BUTTON_RIGHT);
+            WIN_CheckWParamMouseButton(!(rawButtons & RI_MOUSE_BUTTON_2_UP), (mouseFlags & SDL_BUTTON_RMASK), data, SDL_BUTTON_RIGHT, 0);
         if ((rawButtons & RI_MOUSE_BUTTON_3_DOWN))
-            WIN_CheckWParamMouseButton((rawButtons & RI_MOUSE_BUTTON_3_DOWN), (mouseFlags & SDL_BUTTON_MMASK), data, SDL_BUTTON_MIDDLE);
+            WIN_CheckWParamMouseButton((rawButtons & RI_MOUSE_BUTTON_3_DOWN), (mouseFlags & SDL_BUTTON_MMASK), data, SDL_BUTTON_MIDDLE, 0);
         if ((rawButtons & RI_MOUSE_BUTTON_3_UP))
-            WIN_CheckWParamMouseButton(!(rawButtons & RI_MOUSE_BUTTON_3_UP), (mouseFlags & SDL_BUTTON_MMASK), data, SDL_BUTTON_MIDDLE);
+            WIN_CheckWParamMouseButton(!(rawButtons & RI_MOUSE_BUTTON_3_UP), (mouseFlags & SDL_BUTTON_MMASK), data, SDL_BUTTON_MIDDLE, 0);
         if ((rawButtons & RI_MOUSE_BUTTON_4_DOWN))
-            WIN_CheckWParamMouseButton((rawButtons & RI_MOUSE_BUTTON_4_DOWN), (mouseFlags & SDL_BUTTON_X1MASK), data, SDL_BUTTON_X1);
+            WIN_CheckWParamMouseButton((rawButtons & RI_MOUSE_BUTTON_4_DOWN), (mouseFlags & SDL_BUTTON_X1MASK), data, SDL_BUTTON_X1, 0);
         if ((rawButtons & RI_MOUSE_BUTTON_4_UP))
-            WIN_CheckWParamMouseButton(!(rawButtons & RI_MOUSE_BUTTON_4_UP), (mouseFlags & SDL_BUTTON_X1MASK), data, SDL_BUTTON_X1);
+            WIN_CheckWParamMouseButton(!(rawButtons & RI_MOUSE_BUTTON_4_UP), (mouseFlags & SDL_BUTTON_X1MASK), data, SDL_BUTTON_X1, 0);
         if ((rawButtons & RI_MOUSE_BUTTON_5_DOWN))
-            WIN_CheckWParamMouseButton((rawButtons & RI_MOUSE_BUTTON_5_DOWN), (mouseFlags & SDL_BUTTON_X2MASK), data, SDL_BUTTON_X2);
+            WIN_CheckWParamMouseButton((rawButtons & RI_MOUSE_BUTTON_5_DOWN), (mouseFlags & SDL_BUTTON_X2MASK), data, SDL_BUTTON_X2, 0);
         if ((rawButtons & RI_MOUSE_BUTTON_5_UP))
-            WIN_CheckWParamMouseButton(!(rawButtons & RI_MOUSE_BUTTON_5_UP), (mouseFlags & SDL_BUTTON_X2MASK), data, SDL_BUTTON_X2);
+            WIN_CheckWParamMouseButton(!(rawButtons & RI_MOUSE_BUTTON_5_UP), (mouseFlags & SDL_BUTTON_X2MASK), data, SDL_BUTTON_X2, 0);
         data->mouse_button_flags = rawButtons;
     }
 }
@@ -271,23 +274,23 @@ WIN_CheckAsyncMouseRelease(SDL_WindowData *data)
 
     keyState = GetAsyncKeyState(VK_LBUTTON);
     if (!(keyState & 0x8000)) {
-        WIN_CheckWParamMouseButton(SDL_FALSE, (mouseFlags & SDL_BUTTON_LMASK), data, SDL_BUTTON_LEFT);
+        WIN_CheckWParamMouseButton(SDL_FALSE, (mouseFlags & SDL_BUTTON_LMASK), data, SDL_BUTTON_LEFT, 0);
     }
     keyState = GetAsyncKeyState(VK_RBUTTON);
     if (!(keyState & 0x8000)) {
-        WIN_CheckWParamMouseButton(SDL_FALSE, (mouseFlags & SDL_BUTTON_RMASK), data, SDL_BUTTON_RIGHT);
+        WIN_CheckWParamMouseButton(SDL_FALSE, (mouseFlags & SDL_BUTTON_RMASK), data, SDL_BUTTON_RIGHT, 0);
     }
     keyState = GetAsyncKeyState(VK_MBUTTON);
     if (!(keyState & 0x8000)) {
-        WIN_CheckWParamMouseButton(SDL_FALSE, (mouseFlags & SDL_BUTTON_MMASK), data, SDL_BUTTON_MIDDLE);
+        WIN_CheckWParamMouseButton(SDL_FALSE, (mouseFlags & SDL_BUTTON_MMASK), data, SDL_BUTTON_MIDDLE, 0);
     }
     keyState = GetAsyncKeyState(VK_XBUTTON1);
     if (!(keyState & 0x8000)) {
-        WIN_CheckWParamMouseButton(SDL_FALSE, (mouseFlags & SDL_BUTTON_X1MASK), data, SDL_BUTTON_X1);
+        WIN_CheckWParamMouseButton(SDL_FALSE, (mouseFlags & SDL_BUTTON_X1MASK), data, SDL_BUTTON_X1, 0);
     }
     keyState = GetAsyncKeyState(VK_XBUTTON2);
     if (!(keyState & 0x8000)) {
-        WIN_CheckWParamMouseButton(SDL_FALSE, (mouseFlags & SDL_BUTTON_X2MASK), data, SDL_BUTTON_X2);
+        WIN_CheckWParamMouseButton(SDL_FALSE, (mouseFlags & SDL_BUTTON_X2MASK), data, SDL_BUTTON_X2, 0);
     }
     data->mouse_button_flags = 0;
 }
@@ -410,7 +413,8 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
         {
             SDL_Mouse *mouse = SDL_GetMouse();
             if (!mouse->relative_mode || mouse->relative_mode_warp) {
-                SDL_SendMouseMotion(data->window, 0, 0, GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam));
+                SDL_MouseID mouseID = (((GetMessageExtraInfo() & MOUSEEVENTF_FROMTOUCH) == MOUSEEVENTF_FROMTOUCH) ? SDL_TOUCH_MOUSEID : 0);
+                SDL_SendMouseMotion(data->window, mouseID, 0, GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam));
             }
         }
         /* don't break here, fall through to check the wParam like the button presses */
@@ -429,7 +433,8 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
         {
             SDL_Mouse *mouse = SDL_GetMouse();
             if (!mouse->relative_mode || mouse->relative_mode_warp) {
-                WIN_CheckWParamMouseButtons(wParam, data);
+                SDL_MouseID mouseID = (((GetMessageExtraInfo() & MOUSEEVENTF_FROMTOUCH) == MOUSEEVENTF_FROMTOUCH) ? SDL_TOUCH_MOUSEID : 0);
+                WIN_CheckWParamMouseButtons(wParam, data, mouseID);
             }
         }
         break;