Fix [17b509d78f]: wm iconbitmap does not support icon files with png images on Windows.

Author: fvogelnew1

changes.md

@@ -37,6 +37,7 @@ to the userbase.
  - [tk print canvas with smooth lines crashes on windows](https://core.tcl-lang.org/tk/tktview/9b23b6)
  - [Collect utility procs for the Tk test suite](https://core.tcl-lang.org/tk/tktview/718cbc)
  - [Setting ttk state may change the a variable passed by value](https://core.tcl-lang.org/tk/info/7231bf)
+ - [wm iconbitmap does not support icon files with png images on Windows](https://core.tcl-lang.org/tk/info/17b509)
 
 Release Tk 9.0.1 arises from the check-in with tag `core-9-0-1`.
 

win/tkWinWm.c

@@ -549,24 +549,16 @@ MakeIconOrCursorFromResource(
      * Let the OS do the real work :)
      */
 
-    hIcon = (HICON) CreateIconFromResourceEx(lpIcon->lpBits,
-	    lpIcon->dwNumBytes, isIcon, 0x00030000,
-	    (*(LPBITMAPINFOHEADER) lpIcon->lpBits).biWidth,
-	    (*(LPBITMAPINFOHEADER) lpIcon->lpBits).biHeight/2, 0);
+    hIcon = (HICON)CreateIconFromResourceEx(lpIcon->lpBits,
+	    lpIcon->dwNumBytes, isIcon, 0x00030000, 0, 0, 0);
 
     /*
-     * It failed, odds are good we're on NT so try the non-Ex way.
+     * It failed, the non-Ex way might work as a fallback.
      */
 
     if (hIcon == NULL) {
-	/*
-	 * We would break on NT if we try with a 16bpp image.
-	 */
-
-	if (lpIcon->lpbi->bmiHeader.biBitCount != 16) {
-	    hIcon = CreateIconFromResource(lpIcon->lpBits, lpIcon->dwNumBytes,
-		    isIcon, 0x00030000);
-	}
+        hIcon = CreateIconFromResource(lpIcon->lpBits, lpIcon->dwNumBytes,
+		isIcon, 0x00030000);
     }
     return hIcon;
 }
@@ -1104,6 +1096,50 @@ ReadIconFromFile(
  *----------------------------------------------------------------------
  */
 
+static BOOL
+SetSizeAndColorFromHICON(      /* Helper for AdjustIconImagePointers */
+    HICON hicon,
+    LPICONIMAGE lpImage)
+{
+    ICONINFO info;
+    BOOL bRes;
+    BITMAP bmp;
+
+    memset(&info, 0, sizeof(info));
+
+    bRes = GetIconInfo(hicon, &info);
+    if (!bRes) {
+	return FALSE;
+    }
+
+    if (info.hbmColor) {
+	const int nWrittenBytes = GetObject(info.hbmColor, sizeof(bmp), &bmp);
+
+	if (nWrittenBytes > 0) {
+	    lpImage->Width = bmp.bmWidth;
+	    lpImage->Height = bmp.bmHeight;
+	    lpImage->Colors = bmp.bmBitsPixel;
+	}
+    } else if (info.hbmMask) {
+	// Icon has no color plane, image data stored in mask
+	const int nWrittenBytes = GetObject(info.hbmMask, sizeof(bmp), &bmp);
+
+	if (nWrittenBytes > 0) {
+	    lpImage->Width = bmp.bmWidth;
+	    lpImage->Height = bmp.bmHeight / 2;
+	    lpImage->Colors = 1;
+	}
+    }
+
+    if (info.hbmColor) {
+	DeleteObject(info.hbmColor);
+    }
+    if (info.hbmMask) {
+	DeleteObject(info.hbmMask);
+    }
+    return TRUE;
+}
+
 static BOOL
 AdjustIconImagePointers(
     LPICONIMAGE lpImage)
@@ -1123,24 +1159,10 @@ AdjustIconImagePointers(
     lpImage->lpbi = (LPBITMAPINFO) lpImage->lpBits;
 
     /*
-     * Width - simple enough.
-     */
-
-    lpImage->Width = lpImage->lpbi->bmiHeader.biWidth;
-
-    /*
-     * Icons are stored in funky format where height is doubled so account for
-     * that.
+     * Width, height, and number of colors.
      */
 
-    lpImage->Height = (lpImage->lpbi->bmiHeader.biHeight)/2;
-
-    /*
-     * How many colors?
-     */
-
-    lpImage->Colors = lpImage->lpbi->bmiHeader.biPlanes
-	    * lpImage->lpbi->bmiHeader.biBitCount;
+    SetSizeAndColorFromHICON(lpImage->hIcon, lpImage);
 
     /*
      * XOR bits follow the header and color table.
@@ -1153,7 +1175,7 @@ AdjustIconImagePointers(
      */
 
     lpImage->lpAND = lpImage->lpXOR +
-	    lpImage->Height*BytesPerLine((LPBITMAPINFOHEADER) lpImage->lpbi);
+	    lpImage->Height * BytesPerLine((LPBITMAPINFOHEADER) lpImage->lpbi);
     return TRUE;
 }
 
@@ -1533,17 +1555,17 @@ ReadIconOrCursorFromFile(
 	}
 
 	/*
-	 * Set the internal pointers appropriately.
+	 * Create the icon from the resource, and set the internal pointers appropriately.
 	 */
 
+	lpIR->IconImages[i].hIcon =
+		MakeIconOrCursorFromResource(&lpIR->IconImages[i], isIcon);
 	if (!AdjustIconImagePointers(&lpIR->IconImages[i])) {
 	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		    "Error converting to internal format", TCL_INDEX_NONE));
 	    Tcl_SetErrorCode(interp, "TK", "WM", "ICON", "FORMAT", NULL);
 	    goto readError;
 	}
-	lpIR->IconImages[i].hIcon =
-		MakeIconOrCursorFromResource(&lpIR->IconImages[i], isIcon);
     }
 
     /*