From 116c0cd9a57e579ed620725463580cdac1fc25c6 Mon Sep 17 00:00:00 2001
From: Doug Lyons <douglyons@douglyons.com>
Date: Sat, 27 Apr 2024 14:38:06 -0500
Subject: [PATCH] [USER32] Fix resource display of MSVC BI_BITFIELD 32-bit
 bitmaps. (#5942)

This specifically fixes Wordpad's Open and SaveAs dialog toolbars.

* Fix 16 bpp BI_BITFIELDS like 32 bpp was done.
* Add BI_BITFIELDS byte count into bitmap_info_size return value.
* Account for GCC's windres.exe incorrect omission for BI_BITFIELDS DWORD's when processing 32-bpp bitmaps.
* Account for GCC's windres.exe failing with bitmaps with BI_BITFIELDS and bits per plane is 16
* Fix WARN message to show error on either 16-bpp or 32-bpp
* Correct comment regarding GCC compiled bitmaps with compression of BI_BITFIELD's to add 16 bits per plane

CORE-17005
---
 win32ss/user/user32/windows/cursoricon.c | 33 +++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/win32ss/user/user32/windows/cursoricon.c b/win32ss/user/user32/windows/cursoricon.c
index eb160a88c13..531c29abe57 100644
--- a/win32ss/user/user32/windows/cursoricon.c
+++ b/win32ss/user/user32/windows/cursoricon.c
@@ -152,6 +152,8 @@ static BOOL is_dib_monochrome( const BITMAPINFO* info )
     }
 }
 
+/* Return the size of the bitmap info structure including color table and
+ * the bytes required for 3 DWORDS if this is a BI_BITFIELDS bmp. */
 static int bitmap_info_size( const BITMAPINFO * info, WORD coloruse )
 {
     unsigned int colors, size, masks = 0;
@@ -170,8 +172,21 @@ static int bitmap_info_size( const BITMAPINFO * info, WORD coloruse )
                 colors = 256;
         if (!colors && (info->bmiHeader.biBitCount <= 8))
             colors = 1 << info->bmiHeader.biBitCount;
+        /* Account for BI_BITFIELDS in BITMAPINFOHEADER(v1-v3) bmp's. The
+         * 'max' selection using biSize below will exclude v4 & v5's. */
         if (info->bmiHeader.biCompression == BI_BITFIELDS) masks = 3;
         size = max( info->bmiHeader.biSize, sizeof(BITMAPINFOHEADER) + masks * sizeof(DWORD) );
+        /* Test for BI_BITFIELDS format and either 16 or 32 bpp.
+         * If so, account for the 3 DWORD masks (RGB Order).
+         * BITMAPCOREHEADER tested above has no 16 or 32 bpp types.
+         * See table "All of the possible pixel formats in a DIB"
+         * at https://en.wikipedia.org/wiki/BMP_file_format. */
+        if (info->bmiHeader.biSize >= sizeof(BITMAPV4HEADER) &&
+            info->bmiHeader.biCompression == BI_BITFIELDS &&
+            (info->bmiHeader.biBitCount == 16 || info->bmiHeader.biBitCount == 32))
+        {
+            size += 3 * sizeof(DWORD);  // BI_BITFIELDS
+        }
         return size + colors * ((coloruse == DIB_RGB_COLORS) ? sizeof(RGBQUAD) : sizeof(WORD));
     }
 }
@@ -1099,7 +1114,7 @@ BITMAP_LoadImageW(
     HBITMAP hbmpOld, hbmpRet = NULL;
     LONG width, height;
     WORD bpp;
-    DWORD compr;
+    DWORD compr, ResSize = 0;
 
     /* Map the bitmap info */
     if(fuLoad & LR_LOADFROMFILE)
@@ -1137,6 +1152,7 @@ BITMAP_LoadImageW(
         pbmi = LockResource(hgRsrc);
         if(!pbmi)
             return NULL;
+        ResSize = SizeofResource(hinst, hrsrc);
     }
 
     /* Fix up values */
@@ -1162,6 +1178,21 @@ BITMAP_LoadImageW(
         goto end;
     CopyMemory(pbmiCopy, pbmi, iBMISize);
 
+    TRACE("Size Image %d, Size Header %d, ResSize %d\n",
+        pbmiCopy->bmiHeader.biSizeImage, pbmiCopy->bmiHeader.biSize, ResSize);
+
+    /* HACK: If this is a binutils' windres.exe compiled 16 or 32 bpp bitmap
+     * using BI_BITFIELDS, then a bug causes it to fail to include
+     * the bytes for the bitfields. So, we have to substract out the
+     * size of the bitfields previously included from bitmap_info_size. */
+    if (compr == BI_BITFIELDS && (bpp == 16 || bpp == 32) &&
+        pbmiCopy->bmiHeader.biSizeImage + pbmiCopy->bmiHeader.biSize == ResSize)
+    {
+        /* GCC pointer to the image data has 12 less bytes than MSVC */
+        pvBits = (char*)pvBits - 12;
+        WARN("Found GCC Resource Compiled 16-bpp or 32-bpp error\n");
+    }
+
     /* Fix it up, if needed */
     if(fuLoad & (LR_LOADTRANSPARENT | LR_LOADMAP3DCOLORS))
     {