Need to speak out - Ros-dev

8 May 2010

Hello,
This is the second time that work that someone on the ARM Team has worked on has been mostly reverted without any communication with us, and incorrect changes have been added to parts of our work.
The Eng function worked on even clearly stated comments such as "Compressed surfaces don't have scanlines!", yet this new patch restores the old incorrect functionality.
lDelta cannot be anything but != 0 for compressed data such as RLE or JPG/PNG! And creating the DIB should not decompress the bits.
Please read http://www.tech-archive.net/Archive/Development/microsoft.public.development... for example.
I do not understand how you can believe that "RLE" has a scan-line. I am not a graphics expert by no means, but even I understand this fact: by definition scan-lines in an RLE are dynamic, and a scan-line offset table contains information about that.
You do not have to take my word for it, as a simple driver test case will also show that Windows does not decompress RLE data or set lDelta to any other value than 0 with an RLE bitmap. You can find more information on RLE at http://www.fileformat.info/mirror/egff/ch09_03.htm.
If you are wondering why there have not been any commits coming lately, recent actions such as these as the cause.
-r
Author: khornicek
Date: Sat May  8 20:09:45 2010
New Revision: 47134
URL: http://svn.reactos.org/svn/reactos?rev=47134&view=rev
Log:
[WIN32K]
- Bring back support for RLE compressed bitmaps.
- Merge the decompress functions for 4bb and 8bpp bitmaps to one generic function.
- Simplify SURFMEM_bCreateDib a bit by not allowing PNG/JPEG compression at all.
See issue #5276 for more details.
Modified:
   trunk/reactos/subsystems/win32/win32k/eng/surface.c
Modified: trunk/reactos/subsystems/win32/win32k/eng/surface.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/win32/win32k/eng...
==============================================================================

--- trunk/reactos/subsystems/win32/win32k/eng/surface.c [iso-8859-1] (original)
+++ trunk/reactos/subsystems/win32/win32k/eng/surface.c [iso-8859-1] Sat May  8 20:09:45 2010
@@ -204,48 +204,59 @@
    return NewBitmap;
}
-VOID Decompress4bpp(SIZEL Size, BYTE *CompressedBits, BYTE *UncompressedBits, LONG Delta)
-{
-    int x = 0;
-    int y = Size.cy - 1;
-    int c;
-    int length;
-    int width = ((Size.cx+1)/2);
-    int height = Size.cy - 1;
+BOOL DecompressBitmap(SIZEL Size, BYTE *CompressedBits, BYTE *UncompressedBits, LONG Delta, ULONG Format)
+{
+    INT x = 0;
+    INT y = Size.cy - 1;
+    INT c;
+    INT length;
+    INT width;
+    INT height = Size.cy - 1;
    BYTE *begin = CompressedBits;
    BYTE *bits = CompressedBits;
    BYTE *temp;
-    while (y >= 0)
-    {
-        length = *bits++ / 2;
-        if (length)
-        {
-            c = *bits++;
-            while (length--)
-            {
-                if (x >= width) break;
-                temp = UncompressedBits + (((height - y) * Delta) + x);
-                x++;
-                *temp = c;
-            }
-        }
-        else
-        {
-            length = *bits++;
-            switch (length)
-            {
+    INT shift = 0;
+
+    if (Format == BMF_4RLE)
+        shift = 1;
+    else if(Format != BMF_8RLE)
+        return FALSE;
+
+    width = ((Size.cx + shift) >> shift);
+
+    _SEH2_TRY
+    {
+        while (y >= 0)
+        {
+            length = (*bits++) >> shift;
+            if (length)
+            {
+                c = *bits++;
+                while (length--)
+                {
+                    if (x >= width) break;
+                    temp = UncompressedBits + (((height - y) * Delta) + x);
+                    x++;
+                    *temp = c;
+                }
+            }
+            else
+            {
+                length = *bits++;
+                switch (length)
+                {
                case RLE_EOL:
                    x = 0;
                    y--;
                    break;
                case RLE_END:
-                    return;
+                    _SEH2_YIELD(return TRUE);
                case RLE_DELTA:
-                    x += (*bits++)/2;
-                    y -= (*bits++)/2;
+                    x += (*bits++) >> shift;
+                    y -= (*bits++) >> shift;
                    break;
                default:
-                    length /= 2;
+                    length = length >> shift;
                    while (length--)
                    {
                        c = *bits++;
@@ -260,69 +271,18 @@
                    {
                        bits++;
                    }
-            }
-        }
-    }
-}
-
-VOID Decompress8bpp(SIZEL Size, BYTE *CompressedBits, BYTE *UncompressedBits, LONG Delta)
-{
-    int x = 0;
-    int y = Size.cy - 1;
-    int c;
-    int length;
-    int width = Size.cx;
-    int height = Size.cy - 1;
-    BYTE *begin = CompressedBits;
-    BYTE *bits = CompressedBits;
-    BYTE *temp;
-    while (y >= 0)
-    {
-        length = *bits++;
-        if (length)
-        {
-            c = *bits++;
-            while (length--)
-            {
-                if (x >= width) break;
-                temp = UncompressedBits + (((height - y) * Delta) + x);
-                x++;
-                *temp = c;
-            }
-        }
-        else
-        {
-            length = *bits++;
-            switch (length)
-            {
-                case RLE_EOL:
-                    x = 0;
-                    y--;
-                    break;
-                case RLE_END:
-                    return;
-                case RLE_DELTA:
-                    x += *bits++;
-                    y -= *bits++;
-                    break;
-                default:
-                    while (length--)
-                    {
-                        c = *bits++;
-                        if (x < width)
-                        {
-                            temp = UncompressedBits + (((height - y) * Delta) + x);
-                            x++;
-                            *temp = c;
-                        }
-                    }
-                    if ((bits - begin) & 1)
-                    {
-                        bits++;
-                    }
-            }
-        }
-    }
+                }
+            }
+        }
+    }
+    _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
+    {
+        DPRINT1("Decoding error\n");
+        _SEH2_YIELD(return FALSE);
+    }
+    _SEH2_END;
+
+    return TRUE;
}
HBITMAP FASTCALL
@@ -362,7 +322,7 @@
        pso->cjBits = pso->lDelta * Size.cy;
        UncompressedFormat = BMF_4BPP;
        UncompressedBits = EngAllocMem(FL_ZERO_MEMORY, pso->cjBits, TAG_DIB);
-        Decompress4bpp(Size, (BYTE *)Bits, (BYTE *)UncompressedBits, pso->lDelta);
+        DecompressBitmap(Size, (BYTE *)Bits, (BYTE *)UncompressedBits, pso->lDelta, Format);
    }
    else if (Format == BMF_8RLE)
    {
@@ -370,7 +330,7 @@
        pso->cjBits = pso->lDelta * Size.cy;
        UncompressedFormat = BMF_8BPP;
        UncompressedBits = EngAllocMem(FL_ZERO_MEMORY, pso->cjBits, TAG_DIB);
-        Decompress8bpp(Size, (BYTE *)Bits, (BYTE *)UncompressedBits, pso->lDelta);
+        DecompressBitmap(Size, (BYTE *)Bits, (BYTE *)UncompressedBits, pso->lDelta, Format);
    }
    else
    {
@@ -467,6 +427,7 @@
    PSURFACE psurf;
    SIZEL LocalSize;
    BOOLEAN AllocatedLocally = FALSE;
+    PVOID DecompressedBits = NULL;
/*
     * First, check the format so we can get the aligned scanline width.
@@ -500,17 +461,29 @@
            break;
case BMF_8RLE:
+            ScanLine = (BitmapInfo->Width + 3) & ~3;
+            Compressed = TRUE;
+            break;
        case BMF_4RLE:
+            ScanLine = ((BitmapInfo->Width + 7) & ~7) >> 1;
+            Compressed = TRUE;
+            break;
+
        case BMF_JPEG:
        case BMF_PNG:
-            Compressed = TRUE;
-            break;
+            ASSERT(FALSE); // ENGDDI shouldn't be creating PNGs for drivers ;-)
+            DPRINT1("No support for JPEG and PNG formats\n");
+            return NULL;
default:
            DPRINT1("Invalid bitmap format\n");
            return NULL;
    }
+    /* Save local bitmap size */
+    LocalSize.cy = BitmapInfo->Height;
+    LocalSize.cx = BitmapInfo->Width;
+
    /* Does the device manage its own surface? */
    if (!Bits)
    {
@@ -519,7 +492,8 @@
        {
            /* Note: we should not be seeing this scenario from ENGDDI */
            ASSERT(FALSE);
-            Size = BitmapInfo->Size;
+            DPRINT1("RLE compressed bitmap requested with no valid bitmap bits\n");
+            return NULL;
        }
        else
        {
@@ -551,6 +525,22 @@
    {
        /* Should not have asked for user memory */
        ASSERT((BitmapInfo->Flags & BMF_USERMEM) == 0);
+
+        if (Compressed)
+        {
+            DecompressedBits = EngAllocMem(FL_ZERO_MEMORY, BitmapInfo->Height * ScanLine, TAG_DIB);
+
+            if(!DecompressedBits)
+                return NULL;
+
+            if(!DecompressBitmap(LocalSize, (BYTE *)Bits, (BYTE *)DecompressedBits, ScanLine, BitmapInfo->Format))
+            {
+                EngFreeMem(DecompressedBits);
+                return NULL;
+            }
+
+            BitmapInfo->Format = (BitmapInfo->Format == BMF_4RLE) ? BMF_4BPP : BMF_8BPP;
+        }
    }
/* Allocate the actual surface object structure */
@@ -564,6 +554,8 @@
            else
                EngFreeMem(Bits);
        }
+        if (DecompressedBits)
+            EngFreeMem(DecompressedBits);
        return NULL;
    }
@@ -584,11 +576,9 @@
    pso->fjBitmap = BitmapInfo->Flags & (BMF_TOPDOWN | BMF_UMPDMEM | BMF_USERMEM);
/* Save size and type */
-    LocalSize.cy = BitmapInfo->Height;
-    LocalSize.cx = BitmapInfo->Width;
    pso->sizlBitmap = LocalSize;
    pso->iType = STYPE_BITMAP;
-    
+
    /* Device-managed surface, no flags or dimension */
    pso->dhsurf = 0;
    pso->dhpdev = NULL;
@@ -599,48 +589,28 @@
    psurf->hSecure = NULL;
    psurf->hDIBSection = NULL;
    psurf->flHooks = 0;
-    
+
    /* Set bits */
-    pso->pvBits = Bits;
-    
-    /* Check for bitmap type */
-    if (!Compressed)
-    {
-        /* Number of bits is based on the height times the scanline */
-        pso->cjBits = BitmapInfo->Height * ScanLine;
-        if (BitmapInfo->Flags & BMF_TOPDOWN)
-        {
-            /* For topdown, the base address starts with the bits */
-            pso->pvScan0 = pso->pvBits;
-            pso->lDelta = ScanLine;
-        }
-        else
-        {
-            /* Otherwise we start with the end and go up */
-            pso->pvScan0 = (PVOID)((ULONG_PTR)pso->pvBits + pso->cjBits - ScanLine);
-            pso->lDelta = -ScanLine;
-        }
+     if(Compressed)
+         pso->pvBits = DecompressedBits;
+     else
+         pso->pvBits = Bits;
+
+    /* Number of bits is based on the height times the scanline */
+    pso->cjBits = BitmapInfo->Height * ScanLine;
+    if (BitmapInfo->Flags & BMF_TOPDOWN)
+    {
+        /* For topdown, the base address starts with the bits */
+        pso->pvScan0 = pso->pvBits;
+        pso->lDelta = ScanLine;
    }
    else
    {
-        /* Compressed surfaces don't have scanlines! */
-        pso->lDelta = 0;
-        pso->cjBits = BitmapInfo->Size;
-        
-        /* Check for JPG or PNG */
-        if ((BitmapInfo->Format != BMF_JPEG) && (BitmapInfo->Format != BMF_PNG))
-        {
-            /* Wherever the bit data is */
-            pso->pvScan0 = pso->pvBits;
-        }
-        else
-        {
-            /* Fancy formats don't use a base address */
-            pso->pvScan0 = NULL;
-            ASSERT(FALSE); // ENGDDI shouldn't be creating PNGs for drivers ;-)
-        }
-    }
-    
+        /* Otherwise we start with the end and go up */
+        pso->pvScan0 = (PVOID)((ULONG_PTR)pso->pvBits + pso->cjBits - ScanLine);
+        pso->lDelta = -ScanLine;
+    }
+
    /* Finally set the handle and uniq */
    pso->hsurf = (HSURF)psurf->BaseObject.hHmgr;
    pso->iUniq = 0;

    