From 2170901e6ac6f0565bfd854d4a3ddc19d87a0050 Mon Sep 17 00:00:00 2001
From: Timo Kreuzer <timo.kreuzer@reactos.org>
Date: Sun, 11 Mar 2018 23:03:38 +0100
Subject: [PATCH] [WIN32K] Implement RECTL_bClipRectBySize() and use it in
 IntEngBitBlt() to clip the target rect against the bounds of the target
 surface. Also clip the source rect against the source surface. Fixes
 remaining part of CORE-14463

---
 win32ss/gdi/eng/bitblt.c     | 32 ++++++++++++++++++++++++++------
 win32ss/gdi/eng/bitblt_new.c |  9 +++++----
 win32ss/gdi/ntgdi/rect.h     | 14 ++++++++++++++
 3 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/win32ss/gdi/eng/bitblt.c b/win32ss/gdi/eng/bitblt.c
index 9c3e1d1183a..8eea77535bb 100644
--- a/win32ss/gdi/eng/bitblt.c
+++ b/win32ss/gdi/eng/bitblt.c
@@ -619,20 +619,26 @@ IntEngBitBlt(
     BOOL bResult;
     RECTL rclClipped;
     RECTL rclSrc;
+    RECTL rclSrcClipped;
     POINTL ptlBrush;
     PFN_DrvBitBlt pfnBitBlt;
 
+    /* Sanity checks */
+    ASSERT(IS_VALID_ROP4(Rop4));
     ASSERT(psoTrg);
+
     psurfTrg = CONTAINING_RECORD(psoTrg, SURFACE, SurfObj);
 
-    /* FIXME: Should we really allow to pass non-well-ordered rects? */
+    /* Get the target rect and make it well ordered */
     rclClipped = *prclTrg;
     RECTL_vMakeWellOrdered(&rclClipped);
 
-    //DPRINT1("Rop4 : 0x%08x\n", Rop4);
-
-    /* Sanity check */
-    ASSERT(IS_VALID_ROP4(Rop4));
+    /* Clip the target rect against the bounds of the target surface */
+    if (!RECTL_bClipRectBySize(&rclClipped, &rclClipped, &psoTrg->sizlBitmap))
+    {
+        /* Nothing left */
+        return TRUE;
+    }
 
     if (pco)
     {
@@ -660,7 +666,21 @@ IntEngBitBlt(
         rclSrc.top = pptlSrc->y + rclClipped.top - prclTrg->top;
         rclSrc.right = rclSrc.left + rclClipped.right - rclClipped.left;
         rclSrc.bottom = rclSrc.top + rclClipped.bottom - rclClipped.top;
-        pptlSrc = (PPOINTL)&rclSrc;
+
+        /* Clip the source rect against the size of the source surface */
+        if (!RECTL_bClipRectBySize(&rclSrcClipped, &rclSrc, &psoSrc->sizlBitmap))
+        {
+            /* Nothing left */
+            return TRUE;
+        }
+
+        /* Fix up target rect */
+        rclClipped.left += (rclSrcClipped.left - rclSrc.left);
+        rclClipped.top += (rclSrcClipped.top - rclSrc.top);
+        rclClipped.right -= (rclSrc.right - rclSrcClipped.right);
+        rclClipped.bottom -= (rclSrc.bottom - rclSrcClipped.bottom);
+
+        pptlSrc = (PPOINTL)&rclSrcClipped;
     }
     else
     {
diff --git a/win32ss/gdi/eng/bitblt_new.c b/win32ss/gdi/eng/bitblt_new.c
index 56bfade89f4..d97886626ad 100644
--- a/win32ss/gdi/eng/bitblt_new.c
+++ b/win32ss/gdi/eng/bitblt_new.c
@@ -410,10 +410,11 @@ IntEngBitBlt(
     ASSERT(prclTrg);
 
     /* Clip the target rect to the extents of the target surface */
-    rcClipped.left = max(prclTrg->left, 0);
-    rcClipped.top = max(prclTrg->top, 0);
-    rcClipped.right = min(prclTrg->right, psoTrg->sizlBitmap.cx);
-    rcClipped.bottom = min(prclTrg->bottom, psoTrg->sizlBitmap.cy);
+    if (!RECTL_bClipRectBySize(&rcClipped, prclTrg, &psoTrg->sizlBitmap))
+    {
+        /* Nothing left */
+        return TRUE;
+    }
 
     /* If no clip object is given, use trivial one */
     if (!pco) pco = (CLIPOBJ*)&gxcoTrivial;
diff --git a/win32ss/gdi/ntgdi/rect.h b/win32ss/gdi/ntgdi/rect.h
index 6e975c5f945..a268311ad27 100644
--- a/win32ss/gdi/ntgdi/rect.h
+++ b/win32ss/gdi/ntgdi/rect.h
@@ -67,6 +67,20 @@ RECTL_bIsWellOrdered(
             (prcl->top  <= prcl->bottom));
 }
 
+FORCEINLINE
+BOOL
+RECTL_bClipRectBySize(
+    _Out_ RECTL *prclDst,
+    _In_ const RECTL *prclSrc,
+    _In_ const SIZEL *pszl)
+{
+    prclDst->left = max(prclSrc->left, 0);
+    prclDst->top = max(prclSrc->top, 0);
+    prclDst->right = min(prclSrc->right, pszl->cx);
+    prclDst->bottom = min(prclSrc->bottom, pszl->cy);
+    return !RECTL_bIsEmptyRect(prclDst);
+}
+
 BOOL
 FASTCALL
 RECTL_bUnionRect(