gdi32: Avoid unnecessary calls to get_dc_ptr().

dlls/gdi32/dibdrv/bitblt.c

@@ -1390,18 +1390,12 @@ COLORREF get_pixel_bitmapinfo( const BITMAPINFO *info, void *bits, struct bitblt
 BOOL dibdrv_StretchBlt( PHYSDEV dst_dev, struct bitblt_coords *dst,
                         PHYSDEV src_dev, struct bitblt_coords *src, DWORD rop )
 {
-    BOOL ret;
-    DC *dc_dst = get_dc_ptr( dst_dev->hdc );
-
-    if (!dc_dst) return FALSE;
+    DC *dc_dst = get_physdev_dc( dst_dev );
 
     if (dst->width == 1 && src->width > 1) src->width--;
     if (dst->height == 1 && src->height > 1) src->height--;
 
-    ret = dc_dst->nulldrv.funcs->pStretchBlt( &dc_dst->nulldrv, dst,
-                                              src_dev, src, rop );
-    release_dc_ptr( dc_dst );
-    return ret;
+    return dc_dst->nulldrv.funcs->pStretchBlt( &dc_dst->nulldrv, dst, src_dev, src, rop );
 }
 
 /***********************************************************************
@@ -1410,14 +1404,9 @@ BOOL dibdrv_StretchBlt( PHYSDEV dst_dev, struct bitblt_coords *dst,
 BOOL dibdrv_AlphaBlend( PHYSDEV dst_dev, struct bitblt_coords *dst,
                         PHYSDEV src_dev, struct bitblt_coords *src, BLENDFUNCTION blend )
 {
-    BOOL ret;
-    DC *dc_dst = get_dc_ptr( dst_dev->hdc );
+    DC *dc_dst = get_physdev_dc( dst_dev );
 
-    if (!dc_dst) return FALSE;
-
-    ret = dc_dst->nulldrv.funcs->pAlphaBlend( &dc_dst->nulldrv, dst, src_dev, src, blend );
-    release_dc_ptr( dc_dst );
-    return ret;
+    return dc_dst->nulldrv.funcs->pAlphaBlend( &dc_dst->nulldrv, dst, src_dev, src, blend );
 }
 
 /***********************************************************************

dlls/gdi32/gdi_private.h

@@ -469,6 +469,13 @@ static inline DC *get_nulldrv_dc( PHYSDEV dev )
     return CONTAINING_RECORD( dev, DC, nulldrv );
 }
 
+static inline DC *get_physdev_dc( PHYSDEV dev )
+{
+    while (dev->funcs != &null_driver)
+        dev = dev->next;
+    return get_nulldrv_dc( dev );
+}
+
 /* Undocumented value for DIB's iUsage: Indicates a mono DIB w/o pal entries */
 #define DIB_PAL_MONO 2