winex11.drv: Report a non-zero COLORRES capability value.

dlls/gdi32/tests/dc.c

@@ -556,6 +556,45 @@ static void test_boundsrect_invalid(void)
     DeleteDC(hdc);
 }
 
+static void test_desktop_colorres(void)
+{
+    HDC hdc = GetDC(NULL);
+    int bitspixel, colorres;
+
+    bitspixel = GetDeviceCaps(hdc, BITSPIXEL);
+    ok(bitspixel != 0, "Expected to get valid BITSPIXEL capability value\n");
+
+    colorres = GetDeviceCaps(hdc, COLORRES);
+    ok(colorres != 0 ||
+       broken(colorres == 0), /* Win9x */
+       "Expected to get valid COLORRES capability value\n");
+
+    if (colorres)
+    {
+        switch (bitspixel)
+        {
+        case 8:
+            ok(colorres == 18,
+               "Expected COLORRES to be 18, got %d\n", colorres);
+            break;
+        case 16:
+            ok(colorres == 16,
+               "Expected COLORRES to be 16, got %d\n", colorres);
+            break;
+        case 24:
+        case 32:
+            ok(colorres == 24,
+               "Expected COLORRES to be 24, got %d\n", bitspixel);
+            break;
+        default:
+            ok(0, "Got unknown BITSPIXEL %d with COLORRES %d\n", bitspixel, colorres);
+            break;
+        }
+    }
+
+    DeleteDC(hdc);
+}
+
 START_TEST(dc)
 {
     test_savedc();
@@ -565,4 +604,5 @@ START_TEST(dc)
     test_DC_bitmap();
     test_DeleteDC();
     test_boundsrect_invalid();
+    test_desktop_colorres();
 }

dlls/winex11.drv/init.c

@@ -235,6 +235,15 @@ INT CDECL X11DRV_GetDeviceCaps( X11DRV_PDEVICE *physDev, INT cap )
         return text_caps;
     case CLIPCAPS:
         return CP_REGION;
+    case COLORRES:
+        /* The observed correspondence between BITSPIXEL and COLORRES is:
+         * BITSPIXEL: 8  -> COLORRES: 18
+         * BITSPIXEL: 16 -> COLORRES: 16
+         * BITSPIXEL: 24 -> COLORRES: 24
+         * (note that depth_to_bpp never chooses a bpp of 24)
+         * BITSPIXEL: 32 -> COLORRES: 24 */
+        return (screen_bpp <= 8) ? 18 :
+               (screen_bpp == 32) ? 24 : screen_bpp;
     case RASTERCAPS:
         return (RC_BITBLT | RC_BANDING | RC_SCALING | RC_BITMAP64 | RC_DI_BITMAP |
                 RC_DIBTODEV | RC_BIGFONT | RC_STRETCHBLT | RC_STRETCHDIB | RC_DEVBITS |
@@ -258,7 +267,6 @@ INT CDECL X11DRV_GetDeviceCaps( X11DRV_PDEVICE *physDev, INT cap )
     case SIZEPALETTE:
         return palette_size;
     case NUMRESERVED:
-    case COLORRES:
     case PHYSICALWIDTH:
     case PHYSICALHEIGHT:
     case PHYSICALOFFSETX: