[PATCH v4] gdi32: CreatePolyPolygonRgn() returns an empty region when the area is empty.

[Huw Davies]

From: Fabian Maurer <dark.shadow4(a)web.de>

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=46655
Signed-off-by: Fabian Maurer <dark.shadow4(a)web.de>
Signed-off-by: Huw Davies <huw(a)codeweavers.com>
---
 dlls/gdi32/region.c         |  3 +--
 dlls/gdi32/tests/clipping.c | 39 +++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/dlls/gdi32/region.c b/dlls/gdi32/region.c
index cad6428dc9..93238b5a84 100644
--- a/dlls/gdi32/region.c
+++ b/dlls/gdi32/region.c
@@ -2627,8 +2627,7 @@ HRGN create_polypolygon_region( const POINT *Pts, const INT *Count, INT nbpolygo
     if (! (pETEs = HeapAlloc( GetProcessHeap(), 0, sizeof(EdgeTableEntry) * total )))
 	return 0;
 
-    if (!(nb_points = REGION_CreateEdgeTable( Count, nbpolygons, Pts, &ET, pETEs, &SLLBlock, clip_rect )))
-        goto done;
+    nb_points = REGION_CreateEdgeTable( Count, nbpolygons, Pts, &ET, pETEs, &SLLBlock, clip_rect );
     if (!(obj = alloc_region( nb_points / 2 )))
         goto done;
 
diff --git a/dlls/gdi32/tests/clipping.c b/dlls/gdi32/tests/clipping.c
index 60bd31e8e4..d04ef77ca3 100644
--- a/dlls/gdi32/tests/clipping.c
+++ b/dlls/gdi32/tests/clipping.c
@@ -533,6 +533,44 @@ static void test_window_dc_clipping(void)
     DestroyWindow(hwnd);
 }
 
+static void test_CreatePolyPolygonRgn(void)
+{
+    HRGN region;
+    POINT points_zero[] = { {0, 0}, {0, 0}, {0, 0} };
+    POINT points_mixed[] = { {0, 0}, {0, 0}, {0, 0}, {6, 6}, {6, 6}, {6, 6} };
+    POINT points_six[] = { {6, 6}, {6, 6}, {6, 6} };
+    POINT points_line[] = { {1, 0}, {11, 0}, {21, 0}};
+    INT counts_single_poly[] = { 3 };
+    INT counts_two_poly[] = { 3, 3 };
+    int ret;
+    RECT rect;
+
+    /* When all polygons are just one point or line, return must not be NULL */
+
+    region = CreatePolyPolygonRgn(points_zero, counts_single_poly, ARRAY_SIZE(counts_single_poly), ALTERNATE);
+    ok (region != NULL, "region must not be NULL\n");
+    ret = GetRgnBox(region, &rect);
+    ok (ret == NULLREGION, "Expected NULLREGION, got %d\n", ret);
+    DeleteObject(region);
+
+    region = CreatePolyPolygonRgn(points_six, counts_single_poly, ARRAY_SIZE(counts_single_poly), ALTERNATE);
+    ok (region != NULL, "region must not be NULL\n");
+    ret = GetRgnBox(region, &rect);
+    ok (ret == NULLREGION, "Expected NULLREGION, got %d\n", ret);
+    DeleteObject(region);
+
+    region = CreatePolyPolygonRgn(points_line, counts_single_poly, ARRAY_SIZE(counts_single_poly), ALTERNATE);
+    ok (region != NULL, "region must not be NULL\n");
+    ret = GetRgnBox(region, &rect);
+    ok (ret == NULLREGION, "Expected NULLREGION, got %d\n", ret);
+    DeleteObject(region);
+
+    region = CreatePolyPolygonRgn(points_mixed, counts_two_poly, ARRAY_SIZE(counts_two_poly), ALTERNATE);
+    ok (region != NULL, "region must not be NULL\n");
+    ret = GetRgnBox(region, &rect);
+    ok (ret == NULLREGION, "Expected NULLREGION, got %d\n", ret);
+    DeleteObject(region);
+}
 
 START_TEST(clipping)
 {
@@ -541,4 +579,5 @@ START_TEST(clipping)
     test_GetClipRgn();
     test_memory_dc_clipping();
     test_window_dc_clipping();
+    test_CreatePolyPolygonRgn();
 }
-- 
2.18.0