Fix some region transform bugs (mono#526)

* Fix some region transform bugs * Fix checking of infinite regions and their scans Fixes mono#507 Fixes mono#438 Fixes mono#529 Fixes mono#528 Fixes mono#527

Author: hughbe

src/region.c

@@ -320,10 +320,16 @@ gdip_is_region_empty (const GpRegion *region, BOOL allowNegative)
 static BOOL
 gdip_is_rect_infinite (const GpRectF *rect)
 {
-return (rect && (rect->X == REGION_INFINITE_POSITION) && 
-(rect->Y == REGION_INFINITE_POSITION) &&
-(rect->Width == REGION_INFINITE_LENGTH) && 
-(rect->Height == REGION_INFINITE_LENGTH));
+if (!rect)
+return FALSE;
+
+if (gdip_is_rectF_empty (rect, /* allowNegative */ TRUE))
+return FALSE;
+
+if (rect->Width >= REGION_INFINITE_LENGTH || rect->Height >= REGION_INFINITE_LENGTH)
+return TRUE;
+
+return FALSE;
 }
 
 BOOL
@@ -2039,18 +2045,17 @@ GdipGetRegionScans (GpRegion *region, GpRectF* rects, INT* count, GpMatrix* matr
 
 if (gdip_is_region_empty (work, /* allowNegative */ TRUE)) {
 *count = 0;
+} else if (gdip_is_InfiniteRegion (work)) {
+if (rects) {
+rects->X = REGION_INFINITE_POSITION;
+rects->Y = REGION_INFINITE_POSITION;
+rects->Width = REGION_INFINITE_LENGTH;
+rects->Height = REGION_INFINITE_LENGTH;
+}
+
+*count = 1;
 } else {
 switch (region->type) {
-case RegionTypeInfinite:
-if (rects) {
-rects->X = REGION_INFINITE_POSITION;
-rects->Y = REGION_INFINITE_POSITION;
-rects->Width = REGION_INFINITE_LENGTH;
-rects->Height = REGION_INFINITE_LENGTH;
-}
-
-*count = 1;
-break;
 case RegionTypeRect:
 if (rects) {
 for (int i = 0; i < work->cnt; i++) {
@@ -2208,10 +2213,8 @@ GdipTranslateRegion (GpRegion *region, float dx, float dy)
 if (!region)
 return InvalidParameter;
 
-/* can't transforman infinite region to anything else than an infinite region 
- * (even if you scale it by half it's still infinite ;-) see unit tests
- */
-if (gdip_is_InfiniteRegion (region))
+// Infinite regions cannot be transformed.
+if (region->type == RegionTypeInfinite)
 return Ok;
 
 switch (region->type) {
@@ -2251,18 +2254,14 @@ GdipTranslateRegionI (GpRegion *region, int dx, int dy)
 static GpStatus
 ScaleRegion (GpRegion *region, float sx, float sy)
 {
-if (!region)
-return InvalidParameter;
+g_assert (region);
+g_assert (region->type == RegionTypeRect && region->rects);
 
-if ((region->type == RegionTypeRect) && region->rects) {
-int i;
-GpRectF *rect;
-for (i = 0, rect = region->rects ; i < region->cnt; i++, rect++) {
-rect->X *= sx;
-rect->Y *= sy;
-rect->Width *= sx;
-rect->Height *= sy;
-}
+for (int i = 0; i < region->cnt; i++) {
+region->rects[i].X *= sx;
+region->rects[i].Y *= sy;
+region->rects[i].Width *= sx;
+region->rects[i].Height *= sy;
 }
 
 return Ok;
@@ -2276,43 +2275,36 @@ GdipTransformRegion (GpRegion *region, GpMatrix *matrix)
 if (!region || !matrix)
 return InvalidParameter;
 
-/* no transformation to do on an empty region */
-if ((region->cnt == 0) && (region->type == RegionTypeRect))
+// Infinite and empty regions cannot be transformed.
+if (region->type == RegionTypeInfinite || ((region->cnt == 0) && (region->type == RegionTypeRect)))
 return Ok;
 
-/* don't (possibly) convert to a bitmap if the matrix is empty (a no-op) */
+// Nothing to do.
 if (gdip_is_matrix_empty (matrix))
 return Ok;
 
-/* can't transforman infinite region to anything else than an infinite region 
- * (even if you scale it by half it's still infinite ;-) see unit tests
- */
-if (gdip_is_InfiniteRegion (region))
-return Ok;
+BOOL isSimpleMatrix = (matrix->xy == 0) && (matrix->yx == 0);
+BOOL matrixHasTranslate = (matrix->x0 != 0) || (matrix->y0 != 0);
+BOOL matrixHasScale = (matrix->xx != 1) || (matrix->yy != 1);
 
 /* try to avoid heavy stuff (e.g. conversion to path, invalidating 
  * bitmap...) if the transform is:
  * - a translation + scale operations (for rectangle ebased region)
  * - only to do a scale operation (for a rectangle based region)
  * - only to do a simple translation (for both rectangular and bitmap based regions)
  */
-if ((matrix->xy == 0.0f) && (matrix->yx == 0.0f)) {
-BOOL s = (((matrix->xx != 1.0f) || (matrix->yy != 1.0f)) && (region->type == RegionTypeRect));
-BOOL t = ((matrix->x0 != 0.0f) || (matrix->yx != 0.0f));
-if (s) {
-status = ScaleRegion (region, 
-gdip_matrix_get_x_scale (matrix), 
-gdip_matrix_get_y_scale (matrix));
-}
-if (t && (status == Ok)) {
-status = GdipTranslateRegion (region, 
-gdip_matrix_get_x_translation (matrix), 
-gdip_matrix_get_y_translation (matrix));
-}
+if (region->type == RegionTypeRect) {
+if (isSimpleMatrix) {
+if (matrixHasScale)
+ScaleRegion (region, matrix->xx, matrix->yy);
+if (matrixHasTranslate)
+GdipTranslateRegion (region, matrix->x0, matrix->y0);
 
-/* return now if we could optimize the transform (to avoid bitmaps) */
-if (t || s)
-return status;
+return Ok;
+}
+} else if (isSimpleMatrix && !matrixHasScale) {
+GdipTranslateRegion (region, matrix->x0, matrix->y0);
+return Ok;
 }
 
 /* most matrix operations would change the rectangles into path so we always preempt this */