rootston: damage tracking scale support

1 files changed, 29 insertions, 0 deletions

diff --git a/util/region.c b/util/region.c
new file mode 100644
index 00000000..da66d92c
--- /dev/null
+++ b/util/region.c
@@ -0,0 +1,29 @@
+#include <stdlib.h>
+#include <math.h>
+#include <wlr/util/region.h>
+
+void wlr_region_scale(pixman_region32_t *dst, pixman_region32_t *src,
+		float scale) {
+	if (scale == 1) {
+		pixman_region32_copy(dst, src);
+		return;
+	}
+
+	int nrects;
+	pixman_box32_t *src_rects = pixman_region32_rectangles(src, &nrects);
+
+	pixman_box32_t *dst_rects = malloc(nrects * sizeof(pixman_box32_t));
+	if (dst_rects == NULL) {
+		return;
+	}
+
+	for (int i = 0; i < nrects; ++i) {
+		dst_rects[i].x1 = floor(src_rects[i].x1 * scale);
+		dst_rects[i].x2 = ceil(src_rects[i].x2 * scale);
+		dst_rects[i].y1 = floor(src_rects[i].y1 * scale);
+		dst_rects[i].y2 = ceil(src_rects[i].y2 * scale);
+	}
+
+	pixman_region32_fini(dst);
+	pixman_region32_init_rects(dst, dst_rects, nrects);
+}