compositor: Move weston_matrix_transform_region to compositor.c and export it
We're going to use this to replace much of the other transform code so
it's no longer just relevant to pixman-renderer.c
Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
[Pekka: add the warning about matrix restrictions]
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/src/compositor.c b/src/compositor.c
index 67be07d..bbac110 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -726,6 +726,63 @@
return ret;
}
+/** Transform a region by a matrix, restricted to axis-aligned transformations
+ *
+ * Warning: This function does not work for projective, affine, or matrices
+ * that encode arbitrary rotations. Only 90-degree step rotations are
+ * supported.
+ */
+WL_EXPORT void
+weston_matrix_transform_region(pixman_region32_t *dest,
+ struct weston_matrix *matrix,
+ pixman_region32_t *src)
+{
+ pixman_box32_t *src_rects, *dest_rects;
+ int nrects, i;
+
+ src_rects = pixman_region32_rectangles(src, &nrects);
+ dest_rects = malloc(nrects * sizeof(*dest_rects));
+ if (!dest_rects)
+ return;
+
+ for (i = 0; i < nrects; i++) {
+ struct weston_vector vec1 = {{
+ src_rects[i].x1, src_rects[i].y1, 0, 1
+ }};
+ weston_matrix_transform(matrix, &vec1);
+ vec1.f[0] /= vec1.f[3];
+ vec1.f[1] /= vec1.f[3];
+
+ struct weston_vector vec2 = {{
+ src_rects[i].x2, src_rects[i].y2, 0, 1
+ }};
+ weston_matrix_transform(matrix, &vec2);
+ vec2.f[0] /= vec2.f[3];
+ vec2.f[1] /= vec2.f[3];
+
+ if (vec1.f[0] < vec2.f[0]) {
+ dest_rects[i].x1 = floor(vec1.f[0]);
+ dest_rects[i].x2 = ceil(vec2.f[0]);
+ } else {
+ dest_rects[i].x1 = floor(vec2.f[0]);
+ dest_rects[i].x2 = ceil(vec1.f[0]);
+ }
+
+
+ if (vec1.f[1] < vec2.f[1]) {
+ dest_rects[i].y1 = floor(vec1.f[1]);
+ dest_rects[i].y2 = ceil(vec2.f[1]);
+ } else {
+ dest_rects[i].y1 = floor(vec2.f[1]);
+ dest_rects[i].y2 = ceil(vec1.f[1]);
+ }
+ }
+
+ pixman_region32_clear(dest);
+ pixman_region32_init_rects(dest, dest_rects, nrects);
+ free(dest_rects);
+}
+
WL_EXPORT void
weston_transformed_region(int width, int height,
enum wl_output_transform transform,