render/pixman: avoid sqrt() in render_quad without rotation
When the matrix doesn't have a rotation, we can avoid a sqrt() call.
Tested with Sway's tabbed containers.
@@ -230,10 +230,14 @@ static void pixman_render_quad_with_matrix(struct wlr_renderer *wlr_renderer,
memcpy(m, matrix, sizeof(m));
// TODO get the width/height from the caller instead of extracting them
- // TODO detect non rotation with matrix[1] == 0 and matrix[4] == 0 to avoid
- // doing the calculation
- float width = sqrt(matrix[0] * matrix[0] + matrix[1] * matrix[1]);
- float height = sqrt(matrix[3] * matrix[3] + matrix[4] * matrix[4]);
+ float width, height;
+ if (matrix[1] == 0.0 && matrix[3] == 0.0) {
+ width = fabs(matrix[0]);
+ height = fabs(matrix[4]);
+ } else {
+ width = sqrt(matrix[0] * matrix[0] + matrix[1] * matrix[1]);
+ height = sqrt(matrix[3] * matrix[3] + matrix[4] * matrix[4]);
+ }
wlr_matrix_scale(m, 1.0 / width, 1.0 / height);
