Add SkRRect::transform.
Much like SkPath::transform, it transforms an SkRRect based on an
SkMatrix. Unlike SkPath::transform, it will fail for matrices that
contain perspective or skewing.
Required by a future change (https://codereview.chromium.org/48623006)
to speed up drawing large blurry rounded rectangles by using ninepatches.
TODO: This could easily support 90 degree rotations, if desired.
BUG=https://b.corp.google.com/issue?id=11174385
R=reed@google.com, robertphillips@google.com
Review URL: https://codereview.chromium.org/52703003
git-svn-id: http://skia.googlecode.com/svn/trunk/src@12132 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/core/SkRRect.cpp b/core/SkRRect.cpp
index bcbf37e..e5296d4 100644
--- a/core/SkRRect.cpp
+++ b/core/SkRRect.cpp
@@ -6,6 +6,7 @@
*/
#include "SkRRect.h"
+#include "SkMatrix.h"
///////////////////////////////////////////////////////////////////////////////
@@ -233,6 +234,85 @@
fType = kComplex_Type;
}
+static bool matrix_only_scale_and_translate(const SkMatrix& matrix) {
+ const SkMatrix::TypeMask m = (SkMatrix::TypeMask) (SkMatrix::kAffine_Mask
+ | SkMatrix::kPerspective_Mask);
+ return (matrix.getType() & m) == 0;
+}
+
+bool SkRRect::transform(const SkMatrix& matrix, SkRRect* dst) const {
+ if (NULL == dst) {
+ return false;
+ }
+
+ // Assert that the caller is not trying to do this in place, which
+ // would violate const-ness. Do not return false though, so that
+ // if they know what they're doing and want to violate it they can.
+ SkASSERT(dst != this);
+
+ if (matrix.isIdentity()) {
+ *dst = *this;
+ return true;
+ }
+
+ // If transform supported 90 degree rotations (which it could), we could
+ // use SkMatrix::rectStaysRect() to check for a valid transformation.
+ if (!matrix_only_scale_and_translate(matrix)) {
+ return false;
+ }
+
+ SkRect newRect;
+ if (!matrix.mapRect(&newRect, fRect)) {
+ return false;
+ }
+
+ // At this point, this is guaranteed to succeed, so we can modify dst.
+ dst->fRect = newRect;
+
+ // Now scale each corner
+ SkScalar xScale = matrix.getScaleX();
+ const bool flipX = xScale < 0;
+ if (flipX) {
+ xScale = -xScale;
+ }
+ SkScalar yScale = matrix.getScaleY();
+ const bool flipY = yScale < 0;
+ if (flipY) {
+ yScale = -yScale;
+ }
+
+ // Scale the radii without respecting the flip.
+ for (int i = 0; i < 4; ++i) {
+ dst->fRadii[i].fX = SkScalarMul(fRadii[i].fX, xScale);
+ dst->fRadii[i].fY = SkScalarMul(fRadii[i].fY, yScale);
+ }
+
+ // Now swap as necessary.
+ if (flipX) {
+ if (flipY) {
+ // Swap with opposite corners
+ SkTSwap(dst->fRadii[kUpperLeft_Corner], dst->fRadii[kLowerRight_Corner]);
+ SkTSwap(dst->fRadii[kUpperRight_Corner], dst->fRadii[kLowerLeft_Corner]);
+ } else {
+ // Only swap in x
+ SkTSwap(dst->fRadii[kUpperRight_Corner], dst->fRadii[kUpperLeft_Corner]);
+ SkTSwap(dst->fRadii[kLowerRight_Corner], dst->fRadii[kLowerLeft_Corner]);
+ }
+ } else if (flipY) {
+ // Only swap in y
+ SkTSwap(dst->fRadii[kUpperLeft_Corner], dst->fRadii[kLowerLeft_Corner]);
+ SkTSwap(dst->fRadii[kUpperRight_Corner], dst->fRadii[kLowerRight_Corner]);
+ }
+
+ // Since the only transforms that were allowed are scale and translate, the type
+ // remains unchanged.
+ dst->fType = fType;
+
+ SkDEBUGCODE(dst->validate();)
+
+ return true;
+}
+
///////////////////////////////////////////////////////////////////////////////
void SkRRect::inset(SkScalar dx, SkScalar dy, SkRRect* dst) const {
