change mapRectScaleTranslate to pass args/ret by value

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2137853002

TBR=mtklein

Review-Url: https://codereview.chromium.org/2137853002

6 files changed, 15 insertions, 17 deletions

diff --git a/bench/MatrixBench.cpp b/bench/MatrixBench.cpp
index 53e7296731..185ea7924c 100644
--- a/bench/MatrixBench.cpp
+++ b/bench/MatrixBench.cpp
@@ -320,7 +320,7 @@ public:
         SkRect dst;
         if (fScaleTrans) {
             for (int i = 0; i < MEGA_LOOP; ++i) {
-                fM.mapRectScaleTranslate(&dst, fR);
+                dst = fM.mapRectScaleTranslate(fR);
             }
         } else {
             for (int i = 0; i < MEGA_LOOP; ++i) {
diff --git a/include/core/SkMatrix.h b/include/core/SkMatrix.h
index 5b22a77481..8f70d4c91b 100644
--- a/include/core/SkMatrix.h
+++ b/include/core/SkMatrix.h
@@ -565,7 +565,7 @@ public:
      *  Maps a rect to another rect, asserting (in debug mode) that the matrix only contains
      *  scale and translate elements. If it contains other elements, the results are undefined.
      */
-    void mapRectScaleTranslate(SkRect* dst, const SkRect& src) const;
+    SkRect mapRectScaleTranslate(SkRect src) const;
     
     /** Return the mean radius of a circle after it has been mapped by
         this matrix. NOTE: in perspective this value assumes the circle
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index 0ce97fff20..23442779ce 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -75,13 +75,11 @@ bool SkCanvas::wouldOverwriteEntireSurface(const SkRect* rect, const SkPaint* pa
     }
 
     if (rect) {
-        if (!this->getTotalMatrix().isScaleTranslate()) {
+        const SkMatrix& ctm = this->getTotalMatrix();
+        if (!ctm.isScaleTranslate()) {
             return false; // conservative
         }
-
-        SkRect devRect;
-        this->getTotalMatrix().mapRectScaleTranslate(&devRect, *rect);
-        if (!devRect.contains(bounds)) {
+        if (!ctm.mapRectScaleTranslate(*rect).contains(bounds)) {
             return false;
         }
     }
@@ -1544,8 +1542,7 @@ void SkCanvas::clipRect(const SkRect& rect, SkRegion::Op op, bool doAA) {
     // Check if we can quick-accept the clip call (and do nothing)
     //
     if (SkRegion::kIntersect_Op == op && !doAA && fMCRec->fMatrix.isScaleTranslate()) {
-        SkRect devR;
-        fMCRec->fMatrix.mapRectScaleTranslate(&devR, rect);
+        SkRect devR = fMCRec->fMatrix.mapRectScaleTranslate(rect);
         // NOTE: this check is CTM specific, since we might round differently with a different
         //       CTM. Thus this is only 100% reliable if there is not global CTM scale to be
         //       applied later (i.e. if this is going into a picture).
@@ -1585,7 +1582,7 @@ void SkCanvas::onClipRect(const SkRect& rect, SkRegion::Op op, ClipEdgeStyle edg
     const bool isScaleTrans = fMCRec->fMatrix.isScaleTranslate();
     SkRect devR;
     if (isScaleTrans) {
-        fMCRec->fMatrix.mapRectScaleTranslate(&devR, rect);
+        devR = fMCRec->fMatrix.mapRectScaleTranslate(rect);
     }
 
 #ifndef SK_SUPPORT_PRECHECK_CLIPRECT
diff --git a/src/core/SkMatrix.cpp b/src/core/SkMatrix.cpp
index 492f3f6ac4..71ef24c5e8 100644
--- a/src/core/SkMatrix.cpp
+++ b/src/core/SkMatrix.cpp
@@ -1097,8 +1097,7 @@ void SkMatrix::mapVectors(SkPoint dst[], const SkPoint src[], int count) const {
     }
 }
 
-void SkMatrix::mapRectScaleTranslate(SkRect* dst, const SkRect& src) const {
-    SkASSERT(dst);
+SkRect SkMatrix::mapRectScaleTranslate(SkRect src) const {
     SkASSERT(this->isScaleTranslate());
     
     SkScalar sx = fMat[kMScaleX];
@@ -1107,7 +1106,7 @@ void SkMatrix::mapRectScaleTranslate(SkRect* dst, const SkRect& src) const {
     SkScalar ty = fMat[kMTransY];
     Sk4f scale(sx, sy, sx, sy);
     Sk4f trans(tx, ty, tx, ty);
-
+    
     Sk4f ltrb = Sk4f::Load(&src.fLeft) * scale + trans;
     // need to sort so we're not inverted
     Sk4f rblt(ltrb[2], ltrb[3], ltrb[0], ltrb[1]);
@@ -1115,14 +1114,16 @@ void SkMatrix::mapRectScaleTranslate(SkRect* dst, const SkRect& src) const {
     Sk4f max = Sk4f::Max(ltrb, rblt);
     // We can extract either pair [0,1] or [2,3] from min and max and be correct, but on
     // ARM this sequence generates the fastest (a single instruction).
-    Sk4f(min[2], min[3], max[0], max[1]).store(&dst->fLeft);
+    SkRect dst;
+    Sk4f(min[0], min[1], max[0], max[1]).store(&dst.fLeft);
+    return dst;
 }
 
 bool SkMatrix::mapRect(SkRect* dst, const SkRect& src) const {
     SkASSERT(dst);
 
     if (this->isScaleTranslate()) {
-        this->mapRectScaleTranslate(dst, src);
+        *dst = this->mapRectScaleTranslate(src);
         return true;
     } else {
         SkPoint quad[4];
diff --git a/src/utils/SkDeferredCanvas.cpp b/src/utils/SkDeferredCanvas.cpp
index 14220209cc..c8a37c36b7 100644
--- a/src/utils/SkDeferredCanvas.cpp
+++ b/src/utils/SkDeferredCanvas.cpp
@@ -200,7 +200,7 @@ void SkDeferredCanvas::flush_check(SkRect* bounds, const SkPaint* paint, unsigne
                 if (canScale) {
                     SkMatrix m;
                     rec.getConcat(&m);
-                    m.mapRectScaleTranslate(bounds, *bounds);
+                    *bounds = m.mapRectScaleTranslate(*bounds);
                 } else {
                     goto STOP;
                 }
diff --git a/tests/MatrixTest.cpp b/tests/MatrixTest.cpp
index c4eb9c7011..4386c5f491 100644
--- a/tests/MatrixTest.cpp
+++ b/tests/MatrixTest.cpp
@@ -978,7 +978,7 @@ DEF_TEST(Matrix_maprects, r) {
         mat.mapPoints((SkPoint*)&dst[0].fLeft, (SkPoint*)&src.fLeft, 2);
         dst[0].sort();
         mat.mapRect(&dst[1], src);
-        mat.mapRectScaleTranslate(&dst[2], src);
+        dst[2] = mat.mapRectScaleTranslate(src);
 
         REPORTER_ASSERT(r, dst[0] == dst[1]);
         REPORTER_ASSERT(r, dst[0] == dst[2]);