Fast path translate() in SkCanvas and SkLiteDL.

src/core/SkMatrix.cpp

Index: src/core/SkMatrix.cpp
diff --git a/src/core/SkMatrix.cpp b/src/core/SkMatrix.cpp
index 0fd802087fc0c5f52e6da2be56edbfb1b9fcc442..fb8b89e9f1feddd0a25fc2f21e38faaa69e10c79 100644
--- a/src/core/SkMatrix.cpp
+++ b/src/core/SkMatrix.cpp
@@ -290,7 +290,11 @@ void SkMatrix::preTranslate(SkScalar dx, SkScalar dy) {
         return;
     }
 
-    if (this->hasPerspective()) {
+    if (fTypeMask <= kTranslate_Mask) {
+        fMat[kMTransX] += dx;
+        fMat[kMTransY] += dy;
+        this->setTypeMask(kTranslate_Mask);

[reed1, 2016/08/18 21:22:20]

I *think* we can assert that the matrix is mislabeled if in fact it is
identity... Its possibly you need to actually check the resulting 2 floats and
set this bit conditionally.

+    } else if (this->hasPerspective()) {
         SkMatrix    m;
         m.setTranslate(dx, dy);
         this->preConcat(m);
@@ -1100,7 +1104,7 @@ void SkMatrix::mapVectors(SkPoint dst[], const SkPoint src[], int count) const {
 void SkMatrix::mapRectScaleTranslate(SkRect* dst, const SkRect& src) const {
     SkASSERT(dst);
     SkASSERT(this->isScaleTranslate());
-    
+
     SkScalar sx = fMat[kMScaleX];
     SkScalar sy = fMat[kMScaleY];
     SkScalar tx = fMat[kMTransX];