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..96ad8a093ec1b94bfc18355278a58d31c228c84a 100644
--- a/src/core/SkMatrix.cpp
+++ b/src/core/SkMatrix.cpp
@@ -290,7 +290,12 @@ void SkMatrix::preTranslate(SkScalar dx, SkScalar dy) {
         return;
     }
 
-    if (this->hasPerspective()) {
+    if (fTypeMask == kTranslate_Mask) {
+        fMat[kMTransX] += dx;
+        fMat[kMTransY] += dy;
+        // Translate x Translate == Translate
+        SkASSERT(kTranslate_Mask == this->computeTypeMask());

[reed1, 2016/08/18 19:28:18]

This could fail if the translate sent those fields to zero -- we'd be
identity...

[mtklein_C, 2016/08/18 19:35:59]

Good catch.  Fixed.

+    } else if (this->hasPerspective()) {
         SkMatrix    m;
         m.setTranslate(dx, dy);
         this->preConcat(m);