Fast path translate() in SkCanvas and SkLiteDL.

src/core/SkMatrix.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkFloatBits.h"
 #include "SkMatrix.h"
 #include "SkNx.h"
@@ skipping 272 matching lines @@
     } else {
         this->reset();
     }
 }
 
 void SkMatrix::preTranslate(SkScalar dx, SkScalar dy) {
     if (!dx && !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);
     } else {
         fMat[kMTransX] += sdot(fMat[kMScaleX], dx, fMat[kMSkewX], dy);
         fMat[kMTransY] += sdot(fMat[kMSkewY], dx, fMat[kMScaleY], dy);
         this->setTypeMask(kUnknown_Mask | kOnlyPerspectiveValid_Mask);
     }
 }
 
@@ skipping 1582 matching lines @@
     const SkScalar m10 = -m01;
     const SkScalar m11 = m00;
     const SkScalar m12 = fTy;
 
     quad[0].set(m02, m12);
     quad[1].set(m00 * width + m02, m10 * width + m12);
     quad[2].set(m00 * width + m01 * height + m02, m10 * width + m11 * height + m12);
     quad[3].set(m01 * height + m02, m11 * height + m12);
 #endif
 }