Optimize SkTileImageFilter in an offset filter when possible.

src/effects/SkTileImageFilter.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTileImageFilter.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
+#include "SkOffsetImageFilter.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkMatrix.h"
 #include "SkPaint.h"
 #include "SkShader.h"
 #include "SkValidationUtils.h"
 
 SkImageFilter* SkTileImageFilter::Create(const SkRect& srcRect, const SkRect& dstRect,
                                          SkImageFilter* input) {
     if (!SkIsValidRect(srcRect) || !SkIsValidRect(dstRect)) {
         return nullptr;
     }

[robertphillips, 2016/01/12 14:18:29]

Can this fit on one line ?

[Stephen White, 2016/01/12 14:23:12]

Done.

+    if (srcRect.width() == dstRect.width() &&
+        srcRect.height() == dstRect.height()) {
+        SkRect ir = dstRect;
+        if (!ir.intersect(srcRect)) {
+            return SkSafeRef(input);
+        }
+        CropRect cropRect(ir);
+        return SkOffsetImageFilter::Create(dstRect.x() - srcRect.x(),
+                                           dstRect.y() - srcRect.y(),
+                                           input, &cropRect);
+    }
     return new SkTileImageFilter(srcRect, dstRect, input);
 }
 
 bool SkTileImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src,
                                       const Context& ctx,
                                       SkBitmap* dst, SkIPoint* offset) const {
     SkBitmap source = src;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
     if (!this->filterInput(0, proxy, src, ctx, &source, &srcOffset)) {
         return false;
@@ skipping 113 matching lines @@
     str->appendf(" dst: %.2f %.2f %.2f %.2f",
                  fDstRect.fLeft, fDstRect.fTop, fDstRect.fRight, fDstRect.fBottom);
     if (this->getInput(0)) {
         str->appendf("input: (");
         this->getInput(0)->toString(str);
         str->appendf(")");
     }
     str->append(")");
 }
 #endif