Clarify subrect semantics for GrTextureAdjuster and handle mip maps correctly.

src/gpu/GrTextureParamsAdjuster.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrTextureParamsAdjuster.h"
 
 #include "GrCaps.h"
@@ skipping 100 matching lines @@
     SkAutoTUnref<GrDrawContext> drawContext(context->drawContext(copy->asRenderTarget()));
     if (!drawContext) {
         return nullptr;
     }
 
     SkRect dstRect = SkRect::MakeWH(SkIntToScalar(rtDesc.fWidth), SkIntToScalar(rtDesc.fHeight));
     drawContext->drawNonAARectToRect(GrClip::WideOpen(), paint, SkMatrix::I(), dstRect, localRect);
     return copy.detach();
 }
 
-GrTextureAdjuster::GrTextureAdjuster(GrTexture* original, const SkIRect& subset)
+GrTextureAdjuster::GrTextureAdjuster(GrTexture* original, const SkIRect& contentArea)
     : fOriginal(original) {
-    if (subset.fLeft > 0 || subset.fTop > 0 ||
-        subset.fRight < original->width() || subset.fBottom < original->height()) {
-        fSubset.set(subset);
+    if (contentArea.fLeft > 0 || contentArea.fTop > 0 ||
+        contentArea.fRight < original->width() || contentArea.fBottom < original->height()) {
+        fContentArea.set(contentArea);
     }
 }
 
 GrTexture* GrTextureAdjuster::refTextureSafeForParams(const GrTextureParams& params,
                                                       SkIPoint* outOffset) {
     GrTexture* texture = this->originalTexture();
     GrContext* context = texture->getContext();
     CopyParams copyParams;
-    const SkIRect* subset = this->subset();
+    const SkIRect* contentArea = this->contentArea();
 
-    if (!context->getGpu()->makeCopyForTextureParams(texture->width(), texture->height(), params,
-                                                     &copyParams)) {
+    if (contentArea && GrTextureParams::kMipMap_FilterMode == params.filterMode()) {
+        // If we generate a MIP chain for texture it will read pixel values from outside the content
+        // area.
+        copyParams.fWidth = contentArea->width();
+        copyParams.fHeight = contentArea->height();
+        copyParams.fFilter = GrTextureParams::kBilerp_FilterMode;
+    } else if (!context->getGpu()->makeCopyForTextureParams(texture->width(), texture->height(),
+                                                            params, &copyParams)) {
         if (outOffset) {
-            if (subset) {
-                outOffset->set(subset->fLeft, subset->fRight);
+            if (contentArea) {
+                outOffset->set(contentArea->fLeft, contentArea->fRight);
             } else {
                 outOffset->set(0, 0);
             }
         }
         return SkRef(texture);
     }
     GrUniqueKey key;
     this->makeCopyKey(copyParams, &key);
     if (key.isValid()) {
         GrTexture* result = context->textureProvider()->findAndRefTextureByUniqueKey(key);
         if (result) {
             return result;
         }
     }
-    GrTexture* result = copy_on_gpu(texture, subset, copyParams);
+    GrTexture* result = copy_on_gpu(texture, contentArea, copyParams);
     if (result) {
         if (key.isValid()) {
             result->resourcePriv().setUniqueKey(key);
             this->didCacheCopy(key);
         }
         if (outOffset) {
             outOffset->set(0, 0);
         }
     }
     return result;
@@ skipping 28 matching lines @@
     return result;
 }
 
 GrTexture* GrTextureMaker::generateTextureForParams(GrContext* ctx, const CopyParams& copyParams) {
     SkAutoTUnref<GrTexture> original(this->refOriginalTexture(ctx));
     if (!original) {
         return nullptr;
     }
     return copy_on_gpu(original, nullptr, copyParams);
 }