some utils for rect and matrix

src/core/SkDraw.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 "SkDraw.h"
 #include "SkBlitter.h"
 #include "SkCanvas.h"
@@ skipping 2163 matching lines @@
 #include "SkBlitter.h"
 
 static bool compute_bounds(const SkPath& devPath, const SkIRect* clipBounds,
                            const SkMaskFilter* filter, const SkMatrix* filterMatrix,
                            SkIRect* bounds) {
     if (devPath.isEmpty()) {
         return false;
     }
 
     //  init our bounds from the path
-    {
-        SkRect pathBounds = devPath.getBounds();
-        pathBounds.inset(-SK_ScalarHalf, -SK_ScalarHalf);
-        pathBounds.roundOut(bounds);
-    }
+    *bounds = devPath.getBounds().makeOutset(SK_ScalarHalf, SK_ScalarHalf).roundOut();
 
     SkIPoint margin = SkIPoint::Make(0, 0);
     if (filter) {
         SkASSERT(filterMatrix);
 
         SkMask srcM, dstM;
 
         srcM.fBounds = *bounds;
         srcM.fFormat = SkMask::kA8_Format;
         srcM.fImage = NULL;
         if (!filter->filterMask(&dstM, srcM, *filterMatrix, &margin)) {
             return false;
         }
     }
 
     // (possibly) trim the bounds to reflect the clip
     // (plus whatever slop the filter needs)
     if (clipBounds) {
-        SkIRect tmp = *clipBounds;
         // Ugh. Guard against gigantic margins from wacky filters. Without this
         // check we can request arbitrary amounts of slop beyond our visible
         // clip, and bring down the renderer (at least on finite RAM machines
         // like handsets, etc.). Need to balance this invented value between
         // quality of large filters like blurs, and the corresponding memory
         // requests.
         static const int MAX_MARGIN = 128;
-        tmp.inset(-SkMin32(margin.fX, MAX_MARGIN),
-                  -SkMin32(margin.fY, MAX_MARGIN));
-        if (!bounds->intersect(tmp)) {
+        if (!bounds->intersect(clipBounds->makeOutset(SkMin32(margin.fX, MAX_MARGIN),
+                                                      SkMin32(margin.fY, MAX_MARGIN)))) {
             return false;
         }
     }
 
     return true;
 }
 
 static void draw_into_mask(const SkMask& mask, const SkPath& devPath,
                            SkPaint::Style style) {
     SkBitmap        bm;
@@ skipping 38 matching lines @@
         mask->fImage = SkMask::AllocImage(size);
         memset(mask->fImage, 0, mask->computeImageSize());
     }
 
     if (SkMask::kJustComputeBounds_CreateMode != mode) {
         draw_into_mask(*mask, devPath, style);
     }
 
     return true;
 }