Add SkIRect::adjust method

Change-Id: Ib18d1a82944524e20d5d72912d8db7a823c470de
Reviewed-on: https://skia-review.googlesource.com/128884
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Cary Clark <caryclark@google.com>

docs/SkIRect_Reference.bmh

@@ -1041,6 +1041,41 @@ describes an area: fLeft is less than fRight, and fTop is less than fBottom.
 
 # ------------------------------------------------------------------------------
 
+#Method void adjust(int32_t dL, int32_t dT, int32_t dR, int32_t dB)
+
+#In Inset_Outset_Offset
+#Line # moves the sides independently relative to their original locations ##
+Adjusts IRect by adding dL to fLeft, dT to fTop, dR to fRight, and fB to fBottom.
+
+If dL is positive, narrows IRect on the left. If negative, widens it on the left.
+If dT is positive, shrinks IRect on the top. If negative, lengthens it on the top.
+If dR is positive, narrows IRect on the right. If negative, widens it on the right.
+If dB is positive, shrinks IRect on the bottom. If negative, lengthens it on the bottom.
+
+The resulting IRect is not checked for validity. Thus, if the resulting IRect left is
+greater than right, the IRect will be considered empty. Call sort() after this call
+if that is not the desired behavior.
+
+#Param dL  offset added to fLeft ##
+#Param dT  offset added to fTop ##
+#Param dR  offset added to fRight ##
+#Param dB  offset added to fBottom ##
+
+#Example
+    SkIRect rect = { 8, 11, 19, 22 };
+    rect.adjust(2, -1, 1, -2);
+    SkDebugf("rect: %d, %d, %d, %d\n", rect.fLeft, rect.fTop, rect.fRight, rect.fBottom);
+#StdOut
+rect: 10, 10, 20, 20
+##
+##
+
+#SeeAlso inset outset
+
+##
+
+# ------------------------------------------------------------------------------
+
 #Method bool contains(int32_t x, int32_t y) const
 
 #In Intersection

include/core/SkRect.h

@@ -413,6 +413,25 @@ struct SK_API SkIRect {
     */
     void outset(int32_t dx, int32_t dy)  { this->inset(-dx, -dy); }
 
+    /** Adjust SkIRect by adding dL to fLeft, dT to fTop, dR to fRight and fB to fBottom.
+
+        If dL is positive, narrows SkIRect on the left. If negative, widens it on the left.
+        If dT is positive, shrinks SkIRect on the top. If negative, lengthens it on the top.
+        If dR is positive, narrows SkIRect on the right. If negative, widens it on the right.
+        If dB is positive, shrinks SkIRect on the bottom. If negative, lengthens it on the bottom.
+
+        @param dL  offset added to fLeft
+        @param dT  offset added to fTop
+        @param dR  offset added to fRight
+        @param dB  offset added to fBottom
+    */
+    void adjust(int32_t dL, int32_t dT, int32_t dR, int32_t dB) {
+        fLeft   = Sk32_sat_add(fLeft,   dL);
+        fTop    = Sk32_sat_add(fTop,    dT);
+        fRight  = Sk32_sat_add(fRight,  dR);
+        fBottom = Sk32_sat_add(fBottom, dB);
+    }
+
     /** Returns true if: fLeft <= x < fRight && fTop <= y < fBottom.
         Returns false if SkIRect is empty.
 

src/core/SkImageFilter.cpp

@@ -505,9 +505,8 @@ SkIRect SkImageFilter::DetermineRepeatedSrcBound(const SkIRect& srcBounds,
                                                  const SkISize& filterSize,
                                                  const SkIRect& originalSrcBounds) {
     SkIRect tmp = srcBounds;
-    tmp.fRight = Sk32_sat_add(tmp.fRight, filterSize.fWidth);
-    tmp.fBottom = Sk32_sat_add(tmp.fBottom, filterSize.fHeight);
-    tmp.offset(-filterOffset.fX, -filterOffset.fY);
+    tmp.adjust(-filterOffset.fX, -filterOffset.fY,
+               filterSize.fWidth - filterOffset.fX, filterSize.fHeight - filterOffset.fY);
 
     if (tmp.fLeft < originalSrcBounds.fLeft || tmp.fRight > originalSrcBounds.fRight) {
         tmp.fLeft = originalSrcBounds.fLeft;

src/effects/SkMatrixConvolutionImageFilter.cpp

@@ -452,12 +452,12 @@ SkIRect SkMatrixConvolutionImageFilter::onFilterNodeBounds(const SkIRect& src, c
 
     SkIRect dst = src;
     int w = fKernelSize.width() - 1, h = fKernelSize.height() - 1;
-    dst.fRight = Sk32_sat_add(dst.fRight, w);
-    dst.fBottom = Sk32_sat_add(dst.fBottom, h);
+
     if (kReverse_MapDirection == dir) {
-        dst.offset(-fKernelOffset);
+        dst.adjust(-fKernelOffset.fX, -fKernelOffset.fY,
+                   w - fKernelOffset.fX, h - fKernelOffset.fY);
     } else {
-        dst.offset(fKernelOffset - SkIPoint::Make(w, h));
+        dst.adjust(fKernelOffset.fX - w, fKernelOffset.fY - h, fKernelOffset.fX, fKernelOffset.fY);
     }
     return dst;
 }