Add option to skip rects to drawImageLattice()

include/core/SkCanvas.h

Index: include/core/SkCanvas.h
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index acf0ad2a54febf4cb6bbdd14a9112e81a3c8573f..e1a1026c52ee7bf21863cf968f0f53e63c1f7a59 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -934,21 +934,37 @@ public:
      *  Specifies coordinates to divide a bitmap into (xCount*yCount) rects.
      */
     struct Lattice {
+        enum Flags : uint8_t {
+            // If set, indicates that we should not draw corresponding rect.
+            kSkip_Flags = 1 << 0,
+        };
+
         // An array of x-coordinates that divide the bitmap vertically.
         // These must be unique, increasing, and in the set [0, width].
         // Does not have ownership.
-        const int* fXDivs;
+        const int*   fXDivs;
 
         // The number of fXDivs.
-        int        fXCount;
+        int          fXCount;
 
         // An array of y-coordinates that divide the bitmap horizontally.
         // These must be unique, increasing, and in the set [0, height].
         // Does not have ownership.
-        const int* fYDivs;
+        const int*   fYDivs;
 
         // The number of fYDivs.
-        int        fYCount;
+        int          fYCount;
+
+        // If non-null, the length of this array must be equal to the total
+        // number of rects specified in the lattice. The flags correspond
+        // to the rects in the lattice, first moving left to right and then
+        // top to bottom.
+        const Flags* fFlags;
+
+        // The number of fFlags.  Must be equal to the total number of rects
+        // specified in the lattice, or flags will be ignored.  If fFlags is
+        // null, this should be set to zero.
+        int          fFlagCount;

[reed1, 2016/09/01 14:15:23]

Lets try not having this, and just documenting that fFlags must be (xdivs +
1)*(ydivs + 1) long...?

[msarett, 2016/09/01 16:27:24]

SGTM

     };
 
     /**