Add option to skip rects to drawImageLattice()

gm/lattice.cpp

Index: gm/lattice.cpp
diff --git a/gm/lattice.cpp b/gm/lattice.cpp
index 63de2a66b407d6d2d2adbf6d549a24d06d1930ea..919fb3588e7dde16ec073b487ec0a5e66abcc8ee 100644
--- a/gm/lattice.cpp
+++ b/gm/lattice.cpp
@@ -113,6 +113,7 @@ protected:
         lattice.fXDivs = xDivs + 1;
         lattice.fYCount = 4;
         lattice.fYDivs = yDivs + 1;
+        lattice.fFlags = nullptr;
 
         for (int iy = 0; iy < 2; ++iy) {
             for (int ix = 0; ix < 2; ++ix) {
@@ -130,6 +131,15 @@ protected:
         lattice.fYCount = 5;
         lattice.fYDivs = yDivs;
 
+        // Let's skip a few rects.
+        SkCanvas::Lattice::Flags flags[36];
+        sk_bzero(flags, 36 * sizeof(SkCanvas::Lattice::Flags));
+        flags[4] = SkCanvas::Lattice::kTransparent_Flags;
+        flags[9] = SkCanvas::Lattice::kTransparent_Flags;
+        flags[12] = SkCanvas::Lattice::kTransparent_Flags;
+        flags[19] = SkCanvas::Lattice::kTransparent_Flags;
+        lattice.fFlags = flags;
+
         canvas->translate(400, 0);
         for (int iy = 0; iy < 2; ++iy) {
             for (int ix = 0; ix < 2; ++ix) {