add drawImageNine

src/core/SkNinePatchIter.cpp

Index: src/core/SkNinePatchIter.cpp
diff --git a/src/core/SkNinePatchIter.cpp b/src/core/SkNinePatchIter.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..c6bd16dcdb6665bae4eed635c38e3ad79143e3f5
--- /dev/null
+++ b/src/core/SkNinePatchIter.cpp
@@ -0,0 +1,72 @@
+/*
+ * 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 "SkNinePatchIter.h"
+#include "SkRect.h"
+
+bool SkNinePatchIter::Valid(int width, int height, const SkIRect& center) {
+    return !center.isEmpty() && SkIRect::MakeWH(width, height).contains(center);
+}
+
+SkNinePatchIter::SkNinePatchIter(int w, int h, const SkIRect& c, const SkRect& dst) {
+    SkASSERT(SkIRect::MakeWH(w, h).contains(c));
+
+    fSrcX[0] = 0;
+    fSrcX[1] = SkIntToScalar(c.fLeft);
+    fSrcX[2] = SkIntToScalar(c.fRight);
+    fSrcX[3] = SkIntToScalar(w);
+    
+    fSrcY[0] = 0;
+    fSrcY[1] = SkIntToScalar(c.fTop);
+    fSrcY[2] = SkIntToScalar(c.fBottom);
+    fSrcY[3] = SkIntToScalar(h);
+    
+    fDstX[0] = dst.fLeft;
+    fDstX[1] = dst.fLeft + SkIntToScalar(c.fLeft);
+    fDstX[2] = dst.fRight - SkIntToScalar(w - c.fRight);
+    fDstX[3] = dst.fRight;
+    
+    fDstY[0] = dst.fTop;
+    fDstY[1] = dst.fTop + SkIntToScalar(c.fTop);
+    fDstY[2] = dst.fBottom - SkIntToScalar(h - c.fBottom);
+    fDstY[3] = dst.fBottom;
+    
+    if (fDstX[1] > fDstX[2]) {
+        fDstX[1] = fDstX[0] + (fDstX[3] - fDstX[0]) * c.fLeft / (w - c.width());
+        fDstX[2] = fDstX[1];
+    }
+
+    if (fDstY[1] > fDstY[2]) {
+        fDstY[1] = fDstY[0] + (fDstY[3] - fDstY[0]) * c.fTop / (h - c.height());
+        fDstY[2] = fDstY[1];
+    }
+
+    fCurrX = fCurrY = 0;
+    fDone = false;
+}
+
+bool SkNinePatchIter::next(SkRect* src, SkRect* dst) {
+    if (fDone) {
+        return false;
+    }
+
+    const int x = fCurrX;
+    const int y = fCurrY;
+    SkASSERT(x >= 0 && x < 4);
+    SkASSERT(y >= 0 && y < 4);
+
+    src->set(fSrcX[x], fSrcY[y], fSrcX[x + 1], fSrcY[y + 1]);
+    dst->set(fDstX[x], fDstY[y], fDstX[x + 1], fDstY[y + 1]);
+    if (4 == ++fCurrX) {
+        fCurrX = 0;
+        fCurrY += 1;
+        if (fCurrY >= 4) {
+            fDone = true;
+        }
+    }
+    return true;
+}