add drawImageRect to lua, update sample

src/utils/SkLua.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkLua.h"
 
 #if SK_SUPPORT_GPU
@@ skipping 442 matching lines @@
     SkPaint paint;
     const SkPaint* paintPtr = NULL;
     if (lua_isnumber(L, 5)) {
         paint.setAlpha(SkScalarRoundToInt(lua2scalar(L, 5) * 255));
         paintPtr = &paint;
     }
     canvas->drawImage(image, x, y, paintPtr);
     return 0;
 }
 
+static int lcanvas_drawImageRect(lua_State* L) {
+    SkCanvas* canvas = get_ref<SkCanvas>(L, 1);
+    SkImage* image = get_ref<SkImage>(L, 2);
+    if (NULL == image) {
+        return 0;
+    }
+
+    SkRect srcR, dstR;
+    SkRect* srcRPtr = NULL;
+    if (!lua_isnil(L, 3)) {
+        srcRPtr = lua2rect(L, 3, &srcR);
+    }
+    lua2rect(L, 4, &dstR);
+    
+    SkPaint paint;
+    const SkPaint* paintPtr = NULL;
+    if (lua_isnumber(L, 5)) {
+        paint.setAlpha(SkScalarRoundToInt(lua2scalar(L, 5) * 255));
+        paintPtr = &paint;
+    }
+    canvas->drawImageRect(image, srcRPtr, dstR, paintPtr);
+    return 0;
+}
+
 static int lcanvas_drawPath(lua_State* L) {
     get_ref<SkCanvas>(L, 1)->drawPath(*get_obj<SkPath>(L, 2),
                                       *get_obj<SkPaint>(L, 3));
     return 0;
 }
 
 static int lcanvas_drawText(lua_State* L) {
     if (lua_gettop(L) < 5) {
         return 0;
     }
@@ skipping 96 matching lines @@
     get_ref<SkCanvas>(L, 1)->unref();
     return 0;
 }
 
 const struct luaL_Reg gSkCanvas_Methods[] = {
     { "drawColor", lcanvas_drawColor },
     { "drawRect", lcanvas_drawRect },
     { "drawOval", lcanvas_drawOval },
     { "drawCircle", lcanvas_drawCircle },
     { "drawImage", lcanvas_drawImage },
+    { "drawImageRect", lcanvas_drawImageRect },
     { "drawPath", lcanvas_drawPath },
     { "drawText", lcanvas_drawText },
     { "getSaveCount", lcanvas_getSaveCount },
     { "getTotalMatrix", lcanvas_getTotalMatrix },
     { "getClipStack", lcanvas_getClipStack },
 #if SK_SUPPORT_GPU
     { "getReducedClipStack", SkLua::lcanvas_getReducedClipStack },
 #endif
     { "save", lcanvas_save },
     { "restore", lcanvas_restore },
@@ skipping 921 matching lines @@
     REG_CLASS(L, SkShader);
     REG_CLASS(L, SkTypeface);
     REG_CLASS(L, SkMatrix);
 }
 
 extern "C" int luaopen_skia(lua_State* L);
 extern "C" int luaopen_skia(lua_State* L) {
     SkLua::Load(L);
     return 0;
 }