Make the API more extendable

cocos/2d/CCRenderTexture.cpp

@@ -409,14 +409,32 @@ void RenderTexture::visit(Renderer *renderer, const Mat4 &parentTransform, uint3
     _orderOfArrival = 0;
 }
 
-bool RenderTexture::saveToFile(const std::string& filename)
+bool RenderTexture::saveToFile(const std::string& filename, bool isRGBA)
 {
-    return saveToFile(filename,Image::Format::JPG);
+    std::string basename(filename);
+    std::transform(basename.begin(), basename.end(), basename.begin(), ::tolower);
+    
+    if (basename.find(".png") != std::string::npos)
+    {
+        return saveToFile(filename, Image::Format::PNG, isRGBA);
+    }
+    else if (basename.find(".jpg") != std::string::npos)
+    {
+        if (isRGBA) CCLOG("RGBA is not supported for JPG format.");
+        return saveToFile(filename, Image::Format::JPG, false);
+    }
+    else
+    {
+        CCLOG("Only PNG and JPG format are supported now!");
+    }
+    
+    return saveToFile(filename, Image::Format::JPG, false);
 }
 bool RenderTexture::saveToFile(const std::string& fileName, Image::Format format, bool isRGBA)
 {
     CCASSERT(format == Image::Format::JPG || format == Image::Format::PNG,
              "the image can only be saved as JPG or PNG format");
+    if (isRGBA && format == Image::Format::JPG) CCLOG("RGBA is not supported for JPG format");
     
     std::string fullpath = FileUtils::getInstance()->getWritablePath() + fileName;
     _saveToFileCommand.init(_globalZOrder);

cocos/2d/CCRenderTexture.h

@@ -103,7 +103,7 @@ public:
     /** saves the texture into a file using JPEG format. The file will be saved in the Documents folder.
         Returns true if the operation is successful.
      */
-    bool saveToFile(const std::string& filename);
+    bool saveToFile(const std::string& filename, bool isRGBA = true);
 
     /** saves the texture into a file. The format could be JPG or PNG. The file will be saved in the Documents folder.
         Returns true if the operation is successful.