Add blend function to Text (#18631)

Author: newnon

cocos/ui/UIText.cpp

@@ -409,6 +409,16 @@ Sprite * Text::getLetter(int lettetIndex)
     return _labelRenderer->getLetter(lettetIndex);
 }
 
+void Text::setBlendFunc(const BlendFunc &blendFunc)
+{
+    _labelRenderer->setBlendFunc(blendFunc);
+}
+
+const BlendFunc& Text::getBlendFunc() const
+{
+    return _labelRenderer->getBlendFunc();
+}
+    
 Widget* Text::createCloneInstance()
 {
     return Text::create();

cocos/ui/UIText.h

@@ -44,7 +44,7 @@ namespace ui {
 /**
  *  For creating a system font or a TTF font Text
  */
-class CC_GUI_DLL Text : public Widget
+class CC_GUI_DLL Text : public Widget, public cocos2d::BlendProtocol
 {
 
     DECLARE_CLASS_GUI_INFO
@@ -329,6 +329,24 @@ class CC_GUI_DLL Text : public Widget
      * @warning No support system font.
      */
     virtual Sprite * getLetter(int lettetIndex);
+    
+    /**
+     * Sets the source blending function.
+     *
+     * @param blendFunc A structure with source and destination factor to specify pixel arithmetic. e.g. {GL_ONE, GL_ONE}, {GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA}.
+     * @js NA
+     * @lua NA
+     */
+    virtual void setBlendFunc(const BlendFunc &blendFunc) override;
+    
+    /**
+     * Returns the blending function that is currently being used.
+     *
+     * @return A BlendFunc structure with source and destination factor which specified pixel arithmetic.
+     * @js NA
+     * @lua NA
+     */
+    virtual const BlendFunc &getBlendFunc() const override;
 
 CC_CONSTRUCTOR_ACCESS:
     virtual bool init() override;