Java Graphics2D transparent background
You can construct a Color object by specifying a transparency. For example the following code constructs a RED color with 50% transparency
Color c=new Color(1f,0f,0f,.5f );
You can call the constructor of Color in the following way:
Color c = new Color(r,g,b,a);
where a is the alpha (transparency) value.
As with all Java classes, you can find this information in the official API: http://docs.oracle.com/javase/7/docs/api/java/awt/Color.html
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