How to make Canvas draw area transparent in android?

Question

I would like to make Canvas area transparent because I would like to add an Image behind it so that Canvas actions happen above the image.My code for the canvas is here

Answer 1

If you want to have a canvas with a transparent background you have to configure the background image for the

mCanvas = new Canvas(mBackgroundBitmap);

with Bitmap.Config.ARGB_4444

And use colors like 0x00000000 as transparent

    Bitmap mBackgroundImage = Bitmap.createBitmap(Size, Size,
                    Bitmap.Config.ARGB_4444);
    mCanvas = new Canvas(mBackgroundImage);

hope this helps! I have a pretty transparent canvas :D yay!

Answer 2

I got the output by this

 public Panel(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    this.setBackgroundColor(Color.TRANSPARENT);                 
    this.setZOrderOnTop(true); //necessary                
    getHolder().setFormat(PixelFormat.TRANSPARENT); 
    getHolder().addCallback(this); 
    mThread = new ViewThread(this); 

} 

Answer 3

canvas.drawColor(Color.argb(0, 255, 255, 255));

first attribute is alpha and rest are RGB colors.

or

canvas.drawColor(Color.TRANSPARENT);

Answer 4

canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR)

Works fine for me with

override fun onFinishInflate() {
    super.onFinishInflate()
    setZOrderOnTop(true)
    holder.setFormat(PixelFormat.TRANSLUCENT)
    isFocusable = true
    holder.addCallback(surfaceCallback)
}

Answer 5

this make canvas tramsparent and it is work for me :)

canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.OVERLAY);

Answer 6

Set canvas's view background color to #00000000