How to set an onclick listener to a canvas?

Question

I have some rectangles drawn on Canvas. And now I need for each rectangle an onclickListener. But because I'm very new to android and specially Canvas, I need some help. Anyway is it possible to add a listener?

It looks like this:

And this is my code for it:

RelativeLayout ll = (RelativeLayout) findViewById(R.id.rect);
        Paint paint = new Paint();
        Paint paintForSize = new Paint();
        paintForSize.setColor(Color.parseColor("#FFFFFF")); 
        paintForSize.setTextSize(45);
        Bitmap bg = Bitmap.createBitmap(480, 800, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bg);

        int left = 0; // initial start position of rectangles (50 pixels from left)
        int leftText =70;
        int topText = 93;
        int top = 50; // 50 pixels from the top
        int width = 60;
        int height = 60;

        for(int x = 0; x < 4; x++) { // draw 4 rectangles
            if(x == 0){
            paint.setColor(Color.parseColor("#FF7979"));
            canvas.drawText("Rec 1", leftText, topText, paintForSize);
            }
            if(x == 1){
            paint.setColor(Color.parseColor("#FFD060"));
            canvas.drawText("Rec 2", leftText, topText, paintForSize);
            }
            if(x == 2){
            paint.setColor(Color.parseColor("#B6DB49"));
            canvas.drawText("Rec 3", leftText, topText, paintForSize);
            }
            if(x == 3){
            paint.setColor(Color.parseColor("#CB97E5"));
            canvas.drawText("Rec 4", leftText, topText, paintForSize);
            }

            canvas.drawRect(left, top, left+width, top+height, paint);

            top = (top + height + 10); // set new left co-ordinate + 10 pixel gap

            topText = (topText + height + 10);
        }



        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,
                LayoutParams.WRAP_CONTENT);
                params.addRule(RelativeLayout.ALIGN_PARENT_LEFT);

        ImageView iV = new ImageView(this);
        iV.setImageBitmap(bg);

        ll.addView(iV,params);

Can anybody guide me through this, how should I do it?

Answer 1

Canvas is not a View. You cannot add listeners to them. You could create a custom View implementation. Whatever you do with the Canvas, implement that in onDraw(), which receives a Canvas as a parameter. Then add your view to a layout and give it whatever listeners you want. You may as well look into SurfaceView for drawing, which is a View.

This might help you.

Answer 2

Might I suggest rethinking how this is going to work. If these rectangles are going to be buttons of some sort, perhaps your better off drawing buttons in your user interface, or using images instead of the rectangles. (Sorry didnt realise this is what you were going to do in your previous question)

Have a look at: Difference between a clickable ImageView and ImageButton

You can set an eventlistener on your imageview, as mentioned in another answer. See here: Image in Canvas with touch events