Question

I have a custom view extending from View with lots of text drawn at different angles and I want a particular string to decrease its alpha value to a certain level once, after first start. Any suggestion or snippet would be appreciated 🙂

postInvalidateDelayed(...) doesn’t seem to work for this task.

Answer 1

There was a mistake in the correct measurement of vertical text bounds to be faded. Here is my onDraw method

Paint myPaint = new Paint();
myPaint.setColor(Color.parseColor("#" + colorAlpha + "3AA6D0"));// initially colorAlpha is ff
Rect r = new Rect();
char[] a = "Hello World".toCharArray();
datePaint.getTextBounds(a, 0, a.length, r);// get the bound of the text, I was not calculating this correctly
canvas.drawText("Hello World", 0, 0, myPaint);// draw the text

int colorValue = Integer.parseInt(colorAlpha, 16);
    colorValue -= 20;// decrease alpha value for next call to onDraw method by postInvalidateDelayed
if (colorValue > 40) {
        colorAlpha = Integer.toHexString(colorValue);


 // this will create the effect of fade out animation
 // because each call to onDraw method is at the difference of 50 millisecond delay 
 // and in each call we are decreasing alpha value by 20.
        postInvalidateDelayed(50, r.left, r.top, r.right, r.bottom);
}