Question

I created a custom View and am trying to draw an array of ints (colors) onto it.

This draws a red screen:

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    int width = canvas.getWidth();
    int height = canvas.getHeight();

    int[] pixels = new int[width*height];
    for(int i=0; i<pixels.length; i++) {
        pixels[i] = 0xFF0000;
    }

    canvas.drawBitmap(pixels, 0, width, 0,0,width,height,false,null);
}

This doesn’t:

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    int width = canvas.getWidth();
    int height = canvas.getHeight();

    int[] pixels = new int[width*height];
    for(int i=0; i<pixels.length; i++) {
        pixels[i] = 0xFF0000;
    }

    Bitmap bmp = Bitmap.createBitmap(pixels, width, height, Bitmap.Config.ARGB_8888);
    canvas.drawBitmap(bmp, 0, 0, null);
}

The difference is in those last line(s). What’s wrong with the second way of doing things? Am I creating the Bitmap object wrong somehow?

Answer 1

In your second example try changing pixels[i] = 0xFF0000; to pixels[i] = 0xFFFF0000; you’re creating a Bitmap with alpha channel so you have to specify your colors in AARRGGBB format to get them interpreted correctly.