Question

For Bitmaps drawn with simple (x,y) coordinates,

float _x = x - (bitmap.getWidth() / 2);
float _y = y - (bitmap.getHeight() / 2);
canvas.drawBitmap(bitmap, _x, _y, null);

I can detect if the bitmap has been touched.

I’m drawing a bitmap to the screen with

    dest = new Rect(0,0,0,0);
    src = new Rect(0,0,0,0);
    mSpriteHeight = (int) (sprite_pixel_height * mScale + 0.5f);
    mSpriteWidth = (int) (sprite_pixel_width * mScale + 0.5f);
    src.top = 0;
    src.left = 0;
    src.bottom = mSpriteHeight;
    src.right = mSpriteWidth;
    dest.top = (int) (_x * mScale);
    dest.bottom = (int) ((_x + mSpriteHeight) * mScale);
    dest.left = (int) (_y * mScale);
    dest.right = (int) ((_y + mSpriteWidth) * mScale);
    canvas.drawBitmap(bitmap, src, dest, null);

trying to incorporate the
screen density because “This function ignores the density associated with the bitmap. … so must already have the appropriate scaling factor applied.”

I haven’t been able to detect touches to the translated bitmaps. I must need to do a similar translation using mScale, but I’m lost.

Is there a better way to define the src and dest in my original canvas.drawBitmap(bitmap, src, dest, null);?

Anyone know an example where this has been done? I can’t seem to find the right search terms to find such an example.

Answer 1

It seems to me that the same method applies as for simple x,y coordinates. You simply need to use the coordinates and size of Rect dest to calculate whether the bitmap has been touched.

In other words, you need to do something like this:

public boolean picked(Rect dest, int touchX, int touchY) {
     if(touchX > dest.left && touchX < dest.left + dest.width() &&
        touchY > dest.top && touchY < dest.top + dest.height())
            return true;
     return false;
}