Question

I’m a noob to android and I am trying to implement the 9 Old Androids flakes demo into my app. However, when i change the the image resource from the image used by the demo to one of my choosing the app crashes and says IllegalArgumentException: width and height must be > 0. My logcat says the line where I createscaledbitmap and createFlake is causing the issue. I’m lost as why this is happening the demo image has a width of 75px x 90px and my image has a width of 166px x 72px. Any help is greatly appreciated.

FLAKE VIEW CLASS (Where i create Flake)

void addFlakes(int quantity) {
    for (int i = 0; i < quantity; ++i) {
        flakes.add(Flake.createFlake(getWidth(), droid)); //This line causes exception
    }
    setNumFlakes(numFlakes + quantity);
}

/**
 * Subtract the specified number of droidflakes. We just take them off the end of the
 * list, leaving the others unchanged.
 */
void subtractFlakes(int quantity) {
    for (int i = 0; i < quantity; ++i) {
        int index = numFlakes - i - 1;
        flakes.remove(index);
    }
    setNumFlakes(numFlakes - quantity);
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    // Reset list of droidflakes, then restart it with 8 flakes
    flakes.clear();
    numFlakes = 0;
    addFlakes(8); //This line causes exception
    // Cancel animator in case it was already running
    animator.cancel();
    // Set up fps tracking and start the animation
    startTime = System.currentTimeMillis();
    prevTime = startTime;
    frames = 0;
    animator.start();
}

FLAKE CLASS (Where I create scaled bitmap)

static Flake createFlake(float xRange, Bitmap originalBitmap) {
    Flake flake = new Flake();
    // Size each flake with a width between 5 and 55 and a proportional height
    flake.width = (int)(5 + (float)Math.random() * 50);
    float hwRatio = originalBitmap.getHeight() / originalBitmap.getWidth();
    flake.height = (int)(flake.width * hwRatio);

    // Position the flake horizontally between the left and right of the range
    flake.x = (float)Math.random() * (xRange - flake.width);
    // Position the flake vertically slightly off the top of the display
    flake.y = 0 - (flake.height + (float)Math.random() * flake.height);

    // Each flake travels at 50-200 pixels per second
    flake.speed = 50 + (float) Math.random() * 150;

    // Flakes start at -90 to 90 degrees rotation, and rotate between -45 and 45
    // degrees per second
    flake.rotation = (float) Math.random() * 180 - 90;
    flake.rotationSpeed = (float) Math.random() * 90 - 45;

    // Get the cached bitmap for this size if it exists, otherwise create and cache one
    flake.bitmap = bitmapMap.get(flake.width);
    if (flake.bitmap == null) {
        flake.bitmap = Bitmap.createScaledBitmap(originalBitmap, //This line causes exception
                (int)flake.width, (int)flake.height, true);
        bitmapMap.put(flake.width, flake.bitmap);
    }
    return flake;
}

Answer 1

Since the width of your image is larger than the height you need to basically reverse these three lines of code.

flake.width = (int)(5 + (float)Math.random() * 50);
float hwRatio = originalBitmap.getHeight() / originalBitmap.getWidth();
flake.height = (int)(flake.width * hwRatio);

to this

flake.height = (int)(5 + (float)Math.random() * 50);
float hwRatio = originalBitmap.getWidth() / originalBitmap.getheight();
flake.width = (int)(flake.height * hwRatio);