Display Image with Fade Effect in Android Live Wallpaper

Question

I am trying to create a slideshow in Android using its WallpaperService class. I am using Canvas and Bitmap to display images. I am able to display images sequentially but I am unable to figure out a way to add fade in animation to the images while they change. I know how to animate Views in Android but I am unable to implement the same on Canvas. I tried looking for a similar question on SO and found one here but it would have been great had the answer been a detailed one.

I'd be grateful if someone pointed me to a source that can help me overcome this problem.

EDIT:

I set the image on the Canvas as follows:

Inside the class extending WallpaperService.Engine, I do the following:

@Override
    public void run() {
        SurfaceHolder holder = getSurfaceHolder();
        Canvas canvas = null;
        try {
            canvas = holder.lockCanvas();

            if (canvas != null) {
                canvas.drawColor(0, Mode.CLEAR);
                Bitmap bitmap = //get bitmap
                if (bitmap != null) {
                    paint.setAlpha(alpha);
                    if (alpha < 255 ) {
                        canvas.drawBitmap(bitmap, new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight()), new Rect(0, 0, width, height), paint);
                        bitmap.eraseColor(Color.TRANSPARENT);
                        bitmap.recycle();
                    }
                    alpha+=1;
                }
            }
        } catch (IllegalStateException ignore) {
            ignore.printStackTrace();
        } finally {
            if (canvas != null) {
                holder.unlockCanvasAndPost(canvas);
            }
        }
        handler.removeCallbacks(this);
    }

All I get is a black screen after this.