CODEWITHSUNDEEP
androidanimationbackgroundscrollandroid-canvas
Christian Adam C. Vinluan
Christian Adam C. Vinluan

Reputation: 51

canvas scrolling background for android

I want a scrolling background wherein if I tap, the direction of the scrolling image changes to left and right if I tap again. I want it to continue the position of the image when I tap or touch the screen. What my code does is everytime I tap, the position of the scrolling background doesnt begin on where it was when I tapped the screen. please help and thanks in advance

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

fromRect1 = new Rect(0, 0, bgrW - bgrScroll, bgrH);
toRect1 = new Rect(bgrScroll, 0, bgrW, bgrH);

fromRect2 = new Rect(bgrW - bgrScroll, 0, bgrW, bgrH);
toRect2 = new Rect(0, 0, bgrScroll, bgrH);

if(left == true){

if (!reverseBackroundFirst) {
    canvas.drawBitmap(bgr, toRect1, fromRect1, null);
    canvas.drawBitmap(bgrReverse, toRect2, fromRect2, null);
}
else{
    canvas.drawBitmap(bgr, toRect2, fromRect2, null);
    canvas.drawBitmap(bgrReverse, toRect1, fromRect1, null);
}


}else{

    if (!reverseBackroundFirst) {
        canvas.drawBitmap(bgr, fromRect1, toRect1, null);
        canvas.drawBitmap(bgrReverse, fromRect2, toRect2, null);
    }
    else{
        canvas.drawBitmap(bgr, fromRect2, toRect2, null);
        canvas.drawBitmap(bgrReverse, fromRect1, toRect1, null);
    }


}
if ( (bgrScroll += dBgrY) >= bgrW) {
    bgrScroll = 0;
    reverseBackroundFirst = !reverseBackroundFirst;
}

}

//***************************************
//*************  TOUCH  *****************
//***************************************
@Override
public synchronized boolean onTouchEvent(MotionEvent ev) {

switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN: {
left = !left;
invalidate();
break;
}

case MotionEvent.ACTION_MOVE: {


break;
}

case MotionEvent.ACTION_UP:

break;
}
return true;
}

Upvotes: 2

Views: 675

Answers (1)

Chiral Code
Chiral Code

Reputation: 1436

You need to update bgrScroll after switching directions, do this:

    case MotionEvent.ACTION_DOWN: {
        left = !left;
        bgrScroll = bgrW - bgrScroll;
        invalidate();
        break;
    }

Upvotes: 1

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