Android: Scrolling an Imageview
I have an ImageView that is twice the height of a normale screen ( 960 dip). I would like to scroll it nicely up and down on the screen. The bottom of the screen should contain a bottom.
解决方案：
// set maximum scroll amount (based on center of image)
int maxX = (int)((bitmapWidth / 2) - (screenWidth / 2));
int maxY = (int)((bitmapHeight / 2) - (screenHeight / 2));
// set scroll limits
final int maxLeft = (maxX * -1);
final int maxRight = maxX;
final int maxTop = (maxY * -1);
final int maxBottom = maxY;// set touchlistener
ImageView_BitmapView.setOnTouchListener(new View.OnTouchListener()
{
float downX, downY;
int totalX, totalY;
int scrollByX, scrollByY;
public boolean onTouch(View view, MotionEvent event)
{
float currentX, currentY;
switch (event.getAction())
{
case MotionEvent.ACTION_DOWN:
downX = event.getX();
downY = event.getY();
break;case MotionEvent.ACTION_MOVE:
currentX = event.getX();
currentY = event.getY();
scrollByX = (int)(downX - currentX);
scrollByY = (int)(downY - currentY);// scrolling to left side of image (pic moving to the right)
if (currentX > downX)
{
if (totalX == maxLeft)
{
scrollByX = 0;
}
if (totalX > maxLeft)
{
totalX = totalX + scrollByX;
}
if (totalX < maxLeft)
{
scrollByX = maxLeft - (totalX - scrollByX);
totalX = maxLeft;
}
}// scrolling to right side of image (pic moving to the left)
if (currentX < downX)
{
if (totalX == maxRight)
{
scrollByX = 0;
}
if (totalX < maxRight)
{
totalX = totalX + scrollByX;
}
if (totalX > maxRight)
{
scrollByX = maxRight - (totalX - scrollByX);
totalX = maxRight;
}
}// scrolling to top of image (pic moving to the bottom)
if (currentY > downY)
{
if (totalY == maxTop)
{
scrollByY = 0;
}
if (totalY > maxTop)
{
totalY = totalY + scrollByY;
}
if (totalY < maxTop)
{
scrollByY = maxTop - (totalY - scrollByY);
totalY = maxTop;
}
}// scrolling to bottom of image (pic moving to the top)
if (currentY < downY)
{
if (totalY == maxBottom)
{
scrollByY = 0;
}
if (totalY < maxBottom)
{
totalY = totalY + scrollByY;
}
if (totalY > maxBottom)
{
scrollByY = maxBottom - (totalY - scrollByY);
totalY = maxBottom;
}
}ImageView_BitmapView.scrollBy(scrollByX, scrollByY);
downX = currentX;
downY = currentY;
break;}
return true;
}
});
I'm sure it could be refined a bit, but it works pretty well. :)
