public void SwitchImageTick(object source, EventArgs args)
{
var moveTop = 0;
var moveLeft = 0;
var usingImageIndex = _currentBackgroundStage % 2;
var otherImageIndex = usingImageIndex ^ 1;
switch (_currentBackgroundStage)
{
case 1:
moveLeft = 1;
break;
case 2:
moveTop = 1;
moveLeft = 1;
break;
case 3:
moveTop = 1;
break;
default:
break;
}
var newTop = -(moveTop * (_backgroundImages[usingImageIndex].Height - ActualHeight));
var oppositeTop = -((moveTop ^ 1) * (_backgroundImages[usingImageIndex].Height - ActualHeight));
var newLeft = -(moveLeft * (_backgroundImages[usingImageIndex].Width - ActualWidth));
var oppositeLeft = -((moveLeft ^ 1) * (_backgroundImages[usingImageIndex].Width - ActualWidth));
_backgroundImages[usingImageIndex].Source =
new BitmapImage(
AssetFinder.PathToUri(
_lastUsedBackgroundSource = GetRandomBackgroundImageAssetPath(_lastUsedBackgroundSource)));
_backgroundImages[usingImageIndex].BeginAnimation(OpacityProperty,
new DoubleAnimation(0, 1.0, TimeSpan.FromSeconds(BackgroundTransitionDuration)));
_backgroundImages[otherImageIndex].BeginAnimation(OpacityProperty,
new DoubleAnimation(1.0, 0, TimeSpan.FromSeconds(BackgroundTransitionDuration)));
StartImageMovement(_backgroundImages[usingImageIndex], newTop, oppositeTop, newLeft, oppositeLeft);
_currentBackgroundStage++;
if (_currentBackgroundStage == 4)
{
_currentBackgroundStage = 0;
}
}