SL4.背景图片拖动

XAML：

        <Grid x:Name="MainGrid">
        <ScrollViewer x:Name="canvasScroller"
                      VerticalScrollBarVisibility="Hidden"
                      HorizontalScrollBarVisibility="Hidden" >
            <Canvas x:Name="LayoutRoot"
                    Width="1024"
                    Height="768"
                    MouseMove="CanvasMove" MouseLeftButtonDown="CanvasDown" MouseLeftButtonUp="CanvasUp" MouseLeave="LayoutRoot_MouseLeave">
                <Image Source="yi.jpg"
                       Width="1024"
                       Height="768"/>

            </Canvas>
        </ScrollViewer >
        </Grid>

　　XAML.CS

        private double horizontalValue = 0;
        private double verticalValue = 0;
        bool? moving = null;
        Point startingPos = new Point();
        Point endingPos = new Point();
        private double dx = 0;
        private double dy = 0;
        bool posChanged = false;

　　　　　private void CanvasDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
        {
            moving = false;
            LayoutRoot.Cursor = Cursors.Arrow;

            startingPos = e.GetPosition(LayoutRoot);
        }
        private void CanvasMove(object sender, System.Windows.Input.MouseEventArgs e)
        {
            if ((moving != null) && (moving == false))
            {
                moving = true;
                posChanged = true;
                LayoutRoot.Cursor = Cursors.Hand;
            }

            if (posChanged)
            {
                endingPos = e.GetPosition(LayoutRoot);

                dx = startingPos.X - endingPos.X;
                dy = startingPos.Y - endingPos.Y;

                double newPosY = canvasScroller.VerticalOffset + dy;
                double newPosX = canvasScroller.HorizontalOffset + dx;

                canvasScroller.ScrollToHorizontalOffset(newPosX);
                canvasScroller.ScrollToVerticalOffset(newPosY);
            }
        }

        private void CanvasUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
        {
            posChanged = false;

            LayoutRoot.Cursor = Cursors.Arrow;
        }

        private void LayoutRoot_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e)
        {
            // 在此处添加事件处理程序实现。
            posChanged = false;

            LayoutRoot.Cursor = Cursors.Arrow;
        }