Geek Answers Handbook

Pinch-to-zoom on huge images?

I found this Pinch-to-zoom example at http://forums.create.msdn.com

Here is the haml:

<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0"> 
            <StackPanel> 
                <TextBlock Text="Tap to center" Style="{StaticResource PhoneTextNormalStyle}"/> 
                <TextBlock Text="Tap and hold to reset" Style="{StaticResource PhoneTextNormalStyle}"/> 
                <TextBlock Text="Touch and move to drag" Style="{StaticResource PhoneTextNormalStyle}"/> 
                <TextBlock Text="Pinch (touch with two fingers) to scale and rotate" Style="{StaticResource PhoneTextNormalStyle}" TextWrapping="Wrap"/> 
                <TextBlock Text="Flick (drag and release the touch while still moving) will show flick data on bottom of screen." Style="{StaticResource PhoneTextNormalStyle}" TextWrapping="Wrap"/> 
            </StackPanel> 
            <TextBlock x:Name="flickData" Text="Flick:" Style="{StaticResource PhoneTextNormalStyle}" VerticalAlignment="Bottom"/> 
            <Image x:Name="image" Source="/map.jpg" RenderTransformOrigin="0.5,0.5" CacheMode="BitmapCache"> 
                <Image.RenderTransform> 
                    <CompositeTransform x:Name="transform"/> 
                </Image.RenderTransform> 
                <toolkit:GestureService.GestureListener> 
                    <toolkit:GestureListener  
                        Tap="OnTap" Hold="OnHold" 
                        DragStarted="OnDragStarted" DragDelta="OnDragDelta" DragCompleted="OnDragCompleted" 
                        Flick="OnFlick" 
                        PinchStarted="OnPinchStarted" PinchDelta="OnPinchDelta" PinchCompleted="OnPinchCompleted"/> 
                </toolkit:GestureService.GestureListener> 
            </Image> 
        </Grid>

And cs source:

public partial class GestureSample : PhoneApplicationPage 
    { 
        double initialAngle; 
        double initialScale; 

        public GestureSample() 
        { 
            InitializeComponent(); 
        } 

        private void OnTap(object sender, GestureEventArgs e) 
        { 
            transform.TranslateX = transform.TranslateY = 0; 
        } 

        private void OnDoubleTap(object sender, GestureEventArgs e) 
        { 
            transform.ScaleX = transform.ScaleY = 1; 
        } 

        private void OnHold(object sender, GestureEventArgs e) 
        { 
            transform.TranslateX = transform.TranslateY = 0; 
            transform.ScaleX = transform.ScaleY = 1; 
            transform.Rotation = 0; 
        } 

        private void OnDragStarted(object sender, DragStartedGestureEventArgs e) 
        { 
            image.Opacity = 0.3; 
        } 

        private void OnDragDelta(object sender, DragDeltaGestureEventArgs e) 
        { 
            transform.TranslateX += e.HorizontalChange; 
            transform.TranslateY += e.VerticalChange; 
        } 

        private void OnDragCompleted(object sender, DragCompletedGestureEventArgs e) 
        { 
            image.Opacity = 1.0; 
        } 

        private void OnPinchStarted(object sender, PinchStartedGestureEventArgs e) 
        { 
            Point point0 = e.GetPosition(image, 0); 
            Point point1 = e.GetPosition(image, 1); 
            Point midpoint = new Point((point0.X + point1.X) / 2, (point0.Y + point1.Y) / 2); 
            image.RenderTransformOrigin = new Point(midpoint.X / image.ActualWidth, midpoint.Y / image.ActualHeight); 
            initialAngle = transform.Rotation; 
            initialScale = transform.ScaleX; 
            image.Opacity = 0.8; 
        } 

        private void OnPinchDelta(object sender, PinchGestureEventArgs e) 
        { 
            transform.Rotation = initialAngle + e.TotalAngleDelta; 
            transform.ScaleX = transform.ScaleY = initialScale * e.DistanceRatio; 
        } 

        private void OnPinchCompleted(object sender, PinchGestureEventArgs e) 
        { 
            image.Opacity = 1.0; 
        } 

        private void OnFlick(object sender, FlickGestureEventArgs e) 
        { 
            flickData.Text = string.Format("{0} Flick: Angle {1} Velocity {2},{3}", 
                e.Direction, Math.Round(e.Angle), e.HorizontalVelocity, e.VerticalVelocity); 
        } 
    }

It works great for small images (less than 2000x2000 pixels). But in my example, I have this huge metro map ( http://www.vasttrafik.se/upload/Linjekartor_hogupplost/Goteborg2010/Linjen%C3%A4tskarta-101212.png or vector http://www.vasttrafik.se/upload /Linjekartor_hogupplost/Goteborg2010/Linjen%C3%A4tskarta-101212.pdf ). It would be even better if the user could scale the vector image, but even import such a huge vector is a serious performance problem.

, " " http://dotnetbyexample.blogspot.com/2010/08/windows-phone-7-multi-touch-panzoom.html, , : (

? ?

+5
3

- MultiScaleImage, . MultiScaleImage iamge, . , .., , .

DeepZoom DeepZoom Composer, .

, MultiScaleImage, , Laurent Multitouch Behavior ( ) .

+6

Silverlight UIElements has a size limit. As you discovered, this is 2000x2000 pixels. No control can be bigger than this, so your problem.

If you must use a larger image, look at MultiScaleImage.

Also look for potential memory problems if you are using very large image files.

+1
source

More articles:


All Articles