How to know that Scale is started

[Vladimir]

     Hello. I have a PanAndZoomImage  to show an Image with Scale ability. When Scale is started I need to show MessageBox where User could choose Image Size(Image quality), after that I would  change the Image source to another for scaling. Could You help me how I could do it? how can I know that scaling is started.

                            <slideView:PanAndZoomImage x:Name="panAndZoomImage"
                                                   ZoomMode="Free"
                                                   MaximumZoom="4,4"
                                                   Source="{Binding FullCover}"                                                       
                                                     >                     
                                    <slideView:PanAndZoomImage.RenderTransform>
                                        <CompositeTransform x:Name="transformFront" ScaleX="1" ScaleY="1"  />
                                    </slideView:PanAndZoomImage.RenderTransform>
                                    <slideView:PanAndZoomImage.Projection>
                                        <PlaneProjection/>
                                    </slideView:PanAndZoomImage.Projection>
                                </slideView:PanAndZoomImage>
                                   

[Victor]

Hello Vladimir,

You can inherit from PanAndZoomImage and override the OnZoomChanged method. It's a callback that is called whenever the Zoom property changes and it does so when the user pinches or sets it through code.

You can also take a less optimal approach and create a FrameworElement child class that has a Zoom property. Then you can bind that property to PanAndZoomImage a listen for property changes this way.

All the best,
Victor
the Telerik team