+ // Zoom on the current image.
+ let adjustCurrentImageMargins () =
+ borderCurrentImage.BorderThickness <-
+ Thickness(scrollViewCurrentImage.ViewportWidth / 2., scrollViewCurrentImage.ViewportHeight / 2., scrollViewCurrentImage.ViewportWidth / 2., scrollViewCurrentImage.ViewportHeight / 2.)
+
+ scrollViewCurrentImage.Loaded.AddHandler(fun obj args -> adjustCurrentImageMargins ())
+ scrollViewCurrentImage.SizeChanged.AddHandler(fun obj args -> adjustCurrentImageMargins ())
+
+ let mutable currentScale = 1.
+ let mutable maxScale = 5.
+ let mutable minScale = 0.1
+ let currentImageScaleTransform = ScaleTransform()
+ borderCurrentImage.LayoutTransform <- currentImageScaleTransform
+ borderCurrentImage.PreviewMouseWheel.AddHandler(fun obj args ->
+ let scaleFactor = if args.Delta > 0 then 2.0 else 0.5
+ if scaleFactor > 1. && currentScale < maxScale || scaleFactor < 1. && currentScale > minScale
+ then
+ let previousScale = currentScale
+ currentScale <-
+ let newScale = currentScale * scaleFactor
+ if newScale > maxScale then maxScale elif newScale < minScale then minScale else newScale
+ let realScaleFactor = currentScale / previousScale
+
+ let centerX = scrollViewCurrentImage.HorizontalOffset + scrollViewCurrentImage.ViewportWidth / 2. - canvasCurrentImage.Margin.Left
+ let centerY = scrollViewCurrentImage.VerticalOffset + scrollViewCurrentImage.ViewportHeight / 2. - canvasCurrentImage.Margin.Top
+
+ canvasCurrentImage.Margin <- Thickness(canvasCurrentImage.Margin.Top * realScaleFactor)
+ currentImageScaleTransform.ScaleX <- currentScale
+ currentImageScaleTransform.ScaleY <- currentScale
+
+ scrollViewCurrentImage.ScrollToHorizontalOffset(centerX * realScaleFactor - scrollViewCurrentImage.ViewportWidth / 2. + canvasCurrentImage.Margin.Left)
+ scrollViewCurrentImage.ScrollToVerticalOffset(centerY * realScaleFactor - scrollViewCurrentImage.ViewportHeight / 2. + canvasCurrentImage.Margin.Top)
+ args.Handled <- true)
+
+ // Pan on the current image.
+ let mutable scrollStartPosition = Point(0., 0.)
+ let mutable scrollStartOffsetX = 0.
+ let mutable scrollStartOffsetY = 0.
+ borderCurrentImage.PreviewMouseLeftButtonDown.AddHandler(fun obj args ->
+ scrollStartPosition <- args.GetPosition(scrollViewCurrentImage)
+ scrollStartOffsetX <- scrollViewCurrentImage.HorizontalOffset
+ scrollStartOffsetY <- scrollViewCurrentImage.VerticalOffset
+ borderCurrentImage.Cursor <- Input.Cursors.ScrollAll
+ borderCurrentImage.CaptureMouse() |> ignore
+ args.Handled <- true)
+
+ borderCurrentImage.PreviewMouseMove.AddHandler(fun obj args ->
+ if borderCurrentImage.IsMouseCaptured
+ then
+ let position = args.GetPosition(scrollViewCurrentImage)
+ let deltaX = scrollStartPosition.X - position.X
+ let deltaY = scrollStartPosition.Y - position.Y
+ scrollViewCurrentImage.ScrollToHorizontalOffset(deltaX + scrollStartOffsetX)
+ scrollViewCurrentImage.ScrollToVerticalOffset(deltaY + scrollStartOffsetY)
+ args.Handled <- true)
+
+ borderCurrentImage.PreviewMouseLeftButtonUp.AddHandler(fun obj args ->
+ if borderCurrentImage.IsMouseCaptured
+ then
+ borderCurrentImage.Cursor <- Input.Cursors.Arrow
+ borderCurrentImage.ReleaseMouseCapture()
+ args.Handled <- true)
+
+