Parasitemia/Parasitemia/GUI/GUI.fs

   1 module Parasitemia.GUI.Main
   2
   3 open System
   4 open System.IO
   5 open System.Linq
   6 open System.Windows
   7 open System.Windows.Media
   8 open System.Windows.Markup
   9 open System.Windows.Shapes
  10 open System.Windows.Controls
  11 open System.Diagnostics
  12 open Microsoft.Win32 // For the common dialogs.
  13
  14 open Emgu.CV.WPF
  15
  16 open Config
  17 open Types
  18
  19 let run (defaultConfig: Config) =
  20     let app = new Application()
  21     let mainWindow = Views.MainWindow()
  22     let ctrl (name: string): 'a =
  23         mainWindow.Root.FindName(name) :?> 'a
  24
  25     let colorRBCHealthy = Brushes.YellowGreen
  26     let colorRBCInfected = Brushes.Red
  27
  28     let state = State.State()
  29     let mutable currentScale = 1.
  30     let mutable displayHealthy = false
  31
  32     let menuExit: MenuItem = ctrl "menuExit"
  33     let menuSaveFile: MenuItem = ctrl "menuSave"
  34     let menuLoadFile: MenuItem = ctrl "menuOpen"
  35     let menuNewFile: MenuItem = ctrl "menuNew"
  36     let menuAddSourceImage: MenuItem = ctrl "menuAddSourceImage"
  37     let menuStartAnalysis: MenuItem = ctrl "menuStartAnalysis"
  38     let menuHightlightRBC: MenuItem = ctrl "menuHightlightRBC"
  39
  40     let txtPatient: TextBox = ctrl "txtPatient"
  41     let txtGlobalParasitemia: TextBox = ctrl "txtGlobalParasitemia"
  42
  43     let stackPreviews: StackPanel = ctrl "stackPreviews"
  44
  45     let scrollViewCurrentImage: ScrollViewer = ctrl "scrollViewCurrentImage"
  46     let borderCurrentImage: Border = ctrl "borderCurrentImage"
  47     let canvasCurrentImage: Canvas = ctrl "canvasCurrentImage"
  48     let txtImageInformation: TextBlock = ctrl "txtImageInformation"
  49
  50     let scrollRBC: ScrollViewer = ctrl "scrollRBC"
  51     let stackRBC: StackPanel = ctrl "stackRBC"
  52
  53     // Initializations.
  54     menuHightlightRBC.IsChecked <- displayHealthy
  55
  56     // Utils.
  57     let extractRBCPreview (img: Emgu.CV.Image<Emgu.CV.Structure.Bgr, byte>) (rbc: RBC) : Emgu.CV.Image<Emgu.CV.Structure.Bgr, byte> =
  58         let rbcWidth = rbc.size.Width
  59         let rbcHeight = rbc.size.Height
  60         let x = rbc.center.X - rbcWidth / 2. |> Utils.roundInt
  61         let y = rbc.center.Y - rbcHeight / 2. |> Utils.roundInt
  62         let w = Utils.roundInt rbcWidth
  63         let h = Utils.roundInt rbcHeight
  64         //Utils.dprintfn "w: %A, h: %A, cx: %A, cy: %A, img.w: %A, img.h: %A" w h x y img.Width img.Height
  65         img.GetSubRect(System.Drawing.Rectangle(System.Drawing.Point((if x < 0 then 0 else x), (if y < 0 then 0 else y)),
  66                                                 System.Drawing.Size((if x + w >= img.Width then img.Width - x else w),
  67                                                                     (if y + h >= img.Height then img.Height - y else h))))
  68
  69     let setRBCFrameStyle (rbc: RBC) (frame: Views.RBCFrame) =
  70         frame.Opacity <- if displayHealthy || rbc.setManually || rbc.infected then 1. else 0.
  71         let color = if rbc.infected then colorRBCInfected else colorRBCHealthy
  72         frame.manuallyAdded.Visibility <- if rbc.setManually then Visibility.Visible else Visibility.Hidden
  73         frame.manuallyAdded.Fill <- color
  74         frame.border.Stroke <- color
  75
  76     let RBCFrameFromExisting (rbc: RBC) (frame: Views.RBCFrame) : Views.RBCFrame =
  77         frame.Visibility <- Visibility.Visible
  78         frame.Height <- rbc.size.Height
  79         frame.Width <- rbc.size.Width
  80         frame.Tag <- rbc
  81         setRBCFrameStyle rbc frame
  82         frame.border.StrokeThickness <- 1.
  83         frame.txtRBCNumber.Text <- rbc.num.ToString()
  84         frame
  85
  86     let highlightRBCFrame (frame: Views.RBCFrame) (highlight: bool) =
  87         let rbc = frame.Tag :?> RBC
  88         if highlight
  89         then
  90             frame.border.StrokeThickness <- 3.
  91             if not rbc.infected && not rbc.setManually && not displayHealthy then frame.Opacity <- 1.
  92         else
  93             frame.border.StrokeThickness <- 1.
  94             if not rbc.infected && not rbc.setManually && not displayHealthy then frame.Opacity <- 0.
  95
  96     let zoomToRBC (rbc: RBC) =
  97         scrollViewCurrentImage.ScrollToHorizontalOffset(rbc.center.X * currentScale - scrollViewCurrentImage.ViewportWidth / 2. + borderCurrentImage.BorderThickness.Left)
  98         scrollViewCurrentImage.ScrollToVerticalOffset(rbc.center.Y * currentScale - scrollViewCurrentImage.ViewportHeight / 2. + borderCurrentImage.BorderThickness.Top)
  99
 100     let parasitemiaText (nbTotal: int, nbInfected: int) : string =
 101         if nbTotal = 0
 102         then
 103             ""
 104         else
 105             let percent = 100. * (float nbInfected) / (float nbTotal)
 106             sprintf "%.1f %% (%d / %d)" percent nbInfected nbTotal
 107
 108     let updateCurrentImageInformation () =
 109         match state.CurrentImage with
 110         | Some srcImg ->
 111             let parasitemiaStr = parasitemiaText (state.ImageParasitemia srcImg)
 112             txtImageInformation.Inlines.Clear()
 113             txtImageInformation.Inlines.Add(Documents.Run("Parasitemia: ", FontWeight = FontWeights.Bold))
 114             txtImageInformation.Inlines.Add(parasitemiaStr)
 115             txtImageInformation.Inlines.Add(Documents.LineBreak())
 116
 117             txtImageInformation.Inlines.Add(Documents.Run("Average erytrocyte diameter: ", FontWeight = FontWeights.Bold))
 118             txtImageInformation.Inlines.Add(Documents.Run(string (Utils.roundInt <| 2. * srcImg.rbcRadius)))
 119             txtImageInformation.Inlines.Add(Documents.Run(" px"))
 120             txtImageInformation.Inlines.Add(Documents.LineBreak())
 121
 122             txtImageInformation.Inlines.Add(Documents.Run("Last analysis: ", FontWeight = FontWeights.Bold))
 123             txtImageInformation.Inlines.Add(Documents.Run(if srcImg.dateLastAnalysis.Ticks = 0L then "<Never>" else srcImg.dateLastAnalysis.ToLocalTime().ToString()))
 124         | _ -> ()
 125
 126     let updateGlobalParasitemia () =
 127         txtGlobalParasitemia.Text <- parasitemiaText state.GlobalParasitemia
 128
 129     let rec setAsInfected (rbc: RBC) (infected: bool) =
 130         state.SetAsInfected rbc infected
 131         canvasCurrentImage.Children
 132         |> Seq.cast<Views.RBCFrame>
 133         |> Seq.iter
 134             (fun frame ->
 135                 if (frame.Tag :?> RBC) = rbc
 136                 then
 137                     setRBCFrameStyle rbc frame)
 138         updateRBCFramesPreview ()
 139         updateCurrentImageInformation ()
 140         updateGlobalParasitemia ()
 141
 142     and RBCFrame (rbc: RBC) : Views.RBCFrame =
 143         let f = RBCFrameFromExisting rbc (Views.RBCFrame())
 144         f.menuRBCSetAsHealthy.Click.AddHandler(fun obj args -> setAsInfected (f.Tag :?> RBC) false)
 145         f.menuRBCSetAsInfected.Click.AddHandler(fun obj args -> setAsInfected (f.Tag :?> RBC) true)
 146         f.ContextMenuOpening.AddHandler(
 147             fun obj args ->
 148                 if (f.Tag :?> RBC).infected
 149                 then
 150                     f.menuRBCSetAsHealthy.Visibility <- Visibility.Visible
 151                     f.menuRBCSetAsInfected.Visibility <- Visibility.Collapsed
 152                 else
 153                     f.menuRBCSetAsHealthy.Visibility <- Visibility.Collapsed
 154                     f.menuRBCSetAsInfected.Visibility <- Visibility.Visible)
 155
 156         f.ContextMenuClosing.AddHandler(fun obj args -> if not f.IsMouseOver then highlightRBCFrame f false )
 157         f.MouseEnter.AddHandler(fun obj args -> highlightRBCFrame f true)
 158         f.MouseLeave.AddHandler(fun obj args -> if not f.grid.ContextMenu.IsOpen then highlightRBCFrame f false)
 159         f
 160
 161     and updateRBCFramesPreview () =
 162         match state.CurrentImage with
 163         | Some srcImg ->
 164             let mutable currentPreview = 0
 165             for rbc in srcImg.rbcs |> List.filter (fun rbc -> displayHealthy || rbc.infected) do
 166                 let previewInfected =
 167                     if currentPreview < stackRBC.Children.Count
 168                     then
 169                         RBCFrameFromExisting rbc (stackRBC.Children.[currentPreview] :?> Views.RBCFrame)
 170                     else
 171                         let f = RBCFrame rbc
 172                         f.MouseLeftButtonUp.AddHandler(fun obj args -> zoomToRBC (f.Tag :?> RBC))
 173                         stackRBC.Children.Add(f) |> ignore
 174                         f
 175
 176                 currentPreview <- currentPreview + 1
 177
 178                 previewInfected.Height <- stackRBC.ActualHeight
 179                 previewInfected.Width <- stackRBC.ActualHeight * rbc.size.Width / rbc.size.Height
 180                 previewInfected.border.Fill <- ImageBrush(BitmapSourceConvert.ToBitmapSource(extractRBCPreview srcImg.img rbc))
 181
 182             stackRBC.Children.RemoveRange(currentPreview, stackRBC.Children.Count - currentPreview)
 183         | _ -> ()
 184
 185     let updateRBCFramesCurrent () =
 186         match state.CurrentImage with
 187         | Some srcImg ->
 188             let mutable currentCanvas = 0
 189             for rbc in srcImg.rbcs do
 190                 let frame =
 191                     if currentCanvas < canvasCurrentImage.Children.Count
 192                     then
 193                         RBCFrameFromExisting rbc (canvasCurrentImage.Children.[currentCanvas] :?> Views.RBCFrame)
 194                     else
 195                         let f = RBCFrame rbc
 196                         canvasCurrentImage.Children.Add(f) |> ignore
 197                         f
 198
 199                 currentCanvas <- currentCanvas + 1
 200
 201                 Canvas.SetLeft(frame, rbc.center.X - rbc.size.Width / 2.)
 202                 Canvas.SetTop(frame, rbc.center.Y - rbc.size.Height / 2.)
 203
 204             for i in currentCanvas .. canvasCurrentImage.Children.Count - 1 do
 205                 canvasCurrentImage.Children.[i].Visibility <- Visibility.Hidden
 206         | _ -> ()
 207
 208     let saveCurrentDocument () =
 209         if state.FilePath = ""
 210         then
 211             let dialog = SaveFileDialog(AddExtension = true, DefaultExt = PiaZ.extension, Filter = PiaZ.filter);
 212             let res = dialog.ShowDialog()
 213             if res.HasValue && res.Value
 214             then
 215                 state.FilePath <- dialog.FileName
 216                 state.Save()
 217         else
 218             state.Save()
 219
 220     // Ask the use to save the current document if neccessary.
 221     let askSaveCurrent () =
 222         if state.AlteredSinceLastSave
 223         then
 224             match MessageBox.Show("Would you like to save the current document?", "Saving the current document", MessageBoxButton.YesNo, MessageBoxImage.Question) with
 225             | MessageBoxResult.Yes -> saveCurrentDocument ()
 226             | _ -> ()
 227
 228     let updateCurrentImage () =
 229         match state.CurrentImage with
 230         | Some srcImg ->
 231             // Highlight the preview.
 232             stackPreviews.Children
 233             |> Seq.cast<Views.ImageSourcePreview>
 234             |> Seq.iter (fun preview -> preview.border.BorderThickness <- Thickness(if preview.Tag = (srcImg :> Object) then 3. else 0.))
 235
 236             canvasCurrentImage.Height <- float srcImg.img.Height
 237             canvasCurrentImage.Width <- float srcImg.img.Width
 238             canvasCurrentImage.Background <- ImageBrush(BitmapSourceConvert.ToBitmapSource(srcImg.img))
 239
 240             updateRBCFramesCurrent ()
 241             updateRBCFramesPreview ()
 242             updateCurrentImageInformation ()
 243         | None ->
 244             stackRBC.Children.Clear()
 245             canvasCurrentImage.Children.Clear()
 246             canvasCurrentImage.Background <- Brushes.Black
 247
 248     let setCurrentImage (srcImg: SourceImage) =
 249         if state.CurrentImage.IsNone || state.CurrentImage.Value <> srcImg
 250         then
 251             state.CurrentImage <- Some srcImg
 252             updateCurrentImage ()
 253
 254     let updateViewportPreview () =
 255         for preview in stackPreviews.Children |> Seq.cast<Views.ImageSourcePreview> do
 256             let srcImg = preview.Tag :?> SourceImage
 257             if Some srcImg = state.CurrentImage then
 258                 preview.viewport.Visibility <- Visibility.Visible
 259
 260                 let canvasWidth = canvasCurrentImage.ActualWidth * currentScale
 261                 let canvasHeight = canvasCurrentImage.ActualHeight * currentScale
 262                 let previewWidth = (preview.ActualWidth - preview.BorderThickness.Left - preview.BorderThickness.Right)
 263                 let previewHeight = (preview.ActualHeight - preview.BorderThickness.Top - preview.BorderThickness.Bottom)
 264
 265                 let marginLeft = previewWidth * (scrollViewCurrentImage.HorizontalOffset - borderCurrentImage.BorderThickness.Left) / canvasWidth - 2.
 266                 let marginRight = previewWidth * (canvasWidth - (scrollViewCurrentImage.HorizontalOffset - borderCurrentImage.BorderThickness.Right) - scrollViewCurrentImage.ViewportWidth) / canvasWidth - 2.
 267                 let marginTop = previewHeight * (scrollViewCurrentImage.VerticalOffset - borderCurrentImage.BorderThickness.Top) / canvasHeight - 2.
 268                 let marginBottom = previewHeight * (canvasHeight - (scrollViewCurrentImage.VerticalOffset - borderCurrentImage.BorderThickness.Bottom) - scrollViewCurrentImage.ViewportHeight) / canvasHeight - 2.
 269
 270                 preview.viewport.Margin <-
 271                     Thickness(
 272                         marginLeft,
 273                         marginTop,
 274                         marginRight,
 275                         marginBottom)
 276             else
 277                 preview.viewport.Visibility <- Visibility.Hidden
 278
 279     let addPreview (srcImg: SourceImage) =
 280         let imgCtrl = Views.ImageSourcePreview(Margin = Thickness(3.))
 281
 282         imgCtrl.menuRemoveImage.Click.AddHandler(fun obj args ->
 283             stackPreviews.Children.Remove(imgCtrl)
 284             let srcImg = imgCtrl.Tag :?> SourceImage
 285             let currentRemoved = Some srcImg = state.CurrentImage
 286             state.RemoveSourceImage srcImg
 287             if currentRemoved
 288             then
 289                 updateCurrentImage()
 290             stackPreviews.Children |> Seq.cast<Views.ImageSourcePreview> |> Seq.iter (fun imgPreview -> imgPreview.txtImageNumber.Text <- (imgPreview.Tag :?> SourceImage).num.ToString()))
 291
 292         imgCtrl.Tag <- srcImg
 293         imgCtrl.txtImageNumber.Text <- srcImg.num.ToString()
 294         let width = 200
 295         let height = srcImg.img.Height * width / srcImg.img.Width
 296         imgCtrl.imagePreview.Source <- BitmapSourceConvert.ToBitmapSource(srcImg.img.Resize(width, height, Emgu.CV.CvEnum.Inter.Cubic))
 297         stackPreviews.Children.Add(imgCtrl) |> ignore
 298
 299         // Zoom to a mouse position into the control 'imgCtrl'.
 300         let zoomTo (mousePos: Point) =
 301             let canvasW = canvasCurrentImage.ActualWidth * currentScale
 302             let canvasH = canvasCurrentImage.ActualHeight * currentScale
 303             let centerX = (mousePos.X - imgCtrl.BorderThickness.Left) / (imgCtrl.ActualWidth - imgCtrl.BorderThickness.Left) * canvasW
 304             let centerY = (mousePos.Y - imgCtrl.BorderThickness.Top) / (imgCtrl.ActualHeight - imgCtrl.BorderThickness.Top) * canvasH
 305             scrollViewCurrentImage.ScrollToHorizontalOffset(centerX - scrollViewCurrentImage.ViewportWidth / 2. + borderCurrentImage.BorderThickness.Left)
 306             scrollViewCurrentImage.ScrollToVerticalOffset(centerY - scrollViewCurrentImage.ViewportHeight / 2. + borderCurrentImage.BorderThickness.Top)
 307
 308         imgCtrl.MouseLeftButtonDown.AddHandler(fun obj args ->
 309             setCurrentImage (state.SourceImages |> Seq.find (fun srcImg -> (srcImg :> Object) = imgCtrl.Tag))
 310             imgCtrl.UpdateLayout()
 311             zoomTo (args.GetPosition(imgCtrl))
 312             imgCtrl.CaptureMouse() |> ignore)
 313
 314         imgCtrl.MouseMove.AddHandler(fun obj args ->
 315             if imgCtrl.IsMouseCaptured
 316             then
 317                 zoomTo (args.GetPosition(imgCtrl)))
 318
 319         imgCtrl.MouseLeftButtonUp.AddHandler(fun obj args ->
 320             if imgCtrl.IsMouseCaptured
 321             then
 322                 imgCtrl.ReleaseMouseCapture())
 323
 324
 325     let updatePreviews () =
 326         stackPreviews.Children.Clear ()
 327         for srcImg in state.SourceImages do
 328             addPreview srcImg
 329         updateCurrentImage ()
 330
 331     let updateGUI () =
 332         txtPatient.Text <- state.PatientID
 333         updatePreviews ()
 334         updateGlobalParasitemia ()
 335
 336     txtPatient.TextChanged.AddHandler(fun obj args -> state.PatientID <- txtPatient.Text)
 337
 338     menuExit.Click.AddHandler(fun obj args ->
 339         askSaveCurrent ()
 340         mainWindow.Root.Close())
 341
 342     menuSaveFile.Click.AddHandler(fun obj args -> saveCurrentDocument ())
 343
 344     menuLoadFile.Click.AddHandler(fun obj args ->
 345         // TODO: if current state not saved and not empty, ask to save it.
 346         let dialog = OpenFileDialog(Filter = PiaZ.filter)
 347         let res = dialog.ShowDialog()
 348         if res.HasValue && res.Value
 349         then
 350             askSaveCurrent ()
 351             state.FilePath <- dialog.FileName
 352             state.Load()
 353             updateGUI ())
 354
 355     menuNewFile.Click.AddHandler(fun obj args ->
 356         askSaveCurrent ()
 357         state.Reset()
 358         updateGUI())
 359
 360     menuAddSourceImage.Click.AddHandler(fun obj args ->
 361         let dialog = OpenFileDialog(Filter = "Image Files|*.png;*.jpg;*.tif;*.tiff")
 362         let res = dialog.ShowDialog()
 363         if res.HasValue && res.Value
 364         then
 365             let srcImg = state.AddSourceImage(dialog.FileName)
 366             addPreview srcImg
 367             updateGlobalParasitemia ()
 368             if state.SourceImages.Count() = 1
 369             then
 370                 updateCurrentImage ())
 371
 372     menuStartAnalysis.Click.AddHandler(fun obj args ->
 373         if Analysis.showWindow mainWindow.Root state defaultConfig
 374         then
 375             updateGlobalParasitemia ()
 376             updateCurrentImage ())
 377
 378     menuHightlightRBC.Click.AddHandler(fun obj args ->
 379         displayHealthy <- menuHightlightRBC.IsChecked
 380         updateRBCFramesPreview ()
 381         updateRBCFramesCurrent ())
 382
 383     // Zoom on the current image.
 384     let adjustCurrentImageBorders (deltaX: float) (deltaY: float) =
 385         borderCurrentImage.BorderThickness <-
 386             Thickness(
 387                 (scrollViewCurrentImage.ViewportWidth + deltaX) / 2.,
 388                 (scrollViewCurrentImage.ViewportHeight + deltaY) / 2.,
 389                 (scrollViewCurrentImage.ViewportWidth + deltaX) / 2.,
 390                 (scrollViewCurrentImage.ViewportHeight + deltaY) / 2.)
 391
 392     canvasCurrentImage.SizeChanged.AddHandler(fun obj args ->
 393         let deltaX = args.NewSize.Width - args.PreviousSize.Width
 394         let deltaY = args.NewSize.Height - args.PreviousSize.Height
 395         if deltaX > 0.5 || deltaY > 0.5
 396         then
 397             adjustCurrentImageBorders 0.0 0.0
 398             // Center the view at the center of the image initialy.
 399             scrollViewCurrentImage.UpdateLayout()
 400             scrollViewCurrentImage.ScrollToHorizontalOffset(borderCurrentImage.ActualWidth / 2. - scrollViewCurrentImage.ViewportWidth / 2.)
 401             scrollViewCurrentImage.ScrollToVerticalOffset(borderCurrentImage.ActualHeight / 2. - scrollViewCurrentImage.ViewportHeight / 2.))
 402
 403     scrollViewCurrentImage.SizeChanged.AddHandler(fun obj args ->
 404         let deltaX = args.NewSize.Width - args.PreviousSize.Width
 405         let deltaY = args.NewSize.Height - args.PreviousSize.Height
 406         adjustCurrentImageBorders deltaX deltaY
 407         scrollViewCurrentImage.ScrollToHorizontalOffset(scrollViewCurrentImage.HorizontalOffset + deltaX / 8.)
 408         scrollViewCurrentImage.ScrollToVerticalOffset(scrollViewCurrentImage.VerticalOffset + deltaY / 8.))
 409
 410     let mutable maxScale = 4.
 411     let mutable minScale = 0.25
 412     let currentImageScaleTransform = ScaleTransform()
 413     canvasCurrentImage.LayoutTransform <- currentImageScaleTransform
 414     borderCurrentImage.PreviewMouseWheel.AddHandler(fun obj args ->
 415         let scaleFactor = if args.Delta > 0 then 2.0 else 0.5
 416         if scaleFactor > 1. && currentScale < maxScale || scaleFactor < 1. && currentScale > minScale
 417         then
 418             let previousScale = currentScale
 419             currentScale <-
 420                 let newScale = currentScale * scaleFactor
 421                 if newScale > maxScale then maxScale elif newScale < minScale then minScale else newScale
 422             let realScaleFactor = currentScale / previousScale
 423
 424             let centerX = scrollViewCurrentImage.HorizontalOffset + scrollViewCurrentImage.ViewportWidth / 2. - borderCurrentImage.BorderThickness.Left
 425             let centerY = scrollViewCurrentImage.VerticalOffset + scrollViewCurrentImage.ViewportHeight / 2. - borderCurrentImage.BorderThickness.Top
 426
 427             currentImageScaleTransform.ScaleX <- currentScale
 428             currentImageScaleTransform.ScaleY <- currentScale
 429
 430             scrollViewCurrentImage.ScrollToHorizontalOffset(centerX * realScaleFactor - scrollViewCurrentImage.ViewportWidth / 2. + borderCurrentImage.BorderThickness.Left)
 431             scrollViewCurrentImage.ScrollToVerticalOffset(centerY * realScaleFactor - scrollViewCurrentImage.ViewportHeight / 2. + borderCurrentImage.BorderThickness.Top)
 432
 433         args.Handled <- true)
 434
 435     // Pan on the current image.
 436     let mutable scrollStartPosition = Point(0., 0.)
 437     let mutable scrollStartOffsetX = 0.
 438     let mutable scrollStartOffsetY = 0.
 439     borderCurrentImage.PreviewMouseLeftButtonDown.AddHandler(fun obj args ->
 440         scrollStartPosition <- args.GetPosition(scrollViewCurrentImage)
 441         scrollStartOffsetX <- scrollViewCurrentImage.HorizontalOffset
 442         scrollStartOffsetY <- scrollViewCurrentImage.VerticalOffset
 443         borderCurrentImage.Cursor <- Input.Cursors.ScrollAll
 444         borderCurrentImage.CaptureMouse() |> ignore
 445         args.Handled <- true)
 446
 447     borderCurrentImage.PreviewMouseMove.AddHandler(fun obj args ->
 448         if borderCurrentImage.IsMouseCaptured
 449         then
 450             let position = args.GetPosition(scrollViewCurrentImage)
 451             let deltaX = scrollStartPosition.X - position.X
 452             let deltaY = scrollStartPosition.Y - position.Y
 453             scrollViewCurrentImage.ScrollToHorizontalOffset(deltaX + scrollStartOffsetX)
 454             scrollViewCurrentImage.ScrollToVerticalOffset(deltaY + scrollStartOffsetY)
 455
 456             args.Handled <- true)
 457
 458     borderCurrentImage.PreviewMouseLeftButtonUp.AddHandler(fun obj args ->
 459         if borderCurrentImage.IsMouseCaptured
 460         then
 461             borderCurrentImage.Cursor <- Input.Cursors.Arrow
 462             borderCurrentImage.ReleaseMouseCapture()
 463             args.Handled <- true)
 464
 465     // Viewport preview.
 466     scrollViewCurrentImage.ScrollChanged.AddHandler(fun obj args -> updateViewportPreview ())
 467
 468     mainWindow.Root.Show()
 469     app.Run()