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         img.GetSubRect(System.Drawing.Rectangle(System.Drawing.Point((if x < 0 then 0 else x), (if y < 0 then 0 else y)),
  65                                                 System.Drawing.Size((if x + w >= img.Width then img.Width - x else w),
  66                                                                     (if y + h >= img.Height then img.Height - y else h))))
  67
  68     let setRBCFrameStyle (rbc: RBC) (frame: Views.RBCFrame) =
  69         frame.Opacity <- if displayHealthy || rbc.setManually || rbc.infected then 1. else 0.
  70         let color = if rbc.infected then colorRBCInfected else colorRBCHealthy
  71         frame.manuallyAdded.Visibility <- if rbc.setManually then Visibility.Visible else Visibility.Hidden
  72         frame.manuallyAdded.Fill <- color
  73         frame.border.Stroke <- color
  74
  75     let RBCFrameFromExisting (rbc: RBC) (frame: Views.RBCFrame) : Views.RBCFrame =
  76         frame.Visibility <- Visibility.Visible
  77         frame.Height <- rbc.size.Height
  78         frame.Width <- rbc.size.Width
  79         frame.Tag <- rbc
  80         setRBCFrameStyle rbc frame
  81         frame.border.StrokeThickness <- 1.
  82         frame.txtRBCNumber.Text <- rbc.num.ToString()
  83         frame
  84
  85     let highlightRBCFrame (frame: Views.RBCFrame) (highlight: bool) =
  86         let rbc = frame.Tag :?> RBC
  87         if highlight
  88         then
  89             frame.border.StrokeThickness <- 3.
  90             if not rbc.infected && not rbc.setManually && not displayHealthy then frame.Opacity <- 1.
  91         else
  92             frame.border.StrokeThickness <- 1.
  93             if not rbc.infected && not rbc.setManually && not displayHealthy then frame.Opacity <- 0.
  94
  95     let zoomToRBC (rbc: RBC) =
  96         scrollViewCurrentImage.ScrollToHorizontalOffset(rbc.center.X * currentScale - scrollViewCurrentImage.ViewportWidth / 2. + borderCurrentImage.BorderThickness.Left)
  97         scrollViewCurrentImage.ScrollToVerticalOffset(rbc.center.Y * currentScale - scrollViewCurrentImage.ViewportHeight / 2. + borderCurrentImage.BorderThickness.Top)
  98
  99     let parasitemiaText (nbTotal: int, nbInfected: int) : string =
 100         if nbTotal = 0
 101         then
 102             ""
 103         else
 104             let percent = 100. * (float nbInfected) / (float nbTotal)
 105             sprintf "%.1f %% (%d / %d)" percent nbInfected nbTotal
 106
 107     let updateCurrentImageInformation () =
 108         match state.CurrentImage with
 109         | Some srcImg ->
 110             let parasitemiaStr = parasitemiaText (state.ImageParasitemia srcImg)
 111             txtImageInformation.Inlines.Clear()
 112             txtImageInformation.Inlines.Add(Documents.Run("Parasitemia: ", FontWeight = FontWeights.Bold))
 113             txtImageInformation.Inlines.Add(parasitemiaStr)
 114             txtImageInformation.Inlines.Add(Documents.LineBreak())
 115
 116             txtImageInformation.Inlines.Add(Documents.Run("Average erytrocyte diameter: ", FontWeight = FontWeights.Bold))
 117             txtImageInformation.Inlines.Add(Documents.Run(srcImg.config.RBCRadius.ToString()))
 118             txtImageInformation.Inlines.Add(Documents.LineBreak())
 119
 120             txtImageInformation.Inlines.Add(Documents.Run("Last analysis: ", FontWeight = FontWeights.Bold))
 121             txtImageInformation.Inlines.Add(Documents.Run(if srcImg.dateLastAnalysis.Ticks = 0L then "<Never>" else srcImg.dateLastAnalysis.ToLocalTime().ToString()))
 122         | _ -> ()
 123
 124     let updateGlobalParasitemia () =
 125         txtGlobalParasitemia.Text <- parasitemiaText state.GlobalParasitemia
 126
 127     let updateViewportPreview () =
 128         for preview in stackPreviews.Children |> Seq.cast<Views.ImageSourcePreview> do
 129             let srcImg = preview.Tag :?> SourceImage
 130             if Some srcImg = state.CurrentImage then
 131                 preview.viewport.Visibility <- Visibility.Visible
 132
 133                 let canvasWidth = canvasCurrentImage.ActualWidth * currentScale
 134                 let canvasHeight = canvasCurrentImage.ActualHeight * currentScale
 135                 let previewWidth = (preview.ActualWidth - preview.BorderThickness.Left - preview.BorderThickness.Right)
 136                 let previewHeight = (preview.ActualHeight - preview.BorderThickness.Top - preview.BorderThickness.Bottom)
 137
 138                 let marginLeft = previewWidth * (scrollViewCurrentImage.HorizontalOffset - borderCurrentImage.BorderThickness.Left) / canvasWidth - 2.
 139                 let marginRight = previewWidth * (canvasWidth - (scrollViewCurrentImage.HorizontalOffset - borderCurrentImage.BorderThickness.Right) - scrollViewCurrentImage.ViewportWidth) / canvasWidth - 2.
 140                 let marginTop = previewHeight * (scrollViewCurrentImage.VerticalOffset - borderCurrentImage.BorderThickness.Top) / canvasHeight - 2.
 141                 let marginBottom = previewHeight * (canvasHeight - (scrollViewCurrentImage.VerticalOffset - borderCurrentImage.BorderThickness.Bottom) - scrollViewCurrentImage.ViewportHeight) / canvasHeight - 2.
 142
 143                 preview.viewport.Margin <-
 144                     Thickness(
 145                         marginLeft,
 146                         marginTop,
 147                         marginRight,
 148                         marginBottom)
 149             else
 150                 preview.viewport.Visibility <- Visibility.Hidden
 151
 152     let rec setAsInfected (rbc: RBC) (infected: bool) =
 153         state.SetAsInfected rbc infected
 154         canvasCurrentImage.Children
 155         |> Seq.cast<Views.RBCFrame>
 156         |> Seq.iter
 157             (fun frame ->
 158                 if (frame.Tag :?> RBC) = rbc
 159                 then
 160                     setRBCFrameStyle rbc frame)
 161         updateRBCFramesPreview ()
 162         updateCurrentImageInformation ()
 163         updateGlobalParasitemia ()
 164
 165     and RBCFrame (rbc: RBC) : Views.RBCFrame =
 166         let frame = RBCFrameFromExisting rbc (Views.RBCFrame())
 167         frame.SetValue(Panel.ZIndexProperty, Int32.MaxValue - rbc.num) // To be sure the
 168         frame.menuRBCSetAsHealthy.Click.AddHandler(fun obj args -> setAsInfected (frame.Tag :?> RBC) false)
 169         frame.menuRBCSetAsInfected.Click.AddHandler(fun obj args -> setAsInfected (frame.Tag :?> RBC) true)
 170         frame.ContextMenuOpening.AddHandler(
 171             fun obj args ->
 172                 if (frame.Tag :?> RBC).infected
 173                 then
 174                     frame.menuRBCSetAsHealthy.Visibility <- Visibility.Visible
 175                     frame.menuRBCSetAsInfected.Visibility <- Visibility.Collapsed
 176                 else
 177                     frame.menuRBCSetAsHealthy.Visibility <- Visibility.Collapsed
 178                     frame.menuRBCSetAsInfected.Visibility <- Visibility.Visible)
 179
 180         frame.ContextMenuClosing.AddHandler(fun obj args -> if not frame.IsMouseOver then highlightRBCFrame frame false )
 181         frame.MouseEnter.AddHandler(fun obj args -> highlightRBCFrame frame true)
 182         frame.MouseLeave.AddHandler(fun obj args -> if not frame.grid.ContextMenu.IsOpen then highlightRBCFrame frame false)
 183         frame
 184
 185     and updateRBCFramesPreview () =
 186         match state.CurrentImage with
 187         | Some srcImg ->
 188             let mutable currentPreview = 0
 189             for rbc in srcImg.rbcs |> List.filter (fun rbc -> displayHealthy || rbc.infected) do
 190                 let previewInfected =
 191                     if currentPreview < stackRBC.Children.Count
 192                     then
 193                         RBCFrameFromExisting rbc (stackRBC.Children.[currentPreview] :?> Views.RBCFrame)
 194                     else
 195                         let f = RBCFrame rbc
 196                         f.MouseLeftButtonUp.AddHandler(fun obj args -> zoomToRBC (f.Tag :?> RBC))
 197                         stackRBC.Children.Add(f) |> ignore
 198                         f
 199
 200                 currentPreview <- currentPreview + 1
 201
 202                 previewInfected.Height <- stackRBC.ActualHeight
 203                 previewInfected.Width <- stackRBC.ActualHeight * rbc.size.Width / rbc.size.Height
 204                 previewInfected.border.Fill <- ImageBrush(BitmapSourceConvert.ToBitmapSource(extractRBCPreview srcImg.img rbc))
 205
 206             stackRBC.Children.RemoveRange(currentPreview, stackRBC.Children.Count - currentPreview)
 207         | _ -> ()
 208
 209         updateViewportPreview ()
 210
 211     let updateRBCFramesCurrent () =
 212         match state.CurrentImage with
 213         | Some srcImg ->
 214             let mutable currentCanvas = 0
 215             for rbc in srcImg.rbcs do
 216                 let frame =
 217                     if currentCanvas < canvasCurrentImage.Children.Count
 218                     then
 219                         RBCFrameFromExisting rbc (canvasCurrentImage.Children.[currentCanvas] :?> Views.RBCFrame)
 220                     else
 221                         let f = RBCFrame rbc
 222                         f.Root.Opacity <- 0.7
 223                         canvasCurrentImage.Children.Add(f) |> ignore
 224                         f
 225
 226                 currentCanvas <- currentCanvas + 1
 227
 228                 Canvas.SetLeft(frame, rbc.center.X - rbc.size.Width / 2.)
 229                 Canvas.SetTop(frame, rbc.center.Y - rbc.size.Height / 2.)
 230
 231             for i in currentCanvas .. canvasCurrentImage.Children.Count - 1 do
 232                 canvasCurrentImage.Children.[i].Visibility <- Visibility.Hidden
 233         | _ -> ()
 234
 235     let saveCurrentDocument () =
 236         if state.FilePath = ""
 237         then
 238             let dialog = SaveFileDialog(AddExtension = true, DefaultExt = PiaZ.extension, Filter = PiaZ.filter);
 239             let res = dialog.ShowDialog()
 240             if res.HasValue && res.Value
 241             then
 242                 state.FilePath <- dialog.FileName
 243                 state.Save()
 244         else
 245             state.Save()
 246
 247     // Ask the use to save the current document if neccessary.
 248     let askSaveCurrent () =
 249         if state.AlteredSinceLastSave
 250         then
 251             match MessageBox.Show("Would you like to save the current document?", "Saving the current document", MessageBoxButton.YesNo, MessageBoxImage.Question) with
 252             | MessageBoxResult.Yes -> saveCurrentDocument ()
 253             | _ -> ()
 254
 255     let updateCurrentImage () =
 256         match state.CurrentImage with
 257         | Some srcImg ->
 258             // Highlight the preview.
 259             stackPreviews.Children
 260             |> Seq.cast<Views.ImageSourcePreview>
 261             |> Seq.iter (fun preview -> preview.border.BorderThickness <- Thickness(if preview.Tag = (srcImg :> Object) then 3. else 0.))
 262
 263             canvasCurrentImage.Height <- float srcImg.img.Height
 264             canvasCurrentImage.Width <- float srcImg.img.Width
 265             canvasCurrentImage.Background <- ImageBrush(BitmapSourceConvert.ToBitmapSource(srcImg.img))
 266
 267             updateRBCFramesCurrent ()
 268             updateRBCFramesPreview ()
 269             updateCurrentImageInformation ()
 270         | None ->
 271             stackRBC.Children.Clear()
 272             canvasCurrentImage.Children.Clear()
 273             canvasCurrentImage.Background <- Brushes.Black
 274
 275     let setCurrentImage (srcImg: SourceImage) =
 276         if state.CurrentImage.IsNone || state.CurrentImage.Value <> srcImg
 277         then
 278             state.CurrentImage <- Some srcImg
 279             updateCurrentImage ()
 280
 281     let addPreview (srcImg: SourceImage) =
 282         let imgCtrl = Views.ImageSourcePreview(Margin = Thickness(3.))
 283
 284         imgCtrl.menuRemoveImage.Click.AddHandler(fun obj args ->
 285             stackPreviews.Children.Remove(imgCtrl)
 286             let srcImg = imgCtrl.Tag :?> SourceImage
 287             let currentRemoved = Some srcImg = state.CurrentImage
 288             state.RemoveSourceImage srcImg
 289             if currentRemoved
 290             then
 291                 updateCurrentImage()
 292             stackPreviews.Children |> Seq.cast<Views.ImageSourcePreview> |> Seq.iter (fun imgPreview -> imgPreview.txtImageNumber.Text <- (imgPreview.Tag :?> SourceImage).num.ToString()))
 293
 294         imgCtrl.Tag <- srcImg
 295         imgCtrl.txtImageNumber.Text <- srcImg.num.ToString()
 296         let width = 200
 297         let height = srcImg.img.Height * width / srcImg.img.Width
 298         imgCtrl.imagePreview.Source <- BitmapSourceConvert.ToBitmapSource(srcImg.img.Resize(width, height, Emgu.CV.CvEnum.Inter.Cubic))
 299         stackPreviews.Children.Add(imgCtrl) |> ignore
 300
 301         // Zoom to a mouse position into the control 'imgCtrl'.
 302         let zoomTo (mousePos: Point) =
 303             let canvasW = canvasCurrentImage.ActualWidth * currentScale
 304             let canvasH = canvasCurrentImage.ActualHeight * currentScale
 305             let centerX = (mousePos.X - imgCtrl.BorderThickness.Left) / (imgCtrl.ActualWidth - imgCtrl.BorderThickness.Left) * canvasW
 306             let centerY = (mousePos.Y - imgCtrl.BorderThickness.Top) / (imgCtrl.ActualHeight - imgCtrl.BorderThickness.Top) * canvasH
 307             scrollViewCurrentImage.ScrollToHorizontalOffset(centerX - scrollViewCurrentImage.ViewportWidth / 2. + borderCurrentImage.BorderThickness.Left)
 308             scrollViewCurrentImage.ScrollToVerticalOffset(centerY - scrollViewCurrentImage.ViewportHeight / 2. + borderCurrentImage.BorderThickness.Top)
 309
 310         imgCtrl.MouseLeftButtonDown.AddHandler(fun obj args ->
 311             setCurrentImage (state.SourceImages |> Seq.find (fun srcImg -> (srcImg :> Object) = imgCtrl.Tag))
 312             imgCtrl.UpdateLayout()
 313             zoomTo (args.GetPosition(imgCtrl))
 314             imgCtrl.CaptureMouse() |> ignore)
 315
 316         imgCtrl.MouseMove.AddHandler(fun obj args ->
 317             if imgCtrl.IsMouseCaptured
 318             then
 319                 zoomTo (args.GetPosition(imgCtrl)))
 320
 321         imgCtrl.MouseLeftButtonUp.AddHandler(fun obj args ->
 322             if imgCtrl.IsMouseCaptured
 323             then
 324                 imgCtrl.ReleaseMouseCapture())
 325
 326     let updatePreviews () =
 327         stackPreviews.Children.Clear ()
 328         for srcImg in state.SourceImages do
 329             addPreview srcImg
 330         updateCurrentImage ()
 331
 332     let updateGUI () =
 333         txtPatient.Text <- state.PatientID
 334         updatePreviews ()
 335         updateGlobalParasitemia ()
 336
 337     txtPatient.LostFocus.AddHandler(fun obj args -> state.PatientID <- txtPatient.Text)
 338
 339     menuExit.Click.AddHandler(fun obj args ->
 340         askSaveCurrent ()
 341         mainWindow.Root.Close())
 342
 343     menuSaveFile.Click.AddHandler(fun obj args -> saveCurrentDocument ())
 344
 345     menuLoadFile.Click.AddHandler(fun obj args ->
 346         // TODO: if current state not saved and not empty, ask to save it.
 347         let dialog = OpenFileDialog(Filter = PiaZ.filter)
 348         let res = dialog.ShowDialog()
 349         if res.HasValue && res.Value
 350         then
 351             askSaveCurrent ()
 352             state.FilePath <- dialog.FileName
 353             state.Load()
 354             updateGUI ())
 355
 356     menuNewFile.Click.AddHandler(fun obj args ->
 357         askSaveCurrent ()
 358         state.Reset()
 359         updateGUI())
 360
 361     menuAddSourceImage.Click.AddHandler(fun obj args ->
 362         let dialog = OpenFileDialog(Filter = "Image Files|*.png;*.jpg;*.tif;*.tiff")
 363         let res = dialog.ShowDialog()
 364         if res.HasValue && res.Value
 365         then
 366             let srcImg = state.AddSourceImage dialog.FileName defaultConfig
 367             addPreview srcImg
 368             updateGlobalParasitemia ()
 369             if state.SourceImages.Count() = 1
 370             then
 371                 updateCurrentImage ())
 372
 373     menuStartAnalysis.Click.AddHandler(fun obj args ->
 374         if Analysis.showWindow mainWindow.Root state
 375         then
 376             updateGlobalParasitemia ()
 377             updateCurrentImage ())
 378
 379     menuHightlightRBC.Click.AddHandler(fun obj args ->
 380         displayHealthy <- menuHightlightRBC.IsChecked
 381         updateRBCFramesPreview ()
 382         updateRBCFramesCurrent ())
 383
 384     // Zoom on the current image.
 385     let adjustCurrentImageBorders (deltaX: float) (deltaY: float) =
 386         borderCurrentImage.BorderThickness <-
 387             Thickness(
 388                 (scrollViewCurrentImage.ViewportWidth + deltaX) / 2.,
 389                 (scrollViewCurrentImage.ViewportHeight + deltaY) / 2.,
 390                 (scrollViewCurrentImage.ViewportWidth + deltaX) / 2.,
 391                 (scrollViewCurrentImage.ViewportHeight + deltaY) / 2.)
 392
 393     canvasCurrentImage.SizeChanged.AddHandler(fun obj args ->
 394         let deltaX = args.NewSize.Width - args.PreviousSize.Width
 395         let deltaY = args.NewSize.Height - args.PreviousSize.Height
 396         if deltaX > 0.5 || deltaY > 0.5
 397         then
 398             adjustCurrentImageBorders 0.0 0.0
 399             // Center the view at the center of the image initialy.
 400             scrollViewCurrentImage.UpdateLayout()
 401             scrollViewCurrentImage.ScrollToHorizontalOffset(borderCurrentImage.ActualWidth / 2. - scrollViewCurrentImage.ViewportWidth / 2.)
 402             scrollViewCurrentImage.ScrollToVerticalOffset(borderCurrentImage.ActualHeight / 2. - scrollViewCurrentImage.ViewportHeight / 2.))
 403
 404     scrollViewCurrentImage.SizeChanged.AddHandler(fun obj args ->
 405         let deltaX = args.NewSize.Width - args.PreviousSize.Width
 406         let deltaY = args.NewSize.Height - args.PreviousSize.Height
 407         adjustCurrentImageBorders deltaX deltaY
 408         scrollViewCurrentImage.ScrollToHorizontalOffset(scrollViewCurrentImage.HorizontalOffset + deltaX / 8.)
 409         scrollViewCurrentImage.ScrollToVerticalOffset(scrollViewCurrentImage.VerticalOffset + deltaY / 8.))
 410
 411     let mutable maxScale = 4.
 412     let mutable minScale = 0.25
 413     let currentImageScaleTransform = ScaleTransform()
 414     canvasCurrentImage.LayoutTransform <- currentImageScaleTransform
 415     borderCurrentImage.PreviewMouseWheel.AddHandler(fun obj args ->
 416         let scaleFactor = if args.Delta > 0 then 2.0 else 0.5
 417         if scaleFactor > 1. && currentScale < maxScale || scaleFactor < 1. && currentScale > minScale
 418         then
 419             let previousScale = currentScale
 420             currentScale <-
 421                 let newScale = currentScale * scaleFactor
 422                 if newScale > maxScale then maxScale elif newScale < minScale then minScale else newScale
 423             let realScaleFactor = currentScale / previousScale
 424
 425             let centerX = scrollViewCurrentImage.HorizontalOffset + scrollViewCurrentImage.ViewportWidth / 2. - borderCurrentImage.BorderThickness.Left
 426             let centerY = scrollViewCurrentImage.VerticalOffset + scrollViewCurrentImage.ViewportHeight / 2. - borderCurrentImage.BorderThickness.Top
 427
 428             currentImageScaleTransform.ScaleX <- currentScale
 429             currentImageScaleTransform.ScaleY <- currentScale
 430
 431             scrollViewCurrentImage.ScrollToHorizontalOffset(centerX * realScaleFactor - scrollViewCurrentImage.ViewportWidth / 2. + borderCurrentImage.BorderThickness.Left)
 432             scrollViewCurrentImage.ScrollToVerticalOffset(centerY * realScaleFactor - scrollViewCurrentImage.ViewportHeight / 2. + borderCurrentImage.BorderThickness.Top)
 433
 434         args.Handled <- true)
 435
 436     // Pan on the current image.
 437     let mutable scrollStartPosition = Point(0., 0.)
 438     let mutable scrollStartOffsetX = 0.
 439     let mutable scrollStartOffsetY = 0.
 440     borderCurrentImage.PreviewMouseLeftButtonDown.AddHandler(fun obj args ->
 441         scrollStartPosition <- args.GetPosition(scrollViewCurrentImage)
 442         scrollStartOffsetX <- scrollViewCurrentImage.HorizontalOffset
 443         scrollStartOffsetY <- scrollViewCurrentImage.VerticalOffset
 444         borderCurrentImage.Cursor <- Input.Cursors.ScrollAll
 445         borderCurrentImage.CaptureMouse() |> ignore
 446         args.Handled <- true)
 447
 448     borderCurrentImage.PreviewMouseMove.AddHandler(fun obj args ->
 449         if borderCurrentImage.IsMouseCaptured
 450         then
 451             let position = args.GetPosition(scrollViewCurrentImage)
 452             let deltaX = scrollStartPosition.X - position.X
 453             let deltaY = scrollStartPosition.Y - position.Y
 454             scrollViewCurrentImage.ScrollToHorizontalOffset(deltaX + scrollStartOffsetX)
 455             scrollViewCurrentImage.ScrollToVerticalOffset(deltaY + scrollStartOffsetY)
 456
 457             args.Handled <- true)
 458
 459     borderCurrentImage.PreviewMouseLeftButtonUp.AddHandler(fun obj args ->
 460         if borderCurrentImage.IsMouseCaptured
 461         then
 462             borderCurrentImage.Cursor <- Input.Cursors.Arrow
 463             borderCurrentImage.ReleaseMouseCapture()
 464             args.Handled <- true)
 465
 466     // Viewport preview.
 467     scrollViewCurrentImage.ScrollChanged.AddHandler(fun obj args -> updateViewportPreview ())
 468
 469     mainWindow.Root.Show()
 470     app.Run()