Parasitemia/ParasitemiaUI/GUI.fs

   1 module ParasitemiaUI.GUI
   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 Logger
  17
  18 open ParasitemiaCore.Config
  19 open ParasitemiaCore.Utils
  20 open Types
  21
  22 let run (defaultConfig: Config) (fileToOpen: string option) =
  23     let app = new Application()
  24     let mainWindow = Views.MainWindow()
  25     let ctrl (name: string): 'a = mainWindow.Root.FindName(name) :?> 'a
  26
  27     let colorRBCHealthy = Brushes.YellowGreen
  28     let colorRBCInfected = Brushes.Red
  29
  30     let state = State.State()
  31     let mutable currentScale = 1.
  32     let mutable displayHealthy = false
  33
  34     let menuExit: MenuItem = ctrl "menuExit"
  35     let menuSaveFile: MenuItem = ctrl "menuSave"
  36     let menuLoadFile: MenuItem = ctrl "menuOpen"
  37     let menuNewFile: MenuItem = ctrl "menuNew"
  38     let menuAddSourceImage: MenuItem = ctrl "menuAddSourceImage"
  39     let menuAnalysis: MenuItem = ctrl "menuAnalysis"
  40     let menuStartAnalysis: MenuItem = ctrl "menuStartAnalysis"
  41     let menuView: MenuItem = ctrl "menuView"
  42     let menuHightlightRBC: MenuItem = ctrl "menuHightlightRBC"
  43     let menuAbout: MenuItem = ctrl "menuAbout"
  44
  45     let txtPatient: TextBox = ctrl "txtPatient"
  46     let txtGlobalParasitemia: TextBox = ctrl "txtGlobalParasitemia"
  47
  48     let stackPreviews: StackPanel = ctrl "stackPreviews"
  49
  50     let scrollViewCurrentImage: ScrollViewer = ctrl "scrollViewCurrentImage"
  51     let borderCurrentImage: Border = ctrl "borderCurrentImage"
  52     let canvasCurrentImage: Canvas = ctrl "canvasCurrentImage"
  53     let txtImageInformation: TextBlock = ctrl "txtImageInformation"
  54
  55     let scrollRBC: ScrollViewer = ctrl "scrollRBC"
  56     let stackRBC: StackPanel = ctrl "stackRBC"
  57
  58     // Initializations.
  59     menuHightlightRBC.IsChecked <- displayHealthy
  60
  61     // Utils.
  62     let extractRBCPreview (img: Emgu.CV.Image<Emgu.CV.Structure.Bgr, byte>) (rbc: RBC) : Emgu.CV.Image<Emgu.CV.Structure.Bgr, byte> =
  63         let rbcWidth = rbc.size.Width
  64         let rbcHeight = rbc.size.Height
  65         let x = rbc.center.X - rbcWidth / 2. |> roundInt
  66         let y = rbc.center.Y - rbcHeight / 2. |> roundInt
  67         let w = roundInt rbcWidth
  68         let h = roundInt rbcHeight
  69         img.GetSubRect(System.Drawing.Rectangle(System.Drawing.Point((if x < 0 then 0 else x), (if y < 0 then 0 else y)),
  70                                                 System.Drawing.Size((if x + w >= img.Width then img.Width - x else w),
  71                                                                     (if y + h >= img.Height then img.Height - y else h))))
  72
  73     let setRBCFrameStyle (rbc: RBC) (frame: Views.RBCFrame) =
  74         frame.Opacity <- if displayHealthy || rbc.setManually || rbc.infected then 1. else 0.
  75         let color = if rbc.infected then colorRBCInfected else colorRBCHealthy
  76         frame.manuallyAdded.Visibility <- if rbc.setManually then Visibility.Visible else Visibility.Hidden
  77         frame.manuallyAdded.Fill <- color
  78         frame.border.Stroke <- color
  79
  80     let RBCFrameFromExisting (rbc: RBC) (frame: Views.RBCFrame) : Views.RBCFrame =
  81         frame.Visibility <- Visibility.Visible
  82         frame.Height <- rbc.size.Height
  83         frame.Width <- rbc.size.Width
  84         frame.Tag <- rbc
  85         setRBCFrameStyle rbc frame
  86         frame.border.StrokeThickness <- 1.
  87         frame.txtRBCNumber.Text <- rbc.num.ToString()
  88         frame
  89
  90     let highlightRBCFrame (frame: Views.RBCFrame) (highlight: bool) =
  91         let rbc = frame.Tag :?> RBC
  92         if highlight
  93         then
  94             frame.border.StrokeThickness <- 3.
  95             if not rbc.infected && not rbc.setManually && not displayHealthy then frame.Opacity <- 1.
  96         else
  97             frame.border.StrokeThickness <- 1.
  98             if not rbc.infected && not rbc.setManually && not displayHealthy then frame.Opacity <- 0.
  99
 100     let zoomToRBC (rbc: RBC) =
 101         scrollViewCurrentImage.ScrollToHorizontalOffset(rbc.center.X * currentScale - scrollViewCurrentImage.ViewportWidth / 2. + borderCurrentImage.BorderThickness.Left)
 102         scrollViewCurrentImage.ScrollToVerticalOffset(rbc.center.Y * currentScale - scrollViewCurrentImage.ViewportHeight / 2. + borderCurrentImage.BorderThickness.Top)
 103
 104     let parasitemiaText (nbTotal: int, nbInfected: int) : string =
 105         if nbTotal = 0
 106         then
 107             ""
 108         else
 109             let percent = 100. * (float nbInfected) / (float nbTotal)
 110             sprintf "%.1f %% (%d / %d)" percent nbInfected nbTotal
 111
 112     let updateCurrentImageInformation () =
 113         match state.CurrentImage with
 114         | Some srcImg ->
 115             let parasitemiaStr = parasitemiaText (state.ImageParasitemia srcImg)
 116             txtImageInformation.Inlines.Clear()
 117             txtImageInformation.Inlines.Add(Documents.Run("Parasitemia: ", FontWeight = FontWeights.Bold))
 118             txtImageInformation.Inlines.Add(parasitemiaStr)
 119             txtImageInformation.Inlines.Add(Documents.LineBreak())
 120
 121             txtImageInformation.Inlines.Add(Documents.Run("Average erytrocyte diameter: ", FontWeight = FontWeights.Bold))
 122             txtImageInformation.Inlines.Add(Documents.Run(srcImg.config.RBCRadius.ToString()))
 123             txtImageInformation.Inlines.Add(Documents.LineBreak())
 124
 125             txtImageInformation.Inlines.Add(Documents.Run("Last analysis: ", FontWeight = FontWeights.Bold))
 126             txtImageInformation.Inlines.Add(Documents.Run(if srcImg.dateLastAnalysis.Ticks = 0L then "<Never>" else srcImg.dateLastAnalysis.ToLocalTime().ToString()))
 127         | _ -> ()
 128
 129     let updateGlobalParasitemia () =
 130         txtGlobalParasitemia.Text <- parasitemiaText state.GlobalParasitemia
 131
 132     let updateViewportPreview () =
 133         for preview in stackPreviews.Children |> Seq.cast<Views.ImageSourcePreview> do
 134             let srcImg = preview.Tag :?> SourceImage
 135             if Some srcImg = state.CurrentImage then
 136                 preview.viewport.Visibility <- Visibility.Visible
 137
 138                 let canvasWidth = canvasCurrentImage.ActualWidth * currentScale
 139                 let canvasHeight = canvasCurrentImage.ActualHeight * currentScale
 140                 let previewWidth = (preview.ActualWidth - preview.BorderThickness.Left - preview.BorderThickness.Right)
 141                 let previewHeight = (preview.ActualHeight - preview.BorderThickness.Top - preview.BorderThickness.Bottom)
 142
 143                 let marginLeft = previewWidth * (scrollViewCurrentImage.HorizontalOffset - borderCurrentImage.BorderThickness.Left) / canvasWidth - 2.
 144                 let marginRight = previewWidth * (canvasWidth - (scrollViewCurrentImage.HorizontalOffset - borderCurrentImage.BorderThickness.Right) - scrollViewCurrentImage.ViewportWidth) / canvasWidth - 2.
 145                 let marginTop = previewHeight * (scrollViewCurrentImage.VerticalOffset - borderCurrentImage.BorderThickness.Top) / canvasHeight - 2.
 146                 let marginBottom = previewHeight * (canvasHeight - (scrollViewCurrentImage.VerticalOffset - borderCurrentImage.BorderThickness.Bottom) - scrollViewCurrentImage.ViewportHeight) / canvasHeight - 2.
 147
 148                 preview.viewport.Margin <-
 149                     Thickness(
 150                         marginLeft,
 151                         marginTop,
 152                         marginRight,
 153                         marginBottom)
 154             else
 155                 preview.viewport.Visibility <- Visibility.Hidden
 156
 157     let rec setAsInfected (rbc: RBC) (infected: bool) =
 158         state.SetAsInfected rbc infected
 159         canvasCurrentImage.Children
 160         |> Seq.cast<Views.RBCFrame>
 161         |> Seq.iter
 162             (fun frame ->
 163                 if (frame.Tag :?> RBC) = rbc
 164                 then
 165                     setRBCFrameStyle rbc frame)
 166         updateRBCFramesPreview ()
 167         updateCurrentImageInformation ()
 168         updateGlobalParasitemia ()
 169
 170     and RBCFrame (rbc: RBC) : Views.RBCFrame =
 171         let frame = RBCFrameFromExisting rbc (Views.RBCFrame())
 172         frame.SetValue(Panel.ZIndexProperty, Int32.MaxValue - rbc.num) // To be sure the
 173         frame.menuRBCSetAsHealthy.Click.AddHandler(fun obj args -> setAsInfected (frame.Tag :?> RBC) false)
 174         frame.menuRBCSetAsInfected.Click.AddHandler(fun obj args -> setAsInfected (frame.Tag :?> RBC) true)
 175         frame.ContextMenuOpening.AddHandler(
 176             fun obj args ->
 177                 if (frame.Tag :?> RBC).infected
 178                 then
 179                     frame.menuRBCSetAsHealthy.Visibility <- Visibility.Visible
 180                     frame.menuRBCSetAsInfected.Visibility <- Visibility.Collapsed
 181                 else
 182                     frame.menuRBCSetAsHealthy.Visibility <- Visibility.Collapsed
 183                     frame.menuRBCSetAsInfected.Visibility <- Visibility.Visible)
 184
 185         frame.ContextMenuClosing.AddHandler(fun obj args -> if not frame.IsMouseOver then highlightRBCFrame frame false )
 186         frame.MouseEnter.AddHandler(fun obj args -> highlightRBCFrame frame true)
 187         frame.MouseLeave.AddHandler(fun obj args -> if not frame.grid.ContextMenu.IsOpen then highlightRBCFrame frame false)
 188         frame
 189
 190     and updateRBCFramesPreview () =
 191         match state.CurrentImage with
 192         | Some srcImg ->
 193             let mutable currentPreview = 0
 194             for rbc in srcImg.rbcs |> List.filter (fun rbc -> displayHealthy || rbc.infected) do
 195                 let previewInfected =
 196                     if currentPreview < stackRBC.Children.Count
 197                     then
 198                         RBCFrameFromExisting rbc (stackRBC.Children.[currentPreview] :?> Views.RBCFrame)
 199                     else
 200                         let f = RBCFrame rbc
 201                         f.MouseLeftButtonUp.AddHandler(fun obj args -> zoomToRBC (f.Tag :?> RBC))
 202                         stackRBC.Children.Add(f) |> ignore
 203                         f
 204
 205                 currentPreview <- currentPreview + 1
 206
 207                 previewInfected.Height <- stackRBC.ActualHeight
 208                 previewInfected.Width <- stackRBC.ActualHeight * rbc.size.Width / rbc.size.Height
 209                 previewInfected.border.Fill <- ImageBrush(BitmapSourceConvert.ToBitmapSource(extractRBCPreview srcImg.img rbc))
 210
 211             stackRBC.Children.RemoveRange(currentPreview, stackRBC.Children.Count - currentPreview)
 212         | _ -> ()
 213
 214         updateViewportPreview ()
 215
 216     let updateRBCFramesCurrent () =
 217         match state.CurrentImage with
 218         | Some srcImg ->
 219             let mutable currentCanvas = 0
 220             for rbc in srcImg.rbcs do
 221                 let frame =
 222                     if currentCanvas < canvasCurrentImage.Children.Count
 223                     then
 224                         RBCFrameFromExisting rbc (canvasCurrentImage.Children.[currentCanvas] :?> Views.RBCFrame)
 225                     else
 226                         let f = RBCFrame rbc
 227                         f.Root.Opacity <- 0.7
 228                         canvasCurrentImage.Children.Add(f) |> ignore
 229                         f
 230
 231                 currentCanvas <- currentCanvas + 1
 232
 233                 Canvas.SetLeft(frame, rbc.center.X - rbc.size.Width / 2.)
 234                 Canvas.SetTop(frame, rbc.center.Y - rbc.size.Height / 2.)
 235
 236             for i in currentCanvas .. canvasCurrentImage.Children.Count - 1 do
 237                 canvasCurrentImage.Children.[i].Visibility <- Visibility.Hidden
 238         | _ -> ()
 239
 240     let saveCurrentDocument () =
 241         try
 242             if state.FilePath = ""
 243             then
 244                 let dialog = SaveFileDialog(AddExtension = true, DefaultExt = PiaZ.extension, Filter = PiaZ.filter);
 245                 let res = dialog.ShowDialog()
 246                 if res.HasValue && res.Value
 247                 then
 248                     state.FilePath <- dialog.FileName
 249                     state.Save()
 250             else
 251                 state.Save()
 252         with
 253         | :? IOException as ex ->
 254             Log.Error(ex.ToString())
 255             MessageBox.Show(sprintf "The document cannot be save in '%s'" state.FilePath, "Error saving the document", MessageBoxButton.OK, MessageBoxImage.Error) |> ignore
 256
 257     // Ask the use to save the current document if neccessary.
 258     let askSaveCurrent () =
 259         if state.AlteredSinceLastSave
 260         then
 261             match MessageBox.Show("Would you like to save the current document?", "Saving the current document", MessageBoxButton.YesNo, MessageBoxImage.Question) with
 262             | MessageBoxResult.Yes -> saveCurrentDocument ()
 263             | _ -> ()
 264
 265     let updateCurrentImage () =
 266         match state.CurrentImage with
 267         | Some srcImg ->
 268             // Highlight the preview.
 269             stackPreviews.Children
 270             |> Seq.cast<Views.ImageSourcePreview>
 271             |> Seq.iter (fun preview -> preview.border.BorderThickness <- Thickness(if preview.Tag = (srcImg :> Object) then 3. else 0.))
 272
 273             canvasCurrentImage.Height <- float srcImg.img.Height
 274             canvasCurrentImage.Width <- float srcImg.img.Width
 275             canvasCurrentImage.Background <- ImageBrush(BitmapSourceConvert.ToBitmapSource(srcImg.img))
 276
 277             updateRBCFramesCurrent ()
 278             updateRBCFramesPreview ()
 279             updateCurrentImageInformation ()
 280         | None ->
 281             stackRBC.Children.Clear()
 282             canvasCurrentImage.Children.Clear()
 283             canvasCurrentImage.Background <- Brushes.Black
 284
 285     let setCurrentImage (srcImg: SourceImage) =
 286         if state.CurrentImage.IsNone || state.CurrentImage.Value <> srcImg
 287         then
 288             state.CurrentImage <- Some srcImg
 289             updateCurrentImage ()
 290
 291     let addPreview (srcImg: SourceImage) =
 292         let imgCtrl = Views.ImageSourcePreview(Margin = Thickness(3.))
 293
 294         imgCtrl.menuRemoveImage.Click.AddHandler(fun obj args ->
 295             stackPreviews.Children.Remove(imgCtrl)
 296             let srcImg = imgCtrl.Tag :?> SourceImage
 297             let currentRemoved = Some srcImg = state.CurrentImage
 298             state.RemoveSourceImage srcImg
 299             if currentRemoved
 300             then
 301                 updateCurrentImage()
 302             stackPreviews.Children |> Seq.cast<Views.ImageSourcePreview> |> Seq.iter (fun imgPreview -> imgPreview.txtImageNumber.Text <- (imgPreview.Tag :?> SourceImage).num.ToString()))
 303
 304         imgCtrl.Tag <- srcImg
 305         imgCtrl.txtImageNumber.Text <- srcImg.num.ToString()
 306         let width = 200
 307         let height = srcImg.img.Height * width / srcImg.img.Width
 308         imgCtrl.imagePreview.Source <- BitmapSourceConvert.ToBitmapSource(srcImg.img.Resize(width, height, Emgu.CV.CvEnum.Inter.Cubic))
 309         stackPreviews.Children.Add(imgCtrl) |> ignore
 310
 311         // Zoom to a mouse position into the control 'imgCtrl'.
 312         let zoomTo (mousePos: Point) =
 313             let canvasW = canvasCurrentImage.ActualWidth * currentScale
 314             let canvasH = canvasCurrentImage.ActualHeight * currentScale
 315             let centerX = (mousePos.X - imgCtrl.BorderThickness.Left) / (imgCtrl.ActualWidth - imgCtrl.BorderThickness.Left) * canvasW
 316             let centerY = (mousePos.Y - imgCtrl.BorderThickness.Top) / (imgCtrl.ActualHeight - imgCtrl.BorderThickness.Top) * canvasH
 317             scrollViewCurrentImage.ScrollToHorizontalOffset(centerX - scrollViewCurrentImage.ViewportWidth / 2. + borderCurrentImage.BorderThickness.Left)
 318             scrollViewCurrentImage.ScrollToVerticalOffset(centerY - scrollViewCurrentImage.ViewportHeight / 2. + borderCurrentImage.BorderThickness.Top)
 319
 320         imgCtrl.MouseLeftButtonDown.AddHandler(fun obj args ->
 321             setCurrentImage (state.SourceImages |> Seq.find (fun srcImg -> (srcImg :> Object) = imgCtrl.Tag))
 322             imgCtrl.UpdateLayout()
 323             zoomTo (args.GetPosition(imgCtrl))
 324             imgCtrl.CaptureMouse() |> ignore)
 325
 326         imgCtrl.MouseMove.AddHandler(fun obj args ->
 327             if imgCtrl.IsMouseCaptured
 328             then
 329                 zoomTo (args.GetPosition(imgCtrl)))
 330
 331         imgCtrl.MouseLeftButtonUp.AddHandler(fun obj args ->
 332             if imgCtrl.IsMouseCaptured
 333             then
 334                 imgCtrl.ReleaseMouseCapture())
 335
 336     let updatePreviews () =
 337         stackPreviews.Children.Clear ()
 338         for srcImg in state.SourceImages do
 339             addPreview srcImg
 340         updateCurrentImage ()
 341
 342     let updateGUI () =
 343         txtPatient.Text <- state.PatientID
 344         updatePreviews ()
 345         updateGlobalParasitemia ()
 346
 347     let loadFile (filepath: string) =
 348         askSaveCurrent ()
 349         let previousFilePath = state.FilePath
 350         try
 351             state.FilePath <- filepath
 352             state.Load()
 353             updateGUI ()
 354         with
 355         | :? IOException as ex ->
 356             Log.Error(ex.ToString())
 357             state.FilePath <- previousFilePath
 358             MessageBox.Show(sprintf "The document cannot be loaded from '%s'" state.FilePath, "Error saving the document", MessageBoxButton.OK, MessageBoxImage.Error) |> ignore
 359
 360     txtPatient.LostFocus.AddHandler(fun obj args -> state.PatientID <- txtPatient.Text)
 361
 362     menuExit.Click.AddHandler(fun obj args ->
 363         askSaveCurrent ()
 364         mainWindow.Root.Close())
 365
 366     menuSaveFile.Click.AddHandler(fun obj args -> saveCurrentDocument ())
 367
 368     menuLoadFile.Click.AddHandler(fun obj args ->
 369         // TODO: if current state not saved and not empty, ask to save it.
 370         let dialog = OpenFileDialog(Filter = PiaZ.filter)
 371         let res = dialog.ShowDialog()
 372         if res.HasValue && res.Value
 373         then loadFile dialog.FileName)
 374
 375     menuNewFile.Click.AddHandler(fun obj args ->
 376         askSaveCurrent ()
 377         state.Reset()
 378         updateGUI())
 379
 380     menuAddSourceImage.Click.AddHandler(fun obj args ->
 381         let dialog = OpenFileDialog(Filter = "Image Files|*.png;*.jpg;*.tif;*.tiff", Multiselect = true)
 382         let res = dialog.ShowDialog()
 383         if res.HasValue && res.Value
 384         then
 385             let noSourceImage = state.SourceImages.Count() = 0
 386
 387             for filename in dialog.FileNames do
 388                 let srcImg = state.AddSourceImage filename defaultConfig
 389                 addPreview srcImg
 390
 391             updateGlobalParasitemia ()
 392
 393             if noSourceImage
 394             then
 395                 updateCurrentImage ())
 396
 397     menuAnalysis.SubmenuOpened.AddHandler(fun obj args -> menuStartAnalysis.IsEnabled <- state.SourceImages.Count() > 0)
 398
 399     menuStartAnalysis.Click.AddHandler(fun obj args ->
 400         if Analysis.showWindow mainWindow.Root state
 401         then
 402             updateGlobalParasitemia ()
 403             updateCurrentImage ())
 404
 405     menuHightlightRBC.Click.AddHandler(fun obj args ->
 406         displayHealthy <- menuHightlightRBC.IsChecked
 407         updateRBCFramesPreview ()
 408         updateRBCFramesCurrent ())
 409
 410     menuAbout.Click.AddHandler(fun obj args -> About.showWindow mainWindow.Root)
 411
 412     // Zoom on the current image.
 413     let adjustCurrentImageBorders (deltaX: float) (deltaY: float) =
 414         borderCurrentImage.BorderThickness <-
 415             Thickness(
 416                 (scrollViewCurrentImage.ViewportWidth + deltaX) / 2.,
 417                 (scrollViewCurrentImage.ViewportHeight + deltaY) / 2.,
 418                 (scrollViewCurrentImage.ViewportWidth + deltaX) / 2.,
 419                 (scrollViewCurrentImage.ViewportHeight + deltaY) / 2.)
 420
 421     canvasCurrentImage.SizeChanged.AddHandler(fun obj args ->
 422         let deltaX = args.NewSize.Width - args.PreviousSize.Width
 423         let deltaY = args.NewSize.Height - args.PreviousSize.Height
 424         if deltaX > 0.5 || deltaY > 0.5
 425         then
 426             adjustCurrentImageBorders 0.0 0.0
 427             // Center the view at the center of the image initialy.
 428             scrollViewCurrentImage.UpdateLayout()
 429             scrollViewCurrentImage.ScrollToHorizontalOffset(borderCurrentImage.ActualWidth / 2. - scrollViewCurrentImage.ViewportWidth / 2.)
 430             scrollViewCurrentImage.ScrollToVerticalOffset(borderCurrentImage.ActualHeight / 2. - scrollViewCurrentImage.ViewportHeight / 2.))
 431
 432     scrollViewCurrentImage.SizeChanged.AddHandler(fun obj args ->
 433         let deltaX = args.NewSize.Width - args.PreviousSize.Width
 434         let deltaY = args.NewSize.Height - args.PreviousSize.Height
 435         adjustCurrentImageBorders deltaX deltaY
 436         scrollViewCurrentImage.ScrollToHorizontalOffset(scrollViewCurrentImage.HorizontalOffset + deltaX / 8.)
 437         scrollViewCurrentImage.ScrollToVerticalOffset(scrollViewCurrentImage.VerticalOffset + deltaY / 8.))
 438
 439     let mutable maxScale = 4.
 440     let mutable minScale = 0.25
 441     let currentImageScaleTransform = ScaleTransform()
 442     canvasCurrentImage.LayoutTransform <- currentImageScaleTransform
 443     borderCurrentImage.PreviewMouseWheel.AddHandler(fun obj args ->
 444         let scaleFactor = if args.Delta > 0 then 2.0 else 0.5
 445         if scaleFactor > 1. && currentScale < maxScale || scaleFactor < 1. && currentScale > minScale
 446         then
 447             let previousScale = currentScale
 448             currentScale <-
 449                 let newScale = currentScale * scaleFactor
 450                 if newScale > maxScale then maxScale elif newScale < minScale then minScale else newScale
 451             let realScaleFactor = currentScale / previousScale
 452
 453             let centerX = scrollViewCurrentImage.HorizontalOffset + scrollViewCurrentImage.ViewportWidth / 2. - borderCurrentImage.BorderThickness.Left
 454             let centerY = scrollViewCurrentImage.VerticalOffset + scrollViewCurrentImage.ViewportHeight / 2. - borderCurrentImage.BorderThickness.Top
 455
 456             currentImageScaleTransform.ScaleX <- currentScale
 457             currentImageScaleTransform.ScaleY <- currentScale
 458
 459             scrollViewCurrentImage.ScrollToHorizontalOffset(centerX * realScaleFactor - scrollViewCurrentImage.ViewportWidth / 2. + borderCurrentImage.BorderThickness.Left)
 460             scrollViewCurrentImage.ScrollToVerticalOffset(centerY * realScaleFactor - scrollViewCurrentImage.ViewportHeight / 2. + borderCurrentImage.BorderThickness.Top)
 461
 462         args.Handled <- true)
 463
 464     // Pan on the current image.
 465     let mutable scrollStartPosition = Point(0., 0.)
 466     let mutable scrollStartOffsetX = 0.
 467     let mutable scrollStartOffsetY = 0.
 468     borderCurrentImage.PreviewMouseLeftButtonDown.AddHandler(fun obj args ->
 469         scrollStartPosition <- args.GetPosition(scrollViewCurrentImage)
 470         scrollStartOffsetX <- scrollViewCurrentImage.HorizontalOffset
 471         scrollStartOffsetY <- scrollViewCurrentImage.VerticalOffset
 472         borderCurrentImage.Cursor <- Input.Cursors.ScrollAll
 473         borderCurrentImage.CaptureMouse() |> ignore
 474         args.Handled <- true)
 475
 476     borderCurrentImage.PreviewMouseMove.AddHandler(fun obj args ->
 477         if borderCurrentImage.IsMouseCaptured
 478         then
 479             let position = args.GetPosition(scrollViewCurrentImage)
 480             let deltaX = scrollStartPosition.X - position.X
 481             let deltaY = scrollStartPosition.Y - position.Y
 482             scrollViewCurrentImage.ScrollToHorizontalOffset(deltaX + scrollStartOffsetX)
 483             scrollViewCurrentImage.ScrollToVerticalOffset(deltaY + scrollStartOffsetY)
 484
 485             args.Handled <- true)
 486
 487     borderCurrentImage.PreviewMouseLeftButtonUp.AddHandler(fun obj args ->
 488         if borderCurrentImage.IsMouseCaptured
 489         then
 490             borderCurrentImage.Cursor <- Input.Cursors.Arrow
 491             borderCurrentImage.ReleaseMouseCapture()
 492             args.Handled <- true)
 493
 494     // Viewport preview.
 495     scrollViewCurrentImage.ScrollChanged.AddHandler(fun obj args -> updateViewportPreview ())
 496
 497     mainWindow.Root.Show()
 498
 499     match fileToOpen with
 500     | Some filepath -> loadFile filepath
 501     | None -> ()
 502
 503     app.Run()