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EnableLowMemoryUsage Method
See Also  Example
Leadtools.MedicalViewer Namespace > MedicalViewerCell Class : EnableLowMemoryUsage Method



hiddenFramesCount
The number of unseen frames that the control will load. Setting this value for example, to 2, makes the control load the 2 frames before the viewed frames as well as the 2 frames after the viewed frames.
imageCount
The number of total frames that will be included in the specified cell.
imagesInformation
An object that contains the image information being set.
Enables loading frames only when viewed, to more efficiently use the system memory.

Syntax

Visual Basic (Declaration) 
Public Sub EnableLowMemoryUsage( _
   ByVal hiddenFramesCount As Integer, _
   ByVal imageCount As Integer, _
   ByVal imagesInformation() As MedicalViewerImageInformation _
)
Visual Basic (Usage)Copy Code
Dim instance As MedicalViewerCell
Dim hiddenFramesCount As Integer
Dim imageCount As Integer
Dim imagesInformation() As MedicalViewerImageInformation
 
instance.EnableLowMemoryUsage(hiddenFramesCount, imageCount, imagesInformation)
C# 
public void EnableLowMemoryUsage( 
   int hiddenFramesCount,
   int imageCount,
   MedicalViewerImageInformation[] imagesInformation
)
C++/CLI 
public:
void EnableLowMemoryUsage( 
   int hiddenFramesCount,
   int imageCount,
   array<MedicalViewerImageInformation^>^ imagesInformation
)

Parameters

hiddenFramesCount
The number of unseen frames that the control will load. Setting this value for example, to 2, makes the control load the 2 frames before the viewed frames as well as the 2 frames after the viewed frames.
imageCount
The number of total frames that will be included in the specified cell.
imagesInformation
An object that contains the image information being set.

Example

Visual BasicCopy Code
Private Class MedicalViewerForm : Inherits Form
   Private _medicalViewer As MedicalViewer
   Public label As Label
   Private Sub MedicalViewerForm_SizeChanged(ByVal sender As Object, ByVal e As EventArgs)
      _medicalViewer.Size = New Size(Me.ClientRectangle.Right, Me.ClientRectangle.Bottom)
   End Sub

   Public Sub New()
      RasterCodecs.Startup()
      Dim _codecs As RasterCodecs = New RasterCodecs()
      Dim _image As RasterImage

      AddHandler SizeChanged, AddressOf MedicalViewerForm_SizeChanged

      ' Create the medical viewer and adjust the size and the location.
      _medicalViewer = New MedicalViewer(1, 2)
      _medicalViewer.Location = New Point(0, 0)
      _medicalViewer.Size = New Size(Me.ClientRectangle.Right, Me.ClientRectangle.Bottom - 10)

      ' add some action that will be used to change the properties of the images inside the control.
      _medicalViewer.AddAction(MedicalViewerActionType.WindowLevel)
      _medicalViewer.AddAction(MedicalViewerActionType.Alpha)
      _medicalViewer.AddAction(MedicalViewerActionType.Offset)

      ' assign the added actions to a mouse button, meaning that when the user click and drag the mouse button, the associted action will be activated.
      _medicalViewer.SetAction(MedicalViewerActionType.WindowLevel, MedicalViewerMouseButtons.Left, MedicalViewerActionFlags.Active Or MedicalViewerActionFlags.RealTime)
      _medicalViewer.SetAction(MedicalViewerActionType.Alpha, MedicalViewerMouseButtons.Middle, MedicalViewerActionFlags.Active Or MedicalViewerActionFlags.RealTime)
      _medicalViewer.SetAction(MedicalViewerActionType.Offset, MedicalViewerMouseButtons.Right, MedicalViewerActionFlags.Active Or MedicalViewerActionFlags.RealTime)

      ' Load an image and then add it to the control.
      Dim cell As MedicalViewerCell = New MedicalViewerCell()
      cell.Rows = 1
      cell.Columns = 1
      cell.FitImageToCell = True

      _medicalViewer.Cells.Add(cell)

      ' adjust some properties to the cell and add some tags.
      _medicalViewer.Cells(0).SetTag(2, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.UserData, "EX. ID 230-36-5448")
      _medicalViewer.Cells(0).SetTag(4, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.Frame)
      _medicalViewer.Cells(0).SetTag(6, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.Scale)
      _medicalViewer.Cells(0).SetTag(2, MedicalViewerTagAlignment.BottomLeft, MedicalViewerTagType.WindowLevelData)
      _medicalViewer.Cells(0).SetTag(1, MedicalViewerTagAlignment.BottomLeft, MedicalViewerTagType.FieldOfView)


      ' Load another image and then add it to the control.
      _image = _codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "mr.dcm")
      _medicalViewer.Cells.Add(New MedicalViewerCell(_image, True, 2, 2))

      ' adjust some properties to the cell and add some tags.
      _medicalViewer.Cells(1).SetTag(2, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.UserData, "EX. ID 230-36-5448")
      _medicalViewer.Cells(1).SetTag(4, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.Frame)
      _medicalViewer.Cells(1).SetTag(6, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.Scale)
      _medicalViewer.Cells(1).SetTag(2, MedicalViewerTagAlignment.BottomLeft, MedicalViewerTagType.WindowLevelData)
      _medicalViewer.Cells(1).SetTag(1, MedicalViewerTagAlignment.BottomLeft, MedicalViewerTagType.FieldOfView)

      label = New Label()
      label.Location = New Point(0, Me.ClientRectangle.Bottom - 10)
      label.Size = New Size(Me.ClientRectangle.Right, 10)
      label.Text = "Here the statistical information will appear"

      RasterCodecs.Shutdown()
      Controls.Add(_medicalViewer)
   End Sub
   Public ReadOnly Property Viewer() As MedicalViewer
      Get
         Return _medicalViewer
      End Get
   End Property
End Class

Private Function GetMedicalControl() As MedicalViewerForm
   Return New MedicalViewerForm()
End Function

' This example shows how to use the low memroy usage feature to display a medical image with multiple pages. it will also invert all the bitmap to show the invert function works even if the bitmap is not loaded yet.

Public Sub MedicalViewerLowMemoryUsageExample()
   Dim myForm As MedicalViewerForm = GetMedicalControl()
   Dim medicalViewer As MedicalViewer = myForm.Viewer


   RasterCodecs.Startup()
   Dim codecs As RasterCodecs = New RasterCodecs()
   Dim i As Integer = 0
   Dim count As Integer


   Dim info As CodecsImageInfo
   Dim fileName As String = LeadtoolsExamples.Common.ImagesPath.Path + "xa.dcm"
   info = codecs.GetInformation(fileName, True)
   count = info.TotalPages
   Dim a As MedicalViewerImageInformation() = New MedicalViewerImageInformation(count - 1) {}

   i = 0
   Do While i < count
      info = codecs.GetInformation(fileName, True, i + 1)
      a(i) = New MedicalViewerImageInformation()
      a(i).ImageHeight = info.Height
      a(i).ImageWidth = info.Width
      a(i).XResolution = info.XResolution
      a(i).YResolution = info.YResolution
      i += 1
   Loop

   AddHandler medicalViewer.ActiveSubCellChanged, AddressOf medicalViewer_ActiveSubCellChanged1
   AddHandler medicalViewer.FramesRequested, AddressOf medicalViewer_FramesRequested
   medicalViewer.Cells(0).EnableLowMemoryUsage(2, count, a)
   myForm.ShowDialog()
   RasterCodecs.Shutdown()
End Sub

Private Sub medicalViewer_ActiveSubCellChanged1(ByVal sender As Object, ByVal e As MedicalViewerActiveSubCellChangedEventArgs)
   Dim imageInformation As String = ""
   Dim viewer As MedicalViewer = CType(sender, MedicalViewer)
   If viewer.Cells(0).VirtualImage(e.SubCellIndex).ImageExist Then
      imageInformation = "Image bit per pixel = " & viewer.Cells(0).VirtualImage(e.SubCellIndex).Image.BitsPerPixel.ToString()
   End If

   CType(viewer.Parent, MedicalViewerForm).label.Text = imageInformation & " HasRegion = " & viewer.Cells(0).VirtualImage(e.SubCellIndex).HasRegion
End Sub

Private Sub medicalViewer_FramesRequested(ByVal sender As Object, ByVal e As MedicalViewerRequestedFramesInformationEventArgs)
   Dim fileName As String = LeadtoolsExamples.Common.ImagesPath.Path + "xa.dcm"
   Dim _codecs As RasterCodecs = New RasterCodecs()
   Dim i As Integer
   Dim b As RasterImage

   If e.RequestedFramesIndexes.Length > 0 Then
      b = _codecs.Load(fileName, 0, CodecsLoadByteOrder.BgrOrGray, e.RequestedFramesIndexes(0) + 1, e.RequestedFramesIndexes(0) + 1)
   Else
      Return
   End If

   i = 1
   Do While i < e.RequestedFramesIndexes.Length
      b.AddPage(_codecs.Load(fileName, 0, CodecsLoadByteOrder.BgrOrGray, e.RequestedFramesIndexes(i) + 1, e.RequestedFramesIndexes(i) + 1))
      i += 1
   Loop

   CType(sender, MedicalViewer).Cells(e.CellIndex).SetRequestedImage(b, e.RequestedFramesIndexes, MedicalViewerSetImageOptions.Insert)
End Sub
C#Copy Code
class MedicalViewerForm : Form 
{ 
   private MedicalViewer _medicalViewer; 
   public Label label; 
   void MedicalViewerForm_SizeChanged(object sender, EventArgs e) 
   { 
      _medicalViewer.Size = new Size(this.ClientRectangle.Right, this.ClientRectangle.Bottom); 
   } 
 
   public MedicalViewerForm() 
   { 
      RasterCodecs.Startup(); 
      RasterCodecs _codecs = new RasterCodecs(); 
      RasterImage _image; 
 
      this.SizeChanged += new EventHandler(MedicalViewerForm_SizeChanged); 
 
      // Create the medical viewer and adjust the size and the location. 
      _medicalViewer = new MedicalViewer(1, 2); 
      _medicalViewer.Location = new Point(0, 0); 
      _medicalViewer.Size = new Size(this.ClientRectangle.Right, this.ClientRectangle.Bottom - 10); 
 
      // add some action that will be used to change the properties of the images inside the control. 
      _medicalViewer.AddAction(MedicalViewerActionType.WindowLevel); 
      _medicalViewer.AddAction(MedicalViewerActionType.Alpha); 
      _medicalViewer.AddAction(MedicalViewerActionType.Offset); 
 
      // assign the added actions to a mouse button, meaning that when the user click and drag the mouse button, the associted action will be activated. 
      _medicalViewer.SetAction(MedicalViewerActionType.WindowLevel, MedicalViewerMouseButtons.Left, MedicalViewerActionFlags.Active | MedicalViewerActionFlags.RealTime); 
      _medicalViewer.SetAction(MedicalViewerActionType.Alpha, MedicalViewerMouseButtons.Middle, MedicalViewerActionFlags.Active | MedicalViewerActionFlags.RealTime); 
      _medicalViewer.SetAction(MedicalViewerActionType.Offset, MedicalViewerMouseButtons.Right, MedicalViewerActionFlags.Active | MedicalViewerActionFlags.RealTime); 
 
      /*// Load an image and then add it to the control. 
      _image = _codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "xa.dcm");*/ 
      MedicalViewerCell cell = new MedicalViewerCell(); 
      cell.Rows = 1; 
      cell.Columns = 1; 
      cell.FitImageToCell = true; 
 
      _medicalViewer.Cells.Add(cell); 
 
      // adjust some properties to the cell and add some tags. 
      _medicalViewer.Cells[0].SetTag(2, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.UserData, "EX. ID 230-36-5448"); 
      _medicalViewer.Cells[0].SetTag(4, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.Frame); 
      _medicalViewer.Cells[0].SetTag(6, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.Scale); 
      _medicalViewer.Cells[0].SetTag(2, MedicalViewerTagAlignment.BottomLeft, MedicalViewerTagType.WindowLevelData); 
      _medicalViewer.Cells[0].SetTag(1, MedicalViewerTagAlignment.BottomLeft, MedicalViewerTagType.FieldOfView); 
 
 
      // Load another image and then add it to the control. 
      _image = _codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "mr.dcm"); 
      _medicalViewer.Cells.Add(new MedicalViewerCell(_image, true, 2, 2)); 
 
      // adjust some properties to the cell and add some tags. 
      _medicalViewer.Cells[1].SetTag(2, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.UserData, "EX. ID 230-36-5448"); 
      _medicalViewer.Cells[1].SetTag(4, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.Frame); 
      _medicalViewer.Cells[1].SetTag(6, MedicalViewerTagAlignment.TopLeft, MedicalViewerTagType.Scale); 
      _medicalViewer.Cells[1].SetTag(2, MedicalViewerTagAlignment.BottomLeft, MedicalViewerTagType.WindowLevelData); 
      _medicalViewer.Cells[1].SetTag(1, MedicalViewerTagAlignment.BottomLeft, MedicalViewerTagType.FieldOfView); 
 
      label = new Label(); 
      label.Location = new Point(0, this.ClientRectangle.Bottom - 10); 
      label.Size = new Size(this.ClientRectangle.Right, 10); 
      label.Text = "Here the statistical information will appear"; 
 
      RasterCodecs.Shutdown(); 
      Controls.Add(_medicalViewer); 
   } 
   public MedicalViewer Viewer 
   { 
      get { return _medicalViewer; } 
   } 
} 
 
MedicalViewerForm GetMedicalControl() 
{ 
   return new MedicalViewerForm(); 
} 
 
// This example shows how to use the low memroy usage feature to display a medical image with multiple pages. it will also invert all the bitmap to show the invert function works even if the bitmap is not loaded yet. 
 
public void MedicalViewerLowMemoryUsageExample() 
{ 
   MedicalViewerForm myForm = GetMedicalControl(); 
   MedicalViewer medicalViewer = myForm.Viewer; 
 
 
   RasterCodecs.Startup(); 
   RasterCodecs codecs = new RasterCodecs(); 
   int i = 0; 
   int count; 
 
 
   CodecsImageInfo info; 
   string fileName = LeadtoolsExamples.Common.ImagesPath.Path + "xa.dcm"; 
   info = codecs.GetInformation(fileName, true); 
   count = info.TotalPages; 
   MedicalViewerImageInformation[] a = new MedicalViewerImageInformation[count]; 
 
   for (i = 0; i < count; i++) 
   { 
      info = codecs.GetInformation(fileName, true, i + 1); 
      a[i] = new MedicalViewerImageInformation(); 
      a[i].ImageHeight = info.Height; 
      a[i].ImageWidth = info.Width; 
      a[i].XResolution = info.XResolution; 
      a[i].YResolution = info.YResolution; 
   } 
 
   medicalViewer.ActiveSubCellChanged += new EventHandler<MedicalViewerActiveSubCellChangedEventArgs>(medicalViewer_ActiveSubCellChanged1); 
   medicalViewer.FramesRequested += new EventHandler<MedicalViewerRequestedFramesInformationEventArgs>(medicalViewer_FramesRequested); 
   medicalViewer.Cells[0].EnableLowMemoryUsage(2, count, a); 
   myForm.ShowDialog(); 
   RasterCodecs.Shutdown(); 
} 
 
void medicalViewer_ActiveSubCellChanged1(object sender, MedicalViewerActiveSubCellChangedEventArgs e) 
{ 
   string imageInformation = ""; 
   MedicalViewer viewer = (MedicalViewer)sender; 
   if (viewer.Cells[0].VirtualImage[e.SubCellIndex].ImageExist) 
   { 
      imageInformation = "Image bit per pixel = " + viewer.Cells[0].VirtualImage[e.SubCellIndex].Image.BitsPerPixel.ToString(); 
   } 
 
   ((MedicalViewerForm)(viewer.Parent)).label.Text = imageInformation + " HasRegion = " + viewer.Cells[0].VirtualImage[e.SubCellIndex].HasRegion; 
} 
 
void medicalViewer_FramesRequested(object sender, MedicalViewerRequestedFramesInformationEventArgs e) 
{ 
   string fileName = LeadtoolsExamples.Common.ImagesPath.Path + "xa.dcm"; 
   RasterCodecs _codecs = new RasterCodecs(); 
   int i; 
   RasterImage b; 
 
   if (e.RequestedFramesIndexes.Length > 0) 
   { 
      b = _codecs.Load(fileName, 0, CodecsLoadByteOrder.BgrOrGray, e.RequestedFramesIndexes[0] + 1, e.RequestedFramesIndexes[0] + 1); 
   } 
   else 
      return; 
 
   for (i = 1; i < e.RequestedFramesIndexes.Length; i++) 
   { 
      b.AddPage(_codecs.Load(fileName, 0, CodecsLoadByteOrder.BgrOrGray, e.RequestedFramesIndexes[i] + 1, e.RequestedFramesIndexes[i] + 1)); 
   } 
 
   ((MedicalViewer)sender).Cells[e.CellIndex].SetRequestedImage(b, e.RequestedFramesIndexes, MedicalViewerSetImageOptions.Insert); 
}

Remarks

  • The low memory usage feature works by preventing the control from loading all of the frames at runtime; instead, the control will load only the frames that are currently visible on the cell (plus the specified number of hidden frames). The control will send a request each time the user scrolls down or up, or changes the number of visible frames…etc. For example, suppose the cell layout is a 2X2 (see MedicalViewer.Rows and MedicalViewer.Columns, and the user needs to load more than 100000 frames. When low memory usage is enabled, the control will not load them all. Instead, this method will send a MedicalViewer.FramesRequested event when the cell is loaded, requesting 4 frames (1, 2, 3 and 4) (because the cell is 2X2). Once the user scrolls down the cell to view frame number 5, frame number 1 will be disposed of because it is no longer visible. Then the event will be fired to request frame number 5. When frames are requested, the user is supposed to send them to the control using the SetRequestedImage method.
  • hiddenFramesCount allows the control load a specific number of frames ahead (so if you have a 2X2 cell and you set hiddenFramesCount to 3, the method will request (1, 2, 3, 4, 5, 6, 7). The method will normally request also 0, -1, -2. but since those indexes are not valid, the control will not request them.
  • If the low memory usage feature is not needed, load images directly by assigning the image to the cell using the Image property.
  • To stop using the low memory usage feature, remove the cell that has this feature enabled and then add it again.

Requirements

Target Platforms: Microsoft .NET Framework 2.0, Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

Leadtools.MedicalViewer requires a Medical Imaging license and unlock key. For more information, refer to: Imaging Pro/Document/Medical Features