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EnableLowMemoryUsage(Boolean,Int32,Int32) Method

Summary

Enables loading frames only when being viewed, to more efficiently use the system memory.

Syntax

C++

public void EnableLowMemoryUsage(  
   bool enabled, 
   int pageCount, 
   int hiddenFramesCount 
)

Public Overloads Sub EnableLowMemoryUsage( _ 
   ByVal enabled As Boolean, _ 
   ByVal pageCount As Integer, _ 
   ByVal hiddenFramesCount As Integer _ 
)

public: 
void EnableLowMemoryUsage(  
   bool enabled, 
   int pageCount, 
   int hiddenFramesCount 
)

Parameters

enabled
true to enable the low memory usage, false to disable the low memory usage.

pageCount
The number of total frames that will be included in the specified cell.

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 displayed frames as well as the 2 frames after the viewed frames.

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 Rows and Columns, and the user needs to load more than 100,000 frames. When low memory usage is enabled, the control will not load them all. Instead, this method will send a 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 frames 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.

Example

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.MedicalViewer 
 
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() 
      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) 
 
      ' Load an image and then add it to the control. 
      '_image = _codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "xa.dcm"); 
      Dim cell As MedicalViewerMultiCell = New MedicalViewerMultiCell(Nothing, True, 1, 1) 
      _medicalViewer.Cells.Add(cell) 
 
      ' add some actions that will be used to change the properties of the images inside the control. 
      cell.AddAction(MedicalViewerActionType.WindowLevel) 
      cell.AddAction(MedicalViewerActionType.Alpha) 
      cell.AddAction(MedicalViewerActionType.Offset) 
 
      ' assign the added actions to a mouse button, meaning that when the user clicks and drags the mouse button, the associated action will be activated. 
      cell.SetAction(MedicalViewerActionType.WindowLevel, MedicalViewerMouseButtons.Left, MedicalViewerActionFlags.Active) 
      cell.SetAction(MedicalViewerActionType.Alpha, MedicalViewerMouseButtons.Middle, MedicalViewerActionFlags.Active) 
      cell.SetAction(MedicalViewerActionType.Offset, MedicalViewerMouseButtons.Right, MedicalViewerActionFlags.Active) 
 
      cell.Rows = 1 
      cell.Columns = 1 
      cell.FitImageToCell = True 
 
      ' adjust some properties of 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(Path.Combine(LEAD_VARS.ImagesDir, "mr.dcm")) 
      _medicalViewer.Cells.Add(New MedicalViewerMultiCell(_image, True, 2, 2)) 
 
      ' add some actions that will be used to change the properties of the images inside the control. 
      _medicalViewer.Cells(1).AddAction(MedicalViewerActionType.WindowLevel) 
      _medicalViewer.Cells(1).AddAction(MedicalViewerActionType.Alpha) 
      _medicalViewer.Cells(1).AddAction(MedicalViewerActionType.Offset) 
      _medicalViewer.Cells(1).AddAction(MedicalViewerActionType.RectangleRegion) 
 
      ' assign the added actions to a mouse button, meaning that when the user clicks and drags the mouse button, the associated action will be activated. 
      _medicalViewer.Cells(1).SetAction(MedicalViewerActionType.RectangleRegion, MedicalViewerMouseButtons.Left, MedicalViewerActionFlags.Active) 
      _medicalViewer.Cells(1).SetAction(MedicalViewerActionType.Alpha, MedicalViewerMouseButtons.Middle, MedicalViewerActionFlags.Active) 
      _medicalViewer.Cells(1).SetAction(MedicalViewerActionType.Offset, MedicalViewerMouseButtons.Right, MedicalViewerActionFlags.Active) 
 
      ' adjust some properties of 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" 
 
      Controls.Add(_medicalViewer) 
      _medicalViewer.Dock = DockStyle.Fill 
   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 memory 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. 
<TestMethod()> _ 
Public Sub MedicalViewerLowMemoryUsageExample() 
   Dim myForm As MedicalViewerForm = GetMedicalControl() 
   Dim medicalViewer As MedicalViewer = myForm.Viewer 
   Dim cell As MedicalViewerMultiCell = CType(medicalViewer.Cells(0), MedicalViewerMultiCell) 
 
 
   Dim codecs As RasterCodecs = New RasterCodecs() 
   Dim i As Integer = 0 
   Dim count As Integer 
 
 
   Dim info As CodecsImageInfo 
   Dim fileName As String = Path.Combine(LEAD_VARS.ImagesDir, "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 cell.ActiveSubCellChanged, AddressOf medicalViewer_ActiveSubCellChanged1 
   AddHandler cell.FramesRequested, AddressOf medicalViewer_FramesRequested 
   cell.EnableLowMemoryUsage(2, count, a) 
   myForm.ShowDialog() 
End Sub 
 
Private Sub medicalViewer_ActiveSubCellChanged1(ByVal sender As Object, ByVal e As MedicalViewerActiveSubCellChangedEventArgs) 
   Dim imageInformation As String = "" 
   Dim cell As MedicalViewerMultiCell = CType(sender, MedicalViewerMultiCell) 
 
   If cell.VirtualImage(e.SubCellIndex).ImageExist Then 
      imageInformation = "Image bit per pixel = " & cell.VirtualImage(e.SubCellIndex).Image.BitsPerPixel.ToString() 
   End If 
 
   CType(cell.ParentViewer.Parent, MedicalViewerForm).label.Text = imageInformation & " HasRegion = " & cell.VirtualImage(e.SubCellIndex).HasRegion 
End Sub 
 
Private Sub medicalViewer_FramesRequested(ByVal sender As Object, ByVal e As MedicalViewerRequestedFramesInformationEventArgs) 
   Dim cell As MedicalViewerMultiCell = CType(sender, MedicalViewerMultiCell) 
   Dim fileName As String = Path.Combine(LEAD_VARS.ImagesDir, "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 
 
   cell.SetRequestedImage(b, e.RequestedFramesIndexes, MedicalViewerSetImageOptions.Insert) 
End Sub 
 
 
Public NotInheritable Class LEAD_VARS 
Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.MedicalViewer; 
 
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 _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); 
 
      // Load an image and then add it to the control. 
      //_image = _codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "xa.dcm"); 
      MedicalViewerMultiCell cell = new MedicalViewerMultiCell(null, true, 1, 1); 
      _medicalViewer.Cells.Add(cell); 
 
      // add some actions that will be used to change the properties of the images inside the control. 
      cell.AddAction(MedicalViewerActionType.WindowLevel); 
      cell.AddAction(MedicalViewerActionType.Alpha); 
      cell.AddAction(MedicalViewerActionType.Offset); 
 
      // assign the added actions to a mouse button, meaning that when the user clicks and drags the mouse button, the associated action will be activated. 
      cell.SetAction(MedicalViewerActionType.WindowLevel, MedicalViewerMouseButtons.Left, MedicalViewerActionFlags.Active); 
      cell.SetAction(MedicalViewerActionType.Alpha, MedicalViewerMouseButtons.Middle, MedicalViewerActionFlags.Active); 
      cell.SetAction(MedicalViewerActionType.Offset, MedicalViewerMouseButtons.Right, MedicalViewerActionFlags.Active); 
 
      cell.Rows = 1; 
      cell.Columns = 1; 
      cell.FitImageToCell = true; 
 
      // adjust some properties of 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(Path.Combine(LEAD_VARS.ImagesDir,"mr.dcm")); 
      _medicalViewer.Cells.Add(new MedicalViewerMultiCell(_image, true, 2, 2)); 
 
      // add some actions that will be used to change the properties of the images inside the control. 
      _medicalViewer.Cells[1].AddAction(MedicalViewerActionType.WindowLevel); 
      _medicalViewer.Cells[1].AddAction(MedicalViewerActionType.Alpha); 
      _medicalViewer.Cells[1].AddAction(MedicalViewerActionType.Offset); 
      _medicalViewer.Cells[1].AddAction(MedicalViewerActionType.RectangleRegion); 
 
      // assign the added actions to a mouse button, meaning that when the user clicks and drags the mouse button, the associated action will be activated. 
      _medicalViewer.Cells[1].SetAction(MedicalViewerActionType.RectangleRegion, MedicalViewerMouseButtons.Left, MedicalViewerActionFlags.Active); 
      _medicalViewer.Cells[1].SetAction(MedicalViewerActionType.Alpha, MedicalViewerMouseButtons.Middle, MedicalViewerActionFlags.Active); 
      _medicalViewer.Cells[1].SetAction(MedicalViewerActionType.Offset, MedicalViewerMouseButtons.Right, MedicalViewerActionFlags.Active); 
 
      // adjust some properties of 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"; 
 
      Controls.Add(_medicalViewer); 
      _medicalViewer.Dock = DockStyle.Fill; 
   } 
   public MedicalViewer Viewer 
   { 
      get { return _medicalViewer; } 
   } 
} 
 
MedicalViewerForm GetMedicalControl() 
{ 
   return new MedicalViewerForm(); 
} 
 
// This example shows how to use the low memory 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; 
   MedicalViewerMultiCell cell = (MedicalViewerMultiCell)(medicalViewer.Cells[0]); 
 
 
   RasterCodecs codecs = new RasterCodecs(); 
   int i = 0; 
   int count; 
 
 
   CodecsImageInfo info; 
   string fileName = Path.Combine(LEAD_VARS.ImagesDir,"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; 
   } 
 
   cell.ActiveSubCellChanged += new EventHandler<MedicalViewerActiveSubCellChangedEventArgs>(medicalViewer_ActiveSubCellChanged1); 
   cell.FramesRequested += new EventHandler<MedicalViewerRequestedFramesInformationEventArgs>(medicalViewer_FramesRequested); 
   cell.EnableLowMemoryUsage(2, count, a); 
   myForm.ShowDialog(); 
} 
 
void medicalViewer_ActiveSubCellChanged1(object sender, MedicalViewerActiveSubCellChangedEventArgs e) 
{ 
   string imageInformation = ""; 
   MedicalViewerMultiCell cell = (MedicalViewerMultiCell)sender; 
 
   if (cell.VirtualImage[e.SubCellIndex].ImageExist) 
   { 
      imageInformation = "Image bit per pixel = " + cell.VirtualImage[e.SubCellIndex].Image.BitsPerPixel.ToString(); 
   } 
 
   ((MedicalViewerForm)(cell.ParentViewer.Parent)).label.Text = imageInformation + " HasRegion = " + cell.VirtualImage[e.SubCellIndex].HasRegion; 
} 
 
void medicalViewer_FramesRequested(object sender, MedicalViewerRequestedFramesInformationEventArgs e) 
{ 
   MedicalViewerMultiCell cell = (MedicalViewerMultiCell)(sender); 
   string fileName =Path.Combine(LEAD_VARS.ImagesDir,"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)); 
   } 
 
   cell.SetRequestedImage(b, e.RequestedFramesIndexes, MedicalViewerSetImageOptions.Insert); 
} 
 
 
static class LEAD_VARS 
{ 
public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; 
}