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UseDpi Property
See Also 
Leadtools.Windows.Controls Namespace > ImageBox Class : UseDpi Property



Gets or sets a value that indicates whether the control must account for the physical resolution of the image when calculating the display properties. This is a dependency property. Supported in Silverlight, Windows Phone 7

Syntax

Visual Basic (Declaration) 
Public Property UseDpi As Boolean
Visual Basic (Usage)Copy Code
Dim instance As ImageBox
Dim value As Boolean
 
instance.UseDpi = value
 
value = instance.UseDpi
C# 
public bool UseDpi {get; set;}
C++/CLI 
public:
property bool UseDpi {
   bool get();
   void set (    bool value);
}

Property Value

true to account for the physical resolution of the image when calculating the display properties; otherwise, false.

Example

Visual BasicCopy Code
Private Class MyWindow1 : Inherits Window
         Private theImage As ImageBox
         Public Sub New()
             ' Create the  viewer
             theImage = New ImageBox()

             ' Create Dock Panel

             Dim panel As DockPanel = New DockPanel()
             Content = panel

             DockPanel.SetDock(theImage, Dock.Bottom)

             theImage.HorizontalAlignment = HorizontalAlignment.Center
             theImage.VerticalAlignment = VerticalAlignment.Bottom
             theImage.UseDpi = True
             theImage.ScreenDpiX = 96
             theImage.ScreenDpiY = 96

             panel.Children.Add(theImage)

             ' load an image into the viewer
             theImage.Source = New BitmapImage(New Uri(Path.Combine(LEAD_VARS.ImagesDir, "cannon.jpg")))

             Title = String.Format("Size mode = {0}, click to change", theImage.SizeMode)

             AddHandler theImage.MouseDown, AddressOf theImage_MouseClick
         End Sub

         Private Sub theImage_MouseClick(ByVal sender As Object, ByVal e As MouseButtonEventArgs)
             Select Case theImage.SizeMode
                 Case SizeMode.Normal
                     theImage.SizeMode = SizeMode.Stretch

                 Case SizeMode.Stretch
                     theImage.SizeMode = SizeMode.Fit

                 Case SizeMode.Fit
                     theImage.SizeMode = SizeMode.FitAlways

                 Case SizeMode.FitAlways
                     theImage.SizeMode = SizeMode.FitWidth

                 Case SizeMode.FitWidth
                     theImage.SizeMode = SizeMode.Normal
             End Select

             Title = String.Format("Size mode = {0}, double click to change", theImage.SizeMode)

         End Sub
     End Class

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class
C#Copy Code
class MyWindow1 : Window
   {
      ImageBox theImage;
      public MyWindow1()
      {
         // Create the  viewer
         theImage = new ImageBox();

         // Create Dock Panel

         DockPanel panel = new DockPanel();
         Content = panel;

         DockPanel.SetDock(theImage, Dock.Bottom);

         theImage.HorizontalAlignment = HorizontalAlignment.Center;
         theImage.VerticalAlignment= VerticalAlignment.Bottom;
         theImage.UseDpi = true;
         theImage.ScreenDpiX = 96;
         theImage.ScreenDpiY = 96;

         panel.Children.Add(theImage);

         // load an image into the viewer
         theImage.Source = new BitmapImage(new Uri(Path.Combine(LEAD_VARS.ImagesDir, "cannon.jpg")));

         Title = string.Format("Size mode = {0}, click to change", theImage.SizeMode);

         theImage.MouseDown += new MouseButtonEventHandler(theImage_MouseClick);
      }

      void theImage_MouseClick(object sender, MouseButtonEventArgs e)
      {
         switch(theImage.SizeMode)
         {
            case SizeMode.Normal:
               theImage.SizeMode = SizeMode.Stretch;
               break;

            case SizeMode.Stretch:
               theImage.SizeMode = SizeMode.Fit;
               break;

            case SizeMode.Fit:
               theImage.SizeMode = SizeMode.FitAlways;
               break;

            case SizeMode.FitAlways:
               theImage.SizeMode = SizeMode.FitWidth;
               break;

            case SizeMode.FitWidth:
               theImage.SizeMode = SizeMode.Normal;
               break;
         }

         Title = string.Format("Size mode = {0}, double click to change", theImage.SizeMode);

      }
   }

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}
SilverlightCSharpCopy Code
class MyWindow1 : ChildWindow
{
   ImageBox theImage;
   public MyWindow1()
   {
      // Create the  viewer
      theImage = new ImageBox();

      // Create Dock Panel

      StackPanel panel = new StackPanel();
      Content = panel;

      theImage.HorizontalAlignment = HorizontalAlignment.Center;
      theImage.VerticalAlignment= VerticalAlignment.Bottom;
      theImage.UseDpi = true;
      theImage.ScreenDpiX = 96;
      theImage.ScreenDpiY = 96;

      panel.Children.Add(theImage);

      // load an image into the viewer
      theImage.Source = new BitmapImage(new Uri(LeadtoolsExamples.Common.ImagesPath.Path + "cannon.jpg"));

      Title = string.Format("Size mode = {0}, click to change", theImage.SizeMode);

      theImage.MouseLeftButtonDown +=new MouseButtonEventHandler(theImage_MouseLeftButtonDown);
   }

   void theImage_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
   {
      switch (theImage.SizeMode)
      {
         case SizeMode.Normal:
            theImage.SizeMode = SizeMode.Stretch;
            break;

         case SizeMode.Stretch:
            theImage.SizeMode = SizeMode.Fit;
            break;

         case SizeMode.Fit:
            theImage.SizeMode = SizeMode.FitAlways;
            break;

         case SizeMode.FitAlways:
            theImage.SizeMode = SizeMode.FitWidth;
            break;

         case SizeMode.FitWidth:
            theImage.SizeMode = SizeMode.Normal;
            break;
      }

      Title = string.Format("Size mode = {0}, double click to change", theImage.SizeMode);
   }
}
SilverlightVBCopy Code
Private Class MyWindow1 : Inherits ChildWindow
   Private theImage As ImageBox
   Public Sub New()
      ' Create the  viewer
      theImage = New ImageBox()

      ' Create Dock Panel

      Dim panel As StackPanel = New StackPanel()
      Content = panel

      theImage.HorizontalAlignment = HorizontalAlignment.Center
      theImage.VerticalAlignment= VerticalAlignment.Bottom
      theImage.UseDpi = True
      theImage.ScreenDpiX = 96
      theImage.ScreenDpiY = 96

      panel.Children.Add(theImage)

      ' load an image into the viewer
      theImage.Source = New BitmapImage(New Uri(LeadtoolsExamples.Common.ImagesPath.Path & "cannon.jpg"))

      Title = String.Format("Size mode = {0}, click to change", theImage.SizeMode)

      AddHandler theImage.MouseLeftButtonDown, AddressOf theImage_MouseLeftButtonDown
   End Sub

   Private Sub theImage_MouseLeftButtonDown(ByVal sender As Object, ByVal e As MouseButtonEventArgs)
      Select Case theImage.SizeMode
         Case SizeMode.Normal
            theImage.SizeMode = SizeMode.Stretch

         Case SizeMode.Stretch
            theImage.SizeMode = SizeMode.Fit

         Case SizeMode.Fit
            theImage.SizeMode = SizeMode.FitAlways

         Case SizeMode.FitAlways
            theImage.SizeMode = SizeMode.FitWidth

         Case SizeMode.FitWidth
            theImage.SizeMode = SizeMode.Normal
      End Select

      Title = String.Format("Size mode = {0}, double click to change", theImage.SizeMode)
   End Sub
End Class
XAMLCopy Code
<Window x:Class="WPFSamples.ImageBox" Height="600" Width="800" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Leadtools_Windows_Controls="clr-namespace:Leadtools.Windows.Controls;assembly=Leadtools.Windows.Controls">
  <DockPanel>
    <Leadtools_Windows_Controls:ImageBox Name="theImage" Source="file:///c:\users\Public\Documents\LEADTOOLS Images\cannon.jpg" DockPanel.Dock="Bottom" HorizontalAlignment="Center" VerticalAlignment="Bottom" SizeMode="Fit" UseDpi="true"></Leadtools_Windows_Controls:ImageBox>
  </DockPanel>
  <Window.Title>
        "Apply a effect"
      </Window.Title>
</Window>

Remarks

The physical resolution of an image is measured in dots per inch (DPI). When you load an image, the Leadtools.RasterImage.XResolution and Leadtools.RasterImage.YResolution properties are updated with the DPI values for the horizontal and vertical resolution. Some images have different horizontal and vertical resolutions. For example, the horizontal resolution of a fax image is typically twice its vertical resolution (for example 200 by 100). In such cases, the displayed images will appear elongated if you do not account for the resolution. If the image horizontal and vertical and resolution are is ot equal, you must set the UseDpi property to true to have the control automated scaling properties account for the physical resolution of the image.

The values of SourceDpiX, SourceDpiY, ScreenDpiX and ScreenDpiY are used when calculating how to display the image if the value of UseDpi is set to true.

For example, a typical A4 document image is 8.5 by 11 inches. Which could be 2550 by 3300 pixels if the image has a resolution of 300 by 300. Most document viewer applications will try to display this image in its original size. i.e. the image will take 8.5 inches of screen horizontal space and 11 inches of screen vertical space. Without using the UseDpi property of this control, you are required to do the calculations yourself as follows:

            control.UseDpi = false;
            control.ScaleFactor = screenResolution / imageResolution;

In the case of the image above, this will be 96 (typical screen resolution) divided by 300. Or, you can set the UseDpi value to true and the control will use the above formula internally keeping the ScaleFactor set to 1 as follows:

            control.UseDpi = true;
            control.ScaleFactor = 1;

This code will produce the same result as the previous one.

The control will automatically set the ScreenDpiX and ScreenDpiY to the current screen resolution, also the SourceDpiX and SourceDpiY will be obtained from the current image set in Source. You can change these values if required for manual calculations.

Requirements

Target Platforms: Windows 2000, Windows XP, Windows Server 2003 family, Windows Server 2008 family

See Also