Leadtools.Windows.Controls Namespace > ImageBox Class : UseDpi Property |
public bool UseDpi {get; set;}
'Declaration Public Property UseDpi As Boolean
'Usage Dim instance As ImageBox Dim value As Boolean instance.UseDpi = value value = instance.UseDpi
public bool UseDpi {get; set;}
get_UseDpi();
set_UseDpi(value);
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.
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
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"; }
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); } }
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
<!--WPF example--> <Window x:Class="WPFSamples.ImageBox" 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" Height="600" Width="800"> <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> <!--Silverlight example--> <UserControl x:Class="SilverlightApplication1.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:Leadtools_Windows_Controls="clr-namespace:Leadtools.Windows.Controls;assembly=Leadtools.Windows.Controls" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="400"> <Grid x:Name="LayoutRoot" Background="White"> <Leadtools_Windows_Controls:ImageBox Name="theImage" Source="http://www.MyServer.com/images/MyImage.png" HorizontalAlignment="Center" VerticalAlignment="Bottom" SizeMode="Fit" UseDpi="true"> </Leadtools_Windows_Controls:ImageBox > </Grid> </UserControl>
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2