CroppedBitmap.BeginInit Method

Definition

Namespace:

System.Windows.Media.Imaging

Assembly:

PresentationCore.dll

Signals the start of the CroppedBitmap initialization.

public:
 virtual void BeginInit();

public void BeginInit ();

abstract member BeginInit : unit -> unit
override this.BeginInit : unit -> unit

Public Sub BeginInit ()

Implements

BeginInit()

Exceptions

InvalidOperationException

The CroppedBitmap is currently being initialized. BeginInit() has already been called.

-or-

The CroppedBitmap has already been initialized.

Examples

The following example demonstrates how to initialize a CroppedBitmap with a set of properties by using the BeginInit and EndInit methods.

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Imaging;

namespace SDKSample
{
    public partial class CroppedBitmapExample : Page
    {
        public CroppedBitmapExample()
        {

            ///// Create a BitmapImage and set it's DecodePixelWidth to 200. Use  /////
            ///// this BitmapImage as a source for other BitmapSource objects.    /////

            BitmapImage myBitmapImage = new BitmapImage();

            // BitmapSource objects like BitmapImage can only have their properties
            // changed within a BeginInit/EndInit block.
            myBitmapImage.BeginInit();
            myBitmapImage.UriSource = new Uri(@"sampleImages/WaterLilies.jpg",UriKind.Relative);

            // To save significant application memory, set the DecodePixelWidth or  
            // DecodePixelHeight of the BitmapImage value of the image source to the desired 
            // height or width of the rendered image. If you don't do this, the application will 
            // cache the image as though it were rendered as its normal size rather then just 
            // the size that is displayed.
            // Note: In order to preserve aspect ratio, set DecodePixelWidth
            // or DecodePixelHeight but not both.
            myBitmapImage.DecodePixelWidth = 200;
            myBitmapImage.EndInit();

            ////////// Crop the BitmapSource ////////////
            // Use the BitmapImage created above as the source for a new BitmapSource object
            // which is cropped.                                               
            // Note: New BitmapSource does not cache. It is always pulled when required.

            CroppedBitmap myCroppedBitmap = new CroppedBitmap();

            // BitmapSource objects like CroppedBitmap can only have their properties
            // changed within a BeginInit/EndInit block.
            myCroppedBitmap.BeginInit();

            // Use the BitmapSource object defined above as the source for this new 
            // BitmapSource (chain the BitmapSource objects together).
            myCroppedBitmap.Source = myBitmapImage;

            // Crop the image to the rectangular area defined below. 
            // The image is cropped to 80 pixels less in width and 60 less 
            // in height then the original source.
            myCroppedBitmap.SourceRect = new Int32Rect(0,0,(int)myBitmapImage.Width-80, (int)myBitmapImage.Height-60);
            myCroppedBitmap.EndInit();

            // Create Image Element
            Image myImage = new Image();
            myImage.Width = 200;
            //set image source
            myImage.Source = myCroppedBitmap;

            // Add Image to the UI
            StackPanel myStackPanel = new StackPanel();
            myStackPanel.Children.Add(myImage);
            this.Content = myStackPanel;
        }
    }
}

Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Media
Imports System.Windows.Media.Imaging

Namespace SDKSample

    Class CroppedBitmapExample
        Inherits Page

        Public Sub New()

            '/// Create a BitmapImage and set it's DecodePixelWidth to 200. Use  /////
            '/// this BitmapImage as a source for other BitmapSource objects.    /////
            Dim myBitmapImage As New BitmapImage()

            ' BitmapSource objects like BitmapImage can only have their properties
            ' changed within a BeginInit/EndInit block.
            myBitmapImage.BeginInit()
            myBitmapImage.UriSource = New Uri("sampleImages/WaterLilies.jpg", UriKind.Relative)

            ' To save significant application memory, set the DecodePixelWidth or  
            ' DecodePixelHeight of the BitmapImage value of the image source to the desired 
            ' height or width of the rendered image. If you don't do this, the application will 
            ' cache the image as though it were rendered as its normal size rather then just 
            ' the size that is displayed.
            ' Note: In order to preserve aspect ratio, set DecodePixelWidth
            ' or DecodePixelHeight but not both.
            myBitmapImage.DecodePixelWidth = 200
            myBitmapImage.EndInit()

            '//////// Crop the BitmapSource ////////////
            ' Use the BitmapImage created above as the source for a new BitmapSource object
            ' which is cropped.                                               
            ' Note: New BitmapSource does not cache. It is always pulled when required.
            Dim myCroppedBitmap As New CroppedBitmap()

            ' BitmapSource objects like CroppedBitmap can only have their properties
            ' changed within a BeginInit/EndInit block.
            myCroppedBitmap.BeginInit()

            ' Use the BitmapSource object defined above as the source for this new 
            ' BitmapSource (chain the BitmapSource objects together).
            myCroppedBitmap.Source = myBitmapImage

            ' Crop the image to the rectangular area defined below. 
            ' The image is cropped to 80 pixels less in width and 60 less 
            ' in height then the original source.
            myCroppedBitmap.SourceRect = New Int32Rect(0, 0, _
                CType(myBitmapImage.Width - 80, Integer), _
                CType(myBitmapImage.Height - 60, Integer))
            myCroppedBitmap.EndInit()

            ' Create Image Element
            Dim myImage As New Image()
            myImage.Width = 200
            'set image source
            myImage.Source = myCroppedBitmap

            ' Add Image to the UI
            Dim myStackPanel As New StackPanel()
            myStackPanel.Children.Add(myImage)
            Me.Content = myStackPanel

        End Sub
    End Class
End Namespace 'ImagingSnippetGallery

Remarks

Property initialization must be done between BeginInit and EndInit calls. Once the CroppedBitmap has been initialized, property changes are ignored.

See also

• EndInit()