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Graphics.DrawImage Method (Image, PointF[], RectangleF, GraphicsUnit, ImageAttributes, Graphics.DrawImageAbort, Int32)

.NET Framework 1.1

Draws the specified portion of the specified Image object at the specified location and with the specified size.

[Visual Basic]
Overloads Public Sub DrawImage( _
   ByVal image As Image, _
   ByVal destPoints() As PointF, _
   ByVal srcRect As RectangleF, _
   ByVal srcUnit As GraphicsUnit, _
   ByVal imageAttr As ImageAttributes, _
   ByVal callback As Graphics.DrawImageAbort, _
   ByVal callbackData As Integer _
)
[C#]
public void DrawImage(
 Image image,
 PointF[] destPoints,
 RectangleF srcRect,
 GraphicsUnit srcUnit,
 ImageAttributes imageAttr,
 Graphics.DrawImageAbort callback,
 int callbackData
);
[C++]
public: void DrawImage(
 Image* image,
 PointF destPoints[],
 RectangleF srcRect,
 GraphicsUnit srcUnit,
 ImageAttributes* imageAttr,
 Graphics.DrawImageAbort* callback,
 int callbackData
);
[JScript]
public function DrawImage(
   image : Image,
 destPoints : PointF[],
 srcRect : RectangleF,
 srcUnit : GraphicsUnit,
 imageAttr : ImageAttributes,
 callback : Graphics.DrawImageAbort,
 callbackData : int
);

Parameters

image
Image object to draw.
destPoints
Array of three Point structures that define a parallelogram.
srcRect
RectangleF structure that specifies the portion of the image object to draw.
srcUnit
Member of the GraphicsUnit enumeration that specifies the units of measure used by the srcRect parameter.
imageAttr
ImageAttributes object that specifies recoloring and gamma information for the image object.
callback
Graphics.DrawImageAbort delegate that specifies a method to call during the drawing of the image. This method is called frequently to check whether to stop execution of the DrawImage method according to application-determined criteria.
callbackData
Value specifying additional data for the DrawImageAbort delegate to use when checking whether to stop execution of the DrawImage method.

Return Value

This method does not return a value.

Remarks

The destPoints parameter specifies three points of a parallelogram. The three Point structures represent the upper-left, upper-right, and lower-left corners of the parallelogram. The fourth point is extrapolated from the first three to form a parallelogram.

The srcRect parameter specifies a rectangular portion of the image object to draw. This portion is scaled and sheared to fit inside the parallelogram specified by the destPoints parameter.

This overload with the callback and callbackData parameters provides the means to stop the drawing of an image once it starts according to criteria and data determined by the application. For example, an application could start drawing a large image and the user might scroll the image off the screen, in which case the application could stop the drawing.

Example

[Visual Basic, C#] The following example is designed for use with Windows Forms, and it requires PaintEventArgs e, which is a parameter of the Paint event handler. The code first defines a callback method for the DrawImageAbort delegate; the definition is simplistic and merely tests to see whether the DrawImage method calls it with a null callBackData parameter. The main body of the example performs the following actions:

  • Creates an instance of the DrawImageAbort callback method.
  • Creates an image from a JPEG file SampImag.jpg in the folder of the example.
  • Creates points that define a parallelogram in which to draw the image.
  • Creates a rectangle to select the portion of the image to draw.
  • Sets the graphics drawing unit to pixel.
  • Draws the original image to the screen.
  • Creates an additional parallelogram in which to draw an adjusted image.
  • Creates and sets the attributes of the adjusted image to have a larger-than-usual gamma value.
  • Draws the adjusted image to the screen.

[Visual Basic, C#] For the original, unadjusted parallelogram, the position locates the image on the screen, and the size of the rectangle and the size and shape of the parallelogram determines the scaling and shearing of the drawn image.

[Visual Basic, C#] Because this example uses an overload that passes a callBackData parameter, the DrawImageAbort callback returns false, which causes the DrawImage method to continue, and the example draws the adjusted image to the screen.

[Visual Basic] 
Private Function DrawImageCallback(callBackData As IntPtr) As Boolean
' Test for call that passes callBackData parameter.
If callBackData.Equals(IntPtr.Zero) Then
' If no callBackData passed, abort DrawImage method.
Return True
Else
' If callBackData passed, continue DrawImage method.
Return False
End If
End Function
Public Sub DrawImageParaFRectAttribAbortData(e As PaintEventArgs)
' Create callback method.
Dim imageCallback As New _
Graphics.DrawImageAbort(AddressOf DrawImageCallback)
Dim imageCallbackData As Integer = 1
' Create image.
Dim newImage As Image = Image.FromFile("SampImag.jpg")
' Create parallelogram for drawing original image.
Dim ulCorner1 As New PointF(100F, 100F)
Dim urCorner1 As New PointF(325F, 100F)
Dim llCorner1 As New PointF(150F, 250F)
Dim destPara1 As PointF() =  {ulCorner1, urCorner1, llCorner1}
' Create rectangle for source image.
Dim srcRect As New RectangleF(50F, 50F, 150F, 150F)
Dim units As GraphicsUnit = GraphicsUnit.Pixel
' Create parallelogram for drawing adjusted image.
Dim ulCorner2 As New PointF(325F, 100F)
Dim urCorner2 As New PointF(550F, 100F)
Dim llCorner2 As New PointF(375F, 250F)
Dim destPara2 As PointF() =  {ulCorner2, urCorner2, llCorner2}
' Draw original image to screen.
e.Graphics.DrawImage(newImage, destPara1, srcRect, units)
' Create image attributes and set large gamma.
Dim imageAttr As New ImageAttributes()
imageAttr.SetGamma(4F)
Try
' Draw adjusted image to screen.
e.Graphics.DrawImage(newImage, destPara2, srcRect, units, _
imageAttr, imageCallback, imageCallbackData)
Catch ex As Exception
e.Graphics.DrawString(ex.ToString(), New Font("Arial", 8), _
Brushes.Black, New PointF(0, 0))
End Try
End Sub
        
[C#] 
// Define DrawImageAbort callback method.
private bool DrawImageCallback(IntPtr callBackData)
{
// Test for call that passes callBackData parameter.
if(callBackData==IntPtr.Zero)
{
// If no callBackData passed, abort DrawImage method.
return true;
}
else
{
// If callBackData passed, continue DrawImage method.
return false;
}
}
public void DrawImageParaFRectAttribAbortData(PaintEventArgs e)
{
// Create callback method.
Graphics.DrawImageAbort imageCallback
= new Graphics.DrawImageAbort(DrawImageCallback);
int imageCallbackData = 1;
// Create image.
Image newImage = Image.FromFile("SampImag.jpg");
// Create parallelogram for drawing original image.
PointF ulCorner1 = new PointF(100.0F, 100.0F);
PointF urCorner1 = new PointF(325.0F, 100.0F);
PointF llCorner1 = new PointF(150.0F, 250.0F);
PointF[] destPara1 = {ulCorner1, urCorner1, llCorner1};
// Create rectangle for source image.
RectangleF srcRect = new RectangleF( 50.0F, 50.0F, 150.0F, 150.0F);
GraphicsUnit units = GraphicsUnit.Pixel;
// Create parallelogram for drawing adjusted image.
PointF ulCorner2 = new PointF(325.0F, 100.0F);
PointF urCorner2 = new PointF(550.0F, 100.0F);
PointF llCorner2 = new PointF(375.0F, 250.0F);
PointF[] destPara2 = {ulCorner2, urCorner2, llCorner2};
// Draw original image to screen.
e.Graphics.DrawImage(newImage, destPara1, srcRect, units);
// Create image attributes and set large gamma.
ImageAttributes imageAttr = new ImageAttributes();
imageAttr.SetGamma(4.0F);
try
{
checked
{
// Draw adjusted image to screen.
e.Graphics.DrawImage(
newImage,
destPara2,
srcRect,
units,
imageAttr,
imageCallback,
imageCallbackData);
}
}
catch (Exception ex)
{
e.Graphics.DrawString(
ex.ToString(),
new Font("Arial", 8),
Brushes.Black,
new PointF(0, 0));
}
}
        

[C++, JScript] No example is available for C++ or JScript. To view a Visual Basic or C# example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

Graphics Class | Graphics Members | System.Drawing Namespace | Graphics.DrawImage Overload List

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