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

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

Namespace:  System.Drawing
Assembly:  System.Drawing (in System.Drawing.dll)

public void DrawImage(
	Image image,
	PointF[] destPoints,
	RectangleF srcRect,
	GraphicsUnit srcUnit,
	ImageAttributes imageAttr,
	Graphics..::.DrawImageAbort callback
)

Parameters

image
Type: System.Drawing.Image

Image to draw.

destPoints
Type: System.Drawing.PointF[]

Array of three PointF structures that define a parallelogram.

srcRect
Type: System.Drawing.RectangleF

RectangleF structure that specifies the portion of the image object to draw.

srcUnit
Type: System.Drawing.GraphicsUnit

Member of the GraphicsUnit enumeration that specifies the units of measure used by the srcRect parameter.

imageAttr
Type: System.Drawing.Imaging.ImageAttributes

ImageAttributes that specifies recoloring and gamma information for the image object.

callback
Type: System.Drawing.Graphics.DrawImageAbort

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.

ExceptionCondition
ArgumentNullException

image is null.

The destPoints parameter specifies three points of a parallelogram. The three PointF 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 parameter provides the means to stop the drawing of an image once it starts according to criteria 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.

The following code 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 Graphics.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 Graphics.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.

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.

Because this example uses an overload that does not pass a callBackData parameter, the Graphics.DrawImageAbort callback returns true, which causes the DrawImage method to end, and the exception-handling code included in the example prints out the exception text rather than drawing the image.

// Define DrawImageAbort callback method. 
private bool DrawImageCallback3(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;
    }
}
private void DrawImageParaFRectAttribAbort(PaintEventArgs e)
{

    // Create callback method.
    Graphics.DrawImageAbort imageCallback
        = new Graphics.DrawImageAbort(DrawImageCallback3);

    // 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);
        }
    }
    catch (Exception ex)
    {
        e.Graphics.DrawString(
            ex.ToString(),
            new Font("Arial", 8),
            Brushes.Black,
            new PointF(0, 0));
    }
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

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