Microsoft KB Archive/71104

= VB3 How to Use Windows BitBlt Function in VB Application =

Article ID: 71104

Article Last Modified on 11/18/2003

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APPLIES TO


 * Microsoft Visual Basic 3.0 Professional Edition
 * Microsoft Visual Basic 1.0 Standard Edition
 * Microsoft Visual Basic 3.0 Professional Edition

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This article was previously published under Q71104



SUMMARY
Windows GDI.EXE has a function called BitBlt that will move the source device given by the hSrcDC parameter to the destination device given by the hDestDC parameter. This article explains in detail the arguments of the Windows BitBlt function call.



MORE INFORMATION
This information is included with the Help file provided with Microsoft Professional Toolkit for Visual Basic version 1.0, Microsoft Visual Basic version 2.0, and Microsoft Visual Basic version 3.0.

To use BitBlt within a Visual Basic application, you must Declare the BitBlt function in one of these places:


 * Global module if using Visual Basic version 1.0.
 * Declaration section of any code module if using Visual Basic version 2.0 or higher.
 * Declaration section of a code window for the form.

Use the following Declare statement to declare the Function. Enter the entire Declare statement on one, single line:

Declare Function BitBlt Lib &quot;GDI&quot; (ByVal hDestDC%, ByVal X%, ByVal Y%,  ByVal nWidth%, ByVal nHeight%, ByVal hSrcDC%, ByVal XSrc%, ByVal YSrc%,   ByVal dwRop&) As Integer

The following defines each of the formal parameters used in the Declare:

  Parameter   Definition --  hDestDC     Specifies the device context that is to receive the bitmap.

X,Y        Specifies the logical x-coordinate and y-coordinate of the upper-left corner of the destination rectangle.

nWidth     Specifies the width (in logical units) of the destination rectangle and the source bitmap.

nHeight    Specifies the height (in logical units) of the destination rectangle and the source bitmap.

hSrcDC    Identifies the device context from which the bitmap will be              copied. It must be NULL(zero) if the dwRop&amp; parameter specifies a raster operation that does not include a source.

XSrc      Specifies the logical x-coordinate and the y-coordinate of              the upper-left corner of the source bitmap.

dwRop     Specifies the raster operation to be performed as defined below.

The following Raster operations are defined using the predefined constants found in the WINDOWS.H file supplied with the Microsoft Windows Software Development Kit (SDK). The value in the parentheses is the value to assign to the dwRop& variable.

  Code/Value (hex)     Description --  BLACKNESS (42)       Turn output black.

DSINVERT(550009)    Inverts the destination bitmap.

MERGECOPY(C000CA)   Combines the pattern and the source bitmap using the Boolean AND operation.

MERGEPAINT(BB0226)   Combines the inverted source bitmap with the destination bitmap using the Boolean OR operator.

NOTSRCCOPY(330008)   Copies the inverted source bitmap to the destination.

NOTSRCERASE(1100A6)  Inverts the result of combining the destination and source bitmap using the Boolean OR operator.

PATCOPY(F00021)      Copies the pattern to the destination bitmap.

PATINVERT(5A0049)    Combines the destination bitmap with the pattern using the Boolean XOR operator.

PATPAINT(FB0A09)     Combines the inverted source bitmap with the pattern using the Boolean OR operator. Combines the result of this operation with the destination bitmap using the Boolean OR operator.

SRCAND(8800C6)       Combines pixels of the destination and source bitmap using the Boolean AND operator.

SRCCOPY(CC0020)      Copies the source bitmap to destination bitmap.

SRCERASE(4400328)    Inverts the destination bitmap and combines the results with the source bitmap using the Boolean AND operator.

SRCINVERT(660046)    Combines pixels of the destination and source bitmap using the Boolean XOR operator.

SRCPAINT(EE0086)     Combines pixels of the destination and source bitmap using the Boolean OR operator.

WHITENESS(FF0062)    Turns all output white.

Step-by-Step Example
Here is an example showing how to copy the contents of a picture control to the contents of another picture control.

 Define a form (Form1) and place two picture controls (Picture1 and Picture2) on Form1. Display some graphics on Picture1 by loading from a picture file or by pasting from the clipboard at design time. You can load a picture from a file as follows:

 Select Picture from the Properties list box and click the arrow at the right of the Settings box. Then select the desired picture file such as a .BMP or .ICO file supplied with Microsoft Windows from the dialog box.   Add the following code to the Form_Click procedure: Sub Form_Click

' Assign information of the destination bitmap. Note that Bitblt ' requires coordinates in pixels. Const PIXEL = 3 Picture1.ScaleMode = PIXEL Picture2.ScaleMode = PIXEL hDestDC% = Picture2.hDC X% = 0: Y% = 0 nWidth% = Picture2.ScaleWidth nHeight% = Picture2.ScaleHeight

' Assign information of the source bitmap. hSrcDC% = Picture1.hDC XSrc% = 0: YSrc% = 0

' Assign the SRCCOPY constant to the Raster operation. dwRop& = &HCC0020

Suc% = BitBlt(hDestDC%, X%, Y%, nWidth%, nHeight%,_     hSrcDC%, XSrc%, YSrc%, dwRop&amp;) End Sub

</li> Run the program.</li></ol>

Click the form. The contents of the first picture will be displayed on the the second picture.

Additional query words: 2.00 3.00 vb3only

Keywords: kbcode KB71104

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