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  • Coordinates
  • Using the drawing functions
  • Drawing in an image with opacity
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Stored procedures
Identifies the opacity of a pixel in an image that has an Alpha channel. This image can be:
  • an Image control,
  • in a variable of type Image.
// Identify the opacity of the pixel (15, 25)
// on the "IMG_ImageDrawing" control
ResOpacity = dPixelOpacity(IMG_ImageDrawing, 15, 25)
<Result> = dPixelOpacity([<Image>, ] <X-coordinate> , <Y-coordinate>)
<Result>: Integer
Opacity of specified pixel (included between 0 for transparent and 255 for opaque).
<Image>: Optional control name or optional Image, WDPic or picLayer variable
Image to use. The image can correspond to:
  • the name of an Image control.
  • the name of a variable of type Image.
If this parameter is not specified, the image handled by dStartDrawing will be used.
<X-coordinate>: Integer
Horizontal position of pixel to use.
<Y-coordinate>: Integer
Vertical position of pixel to use.


Coordinates are given in pixels with respect to the upper-left corner of the image (coordinates: (0.0)).
To retrieve the position of a mouse click in an Image control, use MouseXPos and MouseYPos.

Using the drawing functions

The drawing functions can be used according to 2 methods:
  • Method 1: Using dStartDrawing
    • dStartDrawing must be called before any other drawing function. dStartDrawing is used to define the element (Image control or variable) to which the drawing functions will be applied.
    • When drawing on an Image control:
      • The drawing functions operate on a copy ("bitmap") of the image. You can use the drawing functions of Windows (via API or CallDLL32) but these functions must use the DC (Device Context) returned by dStartDrawing.
      • dEndDrawing and dStartDrawing must not be called in the same process.
        The drawing will not be displayed if dEndDrawing and dStartDrawing are called in the same process: it will be automatically erased.
  • Reports and QueriesWindows Method 2: indicating the drawing target directly in the syntax (via a parameter)
    The <Image> parameter is used to specify directly the target of the drawing. dStartDrawing becomes useless. This function must be deleted.

Drawing in an image with opacity

To specify that the drawing in the image supports opacity (Alpha channel), use dStartDrawing and the dWithOpacity constant.
Component: wd270obj.dll
Minimum version required
  • Version 12
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