dPixelColor (Function)

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How to retrieve the components of the color?
Using the drawing functions

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dPixelColor (Function)

In french: dPixelCouleur

Identifies the color of a pixel:

in an Image control,
in a variable of type Image.

Example

See additional examples

// Identify the color of the pixel (15, 25)
// in the Image control named "IMG_Drawing"
ResColor = dPixelColor(IMG_ImageDrawing, 15, 25)

Syntax

<Result> = dPixelColor([<Image>, ] <X-coordinate> , <Y-coordinate>)

<Result>: Integer

Color of the specified pixel in RGB format.
Caution: the value returned may differ according to the display configuration (resolution, ...).

<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.
This parameter is not available in a report. To specify the image to use, dStartDrawing must be used before the call to dPixelColor.

<X-coordinate>: Integer

Horizontal position of pixel to use.

<Y-coordinate>: Integer

Vertical position of pixel to use.

Remarks

Coordinates

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.

How to retrieve the components of the color?

To retrieve the components of the color returned by dPixelColor:

To get the red component, use RGBRed (or perform a division modulo 256 of <Result>),
To get the green component, use RGBGreen (or perform a division modulo 256 of <Result>/256),
To get the blue component, use RGBBlue (or perform a division modulo 256 of <Result>/256/256).

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.
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.

Component: wd280obj.dll