<Image>.PixelOpacity (Function)

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Drawing functions on Image controls

PixelOpacity

Presentation

Example

Coordinates

Drawing in an image with opacity

Drawing in PHP

Drawing in Browser code

See also

<Image>.PixelOpacity (Function)

In french: <Image>.PixelOpacité

Identifies the opacity of a pixel in an image (in an Image control) with an Alpha channel.

Caution: A specific configuration is required to use this function in Linux. For more details, see The drawings.

Example

// Identify the opacity of the pixel (15, 25)
// on the "IMG_ImageDrawing" control
ResOpacity = IMG_ImageDrawing.PixelOpacity(15, 25)

Syntax

<Result> = <Image control>.PixelOpacity(<X-coordinate> , <Y-coordinate>)

<Result>: Integer

Opacity of specified pixel (included between 0 for transparent and 255 for opaque).

<Image control>: Control name

Name of the Image control to be used.

<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.

Drawing in an image with opacity

To specify that the drawing in the image supports opacity (Alpha channel), use <Image>.StartDrawing and the dWithOpacity constant.

Drawing in PHP

In PHP, the drawing functions are based on the graphic library GD. This library is commonly used by the PHP hosting companies and therefore it is always enabled. The version of the GD library must be version 2.0.28 (or later). This library can be downloaded from the PHP site.

To enable (if necessary) this library locally, the following elements are required:

PHP installed.
the PHP.INI file found in the Windows directory must contain the following line: "extension=php_gd2.dll" (instead of ";extension=php_gd2.dll").
the php_gd2.dll file must exist in the directory of PHP extensions. This directory is defined in the PHP.INI file by the "extension_dir" variable.

Drawing in Browser code

Some drawing functions are available in Browser code. The drawing functions in Browser code are based on the HTML 5 standard. More specifically, these functions are based on the "canvas" tag of HTML 5.

The drawing features in browser code are available for the recent browsers only (supporting the HTML 5 standard). To find out whether the drawing features are proposed by your browser, use DrawingAvailable.

Caution: To use the drawing functions with Internet Explorer 9, the project must include the reference to the DTD file. To do so, the HTML mode must be "HTML 4.01 Transitional + DTD". This option is available in the "Advanced" tab of the project description window.
Reminder: To open the project description window, go to the "Project" tab, "Project" group and click "Description".

Special case: Drawing in the browser of an Android phone: The browser drawing functions are only available starting with version 3 of Android.

Component: wd280obj.dll