dPixelOpacity (Function)

Identifies the opacity of a pixel in an image that supports the Alpha layer. This image can be:

an Image control,
Versions 17 and later
in an Image variable.
New in version 17
in an Image variable.
in an Image variable. in an Image variable.
This type of variable is not available.

Versions 15 and later

This function is now available for Java applications.

New in version 15

This function is now available for Java applications.

Versions 16 and later

This function is now available for Android applications.

This function is now available in Browser code.

This function is now available for WINDEV applications in Linux.

Caution: A specific configuration is required to use this function in Linux. See The drawings for more details.

New in version 16

This function is now available for Android applications.

This function is now available in Browser code.

This function is now available for WINDEV applications in Linux.

Caution: A specific configuration is required to use this function in Linux. See The drawings for more details.

This function is now available for Android applications.

This function is now available in Browser code.

This function is now available for WINDEV applications in Linux.

Caution: A specific configuration is required to use this function in Linux. See The drawings for more details.

Versions 17 and later

This function is now available for iPhone/iPad applications.

New in version 17

This function is now available for iPhone/iPad applications.

Example

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

Syntax

<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 variable

Image to use. This image can correspond to:
the name of an Image control.
Versions 17 and later
the name of an Image variable.
New in version 17
the name of an Image variable.
the name of an Image variable. the name of an Image variable.
This type of variable is not available.
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.

Remarks

Coordinates

The coordinates are specified in pixels in relation to the top left corner of Image control (coordinates set to (0, 0)).

To retrieve the position of a mouse click in an Image control, use MouseXPos and MouseYPos.

Drawing in an Image control with opacity

dStartDrawing must be called before using the drawing functions. dStartDrawing is used to define the image (Image control or Image variable) onto which the drawing functions will be applied. The dWithOpacity constant is used to specify that the opacity will be managed by the drawing (Alpha layer).

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 Windows functions must use the DC (Device Context) returned by dStartDrawing.

For an Image control, 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.

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.

Versions 16 and later

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". This option is available in the "Advanced" tab of description window of project ("Project .. Project description"), "Advanced" button, "W3C standard" option.

Caution: To use the drawing functions with Internet Explorer 9, the project must "include the reference to the DTD file". This option is available in the "Advanced" tab of the description window of the project ("Project .. Project description").

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 description window of project.
Reminder: To display the description window of project, on the "Project" pane, in the "Project" group, 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.

New in version 16

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". This option is available in the "Advanced" tab of description window of project ("Project .. Project description"), "Advanced" button, "W3C standard" option.

Caution: To use the drawing functions with Internet Explorer 9, the project must "include the reference to the DTD file". This option is available in the "Advanced" tab of the description window of the project ("Project .. Project description").

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 description window of project.
Reminder: To display the description window of project, on the "Project" pane, in the "Project" group, 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.

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". This option is available in the "Advanced" tab of description window of project ("Project .. Project description"), "Advanced" button, "W3C standard" option.

Caution: To use the drawing functions with Internet Explorer 9, the project must "include the reference to the DTD file". This option is available in the "Advanced" tab of the description window of the project ("Project .. Project description").

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 description window of project.
Reminder: To display the description window of project, on the "Project" pane, in the "Project" group, 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 : wd240obj.dll