dChangeMode (Function)

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dChangeMode (Function)

In french: dChangeMode

Changes the drawing mode used by the drawing functions (dLine, dRectangle, ...). The change is applied to the element being drawn. This element can be:

an Image control,
in a variable of type Image.
This type of variable is not available.
in a variable of type WDPic (on the background layer),
in a variable of type picLayer.

Example

// Initialize the drawing in an Image control
dStartDrawing(IMG_Drawing)

// Draws a rectangle and erases it
dChangeMode(drawXOR)
// Displays the rectangle (in XOR mode)
dRectangle(0, 0, 100, 100)
Multitask(10)
// Erases the rectangle
dRectangle(0, 0, 100, 100)

// Draws a rectangle in an Image control and erases it
dChangeMode(IMG_Drawing, drawXOR)
// Displays the rectangle (in XOR mode)
dRectangle(IMG_Drawing, 0, 0, 100, 100)
Multitask(10)
// Erases the rectangle
dRectangle(IMG_Drawing, 0, 0, 100, 100)

Syntax

dChangeMode([<Image>, ] <New mode>)

<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.
the name of a variable of type WDPic. Only the background layer will be handled.
the name of a variable of type picLayer.
If this parameter is not specified, it is necessary to define the drawing destination with dStartDrawing.

<New mode>: Integer constant

Mode for drawing in the image:
drawAntiAliasing Uses the GDI+ and/or the features of the video card to draw the lines and the circles without jagged effects. This drawing mode is slower but the results are better than with the standard mode.
Constant not available.
This drawing mode is not supported.
drawDefault Standard colors.
drawXOR Colors applied via an "exclusive or" operation with the background. Erases a drawing if this option is used twice.
CAUTION: This drawing mode is not compatible with the management of opacity (the drawing is not erased anymore).
Caution:
The drawing in XOR mode is available for the Image controls only. The drawing in XOR mode is not available for the Image variables.
The drawXOR constant cannot be combined with the drawAntiAliasing constant.
The drawing in XOR mode only affects dPoint.

Remarks

Anti-aliasing

The anti-aliasing consists in drawing the lines and the circles without jagged effects. This feature requires the GDI+ framework (which means the WINDEV framework). Example:

Limits:

dChord is not supported in this mode.
To avoid the jagged edges, the colors and the lines of elements are smoothed out. Some drawing functions can have an unexpected behavior because the specified colors are no longer found. For example, if a borderline color is specified for dFill, this color is not found: the entire area is filled up.
For a drawing with anti-aliasing, dPolygon and dSlice have the following behavior. The outline is drawn above the inside of the polygon: therefore, the line is partly combined with the inside of the polygon. If the line is very thick, it will be displayed in two colors.
For more details on the use of GDI+, see GDI+ framework.

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.

Drawing in PHP

In PHP, the drawing functions are based on the graphic library GD. This library is commonly used by the PHP hosting providers 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.

Related Examples:

Unit examples (WINDEV): The drawing functions

[ + ] Using the main drawing functions of WINDEV to:
- Initialize an Image control for drawing
- Draw simple shapes
- Write a text into a drawing
- Change the color in a drawing

Business / UI classification: Neutral code

Component: wd300pnt.dll