dArc (Function)

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Coordinates of the arc

Drawing a solid figure

Using the drawing functions

Drawing in PHP

Drawing in Browser code

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dArc (Function)

In french: dArc

Draws an arc of circle or an arc of ellipse:

in 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.

The arc is drawn counterclockwise.

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

Example

// Initialize the drawing in the Image control IMG_MyDrawing
dStartDrawing(IMG_MyDrawing)

// Draw an arc of circle in light yellow
dArc(10, 10, 50, 50, 20, 20, 40, 50, LightYellow)

// Draw a light yellow arc of circle in IMG_MyDrawing
dArc(IMG_MyDrawing,10, 10, 50, 50, 20, 20, 40, 50, LightYellow)

Syntax

Drawing an arc Hide the details

dArc([<Image>, ] <X1> , <Y1> , <X2> , <Y2> , <X3> , <Y3> , <X4> , <Y4> [, <Line color> [, <Line thickness>]])

<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.

<X1>: Integer

X-coordinate (in pixels) of the upper-left corner of the rectangle containing the circle.

<Y1>: Integer

Y-coordinate (in pixels) of the upper-left corner of the rectangle containing the circle.

<X2>: Integer

X-coordinate (in pixels) of the lower-right corner of the rectangle containing the circle.

<Y2>: Integer

Y-coordinate (in pixels) of the lower-right corner of the rectangle containing the circle.

<X3>: Integer

X-coordinate (in pixels) of the starting point of the arc.

<Y3>: Integer

Y-coordinate (in pixels) of the starting point of the arc.

<X4>: Integer

X-coordinate (in pixels) of the end point of the arc.

<Y4>: Integer

Y-coordinate (in pixels) of the end point of the arc.

<Line color>: Integer or constant (optional)

Color of the arc of circle. This color can correspond to:
an RGB color (returned by RGB),
an HSL color (returned by HSL),
a WLanguage preset color,
a variable of type Color.
If this parameter is not specified, the line color:
is Transparent if dPen has not been used beforehand,
corresponds to the color specified in the last call to dPen.

<Line thickness>: Optional integer

Thickness (in pixels) of the arc of circle to draw. If this parameter is not specified, the value taken into account can be:
the last value specified in the last call to dPen.
1 if dPen was not used beforehand.

Remarks

Coordinates of the arc

If the start and end points are not located on the border of the circle (or on the border of the ellipse), the point taken into account corresponds to the intersection between the circle and the line that joins the specified point and the center of the rectangle (which means the center of the circle).

The origin used to calculate the coordinates corresponds to the upper-left corner of the image (coordinates: (0,0)).

Drawing a solid figure

To draw a solid figure (a full arc), use dChord or dSlice.

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 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.

Limitation for dArc: The opacity defined by dBackground is ignored.

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 description window of project.
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: wd270pnt.dll