dArc (Function)

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Help / WLanguage / WLanguage functions / Controls, pages and windows / Drawing functions

Coordinates of the arc
Drawing a solid figure
Using the drawing functions

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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.
in a variable of type WDPic (on the background layer),
in a variable of type picLayer.

The arc is drawn counterclockwise.

Caution: In Linux, this function requires a specific configuration. For more details, see Drawing in WINDEV, WEBDEV and WINDEV Mobile.

Example

See additional examples

// 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, specifying all the coordinates of the bounding rectangle 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. This 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 previously used.
For a variable of type Image, the line will be black.
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.

Drawing an arc using a Rectangle variable Hide the details

dArc([<Image>, ] <Rectangle> , <X3> , <Y3> , <X4> , <Y4> [, <Line color> [, <Line thickness>]])

<Image>: Optional control name or optional Image, WDPic or picLayer variable

Image to use. This 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.

<Rectangle>: Rectangle variable

Name of the Rectangle variable that corresponds to 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 previously used.
For a variable of type Image, the line will be black.
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 considered for calculating the coordinates corresponds to the top 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 the dDrawingStartfunction
- 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.
    If function dEndDrawing is called in the same process as function dStartDrawing, the drawing will not appear: it will be automatically deleted.
Method 2: specify design destination directly in syntax (via parameter)
The <Image> parameter is used to specify directly the target of the drawing. dStartDrawing becomes useless. This function must be deleted.

Limitation for function dArc: Opacity defined with function dBackground is not taken into account.

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