TCanvas.Arc procedure

Member of TCanvaspublicIn unit Graphics

Use Arc to draw an elliptically curved line with the current Pen.

Declaration

pascal

procedure Arc(ALeft: Integer; ATop: Integer; ARight: Integer; 
 ABottom: Integer; Angle16Deg: Integer; 
 Angle16DegLength: Integer); virtual; reintroduce
procedure Arc(ALeft: Integer; ATop: Integer; ARight: Integer; 
 ABottom: Integer; SX: Integer; SY: Integer; EX: Integer; 
 EY: Integer); virtual; reintroduce

Arguments

`ALeft`	Coordinate of the left side of the rectangle enclosing the full ellipse.
`ATop`	Coordinate of the top side of the rectangle enclosing the full ellipse.
`ARight`	Coordinate of the top side of the rectangle enclosing the full ellipse.
`ABottom`	Coordinate of the bottom side of the rectangle enclosing the full ellipse.
`Angle16Deg`	Angle in 1/16ths of a degree at which the arc starts.
`Angle16DegLength`	Length of the arc, given in units of 1/16th of a degree.
`SX`	Horizontal coordinate of the point defining the start of the arc.
`SY`	Vertical coordinate of the point defining the start of the arc.
`EX`	Horizontal coordinate of the point defining the end of the arc.
`EY`	Vertical coordinate of the point defining the end of the arc.

Description

Use Arc to draw an elliptically curved line with the current Pen. Arc is re-introduced in TCanvas to provide additional overloads for the method found in the platform-specific LCL interface object. Parameter values passed to the overloaded methods are in turn passed to the widgetset class for the platform.

ALeft, ATop, ABottom, and ARight define the rectangle which encloses the full ellipse from which a part is drawn as arc.

One variant of the method provides the Angle16Deg and Angle16DegLength arguments.

Angle16Deg contains the angle at which the arc begins. Zero degrees lies at the 3 o'clock position. Positive values indicate a counter-clockwise direction to the start point. The angle is expressed in units of 1/16th of a degress.

Angle16DegLength contains the arc length expressed in 1/16ths degrees. For example, a full circle would be represented by the value 5760 (=16*360). A positive value indicates that the arc runs in counter-clockwise direction, a negative value means clockwise direction.

Another variant provides the SX, SY and EX, EY arguments representing the starting and ending radial points between which the Arc is drawn. These points do not necessarily need to be on the ellipse outline. The Arc begins and ends at the intersection between the ellipse and the straight lines between the ellipse center and the points (SX,SY) and (EX,EY), respectively.

Drawing methods which reintroduce those in the TFPCustomCanvas ancestor class were added in LCL version 2.6.1.

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.