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PtArc

An elliptical arc

Class hierarchy:

PtWidget --> PtBasic --> PtGraphic --> PtArc

For more information, see the diagram of the widget hierarchy.

PhAB icon:

Public header:

<photon/PtArc.h>

Description:

You can create an elliptical arc using the PtArc widget. The arc is defined by:

• the origin
• an ellipse
• a start angle
• an end angle

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Arcs, circles, ellipses, wedges, and chords created by PtArc.

The ellipse is specified using two control points stored in Pt_ARG_POINTS. These points are relative to the widget's origin, Pt_ARG_ORIGIN (see PtGraphic). If the points aren't set, the ellipse is specified by the widget's dimensions, Pt_ARG_DIM.

An arc is drawn along the ellipse in a counter-clockwise direction starting at the start angle and finishing at the end angle. The start and end angles are specified by two resources: Pt_ARC_START and Pt_ARC_END.

The arc may be scaled directly by scaling its defining points. Scaling a circular arc by unequal amounts in the x and y directions will result in an elliptical arc.

The arc may also be drawn as a closed curve by specifying the arc type with the Pt_ARG_ARC_TYPE resource:

• Pt_ARC_CURVE - draws the arc inscribed by the points
• Pt_ARC_PIE - draws the arc inscribed by the points with lines drawn from the two end points to the centroid of the arc, creating a pie-slice
• Pt_ARC_CHORD - draws the arc inscribed by the points with the chord connecting the two end points closing the curve.

New resources:

Resource	C type	Pt type	Default
Pt_ARG_ARC_END	unsigned short	Scalar	0
Pt_ARG_ARC_START	unsigned short	Scalar	0
Pt_ARG_ARC_TYPE	unsigned short	Scalar	Pt_ARC_CURVE

Pt_ARG_ARC_END

C type	Pt type	Default
unsigned short	Scalar	0

The end angle in tenths of a degree.

Pt_ARG_ARC_START

C type	Pt type	Default
unsigned short	Scalar	0

The start angle in tenths of a degree. If this angle is 0, the arc starts on the horizon, to the right of the center. Angles increase in a counter-clockwise direction.

Pt_ARG_ARC_TYPE

C type	Pt type	Default
unsigned short	Scalar	Pt_ARC_CURVE

The type of arc. Possible values:

Pt_ARC_CHORD

Curve with ends connected by a straight line.

Pt_ARC_CURVE

Curve only.

Pt_ARC_PIE

Curve with ends connected to the center.

Inherited resources:

If the widget modifies an inherited resource, the "Default override" column indicates the new value. This modification affects any subclasses of the widget.

Resource	Inherited from	Default override
Pt_ARG_AREA	PtWidget
Pt_ARG_BANDWIDTH_THRESHOLD	PtBasic	Not used by this class.
Pt_ARG_BITMAP_CURSOR	PtWidget
Pt_ARG_BORDER_WIDTH	PtWidget
Pt_ARG_BOT_BORDER_COLOR	PtBasic
Pt_ARG_COLOR	PtBasic
Pt_ARG_CURSOR_COLOR	PtWidget
Pt_ARG_CURSOR_TYPE	PtWidget
Pt_ARG_DASH_LIST	PtGraphic
Pt_ARG_DASH_SCALE	PtGraphic
Pt_ARG_DATA	PtWidget
Pt_ARG_DIM	PtWidget
Pt_ARG_EFLAGS	PtWidget
Pt_ARG_FILL_COLOR	PtBasic	Pg_TRANSPARENT
Pt_ARG_FILL_PATTERN	PtBasic
Pt_ARG_FLAGS	PtWidget
Pt_ARG_GRAPHIC_FLAGS	PtGraphic
Pt_ARG_HELP_TOPIC	PtWidget
Pt_ARG_HIGHLIGHT_ROUNDNESS	PtBasic
Pt_ARG_LINE_CAP	PtGraphic
Pt_ARG_LINE_JOIN	PtGraphic
Pt_ARG_LINE_WIDTH	PtGraphic
Pt_ARG_MARGIN_HEIGHT	PtBasic
Pt_ARG_MARGIN_WIDTH	PtBasic
Pt_ARG_ORIGIN	PtGraphic
Pt_ARG_POINTS	PtGraphic
Pt_ARG_POS	PtWidget
Pt_ARG_RESIZE_FLAGS	PtWidget	Pt_RESIZE_XY_AS_REQUIRED
Pt_ARG_TOP_BORDER_COLOR	PtBasic
Pt_ARG_TRANS_PATTERN	PtBasic
Pt_ARG_USER_DATA	PtWidget
Pt_CB_ACTIVATE	PtBasic
Pt_CB_ARM	PtBasic
Pt_CB_BLOCKED	PtWidget
Pt_CB_DESTROYED	PtWidget
Pt_CB_DISARM	PtBasic
Pt_CB_GOT_FOCUS	PtBasic
Pt_CB_HOTKEY	PtWidget
Pt_CB_LOST_FOCUS	PtBasic
Pt_CB_MENU	PtBasic
Pt_CB_RAW	PtWidget
Pt_CB_REALIZED	PtWidget
Pt_CB_REPEAT	PtBasic
Pt_CB_RESCALE	PtGraphic
Pt_CB_UNREALIZED	PtWidget

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