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Improve wxDC::DrawArc() documentation.

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The existing documentation was flat out wrong as it is simply impossible to
pass a circle through any two arbitrary points while also fixing its centre,
explain what this function really does and also use this as an opportunity to
point people to DrawEllipticArc() which is much less confusing.

Also clarify the segments drawing logic of DrawArc() as it is quite
counterintuitive too as it depends on the brush being used and is also
different from DrawEllipticArc() which uses a simpler logic.

See #15609.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75063 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin 2013-10-25 16:16:45 +00:00
parent 4b24fc3944
commit 8b3102cfb6
1 changed files with 21 additions and 7 deletions
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28
interface/wx/dc.h
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@ -258,13 +258,23 @@ public:
void Clear();
/**
Draws an arc of a circle, centred on (@a xc, @a yc), with starting
point (@a xStart, @a yStart) and ending at (@a xEnd, @a yEnd).
The current pen is used for the outline and the current brush for
filling the shape.
Draws an arc from the given start to the given end point.
The arc is drawn in a counter-clockwise direction from the start point
to the end point.
@note DrawEllipticArc() has more clear semantics and it is recommended
to use it instead of this function.
The arc drawn is an arc of the circle centered at (@a xc, @a yc). Its
start point is (@a xStart, @a yStart) whereas its end point is the
point of intersection of the line passing by (@a xc, @a yc) and (@a
xEnd, @a yEnd) with the circle passing by (@a xStart, @a yStart).
The arc is drawn in a counter-clockwise direction between the start and
the end points.
The current pen is used for the outline and the current brush for
filling the shape. Notice that unless the brush is transparent, the
lines connecting the centre of the circle to the end points of the arc
are drawn as well.
*/
void DrawArc(wxCoord xStart, wxCoord yStart, wxCoord xEnd, wxCoord yEnd,
wxCoord xc, wxCoord yc);
@ -348,9 +358,13 @@ public:
@a start and @a end specify the start and end of the arc relative to
the three-o'clock position from the center of the rectangle. Angles are
specified in degrees (360 is a complete circle). Positive values mean
specified in degrees with 0 degree angle corresponding to the positive
horizontal axis (3 o'clock) direction. Positive values mean
counter-clockwise motion. If @a start is equal to @e end, a complete
ellipse will be drawn.
Notice that unlike DrawArc(), this function does not draw the lines to
the arc ends, even when using non-transparent brush.
*/
void DrawEllipticArc(wxCoord x, wxCoord y, wxCoord width, wxCoord height,
double start, double end);