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"Fixed" arcs for now.

This commit is contained in:
Pietro Gagliardi 2015-10-07 12:19:20 -04:00
parent 2906fa5300
commit a7d8a87540
1 changed files with 23 additions and 39 deletions
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62
winarea_d2d/draw.c
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@ -130,7 +130,7 @@ void uiDrawPathNewFigure(uiDrawPath *p, double x, double y)
p->inFigure = TRUE;
}
static void arcStartXY(double xCenter, double yCenter, double radius, double startAngle, double *startX, double *startY)
static void arcEndpoint(double xCenter, double yCenter, double radius, double startAngle, double *startX, double *startY)
{
FLOAT sinStart, cosStart;
@ -143,61 +143,43 @@ static void arcStartXY(double xCenter, double yCenter, double radius, double sta
*startY = yCenter + radius * sinStart;
}
// TODO this is a mess.
static void doDrawArc(ID2D1GeometrySink *sink, double xCenter, double yCenter, double radius, double startAngle, double endAngle)
// An arc in Direct2D is defined by the chord between its endpoints, not solely by the sweep angle.
// There are four possible arcs with the same sweep amount that you can draw this way.
// See https://www.youtube.com/watch?v=ATS0ANW1UxQ for a demonstration.
// TODO stress test this, compare to cairo and Core Graphics; handle the case where sweep >= 2π
static void doDrawArc(ID2D1GeometrySink *sink, double startX, double startY, double endX, double endY, double radius, double sweep)
{
double delta;
int negative;
D2D1_ARC_SEGMENT as;
double endX, endY;
delta = endAngle - startAngle;
negative = 1;
// TODO why do I have to do this? if delta == 360 nothing gets drawn regardless of parameter values
while (delta > M_PI) {
// this line alternates between getting the 180 degree and 360 degree point; the negative variable does the alternating
arcStartXY(xCenter, yCenter, radius, startAngle + (negative * M_PI), &endX, &endY);
as.point.x = endX;
as.point.y = endY;
as.size.width = radius;
as.size.height = radius;
as.rotationAngle = 180;
as.sweepDirection = D2D1_SWEEP_DIRECTION_COUNTER_CLOCKWISE;
as.arcSize = D2D1_ARC_SIZE_SMALL;
ID2D1GeometrySink_AddArc(sink, &as);
delta -= M_PI;
if (negative == 0)
negative = 1;
else
negative = 0;
}
arcStartXY(xCenter, yCenter, radius, endAngle, &endX, &endY);
as.point.x = endX;
as.point.y = endY;
as.size.width = radius;
as.size.height = radius;
// Direct2D expects degrees
as.rotationAngle = delta * (180.0 / M_PI);
if (!negative)
as.rotationAngle += 180;
as.sweepDirection = D2D1_SWEEP_DIRECTION_COUNTER_CLOCKWISE;
as.arcSize = D2D1_ARC_SIZE_SMALL;
if (!negative)
as.rotationAngle = sweep * (180.0 / M_PI);
// TODO explain this
if (sweep < 0)
as.sweepDirection = D2D1_SWEEP_DIRECTION_COUNTER_CLOCKWISE;
else
as.sweepDirection = D2D1_SWEEP_DIRECTION_CLOCKWISE;
if (fabs(sweep) > M_PI)
as.arcSize = D2D1_ARC_SIZE_LARGE;
else
as.arcSize = D2D1_ARC_SIZE_SMALL;
ID2D1GeometrySink_AddArc(sink, &as);
}
void uiDrawPathNewFigureWithArc(uiDrawPath *p, double xCenter, double yCenter, double radius, double startAngle, double endAngle)
{
double startX, startY;
double endX, endY;
// make the new figure
arcStartXY(xCenter, yCenter, radius, startAngle, &startX, &startY);
arcEndpoint(xCenter, yCenter, radius, startAngle, &startX, &startY);
uiDrawPathNewFigure(p, startX, startY);
// draw the arc
doDrawArc(p->sink, xCenter, yCenter, radius, startAngle, endAngle);
arcEndpoint(xCenter, yCenter, radius, endAngle, &endX, &endY);
doDrawArc(p->sink, startX, startY, endX, endY, radius, endAngle - startAngle);
}
void uiDrawPathLineTo(uiDrawPath *p, double x, double y)
@ -212,13 +194,15 @@ void uiDrawPathLineTo(uiDrawPath *p, double x, double y)
void uiDrawPathArcTo(uiDrawPath *p, double xCenter, double yCenter, double radius, double startAngle, double endAngle)
{
double startX, startY;
double endX, endY;
// draw the starting line
arcStartXY(xCenter, yCenter, radius, startAngle, &startX, &startY);
arcEndpoint(xCenter, yCenter, radius, startAngle, &startX, &startY);
uiDrawPathLineTo(p, startX, startY);
// draw the arc
doDrawArc(p->sink, xCenter, yCenter, radius, startAngle, endAngle);
arcEndpoint(xCenter, yCenter, radius, endAngle, &endX, &endY);
doDrawArc(p->sink, startX, startY, endX, endY, radius, endAngle - startAngle);
}
void uiDrawPathBezierTo(uiDrawPath *p, double c1x, double c1y, double c2x, double c2y, double endX, double endY)