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Implemented negative arcs on Windows.

This commit is contained in:
Pietro Gagliardi 2015-10-11 22:14:27 -04:00
parent d789d37ef6
commit 0989454106
2 changed files with 28 additions and 11 deletions
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3
test/drawtests.c
View File

@ -1265,7 +1265,7 @@ static void drawCSRoundRect(uiAreaDrawParams *p)
path = uiDrawNewPath(uiDrawFillModeWinding);
// top right corner
uiDrawPathArcTo(path,
uiDrawPathNewFigureWithArc(path,
x + width - radius, y + radius,
radius,
-90 * degrees, M_PI / 2,
@ -1288,7 +1288,6 @@ static void drawCSRoundRect(uiAreaDrawParams *p)
radius,
180 * degrees, M_PI / 2,
0);
uiDrawPathCloseFigure(path);
uiDrawPathEnd(path);

36
windows/draw.c
View File

@ -142,6 +142,7 @@ struct arc {
double radius;
double startAngle;
double sweep;
int negative;
};
// this is used for the comparison below
@ -155,21 +156,25 @@ static void drawArc(uiDrawPath *p, struct arc *a, void (*startFunction)(uiDrawPa
double endX, endY;
D2D1_ARC_SEGMENT as;
BOOL fullCircle;
double absSweep;
// as above, we can't do a full circle with one arc
// simulate it with two half-circles
// of course, we have a dragon: equality on floating-point values!
// I've chosen to do the AlmostEqualRelative() technique in https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/
fullCircle = FALSE;
if (a->sweep > (2 * M_PI)) // this part is easy
// use the absolute value to tackle both ≥2π and ≤-2π at the same time
absSweep = fabs(a->sweep);
if (absSweep > (2 * M_PI)) // this part is easy
fullCircle = TRUE;
else {
double aerDiff;
aerDiff = fabs(a->sweep - (2 * M_PI));
aerDiff = fabs(absSweep - (2 * M_PI));
// if we got here then we know a->sweep is larger (or the same!)
fullCircle = aerDiff <= a->sweep * aerMax;
fullCircle = aerDiff <= absSweep * aerMax;
}
// TODO make sure this works right for the negative direction
if (fullCircle) {
a->sweep = M_PI;
drawArc(p, a, startFunction);
@ -202,15 +207,26 @@ static void drawArc(uiDrawPath *p, struct arc *a, void (*startFunction)(uiDrawPa
as.size.width = a->radius;
as.size.height = a->radius;
as.rotationAngle = 0; // as above, not relevant for circles
as.sweepDirection = D2D1_SWEEP_DIRECTION_CLOCKWISE;
if (a->sweep > M_PI)
as.arcSize = D2D1_ARC_SIZE_LARGE;
if (a->negative)
as.sweepDirection = D2D1_SWEEP_DIRECTION_COUNTER_CLOCKWISE;
else
as.arcSize = D2D1_ARC_SIZE_SMALL;
as.sweepDirection = D2D1_SWEEP_DIRECTION_CLOCKWISE;
// TODO explain the outer if
if (!a->negative)
if (a->sweep > M_PI)
as.arcSize = D2D1_ARC_SIZE_LARGE;
else
as.arcSize = D2D1_ARC_SIZE_SMALL;
else
// TODO especially this part
if (a->sweep > M_PI)
as.arcSize = D2D1_ARC_SIZE_SMALL;
else
as.arcSize = D2D1_ARC_SIZE_LARGE;
ID2D1GeometrySink_AddArc(p->sink, &as);
}
void uiDrawPathNewFigureWithArc(uiDrawPath *p, double xCenter, double yCenter, double radius, double startAngle, double sweep)
void uiDrawPathNewFigureWithArc(uiDrawPath *p, double xCenter, double yCenter, double radius, double startAngle, double sweep, int negative)
{
struct arc a;
@ -219,6 +235,7 @@ void uiDrawPathNewFigureWithArc(uiDrawPath *p, double xCenter, double yCenter, d
a.radius = radius;
a.startAngle = startAngle;
a.sweep = sweep;
a.negative = negative;
drawArc(p, &a, uiDrawPathNewFigure);
}
@ -231,7 +248,7 @@ void uiDrawPathLineTo(uiDrawPath *p, double x, double y)
ID2D1GeometrySink_AddLine(p->sink, pt);
}
void uiDrawPathArcTo(uiDrawPath *p, double xCenter, double yCenter, double radius, double startAngle, double sweep)
void uiDrawPathArcTo(uiDrawPath *p, double xCenter, double yCenter, double radius, double startAngle, double sweep, int negative)
{
struct arc a;
@ -240,6 +257,7 @@ void uiDrawPathArcTo(uiDrawPath *p, double xCenter, double yCenter, double radiu
a.radius = radius;
a.startAngle = startAngle;
a.sweep = sweep;
a.negative = negative;
drawArc(p, &a, uiDrawPathLineTo);
}