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Fixed circles in Windows once and for all.

This commit is contained in:
Pietro Gagliardi 2015-10-11 07:51:14 -04:00
parent 6fe77e12f9
commit f3a2635f8c
2 changed files with 19 additions and 2 deletions
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20
windows/draw.c
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@ -144,17 +144,33 @@ struct arc {
double sweep; double sweep;
}; };
// this is used for the comparison below
// if it falls apart it can be changed later
#define aerMax 6 * DBL_EPSILON
static void drawArc(uiDrawPath *p, struct arc *a, void (*startFunction)(uiDrawPath *, double, double)) static void drawArc(uiDrawPath *p, struct arc *a, void (*startFunction)(uiDrawPath *, double, double))
{ {
double sinx, cosx; double sinx, cosx;
double startX, startY; double startX, startY;
double endX, endY; double endX, endY;
D2D1_ARC_SEGMENT as; D2D1_ARC_SEGMENT as;
BOOL fullCircle;
// as above, we can't do a full circle with one arc // as above, we can't do a full circle with one arc
// simulate it with two half-circles // simulate it with two half-circles
// TODO THIS ONLY WORKS ON THE ARCS TEST PAGE // of course, we have a dragon: equality on floating-point values!
if (a->sweep >= (2 * M_PI)) { // 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
fullCircle = TRUE;
else {
double aerDiff;
aerDiff = fabs(a->sweep - (2 * M_PI));
// if we got here then we know a->sweep is larger (or the same!)
fullCircle = aerDiff <= a->sweep * aerMax;
}
if (fullCircle) {
a->sweep = M_PI; a->sweep = M_PI;
drawArc(p, a, startFunction); drawArc(p, a, startFunction);
a->startAngle += M_PI; a->startAngle += M_PI;

1
windows/winapi.h
View File

@ -29,3 +29,4 @@
#include <shobjidl.h> #include <shobjidl.h>
#include <math.h> #include <math.h>
#include <d2d1.h> #include <d2d1.h>
#include <float.h>