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Started writing the Haiku drawing code.

This commit is contained in:
Pietro Gagliardi 2015-11-23 11:06:00 -05:00
parent 62e3259db7
commit f7c114cb63
1 changed files with 141 additions and 11 deletions
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152
haiku/draw.cpp
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@ -1,55 +1,185 @@
// 19 november 2015
#include "uipriv_haiku.hpp"
struct uiDrawPath {
BShape *shape;
uiDrawFillMode fillMode;
bool ended;
};
uiDrawPath *uiDrawNewPath(uiDrawFillMode fillMode)
{
// TODO
return NULL;
uiDrawPath *p;
p = uiNew(uiDrawPath);
p->shape = new BShape();
p->fillMode = mode;
return p;
}
void uiDrawFreePath(uiDrawPath *p)
{
// TODO
delete p->shape;
uiFree(p);
}
// TODO add ended checks
// TODO add error checks
void uiDrawPathNewFigure(uiDrawPath *p, double x, double y)
{
// TODO
p->shape->MoveTo(BPoint(x, y));
}
// Even though BView::FillArc()/StrokeArc() existed and used the sane arc drawing model, Haiku decided to use the Direct2D arc drawing model when it added BShape::ArcTo().
// So refer to windows/draw.c for details.
// This is slightly better as it uses center points and sweep amounts instead of endpoints, but *still*.
// TODO split into common/d2darc.c
struct arc {
double xCenter;
double yCenter;
double radius;
double startAngle;
double sweep;
int negative;
};
// 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))
{
double sinx, cosx;
double startX, startY;
double endX, endY;
bool largeArc;
bool counterclockwise;
bool fullCircle;
double absSweep;
// TODO is this relevaith Haiku?
// 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;
// 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(absSweep - (2 * M_PI));
// if we got here then we know a->sweep is larger (or the same!)
fullCircle = aerDiff <= absSweep * aerMax;
}
// TODO make sure this works right for the negative direction
if (fullCircle) {
a->sweep = M_PI;
drawArc(p, a, startFunction);
a->startAngle += M_PI;
drawArc(p, a, NULL);
return;
}
// first, figure out the arc's endpoints
sinx = sin(a->startAngle);
cosx = cos(a->startAngle);
startX = a->xCenter + a->radius * cosx;
startY = a->yCenter + a->radius * sinx;
sinx = sin(a->startAngle + a->sweep);
cosx = cos(a->startAngle + a->sweep);
endX = a->xCenter + a->radius * cosx;
endY = a->yCenter + a->radius * sinx;
// now do the initial step to get the current point to be the start point
// this is either creating a new figure, drawing a line, or (in the case of our full circle code above) doing nothing
if (startFunction != NULL)
(*startFunction)(p, startX, startY);
// now we can draw the arc
if (a->negative)
counterclockwise = true;
else
counterclockwise = false
// TODO explain the outer if
if (!a->negative)
if (a->sweep > M_PI)
largeArc = true;
else
largeArc = false;
else
// TODO especially this part
if (a->sweep > M_PI)
largeArc = false;
else
largeArc = true;
p->shape->ArcTo(a->radius, a->radius,
// TODO should this be sweep amount?
a->startAngle, // TODO convert to degrees
largeArc, counterclockwise,
BPoint(a->xCenter, a->yCenter));
}
void uiDrawPathNewFigureWithArc(uiDrawPath *p, double xCenter, double yCenter, double radius, double startAngle, double sweep, int negative)
{
// TODO
struct arc a;
a.xCenter = xCenter;
a.yCenter = yCenter;
a.radius = radius;
a.startAngle = startAngle;
a.sweep = sweep;
a.negative = negative;
drawArc(p, &a, uiDrawPathNewFigure);
}
void uiDrawPathLineTo(uiDrawPath *p, double x, double y)
{
// TODO
p->shape->LineTo(BPoint(x, y));
}
void uiDrawPathArcTo(uiDrawPath *p, double xCenter, double yCenter, double radius, double startAngle, double sweep, int negative)
{
// TODO
struct arc a;
a.xCenter = xCenter;
a.yCenter = yCenter;
a.radius = radius;
a.startAngle = startAngle;
a.sweep = sweep;
a.negative = negative;
drawArc(p, &a, uiDrawPathLineTo);
}
void uiDrawPathBezierTo(uiDrawPath *p, double c1x, double c1y, double c2x, double c2y, double endX, double endY)
{
// TODO
p->shape->BezierTo(BPoint(c1x, c1y),
BPoint(c2x, c2y),
BPoint(endX, endY));
}
void uiDrawPathCloseFigure(uiDrawPath *p)
{
// TODO
p->shape->Close();
}
void uiDrawPathAddRectangle(uiDrawPath *p, double x, double y, double width, double height)
{
// TODO
// this is the same algorithm used by cairo and Core Graphics, according to their documentations
uiDrawPathNewFigure(p, x, y);
uiDrawPathLineTo(p, x + width, y);
uiDrawPathLineTo(p, x + width, y + height);
uiDrawPathLineTo(p, x, y + height);
uiDrawPathCloseFigure(p);
}
void uiDrawPathEnd(uiDrawPath *p)
{
// TODO
p->ended = true;
}
void uiDrawStroke(uiDrawContext *c, uiDrawPath *path, uiDrawBrush *b, uiDrawStrokeParams *p)