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LibGfx+LibWeb: Wire up CanvasRenderingContext2D.ellipse()

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Note that this is *extremely* naive, and not very good at being correct.
This commit is contained in:
AnotherTest 2021-04-15 18:41:13 +04:30 • committed by Andreas Kling
parent 6c05d6d370
commit 801daf47f0
6 changed files with 104 additions and 12 deletions
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35
Userland/Libraries/LibGfx/Path.cpp
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@ -30,11 +30,14 @@
#include <AK/StringBuilder.h>
#include <LibGfx/Painter.h>
#include <LibGfx/Path.h>
#include <math.h>
namespace Gfx {
void Path::elliptical_arc_to(const FloatPoint& next_point, const FloatPoint& radii, double x_axis_rotation, bool large_arc, bool sweep)
void Path::elliptical_arc_to(const FloatPoint& point, const FloatPoint& radii, double x_axis_rotation, bool large_arc, bool sweep)
{
auto next_point = point;
double rx = radii.x();
double ry = radii.y();
@ -58,6 +61,18 @@ void Path::elliptical_arc_to(const FloatPoint& next_point, const FloatPoint& rad
if (ry < 0)
ry *= -1.0;
// POSSIBLY HACK: Handle the case where both points are the same.
auto same_endpoints = next_point == last_point;
if (same_endpoints) {
if (!large_arc) {
// Nothing is going to be drawn anyway.
return;
}
// Move the endpoint by a small amount to avoid division by zero.
next_point.move_by(0.01f, 0.01f);
}
// Find (cx, cy), theta_1, theta_delta
// Step 1: Compute (x1', y1')
auto x_avg = (last_point.x() - next_point.x()) / 2.0f;
@ -104,20 +119,18 @@ void Path::elliptical_arc_to(const FloatPoint& next_point, const FloatPoint& rad
auto theta_delta = theta_2 - theta_1;
if (!sweep && theta_delta > 0.0f) {
theta_delta -= M_TAU;
theta_delta -= 2 * M_PI;
} else if (sweep && theta_delta < 0) {
theta_delta += M_TAU;
theta_delta += 2 * M_PI;
}
append_segment<EllipticalArcSegment>(
elliptical_arc_to(
next_point,
FloatPoint(cx, cy),
FloatPoint(rx, ry),
static_cast<float>(x_axis_rotation),
static_cast<float>(theta_1),
static_cast<float>(theta_delta));
invalidate_split_lines();
{ cx, cy },
{ rx, ry },
x_axis_rotation,
theta_1,
theta_delta);
}
void Path::close()