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LibGfx: Implement filling paths

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There are some imperfections with intersecting edges (because the main
algorithm used is scanline, and that is not geared towards drawing
complex shapes), however, it behaves mostly fine for normal use :^)
This commit is contained in:
AnotherTest 2020-05-06 11:55:12 +04:30 • committed by Andreas Kling
parent 4d20cf57db
commit f54b41f748
Notes: sideshowbarker 2024-07-19 06:56:14 +09:00
5 changed files with 274 additions and 8 deletions
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61
Libraries/LibGfx/Path.cpp
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@ -24,7 +24,10 @@
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/Function.h>
#include <AK/QuickSort.h>
#include <AK/StringBuilder.h>
#include <LibGfx/Painter.h>
#include <LibGfx/Path.h>
namespace Gfx {
@ -34,6 +37,8 @@ void Path::close()
if (m_segments.size() <= 1)
return;
invalidate_split_lines();
auto& last_point = m_segments.last().point;
for (ssize_t i = m_segments.size() - 1; i >= 0; --i) {
@ -80,4 +85,60 @@ String Path::to_string() const
return builder.to_string();
}
void Path::segmentize_path()
{
Vector<LineSegment> segments;
auto add_line = [&](const auto& p0, const auto& p1) {
if (p0.y() == p1.y())
return; // horizontal lines are not needed (there's nothing to fill inside)
float ymax = p0.y(), ymin = p1.y(), x_of_ymin = p1.x(), x_of_ymax = p0.x();
auto slope = p0.x() == p1.x() ? 0 : ((float)(p0.y() - p1.y())) / ((float)(p0.x() - p1.x()));
if (p0.y() < p1.y()) {
ymin = ymax;
ymax = p1.y();
x_of_ymax = x_of_ymin;
x_of_ymin = p0.x();
}
segments.append({ Point(p0.x(), p0.y()),
Point(p1.x(), p1.y()),
slope == 0 ? 0 : 1 / slope,
x_of_ymin,
ymax, ymin, x_of_ymax });
};
FloatPoint cursor { 0, 0 };
for (auto& segment : m_segments) {
switch (segment.type) {
case Segment::Type::MoveTo:
cursor = segment.point;
break;
case Segment::Type::LineTo: {
add_line(cursor, segment.point);
cursor = segment.point;
break;
}
case Segment::Type::QuadraticBezierCurveTo: {
auto& control = segment.through.value();
Painter::for_each_line_segment_on_bezier_curve(control, cursor, segment.point, [&](const FloatPoint& p0, const FloatPoint& p1) {
add_line(Point(p0.x(), p0.y()), Point(p1.x(), p1.y()));
});
cursor = segment.point;
break;
}
case Segment::Type::Invalid:
ASSERT_NOT_REACHED();
break;
}
}
// sort segments by ymax
quick_sort(segments, [](const auto& line0, const auto& line1) {
return line1.maximum_y < line0.maximum_y;
});
m_split_lines = move(segments);
}
}