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LibGfx: Preserve path order while splitting cubic/quadratic beziers

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This changes the splitting to use a stack, which ensures the resulting
line segments follow the path in order. This will be important for SVG
`<textPath>`s which place text along a path.
This commit is contained in:
MacDue 2023-12-10 19:44:00 +01:00 • committed by Andreas Kling
parent b2abd1dd05
commit 8713968165
1 changed files with 11 additions and 10 deletions
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21
Userland/Libraries/LibGfx/Painter.cpp
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@ -22,6 +22,7 @@
#include <AK/Memory.h> #include <AK/Memory.h>
#include <AK/Queue.h> #include <AK/Queue.h>
#include <AK/QuickSort.h> #include <AK/QuickSort.h>
#include <AK/Stack.h>
#include <AK/StdLibExtras.h> #include <AK/StdLibExtras.h>
#include <AK/StringBuilder.h> #include <AK/StringBuilder.h>
#include <AK/Utf32View.h> #include <AK/Utf32View.h>
@ -2135,14 +2136,14 @@ void Painter::for_each_line_segment_on_bezier_curve(FloatPoint control_point, Fl
auto new_segment = po1_midpoint + po2_midpoint; auto new_segment = po1_midpoint + po2_midpoint;
new_segment /= 2; new_segment /= 2;
segments.enqueue({ po1_midpoint, p1, new_segment }); segments.append({ po2_midpoint, new_segment, p2 });
segments.enqueue({ po2_midpoint, new_segment, p2 }); segments.append({ po1_midpoint, p1, new_segment });
}; };
Queue<SegmentDescriptor> segments; Vector<SegmentDescriptor> segments;
segments.enqueue({ control_point, p1, p2 }); segments.append({ control_point, p1, p2 });
while (!segments.is_empty()) { while (!segments.is_empty()) {
auto segment = segments.dequeue(); auto segment = segments.take_last();
if (can_approximate_bezier_curve(segment.p1, segment.p2, segment.control_point)) if (can_approximate_bezier_curve(segment.p1, segment.p2, segment.control_point))
callback(segment.p1, segment.p2); callback(segment.p1, segment.p2);
@ -2218,14 +2219,14 @@ void Painter::for_each_line_segment_on_cubic_bezier_curve(FloatPoint control_poi
}; };
auto level_3_midpoint = (level_2_midpoints[0] + level_2_midpoints[1]) / 2; auto level_3_midpoint = (level_2_midpoints[0] + level_2_midpoints[1]) / 2;
segments.enqueue({ { level_1_midpoints[0], level_2_midpoints[0] }, p1, level_3_midpoint }); segments.append({ { level_2_midpoints[1], level_1_midpoints[2] }, level_3_midpoint, p2 });
segments.enqueue({ { level_2_midpoints[1], level_1_midpoints[2] }, level_3_midpoint, p2 }); segments.append({ { level_1_midpoints[0], level_2_midpoints[0] }, p1, level_3_midpoint });
}; };
Queue<SegmentDescriptor> segments; Vector<SegmentDescriptor> segments;
segments.enqueue({ { control_point_0, control_point_1 }, p1, p2 }); segments.append({ { control_point_0, control_point_1 }, p1, p2 });
while (!segments.is_empty()) { while (!segments.is_empty()) {
auto segment = segments.dequeue(); auto segment = segments.take_last();
if (can_approximate_cubic_bezier_curve(segment.p1, segment.p2, segment.control_points.control_point_0, segment.control_points.control_point_1)) if (can_approximate_cubic_bezier_curve(segment.p1, segment.p2, segment.control_points.control_point_0, segment.control_points.control_point_1))
callback(segment.p1, segment.p2); callback(segment.p1, segment.p2);