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LibGfx: Allow float thickness lines and fix fill path glitches

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The main fix is stopping fill_path() scanlines being rounded to the
wrong pixel. The y-value is now floored to ensure it always snaps
in the same direction.
This commit is contained in:
MacDue 2022-11-26 20:15:52 +00:00 • committed by Linus Groh
parent 93f85f1a09
commit db235a87bf
1 changed files with 7 additions and 7 deletions
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14
Userland/Libraries/LibGfx/AntiAliasingPainter.cpp
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@ -38,7 +38,7 @@ void AntiAliasingPainter::draw_anti_aliased_line(FloatPoint actual_from, FloatPo
//
// Please delete this code and implement it!
auto int_thickness = round_to<int>(thickness);
int int_thickness = AK::ceil(thickness);
auto mapped_from = m_transform.map(actual_from);
auto mapped_to = m_transform.map(actual_to);
auto length = mapped_to.distance_from(mapped_from);
@ -48,14 +48,14 @@ void AntiAliasingPainter::draw_anti_aliased_line(FloatPoint actual_from, FloatPo
auto start_point = (mapped_from.x() < mapped_to.x() ? mapped_from : mapped_to).translated(0, -int_thickness / 2);
if constexpr (path_hacks == FixmeEnableHacksForBetterPathPainting::Yes) {
// FIXME: SVG fill_path() hack:
// SVG asks for 1px scanlines at floating point y values, if they're not rounded to a pixel they look faint.
start_point.set_y(round_to<int>(start_point.y()));
// SVG asks for 1px scanlines at floating point y values, if they're not snapped to a pixel they look faint.
start_point.set_y(floorf(start_point.y()));
}
return fill_rect(Gfx::FloatRect(start_point, { length, float(int_thickness) }), color);
return fill_rect(Gfx::FloatRect(start_point, { length, thickness }), color);
}
if (mapped_from.x() == mapped_to.x()) {
auto start_point = (mapped_from.y() < mapped_to.y() ? mapped_from : mapped_to).translated(-int_thickness / 2, 0);
return fill_rect(Gfx::FloatRect(start_point, { float(int_thickness), length }), color);
return fill_rect(Gfx::FloatRect(start_point, { thickness, length }), color);
}
if constexpr (path_hacks == FixmeEnableHacksForBetterPathPainting::Yes) {
@ -90,12 +90,12 @@ void AntiAliasingPainter::draw_anti_aliased_line(FloatPoint actual_from, FloatPo
point.y() * cos_inverse_angle + point.x() * sin_inverse_angle);
};
Gfx::FloatRect line_rect({ -(int_thickness * 255) / 2.0f, 0 }, Gfx::FloatSize(int_thickness * 255, length * 255));
Gfx::FloatRect line_rect({ -(thickness * 255) / 2.0f, 0 }, Gfx::FloatSize(thickness * 255, length * 255));
auto gradient = delta.y() / delta.x();
// Work out how long we need to scan along the X-axis to reach the other side of the line.
// E.g. for a vertical line this would be `thickness', in general it is this:
int scan_line_length = AK::ceil(AK::sqrt((gradient * gradient + 1) * int_thickness * int_thickness) / gradient);
int scan_line_length = AK::ceil(AK::sqrt((gradient * gradient + 1) * thickness * thickness) / gradient);
auto x_gradient = 1 / gradient;
int x_step = floorf(x_gradient);