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LibGfx: Clean up PathRasterizer

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No functional changes; mainly cleaning up the code style and
simplifying the code so I could understand it better.
This commit is contained in:
Jelle Raaijmakers 2023-04-18 23:54:34 +02:00 • committed by Andreas Kling
parent 8f736be711
commit 8dc55f5fda
1 changed files with 32 additions and 52 deletions
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84
Userland/Libraries/LibGfx/Font/PathRasterizer.cpp
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@ -1,5 +1,6 @@
/* /*
* Copyright (c) 2020, Srimanta Barua <srimanta.barua1@gmail.com> * Copyright (c) 2020, Srimanta Barua <srimanta.barua1@gmail.com>
* Copyright (c) 2023, Jelle Raaijmakers <jelle@gmta.nl>
* *
* SPDX-License-Identifier: BSD-2-Clause * SPDX-License-Identifier: BSD-2-Clause
*/ */
@ -11,10 +12,9 @@ namespace Gfx {
PathRasterizer::PathRasterizer(Gfx::IntSize size) PathRasterizer::PathRasterizer(Gfx::IntSize size)
: m_size(size) : m_size(size)
{ {
m_data.resize(m_size.width() * m_size.height()); m_data.resize(m_size.area());
for (int i = 0; i < m_size.width() * m_size.height(); i++) { for (int i = 0; i < m_size.area(); i++)
m_data[i] = 0.0f; m_data[i] = 0.f;
}
} }
void PathRasterizer::draw_path(Gfx::Path& path) void PathRasterizer::draw_path(Gfx::Path& path)
@ -31,17 +31,11 @@ RefPtr<Gfx::Bitmap> PathRasterizer::accumulate()
auto bitmap = bitmap_or_error.release_value_but_fixme_should_propagate_errors(); auto bitmap = bitmap_or_error.release_value_but_fixme_should_propagate_errors();
Color base_color = Color::from_rgb(0xffffff); Color base_color = Color::from_rgb(0xffffff);
for (int y = 0; y < m_size.height(); y++) { for (int y = 0; y < m_size.height(); y++) {
float accumulator = 0.0; float accumulator = 0.f;
for (int x = 0; x < m_size.width(); x++) { for (int x = 0; x < m_size.width(); x++) {
accumulator += m_data[y * m_size.width() + x]; accumulator += m_data[y * m_size.width() + x];
float value = accumulator; float value = AK::min(AK::abs(accumulator), 1.f);
if (value < 0.0f) { u8 alpha = value * 255.f;
value = -value;
}
if (value > 1.0f) {
value = 1.0;
}
u8 alpha = value * 255.0f;
bitmap->set_pixel(x, y, base_color.with_alpha(alpha)); bitmap->set_pixel(x, y, base_color.with_alpha(alpha));
} }
} }
@ -51,46 +45,38 @@ RefPtr<Gfx::Bitmap> PathRasterizer::accumulate()
void PathRasterizer::draw_line(Gfx::FloatPoint p0, Gfx::FloatPoint p1) void PathRasterizer::draw_line(Gfx::FloatPoint p0, Gfx::FloatPoint p1)
{ {
// FIXME: Shift x and y according to dy/dx // FIXME: Shift x and y according to dy/dx
if (p0.x() < 0.0f) { if (p0.x() < 0.f)
p0.set_x(roundf(p0.x())); p0.set_x(roundf(p0.x()));
} if (p0.y() < 0.f)
if (p0.y() < 0.0f) {
p0.set_y(roundf(p0.y())); p0.set_y(roundf(p0.y()));
} if (p1.x() < 0.f)
if (p1.x() < 0.0f) {
p1.set_x(roundf(p1.x())); p1.set_x(roundf(p1.x()));
} if (p1.y() < 0.f)
if (p1.y() < 0.0f) {
p1.set_y(roundf(p1.y())); p1.set_y(roundf(p1.y()));
}
if (!(p0.x() >= 0.0f && p0.y() >= 0.0f && p0.x() <= m_size.width() && p0.y() <= m_size.height())) { if (p0.x() < 0.f || p0.y() < 0.f || p0.x() > m_size.width() || p0.y() > m_size.height()) {
dbgln("!P0({},{})", p0.x(), p0.y()); dbgln("!P0({},{})", p0.x(), p0.y());
return; return;
} }
if (!(p1.x() >= 0.0f && p1.y() >= 0.0f && p1.x() <= m_size.width() && p1.y() <= m_size.height())) { if (p1.x() < 0.f || p1.y() < 0.f || p1.x() > m_size.width() || p1.y() > m_size.height()) {
dbgln("!P1({},{})", p1.x(), p1.y()); dbgln("!P1({},{})", p1.x(), p1.y());
return; return;
} }
VERIFY(p0.x() >= 0.0f && p0.y() >= 0.0f && p0.x() <= m_size.width() && p0.y() <= m_size.height());
VERIFY(p1.x() >= 0.0f && p1.y() >= 0.0f && p1.x() <= m_size.width() && p1.y() <= m_size.height());
// If we're on the same Y, there's no need to draw // If we're on the same Y, there's no need to draw
if (p0.y() == p1.y()) { if (p0.y() == p1.y())
return; return;
}
float direction = -1.0; float direction = -1.f;
if (p1.y() < p0.y()) { if (p1.y() < p0.y()) {
direction = 1.0; direction = 1.f;
auto tmp = p0; AK::swap(p0, p1);
p0 = p1;
p1 = tmp;
} }
float dxdy = (p1.x() - p0.x()) / (p1.y() - p0.y()); float const dxdy = (p1.x() - p0.x()) / (p1.y() - p0.y());
float const dydx = AK::abs(1.f / dxdy);
u32 y0 = floorf(p0.y()); u32 y0 = floorf(p0.y());
u32 y1 = ceilf(p1.y()); u32 y1 = ceilf(p1.y());
float x_cur = p0.x(); float x_cur = p0.x();
@ -98,12 +84,10 @@ void PathRasterizer::draw_line(Gfx::FloatPoint p0, Gfx::FloatPoint p1)
for (u32 y = y0; y < y1; y++) { for (u32 y = y0; y < y1; y++) {
u32 line_offset = m_size.width() * y; u32 line_offset = m_size.width() * y;
float dy = min(y + 1.0f, p1.y()) - max((float)y, p0.y()); float dy = AK::min(y + 1.f, p1.y()) - AK::max(static_cast<float>(y), p0.y());
float directed_dy = dy * direction; float directed_dy = dy * direction;
float x_next = x_cur + dy * dxdy; float x_next = x_cur + dy * dxdy;
if (x_next < 0.0f) { x_next = AK::max(x_next, 0.f);
x_next = 0.0f;
}
float x0 = x_cur; float x0 = x_cur;
float x1 = x_next; float x1 = x_next;
if (x1 < x0) { if (x1 < x0) {
@ -112,27 +96,23 @@ void PathRasterizer::draw_line(Gfx::FloatPoint p0, Gfx::FloatPoint p1)
} }
float x0_floor = floorf(x0); float x0_floor = floorf(x0);
float x1_ceil = ceilf(x1); float x1_ceil = ceilf(x1);
u32 x0i = x0_floor; u32 x0_floor_i = x0_floor;
if (x1_ceil <= x0_floor + 1.0f) { if (x1_ceil <= x0_floor + 1.f) {
// If x0 and x1 are within the same pixel, then area to the right is (1 - (mid(x0, x1) - x0_floor)) * dy // If x0 and x1 are within the same pixel, then area to the right is (1 - (mid(x0, x1) - x0_floor)) * dy
float area = ((x0 + x1) * 0.5f) - x0_floor; float area = .5f * (x0 + x1) - x0_floor;
m_data[line_offset + x0i] += directed_dy * (1.0f - area); m_data[line_offset + x0_floor_i] += directed_dy * (1.f - area);
m_data[line_offset + x0i + 1] += directed_dy * area; m_data[line_offset + x0_floor_i + 1] += directed_dy * area;
} else { } else {
float dydx = 1.0f / dxdy; float x0_right = 1.f - (x0 - x0_floor);
if (dydx < 0)
dydx = -dydx;
float x0_right = 1.0f - (x0 - x0_floor);
u32 x1_floor_i = floorf(x1); u32 x1_floor_i = floorf(x1);
float area_upto_here = 0.5f * x0_right * x0_right * dydx; float area_upto_here = .5f * x0_right * x0_right * dydx;
m_data[line_offset + x0i] += direction * area_upto_here; m_data[line_offset + x0_floor_i] += direction * area_upto_here;
for (u32 x = x0i + 1; x < x1_floor_i; x++) { for (u32 x = x0_floor_i + 1; x < x1_floor_i; x++) {
m_data[line_offset + x] += direction * dydx; m_data[line_offset + x] += direction * dydx;
area_upto_here += dydx; area_upto_here += dydx;
} }
float remaining_area = (dy - area_upto_here); float remaining_area = dy - area_upto_here;
m_data[line_offset + x1_floor_i] += direction * remaining_area; m_data[line_offset + x1_floor_i] += direction * remaining_area;
} }