/* * Copyright (c) 2020, Srimanta Barua * Copyright (c) 2023, Jelle Raaijmakers * * SPDX-License-Identifier: BSD-2-Clause */ #include namespace Gfx { PathRasterizer::PathRasterizer(Gfx::IntSize size) : m_size(size) { m_data.resize(m_size.area()); for (int i = 0; i < m_size.area(); i++) m_data[i] = 0.f; } void PathRasterizer::draw_path(Gfx::Path& path) { for (auto& line : path.split_lines()) draw_line(line.a(), line.b()); } RefPtr PathRasterizer::accumulate() { auto bitmap_or_error = Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, m_size); if (bitmap_or_error.is_error()) return {}; auto bitmap = bitmap_or_error.release_value_but_fixme_should_propagate_errors(); Color base_color = Color::from_rgb(0xffffff); for (int y = 0; y < m_size.height(); y++) { float accumulator = 0.f; for (int x = 0; x < m_size.width(); x++) { accumulator += m_data[y * m_size.width() + x]; float value = AK::min(AK::abs(accumulator), 1.f); u8 alpha = value * 255.f; bitmap->set_pixel(x, y, base_color.with_alpha(alpha)); } } return bitmap; } void PathRasterizer::draw_line(Gfx::FloatPoint p0, Gfx::FloatPoint p1) { // FIXME: Shift x and y according to dy/dx if (p0.x() < 0.f) p0.set_x(roundf(p0.x())); if (p0.y() < 0.f) p0.set_y(roundf(p0.y())); if (p1.x() < 0.f) p1.set_x(roundf(p1.x())); if (p1.y() < 0.f) p1.set_y(roundf(p1.y())); 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()); return; } 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()); return; } // If we're on the same Y, there's no need to draw if (p0.y() == p1.y()) return; float direction = -1.f; if (p1.y() < p0.y()) { direction = 1.f; AK::swap(p0, p1); } 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 y1 = ceilf(p1.y()); float x_cur = p0.x(); for (u32 y = y0; y < y1; y++) { u32 line_offset = m_size.width() * y; float dy = AK::min(y + 1.f, p1.y()) - AK::max(static_cast(y), p0.y()); float directed_dy = dy * direction; float x_next = x_cur + dy * dxdy; x_next = AK::max(x_next, 0.f); float x0 = x_cur; float x1 = x_next; if (x1 < x0) { x1 = x_cur; x0 = x_next; } float x0_floor = floorf(x0); float x1_ceil = ceilf(x1); u32 x0_floor_i = x0_floor; 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 float area = .5f * (x0 + x1) - x0_floor; m_data[line_offset + x0_floor_i] += directed_dy * (1.f - area); if (x0_floor_i + 1 < static_cast(m_size.width())) m_data[line_offset + x0_floor_i + 1] += directed_dy * area; } else { float x0_right = 1.f - (x0 - x0_floor); u32 x1_floor_i = floorf(x1); float area_upto_here = .5f * x0_right * x0_right * dydx; m_data[line_offset + x0_floor_i] += direction * area_upto_here; for (u32 x = x0_floor_i + 1; x < x1_floor_i; x++) { m_data[line_offset + x] += direction * dydx; area_upto_here += dydx; } float remaining_area = dy - area_upto_here; m_data[line_offset + x1_floor_i] += direction * remaining_area; } x_cur = x_next; } } }