/*
* Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
* Copyright (c) 2022, Ben Maxwell <macdue@dueutil.tech>
* Copyright (c) 2022, Torsten Engelmann <engelTorsten@gmx.de>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#if defined(AK_COMPILER_GCC)
# pragma GCC optimize("O3")
#endif
#include <AK/Function.h>
#include <AK/NumericLimits.h>
#include <LibGfx/AntiAliasingPainter.h>
#include <LibGfx/Line.h>
#include <LibGfx/Painter.h>
namespace Gfx {
void AntiAliasingPainter::draw_anti_aliased_line(FloatPoint actual_from, FloatPoint actual_to, Color color, float thickness, LineStyle style, Color, LineLengthMode line_length_mode)
{
// FIXME: Implement this :P
VERIFY(style == LineStyle::Solid);
if (color.alpha() == 0)
return;
// FIMXE:
// This is not a proper line drawing algorithm.
// It's hack-ish AA rotated rectangle painting.
// There's probably more optimal ways to achieve this
// (though this still runs faster than the previous AA-line code)
//
// If you, reading this comment, know a better way that:
// 1. Does not overpaint (i.e. painting a line with transparency looks correct)
// 2. Has square end points (i.e. the line is a rectangle)
// 3. Has good anti-aliasing
// 4. Is less hacky than this
//
// Please delete this code and implement it!
int int_thickness = AK::ceil(thickness);
auto mapped_from = m_transform.map(actual_from);
auto mapped_to = m_transform.map(actual_to);
auto distance = mapped_to.distance_from(mapped_from);
auto length = distance + (line_length_mode == LineLengthMode::PointToPoint);
// Axis-aligned lines:
if (mapped_from.y() == mapped_to.y()) {
auto start_point = (mapped_from.x() < mapped_to.x() ? mapped_from : mapped_to).translated(0, -int_thickness / 2);
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, { thickness, length }), color);
}
// The painting only works for the positive XY quadrant (because that is easier).
// So flip things around until we're there:
bool flip_x = false;
bool flip_y = false;
if (mapped_to.x() < mapped_from.x() && mapped_to.y() < mapped_from.y())
swap(mapped_to, mapped_from);
if ((flip_x = mapped_to.x() < mapped_from.x()))
mapped_to.set_x(2 * mapped_from.x() - mapped_to.x());
if ((flip_y = mapped_to.y() < mapped_from.y()))
mapped_to.set_y(2 * mapped_from.y() - mapped_to.y());
auto delta = mapped_to - mapped_from;
auto line_angle_radians = AK::atan2(delta.y(), delta.x()) - 0.5f * AK::Pi<float>;
float sin_inverse_angle;
float cos_inverse_angle;
AK::sincos(-line_angle_radians, sin_inverse_angle, cos_inverse_angle);
auto inverse_rotate_point = [=](FloatPoint point) {
return Gfx::FloatPoint(
point.x() * cos_inverse_angle - point.y() * sin_inverse_angle,
point.y() * cos_inverse_angle + point.x() * sin_inverse_angle);
};
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) * thickness * thickness) / gradient);
auto x_gradient = 1 / gradient;
int x_step = floorf(x_gradient);
float x_error = 0;
float x_error_per_y = x_gradient - x_step;
auto y_offset = int_thickness + 1;
auto x_offset = int(x_gradient * y_offset);
int const line_start_x = mapped_from.x();
int const line_start_y = mapped_from.y();
int const line_end_x = mapped_to.x();
int const line_end_y = mapped_to.y();
auto set_pixel = [=, this](int x, int y, Gfx::Color color) {
// FIXME: The lines seem slightly off (<= 1px) when flipped.
if (flip_x)
x = 2 * line_start_x - x;
if (flip_y)
y = 2 * line_start_y - y;
m_underlying_painter.set_pixel(x, y, color, true);
};
// Scan a bit extra to avoid issues from the x_error:
int const overscan = max(x_step, 1) * 2 + 1;
int x = line_start_x - x_offset;
int const center_offset = (scan_line_length + 1) / 2;
for (int y = line_start_y - y_offset; y < line_end_y + y_offset; y += 1) {
for (int i = -overscan; i < scan_line_length + overscan; i++) {
int scan_x_pos = x + i - center_offset;
// Avoid scanning over pixels definitely outside the line:
int dx = (line_start_x - int_thickness) - (scan_x_pos + 1);
if (dx > 0) {
i += dx;
continue;
}
if (line_end_x + int_thickness <= scan_x_pos - 1)
break;
auto sample = inverse_rotate_point(Gfx::FloatPoint(scan_x_pos - line_start_x, y - line_start_y));
Gfx::FloatRect sample_px(sample * 255, Gfx::FloatSize(255, 255));
sample_px.intersect(line_rect);
auto alpha = (sample_px.width() * sample_px.height()) / 255.0f;
alpha = (alpha * color.alpha()) / 255;
set_pixel(scan_x_pos, y, color.with_alpha(alpha));
}
x += x_step;
x_error += x_error_per_y;
if (x_error > 1.0f) {
x_error -= 1.0f;
x += 1;
}
}
}
void AntiAliasingPainter::draw_dotted_line(IntPoint point1, IntPoint point2, Color color, int thickness)
{
// AA circles don't really work below a radius of 2px.
if (thickness < 4)
return m_underlying_painter.draw_line(point1, point2, color, thickness, LineStyle::Dotted);
auto draw_spaced_dots = [&](int start, int end, auto to_point) {
int step = thickness * 2;
if (start > end)
swap(start, end);
int delta = end - start;
int dots = delta / step;
if (dots == 0)
return;
int fudge_per_dot = 0;
int extra_fudge = 0;
if (dots > 3) {
// Fudge the numbers so the last dot is drawn at the `end' point (otherwise you can get lines cuts short).
// You need at least a handful of dots to do this.
int fudge = delta % step;
fudge_per_dot = fudge / dots;
extra_fudge = fudge % dots;
}
for (int dot = start; dot <= end; dot += (step + fudge_per_dot + (extra_fudge > 0))) {
fill_circle(to_point(dot), thickness / 2, color);
--extra_fudge;
}
};
if (point1.y() == point2.y()) {
draw_spaced_dots(point1.x(), point2.x(), [&](int dot_x) {
return IntPoint { dot_x, point1.y() };
});
} else if (point1.x() == point2.x()) {
draw_spaced_dots(point1.y(), point2.y(), [&](int dot_y) {
return IntPoint { point1.x(), dot_y };
});
} else {
TODO();
}
}
void AntiAliasingPainter::draw_line(IntPoint actual_from, IntPoint actual_to, Color color, float thickness, LineStyle style, Color alternate_color, LineLengthMode line_length_mode)
{
draw_line(actual_from.to_type<float>(), actual_to.to_type<float>(), color, thickness, style, alternate_color, line_length_mode);
}
void AntiAliasingPainter::draw_line(FloatPoint actual_from, FloatPoint actual_to, Color color, float thickness, LineStyle style, Color alternate_color, LineLengthMode line_length_mode)
{
if (style == LineStyle::Dotted)
return draw_dotted_line(actual_from.to_rounded<int>(), actual_to.to_rounded<int>(), color, static_cast<int>(round(thickness)));
draw_anti_aliased_line(actual_from, actual_to, color, thickness, style, alternate_color, line_length_mode);
}
void AntiAliasingPainter::stroke_path(Path const& path, Color color, Path::StrokeStyle const& stroke_style)
{
if (stroke_style.thickness <= 0)
return;
// FIXME: Cache this? Probably at a higher level such as in LibWeb?
fill_path(path.stroke_to_fill(stroke_style), color);
}
void AntiAliasingPainter::stroke_path(Path const& path, Gfx::PaintStyle const& paint_style, Path::StrokeStyle const& stroke_style, float opacity)
{
if (stroke_style.thickness <= 0)
return;
// FIXME: Cache this? Probably at a higher level such as in LibWeb?
fill_path(path.stroke_to_fill(stroke_style), paint_style, opacity);
}
void AntiAliasingPainter::fill_rect(FloatRect const& float_rect, Color color)
{
// Draw the integer part of the rectangle:
float right_x = float_rect.x() + float_rect.width();
float bottom_y = float_rect.y() + float_rect.height();
int x1 = ceilf(float_rect.x());
int y1 = ceilf(float_rect.y());
int x2 = floorf(right_x);
int y2 = floorf(bottom_y);
auto solid_rect = Gfx::IntRect::from_two_points({ x1, y1 }, { x2, y2 });
m_underlying_painter.fill_rect(solid_rect, color);
if (float_rect == solid_rect)
return;
// Draw the rest:
float left_subpixel = x1 - float_rect.x();
float top_subpixel = y1 - float_rect.y();
float right_subpixel = right_x - x2;
float bottom_subpixel = bottom_y - y2;
float top_left_subpixel = top_subpixel * left_subpixel;
float top_right_subpixel = top_subpixel * right_subpixel;
float bottom_left_subpixel = bottom_subpixel * left_subpixel;
float bottom_right_subpixel = bottom_subpixel * right_subpixel;
auto subpixel = [&](float alpha) {
return color.with_alpha(color.alpha() * alpha);
};
auto set_pixel = [&](int x, int y, float alpha) {
m_underlying_painter.set_pixel(x, y, subpixel(alpha), true);
};
auto line_to_rect = [&](int x1, int y1, int x2, int y2) {
return IntRect::from_two_points({ x1, y1 }, { x2 + 1, y2 + 1 });
};
set_pixel(x1 - 1, y1 - 1, top_left_subpixel);
set_pixel(x2, y1 - 1, top_right_subpixel);
set_pixel(x2, y2, bottom_right_subpixel);
set_pixel(x1 - 1, y2, bottom_left_subpixel);
m_underlying_painter.fill_rect(line_to_rect(x1, y1 - 1, x2 - 1, y1 - 1), subpixel(top_subpixel));
m_underlying_painter.fill_rect(line_to_rect(x1, y2, x2 - 1, y2), subpixel(bottom_subpixel));
m_underlying_painter.fill_rect(line_to_rect(x1 - 1, y1, x1 - 1, y2 - 1), subpixel(left_subpixel));
m_underlying_painter.fill_rect(line_to_rect(x2, y1, x2, y2 - 1), subpixel(right_subpixel));
}
void AntiAliasingPainter::draw_ellipse(IntRect const& a_rect, Color color, int thickness)
{
// FIXME: Come up with an allocation-free version of this!
// Using draw_line() for segments of an ellipse was attempted but gave really poor results :^(
// There probably is a way to adjust the fill of draw_ellipse_part() to do this, but getting it rendering correctly is tricky.
// The outline of the steps required to paint it efficiently is:
// - Paint the outer ellipse without the fill (from the fill() lambda in draw_ellipse_part())
// - Paint the inner ellipse, but in the set_pixel() invert the alpha values
// - Somehow fill in the gap between the two ellipses (the tricky part to get right)
// - Have to avoid overlapping pixels and accidentally painting over some of the edge pixels
auto color_no_alpha = color;
color_no_alpha.set_alpha(255);
auto outline_ellipse_bitmap = ({
auto bitmap = Bitmap::create(BitmapFormat::BGRA8888, a_rect.size());
if (bitmap.is_error())
return warnln("Failed to allocate temporary bitmap for antialiased outline ellipse!");
bitmap.release_value();
});
auto outer_rect = a_rect;
outer_rect.set_location({ 0, 0 });
auto inner_rect = outer_rect.shrunken(thickness * 2, thickness * 2);
Painter painter { outline_ellipse_bitmap };
AntiAliasingPainter aa_painter { painter };
aa_painter.fill_ellipse(outer_rect, color_no_alpha);
aa_painter.fill_ellipse(inner_rect, color_no_alpha, BlendMode::AlphaSubtract);
m_underlying_painter.blit(a_rect.location(), outline_ellipse_bitmap, outline_ellipse_bitmap->rect(), color.alpha() / 255.);
}
void AntiAliasingPainter::fill_circle(IntPoint center, int radius, Color color, BlendMode blend_mode)
{
if (radius <= 0)
return;
draw_ellipse_part(center, radius, radius, color, false, {}, blend_mode);
}
void AntiAliasingPainter::fill_ellipse(IntRect const& a_rect, Color color, BlendMode blend_mode)
{
auto center = a_rect.center();
auto radius_a = a_rect.width() / 2;
auto radius_b = a_rect.height() / 2;
if (radius_a <= 0 || radius_b <= 0)
return;
if (radius_a == radius_b)
return fill_circle(center, radius_a, color, blend_mode);
auto x_paint_range = draw_ellipse_part(center, radius_a, radius_b, color, false, {}, blend_mode);
// FIXME: This paints some extra fill pixels that are clipped
draw_ellipse_part(center, radius_b, radius_a, color, true, x_paint_range, blend_mode);
}
FLATTEN AntiAliasingPainter::Range AntiAliasingPainter::draw_ellipse_part(
IntPoint center, int radius_a, int radius_b, Color color, bool flip_x_and_y, Optional<Range> x_clip, BlendMode blend_mode)
{
/*
Algorithm from: https://cs.uwaterloo.ca/research/tr/1984/CS-84-38.pdf
This method can draw a whole circle with a whole circle in one call using
8-way symmetry, or an ellipse in two calls using 4-way symmetry.
*/
center *= m_underlying_painter.scale();
radius_a *= m_underlying_painter.scale();
radius_b *= m_underlying_painter.scale();
// If this is a ellipse everything can be drawn in one pass with 8 way symmetry
bool const is_circle = radius_a == radius_b;
// These happen to be the same here, but are treated separately in the paper:
// intensity is the fill alpha
int const intensity = 255;
// 0 to subpixel_resolution is the range of alpha values for the circle edges
int const subpixel_resolution = intensity;
// Current pixel address
int i = 0;
int q = radius_b;
// 1st and 2nd order differences of y
int delta_y = 0;
int delta2_y = 0;
int const a_squared = radius_a * radius_a;
int const b_squared = radius_b * radius_b;
// Exact and predicted values of f(i) -- the ellipse equation scaled by subpixel_resolution
int y = subpixel_resolution * radius_b;
int y_hat = 0;
// The value of f(i)*f(i)
int f_squared = y * y;
// 1st and 2nd order differences of f(i)*f(i)
int delta_f_squared = (static_cast<int64_t>(b_squared) * subpixel_resolution * subpixel_resolution) / a_squared;
int delta2_f_squared = -delta_f_squared - delta_f_squared;
// edge_intersection_area/subpixel_resolution = percentage of pixel intersected by circle
// (aka the alpha for the pixel)
int edge_intersection_area = 0;
int old_area = edge_intersection_area;
auto predict = [&] {
delta_y += delta2_y;
// y_hat is the predicted value of f(i)
y_hat = y + delta_y;
};
auto minimize = [&] {
// Initialize the minimization
delta_f_squared += delta2_f_squared;
f_squared += delta_f_squared;
int min_squared_error = y_hat * y_hat - f_squared;
int prediction_overshot = 1;
y = y_hat;
// Force error negative
if (min_squared_error > 0) {
min_squared_error = -min_squared_error;
prediction_overshot = -1;
}
// Minimize
int previous_error = min_squared_error;
while (min_squared_error < 0) {
y += prediction_overshot;
previous_error = min_squared_error;
min_squared_error += y + y - prediction_overshot;
}
if (min_squared_error + previous_error > 0)
y -= prediction_overshot;
};
auto correct = [&] {
int error = y - y_hat;
delta2_y += error;
delta_y += error;
};
int min_paint_x = NumericLimits<int>::max();
int max_paint_x = NumericLimits<int>::min();
auto pixel = [&](int x, int y, int alpha) {
if (alpha <= 0 || alpha > 255)
return;
if (flip_x_and_y)
swap(x, y);
if (x_clip.has_value() && x_clip->contains_inclusive(x))
return;
min_paint_x = min(x, min_paint_x);
max_paint_x = max(x, max_paint_x);
alpha = (alpha * color.alpha()) / 255;
if (blend_mode == BlendMode::AlphaSubtract)
alpha = ~alpha;
auto pixel_color = color;
pixel_color.set_alpha(alpha);
m_underlying_painter.set_pixel(center + IntPoint { x, y }, pixel_color, blend_mode == BlendMode::Normal);
};
auto fill = [&](int x, int ymax, int ymin, int alpha) {
while (ymin <= ymax) {
pixel(x, ymin, alpha);
ymin += 1;
}
};
auto symmetric_pixel = [&](int x, int y, int alpha) {
pixel(x, y, alpha);
pixel(x, -y - 1, alpha);
pixel(-x - 1, -y - 1, alpha);
pixel(-x - 1, y, alpha);
if (is_circle) {
pixel(y, x, alpha);
pixel(y, -x - 1, alpha);
pixel(-y - 1, -x - 1, alpha);
pixel(-y - 1, x, alpha);
}
};
// These are calculated incrementally (as it is possibly a tiny bit faster)
int ib_squared = 0;
int qa_squared = q * a_squared;
auto in_symmetric_region = [&] {
// Main fix two stop cond here
return is_circle ? i < q : ib_squared < qa_squared;
};
// Draws a 8 octants for a circle or 4 quadrants for a (partial) ellipse
while (in_symmetric_region()) {
predict();
minimize();
correct();
old_area = edge_intersection_area;
edge_intersection_area += delta_y;
if (edge_intersection_area >= 0) {
// Single pixel on perimeter
symmetric_pixel(i, q, (edge_intersection_area + old_area) / 2);
fill(i, q - 1, -q, intensity);
fill(-i - 1, q - 1, -q, intensity);
} else {
// Two pixels on perimeter
edge_intersection_area += subpixel_resolution;
symmetric_pixel(i, q, old_area / 2);
q -= 1;
qa_squared -= a_squared;
fill(i, q - 1, -q, intensity);
fill(-i - 1, q - 1, -q, intensity);
if (!is_circle || in_symmetric_region()) {
symmetric_pixel(i, q, (edge_intersection_area + subpixel_resolution) / 2);
if (is_circle) {
fill(q, i - 1, -i, intensity);
fill(-q - 1, i - 1, -i, intensity);
}
} else {
edge_intersection_area += subpixel_resolution;
}
}
i += 1;
ib_squared += b_squared;
}
if (is_circle) {
int alpha = edge_intersection_area / 2;
pixel(q, q, alpha);
pixel(-q - 1, q, alpha);
pixel(-q - 1, -q - 1, alpha);
pixel(q, -q - 1, alpha);
}
return Range { min_paint_x, max_paint_x };
}
void AntiAliasingPainter::fill_rect_with_rounded_corners(IntRect const& a_rect, Color color, int radius)
{
fill_rect_with_rounded_corners(a_rect, color, radius, radius, radius, radius);
}
void AntiAliasingPainter::fill_rect_with_rounded_corners(IntRect const& a_rect, Color color, int top_left_radius, int top_right_radius, int bottom_right_radius, int bottom_left_radius)
{
fill_rect_with_rounded_corners(a_rect, color,
{ top_left_radius, top_left_radius },
{ top_right_radius, top_right_radius },
{ bottom_right_radius, bottom_right_radius },
{ bottom_left_radius, bottom_left_radius });
}
void AntiAliasingPainter::fill_rect_with_rounded_corners(IntRect const& a_rect, Color color, CornerRadius top_left, CornerRadius top_right, CornerRadius bottom_right, CornerRadius bottom_left, BlendMode blend_mode)
{
if (!top_left && !top_right && !bottom_right && !bottom_left) {
if (blend_mode == BlendMode::Normal)
return m_underlying_painter.fill_rect(a_rect, color);
else if (blend_mode == BlendMode::AlphaSubtract)
return m_underlying_painter.clear_rect(a_rect, Color());
}
if (color.alpha() == 0)
return;
IntPoint top_left_corner {
a_rect.x() + top_left.horizontal_radius,
a_rect.y() + top_left.vertical_radius,
};
IntPoint top_right_corner {
a_rect.x() + a_rect.width() - top_right.horizontal_radius,
a_rect.y() + top_right.vertical_radius,
};
IntPoint bottom_left_corner {
a_rect.x() + bottom_left.horizontal_radius,
a_rect.y() + a_rect.height() - bottom_left.vertical_radius
};
IntPoint bottom_right_corner {
a_rect.x() + a_rect.width() - bottom_right.horizontal_radius,
a_rect.y() + a_rect.height() - bottom_right.vertical_radius
};
// All corners are centered at the same point, so this can be painted as a single ellipse.
if (top_left_corner == top_right_corner && top_right_corner == bottom_left_corner && bottom_left_corner == bottom_right_corner)
return fill_ellipse(a_rect, color, blend_mode);
IntRect top_rect {
a_rect.x() + top_left.horizontal_radius,
a_rect.y(),
a_rect.width() - top_left.horizontal_radius - top_right.horizontal_radius,
top_left.vertical_radius
};
IntRect right_rect {
a_rect.x() + a_rect.width() - top_right.horizontal_radius,
a_rect.y() + top_right.vertical_radius,
top_right.horizontal_radius,
a_rect.height() - top_right.vertical_radius - bottom_right.vertical_radius
};
IntRect bottom_rect {
a_rect.x() + bottom_left.horizontal_radius,
a_rect.y() + a_rect.height() - bottom_right.vertical_radius,
a_rect.width() - bottom_left.horizontal_radius - bottom_right.horizontal_radius,
bottom_right.vertical_radius
};
IntRect left_rect {
a_rect.x(),
a_rect.y() + top_left.vertical_radius,
bottom_left.horizontal_radius,
a_rect.height() - top_left.vertical_radius - bottom_left.vertical_radius
};
IntRect inner = {
left_rect.x() + left_rect.width(),
left_rect.y(),
a_rect.width() - left_rect.width() - right_rect.width(),
a_rect.height() - top_rect.height() - bottom_rect.height()
};
if (blend_mode == BlendMode::Normal) {
m_underlying_painter.fill_rect(top_rect, color);
m_underlying_painter.fill_rect(right_rect, color);
m_underlying_painter.fill_rect(bottom_rect, color);
m_underlying_painter.fill_rect(left_rect, color);
m_underlying_painter.fill_rect(inner, color);
} else if (blend_mode == BlendMode::AlphaSubtract) {
m_underlying_painter.clear_rect(top_rect, Color());
m_underlying_painter.clear_rect(right_rect, Color());
m_underlying_painter.clear_rect(bottom_rect, Color());
m_underlying_painter.clear_rect(left_rect, Color());
m_underlying_painter.clear_rect(inner, Color());
}
auto fill_corner = [&](auto const& ellipse_center, auto const& corner_point, CornerRadius const& corner) {
PainterStateSaver save { m_underlying_painter };
m_underlying_painter.add_clip_rect(IntRect::from_two_points(ellipse_center, corner_point));
fill_ellipse(IntRect::centered_on(ellipse_center, { corner.horizontal_radius * 2, corner.vertical_radius * 2 }), color, blend_mode);
};
auto bounding_rect = a_rect.inflated(0, 1, 1, 0);
if (top_left)
fill_corner(top_left_corner, bounding_rect.top_left(), top_left);
if (top_right)
fill_corner(top_right_corner, bounding_rect.top_right().moved_left(1), top_right);
if (bottom_left)
fill_corner(bottom_left_corner, bounding_rect.bottom_left().moved_up(1), bottom_left);
if (bottom_right)
fill_corner(bottom_right_corner, bounding_rect.bottom_right().translated(-1), bottom_right);
}
}
