ladybird/Libraries/LibGfx/PainterSkia.cpp
Lucien Fiorini 26970201bd LibGfx: Fix color opacity regression in Canvas2D
The color alpha was being overwritten by the global alpha instead of
being multiplied.
2024-12-19 13:31:12 +01:00

254 lines
8.5 KiB
C++

/*
* Copyright (c) 2024, Andreas Kling <andreas@ladybird.org>
* Copyright (c) 2024, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
* Copyright (c) 2024, Lucien Fiorini <lucienfiorini@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#define AK_DONT_REPLACE_STD
#include <AK/OwnPtr.h>
#include <LibGfx/Filter.h>
#include <LibGfx/ImmutableBitmap.h>
#include <LibGfx/PainterSkia.h>
#include <LibGfx/PathSkia.h>
#include <LibGfx/SkiaUtils.h>
#include <AK/TypeCasts.h>
#include <core/SkCanvas.h>
#include <core/SkPath.h>
#include <effects/SkBlurMaskFilter.h>
#include <effects/SkGradientShader.h>
namespace Gfx {
struct PainterSkia::Impl {
RefPtr<Gfx::PaintingSurface> painting_surface;
Impl(Gfx::PaintingSurface& surface)
: painting_surface(surface)
{
}
SkCanvas* canvas() const
{
return &painting_surface->canvas();
}
};
static void apply_paint_style(SkPaint& paint, Gfx::PaintStyle const& style)
{
if (is<Gfx::SolidColorPaintStyle>(style)) {
auto const& solid_color = static_cast<Gfx::SolidColorPaintStyle const&>(style);
auto color = solid_color.sample_color(Gfx::IntPoint(0, 0));
paint.setColor(to_skia_color(color));
} else if (is<Gfx::CanvasLinearGradientPaintStyle>(style)) {
auto const& linear_gradient = static_cast<Gfx::CanvasLinearGradientPaintStyle const&>(style);
auto const& color_stops = linear_gradient.color_stops();
Vector<SkColor> colors;
colors.ensure_capacity(color_stops.size());
Vector<SkScalar> positions;
positions.ensure_capacity(color_stops.size());
for (auto const& color_stop : color_stops) {
colors.append(to_skia_color(color_stop.color));
positions.append(color_stop.position);
}
Array<SkPoint, 2> points;
points[0] = to_skia_point(linear_gradient.start_point());
points[1] = to_skia_point(linear_gradient.end_point());
SkMatrix matrix;
auto shader = SkGradientShader::MakeLinear(points.data(), colors.data(), positions.data(), color_stops.size(), SkTileMode::kClamp, 0, &matrix);
paint.setShader(shader);
} else if (is<Gfx::CanvasRadialGradientPaintStyle>(style)) {
auto const& radial_gradient = static_cast<Gfx::CanvasRadialGradientPaintStyle const&>(style);
auto const& color_stops = radial_gradient.color_stops();
Vector<SkColor> colors;
colors.ensure_capacity(color_stops.size());
Vector<SkScalar> positions;
positions.ensure_capacity(color_stops.size());
for (auto const& color_stop : color_stops) {
colors.append(to_skia_color(color_stop.color));
positions.append(color_stop.position);
}
auto start_center = radial_gradient.start_center();
auto end_center = radial_gradient.end_center();
auto start_radius = radial_gradient.start_radius();
auto end_radius = radial_gradient.end_radius();
auto start_sk_point = to_skia_point(start_center);
auto end_sk_point = to_skia_point(end_center);
SkMatrix matrix;
auto shader = SkGradientShader::MakeTwoPointConical(start_sk_point, start_radius, end_sk_point, end_radius, colors.data(), positions.data(), color_stops.size(), SkTileMode::kClamp, 0, &matrix);
paint.setShader(shader);
}
}
static void apply_filters(SkPaint& paint, ReadonlySpan<Gfx::Filter> filters)
{
for (auto const& filter : filters) {
paint.setImageFilter(to_skia_image_filter(filter));
}
}
static SkPaint to_skia_paint(Gfx::PaintStyle const& style, ReadonlySpan<Gfx::Filter> filters)
{
SkPaint paint;
apply_paint_style(paint, style);
apply_filters(paint, filters);
return paint;
}
PainterSkia::PainterSkia(NonnullRefPtr<Gfx::PaintingSurface> painting_surface)
: m_impl(adopt_own(*new Impl { move(painting_surface) }))
{
}
PainterSkia::~PainterSkia() = default;
void PainterSkia::clear_rect(Gfx::FloatRect const& rect, Gfx::Color color)
{
SkPaint paint;
paint.setColor(to_skia_color(color));
paint.setBlendMode(SkBlendMode::kClear);
impl().canvas()->drawRect(to_skia_rect(rect), paint);
}
void PainterSkia::fill_rect(Gfx::FloatRect const& rect, Color color)
{
SkPaint paint;
paint.setColor(to_skia_color(color));
impl().canvas()->drawRect(to_skia_rect(rect), paint);
}
void PainterSkia::draw_bitmap(Gfx::FloatRect const& dst_rect, Gfx::ImmutableBitmap const& src_bitmap, Gfx::IntRect const& src_rect, Gfx::ScalingMode scaling_mode, ReadonlySpan<Gfx::Filter> filters, float global_alpha)
{
SkPaint paint;
apply_filters(paint, filters);
paint.setAlpha(static_cast<u8>(global_alpha * 255));
impl().canvas()->drawImageRect(
src_bitmap.sk_image(),
to_skia_rect(src_rect),
to_skia_rect(dst_rect),
to_skia_sampling_options(scaling_mode),
&paint,
SkCanvas::kStrict_SrcRectConstraint);
}
void PainterSkia::set_transform(Gfx::AffineTransform const& transform)
{
auto matrix = SkMatrix::MakeAll(
transform.a(), transform.c(), transform.e(),
transform.b(), transform.d(), transform.f(),
0, 0, 1);
impl().canvas()->setMatrix(matrix);
}
void PainterSkia::stroke_path(Gfx::Path const& path, Gfx::Color color, float thickness)
{
// Skia treats zero thickness as a special case and will draw a hairline, while we want to draw nothing.
if (thickness <= 0)
return;
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(thickness);
paint.setColor(to_skia_color(color));
auto sk_path = to_skia_path(path);
impl().canvas()->drawPath(sk_path, paint);
}
void PainterSkia::stroke_path(Gfx::Path const& path, Gfx::Color color, float thickness, float blur_radius)
{
// Skia treats zero thickness as a special case and will draw a hairline, while we want to draw nothing.
if (thickness <= 0)
return;
SkPaint paint;
paint.setAntiAlias(true);
paint.setMaskFilter(SkMaskFilter::MakeBlur(kNormal_SkBlurStyle, blur_radius / 2));
paint.setStyle(SkPaint::kStroke_Style);
paint.setStrokeWidth(thickness);
paint.setColor(to_skia_color(color));
auto sk_path = to_skia_path(path);
impl().canvas()->drawPath(sk_path, paint);
}
void PainterSkia::stroke_path(Gfx::Path const& path, Gfx::PaintStyle const& paint_style, ReadonlySpan<Gfx::Filter> filters, float thickness, float global_alpha)
{
// Skia treats zero thickness as a special case and will draw a hairline, while we want to draw nothing.
if (thickness <= 0)
return;
auto sk_path = to_skia_path(path);
auto paint = to_skia_paint(paint_style, filters);
paint.setAntiAlias(true);
float alpha = paint.getAlphaf();
paint.setAlphaf(alpha * global_alpha);
paint.setStyle(SkPaint::Style::kStroke_Style);
paint.setStrokeWidth(thickness);
impl().canvas()->drawPath(sk_path, paint);
}
void PainterSkia::fill_path(Gfx::Path const& path, Gfx::Color color, Gfx::WindingRule winding_rule)
{
SkPaint paint;
paint.setAntiAlias(true);
paint.setColor(to_skia_color(color));
auto sk_path = to_skia_path(path);
sk_path.setFillType(to_skia_path_fill_type(winding_rule));
impl().canvas()->drawPath(sk_path, paint);
}
void PainterSkia::fill_path(Gfx::Path const& path, Gfx::Color color, Gfx::WindingRule winding_rule, float blur_radius)
{
SkPaint paint;
paint.setAntiAlias(true);
paint.setMaskFilter(SkMaskFilter::MakeBlur(kNormal_SkBlurStyle, blur_radius / 2));
paint.setColor(to_skia_color(color));
auto sk_path = to_skia_path(path);
sk_path.setFillType(to_skia_path_fill_type(winding_rule));
impl().canvas()->drawPath(sk_path, paint);
}
void PainterSkia::fill_path(Gfx::Path const& path, Gfx::PaintStyle const& paint_style, ReadonlySpan<Gfx::Filter> filters, float global_alpha, Gfx::WindingRule winding_rule)
{
auto sk_path = to_skia_path(path);
sk_path.setFillType(to_skia_path_fill_type(winding_rule));
auto paint = to_skia_paint(paint_style, filters);
paint.setAntiAlias(true);
float alpha = paint.getAlphaf();
paint.setAlphaf(alpha * global_alpha);
impl().canvas()->drawPath(sk_path, paint);
}
void PainterSkia::save()
{
impl().canvas()->save();
}
void PainterSkia::restore()
{
impl().canvas()->restore();
}
void PainterSkia::clip(Gfx::Path const& path, Gfx::WindingRule winding_rule)
{
auto sk_path = to_skia_path(path);
sk_path.setFillType(to_skia_path_fill_type(winding_rule));
impl().canvas()->clipPath(sk_path, SkClipOp::kIntersect, true);
}
}