/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
* Copyright (c) 2022, MacDue <macdue@dueutil.tech>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibGfx/AntiAliasingPainter.h>
#include <LibGfx/Font/ScaledFont.h>
#include <LibWeb/Layout/Node.h>
#include <LibWeb/Layout/Viewport.h>
#include <LibWeb/Painting/BackgroundPainting.h>
#include <LibWeb/Painting/InlinePaintable.h>
#include <LibWeb/Painting/PaintableBox.h>
namespace Web::Painting {
// https://drafts.csswg.org/css-images/#default-sizing
static CSSPixelSize run_default_sizing_algorithm(
Optional<CSSPixels> specified_width, Optional<CSSPixels> specified_height,
Optional<CSSPixels> natural_width, Optional<CSSPixels> natural_height,
Optional<CSSPixelFraction> natural_aspect_ratio,
CSSPixelSize default_size)
{
// If the specified size is a definite width and height, the concrete object size is given that width and height.
if (specified_width.has_value() && specified_height.has_value())
return CSSPixelSize { specified_width.value(), specified_height.value() };
// If the specified size is only a width or height (but not both) then the concrete object size is given that specified width or height.
// The other dimension is calculated as follows:
if (specified_width.has_value() || specified_height.has_value()) {
// 1. If the object has a natural aspect ratio,
// the missing dimension of the concrete object size is calculated using that aspect ratio and the present dimension.
if (natural_aspect_ratio.has_value() && !natural_aspect_ratio->might_be_saturated()) {
if (specified_width.has_value())
return CSSPixelSize { specified_width.value(), (CSSPixels(1) / natural_aspect_ratio.value()) * specified_width.value() };
if (specified_height.has_value())
return CSSPixelSize { specified_height.value() * natural_aspect_ratio.value(), specified_height.value() };
}
// 2. Otherwise, if the missing dimension is present in the object’s natural dimensions,
// the missing dimension is taken from the object’s natural dimensions.
if (specified_height.has_value() && natural_width.has_value())
return CSSPixelSize { natural_width.value(), specified_height.value() };
if (specified_width.has_value() && natural_height.has_value())
return CSSPixelSize { specified_width.value(), natural_height.value() };
// 3. Otherwise, the missing dimension of the concrete object size is taken from the default object size.
if (specified_height.has_value())
return CSSPixelSize { default_size.width(), specified_height.value() };
if (specified_width.has_value())
return CSSPixelSize { specified_width.value(), default_size.height() };
VERIFY_NOT_REACHED();
}
// If the specified size has no constraints:
// 1. If the object has a natural height or width, its size is resolved as if its natural dimensions were given as the specified size.
if (natural_width.has_value() || natural_height.has_value())
return run_default_sizing_algorithm(natural_width, natural_height, natural_width, natural_height, natural_aspect_ratio, default_size);
// FIXME: 2. Otherwise, its size is resolved as a contain constraint against the default object size.
return default_size;
}
static Vector<Gfx::Path> compute_text_clip_paths(PaintContext& context, Paintable const& paintable)
{
Vector<Gfx::Path> text_clip_paths;
auto add_text_clip_path = [&](PaintableFragment const& fragment) {
auto glyph_run = fragment.glyph_run();
if (!glyph_run || glyph_run->glyphs().is_empty())
return;
// Scale to the device pixels.
Gfx::Path glyph_run_path;
auto const& font = fragment.glyph_run()->font();
auto resized_font = font.with_size(font.point_size() * static_cast<float>(context.device_pixels_per_css_pixel()));
auto const* scaled_font = static_cast<Gfx::ScaledFont const*>(resized_font.ptr());
for (auto glyph : fragment.glyph_run()->glyphs()) {
glyph.visit([&](auto& glyph) {
glyph.position = glyph.position.scaled(context.device_pixels_per_css_pixel());
});
if (glyph.has<Gfx::DrawGlyph>()) {
auto const& draw_glyph = glyph.get<Gfx::DrawGlyph>();
// Get the path for the glyph.
Gfx::Path glyph_path;
auto glyph_id = scaled_font->glyph_id_for_code_point(draw_glyph.code_point);
scaled_font->append_glyph_path_to(glyph_path, glyph_id);
// Transform the path to the fragment's position.
// FIXME: Record glyphs and use Painter::draw_glyphs() instead to avoid this duplicated code.
auto top_left = draw_glyph.position + Gfx::FloatPoint(scaled_font->glyph_left_bearing(draw_glyph.code_point), 0);
auto glyph_position = Gfx::GlyphRasterPosition::get_nearest_fit_for(top_left);
auto transform = Gfx::AffineTransform {}.translate(glyph_position.blit_position.to_type<float>());
glyph_run_path.append_path(glyph_path.copy_transformed(transform));
}
}
// Calculate the baseline start position.
auto fragment_absolute_rect = fragment.absolute_rect();
auto fragment_absolute_device_rect = context.enclosing_device_rect(fragment_absolute_rect);
DevicePixelPoint baseline_start { fragment_absolute_device_rect.x(), fragment_absolute_device_rect.y() + context.rounded_device_pixels(fragment.baseline()) };
// Add the path to text_clip_paths.
auto transform = Gfx::AffineTransform {}.translate(baseline_start.to_type<int>().to_type<float>());
text_clip_paths.append(glyph_run_path.copy_transformed(transform));
};
paintable.for_each_in_inclusive_subtree([&](auto& paintable) {
if (is<PaintableWithLines>(paintable)) {
auto const& paintable_lines = static_cast<PaintableWithLines const&>(paintable);
for (auto const& fragment : paintable_lines.fragments()) {
if (is<Layout::TextNode>(fragment.layout_node()))
add_text_clip_path(fragment);
}
} else if (is<InlinePaintable>(paintable)) {
auto const& inline_paintable = static_cast<InlinePaintable const&>(paintable);
for (auto const& fragment : inline_paintable.fragments()) {
if (is<Layout::TextNode>(fragment.layout_node()))
add_text_clip_path(fragment);
}
}
return TraversalDecision::Continue;
});
return text_clip_paths;
}
// https://www.w3.org/TR/css-backgrounds-3/#backgrounds
void paint_background(PaintContext& context, Layout::NodeWithStyleAndBoxModelMetrics const& layout_node, CSSPixelRect const& border_rect, Color background_color, CSS::ImageRendering image_rendering, Vector<CSS::BackgroundLayerData> const* background_layers, BorderRadiiData const& border_radii)
{
Vector<Gfx::Path> clip_paths {};
if (background_layers && !background_layers->is_empty() && background_layers->last().clip == CSS::BackgroundBox::Text) {
clip_paths = compute_text_clip_paths(context, *layout_node.paintable());
}
auto& display_list_recorder = context.display_list_recorder();
struct BackgroundBox {
CSSPixelRect rect;
BorderRadiiData radii;
inline void shrink(CSSPixels top, CSSPixels right, CSSPixels bottom, CSSPixels left)
{
rect.shrink(top, right, bottom, left);
radii.shrink(top, right, bottom, left);
}
};
BackgroundBox border_box {
border_rect,
border_radii
};
auto get_box = [&](CSS::BackgroundBox box_clip) {
auto box = border_box;
switch (box_clip) {
case CSS::BackgroundBox::ContentBox: {
auto& padding = layout_node.box_model().padding;
box.shrink(padding.top, padding.right, padding.bottom, padding.left);
[[fallthrough]];
}
case CSS::BackgroundBox::PaddingBox: {
auto& border = layout_node.box_model().border;
box.shrink(border.top, border.right, border.bottom, border.left);
[[fallthrough]];
}
case CSS::BackgroundBox::BorderBox:
default:
return box;
}
};
auto color_box = border_box;
if (background_layers && !background_layers->is_empty())
color_box = get_box(background_layers->last().clip);
auto layer_is_paintable = [&](auto& layer) {
return layer.background_image && layer.background_image->is_paintable();
};
bool has_paintable_layers = false;
if (background_layers) {
for (auto& layer : *background_layers) {
if (layer_is_paintable(layer)) {
has_paintable_layers = true;
break;
}
}
}
display_list_recorder.fill_rect_with_rounded_corners(
context.rounded_device_rect(color_box.rect).to_type<int>(),
background_color,
color_box.radii.top_left.as_corner(context),
color_box.radii.top_right.as_corner(context),
color_box.radii.bottom_right.as_corner(context),
color_box.radii.bottom_left.as_corner(context),
clip_paths);
if (!has_paintable_layers)
return;
struct {
DevicePixels top { 0 };
DevicePixels bottom { 0 };
DevicePixels left { 0 };
DevicePixels right { 0 };
} clip_shrink;
auto border_top = layout_node.computed_values().border_top();
auto border_bottom = layout_node.computed_values().border_bottom();
auto border_left = layout_node.computed_values().border_left();
auto border_right = layout_node.computed_values().border_right();
if (border_top.color.alpha() == 255 && border_bottom.color.alpha() == 255
&& border_left.color.alpha() == 255 && border_right.color.alpha() == 255) {
clip_shrink.top = context.rounded_device_pixels(border_top.width);
clip_shrink.bottom = context.rounded_device_pixels(border_bottom.width);
clip_shrink.left = context.rounded_device_pixels(border_left.width);
clip_shrink.right = context.rounded_device_pixels(border_right.width);
}
// Note: Background layers are ordered front-to-back, so we paint them in reverse
for (auto& layer : background_layers->in_reverse()) {
if (!layer_is_paintable(layer))
continue;
DisplayListRecorderStateSaver state { display_list_recorder };
// Clip
auto clip_box = get_box(layer.clip);
CSSPixelRect const& css_clip_rect = clip_box.rect;
auto clip_rect = context.rounded_device_rect(css_clip_rect);
display_list_recorder.add_clip_rect(clip_rect.to_type<int>());
ScopedCornerRadiusClip corner_clip { context, clip_rect, clip_box.radii };
if (layer.clip == CSS::BackgroundBox::BorderBox) {
// Shrink the effective clip rect if to account for the bits the borders will definitely paint over
// (if they all have alpha == 255).
clip_rect.shrink(clip_shrink.top, clip_shrink.right, clip_shrink.bottom, clip_shrink.left);
}
auto& image = *layer.background_image;
CSSPixelRect background_positioning_area;
// Attachment and Origin
switch (layer.attachment) {
case CSS::BackgroundAttachment::Fixed:
background_positioning_area = layout_node.root().navigable()->viewport_rect();
break;
case CSS::BackgroundAttachment::Local:
background_positioning_area = get_box(layer.origin).rect;
if (is<Layout::Box>(layout_node)) {
auto* paintable_box = static_cast<Layout::Box const&>(layout_node).paintable_box();
if (paintable_box && !paintable_box->is_viewport()) {
auto scroll_offset = paintable_box->scroll_offset();
background_positioning_area.translate_by(-scroll_offset.x(), -scroll_offset.y());
}
}
break;
case CSS::BackgroundAttachment::Scroll:
background_positioning_area = get_box(layer.origin).rect;
break;
}
Optional<CSSPixels> specified_width {};
Optional<CSSPixels> specified_height {};
if (layer.size_type == CSS::BackgroundSize::LengthPercentage) {
if (!layer.size_x.is_auto())
specified_width = layer.size_x.to_px(layout_node, background_positioning_area.width());
if (!layer.size_y.is_auto())
specified_height = layer.size_y.to_px(layout_node, background_positioning_area.height());
}
auto concrete_image_size = run_default_sizing_algorithm(
specified_width, specified_height,
image.natural_width(), image.natural_height(), image.natural_aspect_ratio(),
background_positioning_area.size());
// If any of these are zero, the NaNs will pop up in the painting code.
if (background_positioning_area.is_empty() || concrete_image_size.is_empty())
continue;
// Size
CSSPixelRect image_rect;
switch (layer.size_type) {
case CSS::BackgroundSize::Contain: {
double max_width_ratio = background_positioning_area.width().to_double() / concrete_image_size.width().to_double();
double max_height_ratio = background_positioning_area.height().to_double() / concrete_image_size.height().to_double();
double ratio = min(max_width_ratio, max_height_ratio);
image_rect.set_size(concrete_image_size.width().scaled(ratio), concrete_image_size.height().scaled(ratio));
break;
}
case CSS::BackgroundSize::Cover: {
double max_width_ratio = background_positioning_area.width().to_double() / concrete_image_size.width().to_double();
double max_height_ratio = background_positioning_area.height().to_double() / concrete_image_size.height().to_double();
double ratio = max(max_width_ratio, max_height_ratio);
image_rect.set_size(concrete_image_size.width().scaled(ratio), concrete_image_size.height().scaled(ratio));
break;
}
case CSS::BackgroundSize::LengthPercentage:
image_rect.set_size(concrete_image_size);
break;
}
// If after sizing we have a 0px image, we're done. Attempting to paint this would be an infinite loop.
if (image_rect.is_empty())
continue;
// If background-repeat is round for one (or both) dimensions, there is a second step.
// The UA must scale the image in that dimension (or both dimensions) so that it fits a
// whole number of times in the background positioning area.
if (layer.repeat_x == CSS::Repeat::Round || layer.repeat_y == CSS::Repeat::Round) {
// If X ≠ 0 is the width of the image after step one and W is the width of the
// background positioning area, then the rounded width X' = W / round(W / X)
// where round() is a function that returns the nearest natural number
// (integer greater than zero).
if (layer.repeat_x == CSS::Repeat::Round) {
image_rect.set_width(background_positioning_area.width() / round(background_positioning_area.width() / image_rect.width()));
}
if (layer.repeat_y == CSS::Repeat::Round) {
image_rect.set_height(background_positioning_area.height() / round(background_positioning_area.height() / image_rect.height()));
}
// If background-repeat is round for one dimension only and if background-size is auto
// for the other dimension, then there is a third step: that other dimension is scaled
// so that the original aspect ratio is restored.
if (layer.repeat_x != layer.repeat_y) {
if (layer.size_x.is_auto()) {
image_rect.set_width(image_rect.height() * (concrete_image_size.width() / concrete_image_size.height()));
}
if (layer.size_y.is_auto()) {
image_rect.set_height(image_rect.width() * (concrete_image_size.height() / concrete_image_size.width()));
}
}
}
CSSPixels space_x = background_positioning_area.width() - image_rect.width();
CSSPixels space_y = background_positioning_area.height() - image_rect.height();
// Position
CSSPixels offset_x = layer.position_offset_x.to_px(layout_node, space_x);
if (layer.position_edge_x == CSS::PositionEdge::Right) {
image_rect.set_right_without_resize(background_positioning_area.right() - offset_x);
} else {
image_rect.set_left(background_positioning_area.left() + offset_x);
}
CSSPixels offset_y = layer.position_offset_y.to_px(layout_node, space_y);
if (layer.position_edge_y == CSS::PositionEdge::Bottom) {
image_rect.set_bottom_without_resize(background_positioning_area.bottom() - offset_y);
} else {
image_rect.set_top(background_positioning_area.top() + offset_y);
}
// Repetition
bool repeat_x = false;
bool repeat_y = false;
CSSPixels x_step = 0;
CSSPixels y_step = 0;
switch (layer.repeat_x) {
case CSS::Repeat::Round:
x_step = image_rect.width();
repeat_x = true;
break;
case CSS::Repeat::Space: {
int whole_images = (background_positioning_area.width() / image_rect.width()).to_int();
if (whole_images <= 1) {
x_step = image_rect.width();
repeat_x = false;
} else {
auto space = fmod(background_positioning_area.width().to_double(), image_rect.width().to_double());
x_step = image_rect.width() + CSSPixels::nearest_value_for(space / static_cast<double>(whole_images - 1));
repeat_x = true;
}
break;
}
case CSS::Repeat::Repeat:
x_step = image_rect.width();
repeat_x = true;
break;
case CSS::Repeat::NoRepeat:
repeat_x = false;
break;
}
// Move image_rect to the left-most tile position that is still visible
if (repeat_x && image_rect.x() > css_clip_rect.x()) {
auto x_delta = floor(x_step * ceil((image_rect.x() - css_clip_rect.x()) / x_step));
image_rect.set_x(image_rect.x() - x_delta);
}
switch (layer.repeat_y) {
case CSS::Repeat::Round:
y_step = image_rect.height();
repeat_y = true;
break;
case CSS::Repeat::Space: {
int whole_images = (background_positioning_area.height() / image_rect.height()).to_int();
if (whole_images <= 1) {
y_step = image_rect.height();
repeat_y = false;
} else {
auto space = fmod(background_positioning_area.height().to_float(), image_rect.height().to_float());
y_step = image_rect.height() + CSSPixels::nearest_value_for(static_cast<double>(space) / static_cast<double>(whole_images - 1));
repeat_y = true;
}
break;
}
case CSS::Repeat::Repeat:
y_step = image_rect.height();
repeat_y = true;
break;
case CSS::Repeat::NoRepeat:
repeat_y = false;
break;
}
// Move image_rect to the top-most tile position that is still visible
if (repeat_y && image_rect.y() > css_clip_rect.y()) {
auto y_delta = floor(y_step * ceil((image_rect.y() - css_clip_rect.y()) / y_step));
image_rect.set_y(image_rect.y() - y_delta);
}
CSSPixels initial_image_x = image_rect.x();
CSSPixels image_y = image_rect.y();
image.resolve_for_size(layout_node, image_rect.size());
auto for_each_image_device_rect = [&](auto callback) {
while (image_y < css_clip_rect.bottom()) {
image_rect.set_y(image_y);
auto image_x = initial_image_x;
while (image_x < css_clip_rect.right()) {
image_rect.set_x(image_x);
auto image_device_rect = context.rounded_device_rect(image_rect);
callback(image_device_rect);
if (!repeat_x)
break;
image_x += x_step;
}
if (!repeat_y)
break;
image_y += y_step;
}
};
if (auto color = image.color_if_single_pixel_bitmap(); color.has_value()) {
// OPTIMIZATION: If the image is a single pixel, we can just fill the whole area with it.
// However, we must first figure out the real coverage area, taking repeat etc into account.
// FIXME: This could be written in a far more efficient way.
auto fill_rect = Optional<DevicePixelRect> {};
for_each_image_device_rect([&](auto const& image_device_rect) {
if (!fill_rect.has_value()) {
fill_rect = image_device_rect;
} else {
fill_rect = fill_rect->united(image_device_rect);
}
});
display_list_recorder.fill_rect(fill_rect->to_type<int>(), color.value(), clip_paths);
} else {
for_each_image_device_rect([&](auto const& image_device_rect) {
image.paint(context, image_device_rect, image_rendering, clip_paths);
});
}
}
}
}
