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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibGfx/AntiAliasingPainter.h>
#include <LibGfx/Painter.h>
#include <LibWeb/Layout/InitialContainingBlock.h>
#include <LibWeb/Layout/Node.h>
#include <LibWeb/Painting/BackgroundPainting.h>
#include <LibWeb/Painting/PaintContext.h>
namespace Web::Painting {
// https://www.w3.org/TR/css-backgrounds-3/#backgrounds
void paint_background(PaintContext& context, Layout::NodeWithStyleAndBoxModelMetrics const& layout_node, Gfx::FloatRect const& border_rect, Color background_color, Vector<CSS::BackgroundLayerData> const* background_layers, BorderRadiiData const& border_radii)
{
auto& painter = context.painter();
auto get_box = [&](CSS::BackgroundBox box) {
auto box_rect = border_rect;
switch (box) {
case CSS::BackgroundBox::ContentBox: {
auto& padding = layout_node.box_model().padding;
box_rect.shrink(padding.top, padding.right, padding.bottom, padding.left);
[[fallthrough]];
}
case CSS::BackgroundBox::PaddingBox: {
auto& border = layout_node.box_model().border;
box_rect.shrink(border.top, border.right, border.bottom, border.left);
[[fallthrough]];
}
case CSS::BackgroundBox::BorderBox:
default:
return box_rect;
}
};
auto color_rect = border_rect;
if (background_layers && !background_layers->is_empty())
color_rect = get_box(background_layers->last().clip);
Gfx::AntiAliasingPainter aa_painter { painter };
aa_painter.fill_rect_with_rounded_corners(color_rect.to_rounded<int>(),
background_color, border_radii.top_left.as_corner(), border_radii.top_right.as_corner(), border_radii.bottom_right.as_corner(), border_radii.bottom_left.as_corner());
if (!background_layers)
return;
// Note: Background layers are ordered front-to-back, so we paint them in reverse
for (int layer_index = background_layers->size() - 1; layer_index >= 0; layer_index--) {
auto& layer = background_layers->at(layer_index);
// TODO: Gradients!
if (!layer.image || !layer.image->bitmap())
continue;
auto& image = *layer.image->bitmap();
// Clip
auto clip_rect = get_box(layer.clip);
painter.save();
painter.add_clip_rect(clip_rect.to_rounded<int>());
Gfx::FloatRect background_positioning_area;
// Attachment and Origin
switch (layer.attachment) {
case CSS::BackgroundAttachment::Fixed:
background_positioning_area = layout_node.root().browsing_context().viewport_rect().to_type<float>();
break;
case CSS::BackgroundAttachment::Local:
case CSS::BackgroundAttachment::Scroll:
background_positioning_area = get_box(layer.origin);
break;
}
// Size
Gfx::FloatRect image_rect;
switch (layer.size_type) {
case CSS::BackgroundSize::Contain: {
float max_width_ratio = background_positioning_area.width() / image.width();
float max_height_ratio = background_positioning_area.height() / image.height();
float ratio = min(max_width_ratio, max_height_ratio);
image_rect.set_size(image.width() * ratio, image.height() * ratio);
break;
}
case CSS::BackgroundSize::Cover: {
float max_width_ratio = background_positioning_area.width() / image.width();
float max_height_ratio = background_positioning_area.height() / image.height();
float ratio = max(max_width_ratio, max_height_ratio);
image_rect.set_size(image.width() * ratio, image.height() * ratio);
break;
}
case CSS::BackgroundSize::LengthPercentage: {
float width;
float height;
bool x_is_auto = layer.size_x.is_length() && layer.size_x.length().is_auto();
bool y_is_auto = layer.size_y.is_length() && layer.size_y.length().is_auto();
if (x_is_auto && y_is_auto) {
width = image.width();
height = image.height();
} else if (x_is_auto) {
height = layer.size_y.resolved(layout_node, CSS::Length::make_px(background_positioning_area.height())).to_px(layout_node);
width = image.width() * (height / image.height());
} else if (y_is_auto) {
width = layer.size_x.resolved(layout_node, CSS::Length::make_px(background_positioning_area.width())).to_px(layout_node);
height = image.height() * (width / image.width());
} else {
width = layer.size_x.resolved(layout_node, CSS::Length::make_px(background_positioning_area.width())).to_px(layout_node);
height = layer.size_y.resolved(layout_node, CSS::Length::make_px(background_positioning_area.height())).to_px(layout_node);
}
image_rect.set_size(width, height);
break;
}
}
// 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() / background_positioning_area.width() / image_rect.width());
}
if (layer.repeat_y == CSS::Repeat::Round) {
image_rect.set_height(background_positioning_area.height() / 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_length() && layer.size_x.length().is_auto()) {
image_rect.set_width(image.width() * (image_rect.height() / image.height()));
}
if (layer.size_y.is_length() && layer.size_y.length().is_auto()) {
image_rect.set_height(image.height() * (image_rect.width() / image.width()));
}
}
}
float space_x = background_positioning_area.width() - image_rect.width();
float space_y = background_positioning_area.height() - image_rect.height();
// Position
float offset_x = layer.position_offset_x.resolved(layout_node, CSS::Length::make_px(space_x)).to_px(layout_node);
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);
}
float offset_y = layer.position_offset_y.resolved(layout_node, CSS::Length::make_px(space_y)).to_px(layout_node);
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;
float x_step = 0;
float 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();
if (whole_images <= 1) {
x_step = image_rect.width();
repeat_x = false;
} else {
float space = fmodf(background_positioning_area.width(), image_rect.width());
x_step = image_rect.width() + ((float)space / (float)(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() > clip_rect.x()) {
auto x_delta = floorf(x_step * ceilf((image_rect.x() - 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();
if (whole_images <= 1) {
y_step = image_rect.height();
repeat_y = false;
} else {
float space = fmodf(background_positioning_area.height(), image_rect.height());
y_step = image_rect.height() + ((float)space / (float)(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() > clip_rect.y()) {
auto y_delta = floorf(y_step * ceilf((image_rect.y() - clip_rect.y()) / y_step));
image_rect.set_y(image_rect.y() - y_delta);
}
// FIXME: Handle rounded corners
float initial_image_x = image_rect.x();
float image_y = image_rect.y();
while (image_y < clip_rect.bottom()) {
image_rect.set_y(image_y);
float image_x = initial_image_x;
while (image_x < clip_rect.right()) {
image_rect.set_x(image_x);
painter.draw_scaled_bitmap(image_rect.to_rounded<int>(), image, image.rect(), 1.0f, Gfx::Painter::ScalingMode::BilinearBlend);
if (!repeat_x)
break;
image_x += x_step;
}
if (!repeat_y)
break;
image_y += y_step;
}
painter.restore();
}
}
}
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