ladybird/Userland/Applications/PixelPaint/Layer.cpp

/*
 * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include "Layer.h"
#include "Image.h"
#include "Selection.h"
#include <AK/RefPtr.h>
#include <AK/Try.h>
#include <LibGfx/Bitmap.h>
#include <LibGfx/Painter.h>

namespace PixelPaint {

ErrorOr<NonnullRefPtr<Layer>> Layer::try_create_with_size(Image& image, Gfx::IntSize const& size, String name)
{
    VERIFY(!size.is_empty());

    if (size.width() > 16384 || size.height() > 16384)
        return Error::from_string_literal("Layer size too large"sv);

    auto bitmap = TRY(Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, size));
    return adopt_nonnull_ref_or_enomem(new (nothrow) Layer(image, move(bitmap), move(name)));
}

ErrorOr<NonnullRefPtr<Layer>> Layer::try_create_with_bitmap(Image& image, NonnullRefPtr<Gfx::Bitmap> bitmap, String name)
{
    VERIFY(!bitmap->size().is_empty());

    if (bitmap->size().width() > 16384 || bitmap->size().height() > 16384)
        return Error::from_string_literal("Layer size too large"sv);

    return adopt_nonnull_ref_or_enomem(new (nothrow) Layer(image, bitmap, move(name)));
}

ErrorOr<NonnullRefPtr<Layer>> Layer::try_create_snapshot(Image& image, Layer const& layer)
{
    auto bitmap = TRY(layer.bitmap().clone());
    auto snapshot = TRY(try_create_with_bitmap(image, move(bitmap), layer.name()));

    /*
        We set these properties directly because calling the setters might
        notify the image of an update on the newly created layer, but this
        layer has not yet been added to the image.
    */
    snapshot->m_opacity_percent = layer.opacity_percent();
    snapshot->m_visible = layer.is_visible();

    snapshot->set_selected(layer.is_selected());
    snapshot->set_location(layer.location());

    return snapshot;
}

Layer::Layer(Image& image, NonnullRefPtr<Gfx::Bitmap> bitmap, String name)
    : m_image(image)
    , m_name(move(name))
    , m_bitmap(move(bitmap))
{
}

void Layer::did_modify_bitmap(Gfx::IntRect const& rect)
{
    m_image.layer_did_modify_bitmap({}, *this, rect);
}

void Layer::set_visible(bool visible)
{
    if (m_visible == visible)
        return;
    m_visible = visible;
    m_image.layer_did_modify_properties({}, *this);
}

void Layer::set_opacity_percent(int opacity_percent)
{
    if (m_opacity_percent == opacity_percent)
        return;
    m_opacity_percent = opacity_percent;
    m_image.layer_did_modify_properties({}, *this);
}

void Layer::set_name(String name)
{
    if (m_name == name)
        return;
    m_name = move(name);
    m_image.layer_did_modify_properties({}, *this);
}

RefPtr<Gfx::Bitmap> Layer::try_copy_bitmap(Selection const& selection) const
{
    if (selection.is_empty()) {
        return {};
    }
    auto selection_rect = selection.bounding_rect();

    auto bitmap_or_error = Gfx::Bitmap::try_create(Gfx::BitmapFormat::BGRA8888, selection_rect.size());
    if (bitmap_or_error.is_error())
        return nullptr;
    auto result = bitmap_or_error.release_value_but_fixme_should_propagate_errors();
    VERIFY(result->has_alpha_channel());

    for (int y = selection_rect.top(); y <= selection_rect.bottom(); y++) {
        for (int x = selection_rect.left(); x <= selection_rect.right(); x++) {

            Gfx::IntPoint image_point { x, y };
            auto layer_point = image_point - m_location;
            auto result_point = image_point - selection_rect.top_left();

            if (!m_bitmap->physical_rect().contains(layer_point)) {
                result->set_pixel(result_point, Gfx::Color::Transparent);
                continue;
            }

            auto pixel = m_bitmap->get_pixel(layer_point);

            // Widen to int before multiplying to avoid overflow issues
            auto pixel_alpha = static_cast<int>(pixel.alpha());
            auto selection_alpha = static_cast<int>(selection.get_selection_alpha(image_point));
            auto new_alpha = (pixel_alpha * selection_alpha) / 0xFF;
            pixel.set_alpha(static_cast<u8>(clamp(new_alpha, 0, 0xFF)));

            result->set_pixel(result_point, pixel);
        }
    }

    return result;
}

void Layer::erase_selection(Selection const& selection)
{
    Gfx::Painter painter { bitmap() };
    auto const image_and_selection_intersection = m_image.rect().intersected(selection.bounding_rect());
    auto const translated_to_layer_space = image_and_selection_intersection.translated(-location());
    painter.clear_rect(translated_to_layer_space, Color::Transparent);
    did_modify_bitmap(translated_to_layer_space);
}

}