mirror of
https://github.com/LadybirdBrowser/ladybird
synced 2026-04-26 01:35:08 +02:00
331815f327
We previously supported autoscroll while the middle mouse button was pressed. We now also support clicking the middle mouse button in-place to begin autoscroll. Pressing any mouse button or the escape key will exit this mode.
93 lines
3.2 KiB
C++
93 lines
3.2 KiB
C++
/*
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* Copyright (c) 2026, Tim Flynn <trflynn89@ladybird.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Math.h>
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#include <LibWeb/DOM/Document.h>
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#include <LibWeb/DOM/Element.h>
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#include <LibWeb/Page/AutoScrollHandler.h>
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#include <LibWeb/Page/MiddleButtonScrollHandler.h>
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#include <LibWeb/Painting/Paintable.h>
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#include <LibWeb/Painting/PaintableBox.h>
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#include <LibWeb/Painting/ViewportPaintable.h>
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namespace Web {
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static constexpr double DEAD_ZONE_RADIUS { 15 };
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static constexpr double SPEED_FACTOR = 5.0;
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static constexpr double MAX_SPEED_PER_SECOND = 5000.0;
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static constexpr double SCROLL_INTERVAL_MS = 16.0;
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MiddleButtonScrollHandler::MiddleButtonScrollHandler(DOM::Element& container, CSSPixelPoint origin)
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: m_container_element(container)
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, m_origin(origin)
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, m_mouse_position(origin)
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{
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if (auto* paintable = m_container_element->document().paintable())
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paintable->set_needs_repaint();
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}
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MiddleButtonScrollHandler::~MiddleButtonScrollHandler()
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{
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if (auto* paintable = m_container_element->document().paintable())
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paintable->set_needs_repaint();
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}
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void MiddleButtonScrollHandler::visit_edges(JS::Cell::Visitor& visitor) const
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{
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visitor.visit(m_container_element);
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}
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GC::Ptr<DOM::Element> MiddleButtonScrollHandler::find_scrollable_ancestor(DOM::Document& document, Painting::Paintable& paintable)
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{
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// AutoScrollHandler::find_scrollable_ancestor begins with the paintable's containing block. For middle mouse
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// scrolling, we want to include the paintable itself. This allows clicking in dead space to being scrolling.
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if (auto* paintable_box = as_if<Painting::PaintableBox>(paintable); paintable_box && paintable_box->could_be_scrolled_by_wheel_event()) {
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if (auto* element = as_if<DOM::Element>(paintable_box->dom_node().ptr()))
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return element;
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}
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if (auto container = AutoScrollHandler::find_scrollable_ancestor(paintable))
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return container;
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if (auto scrolling_element = document.scrolling_element())
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return const_cast<DOM::Element*>(scrolling_element.ptr());
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return {};
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}
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void MiddleButtonScrollHandler::perform_tick()
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{
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auto distance_x = (m_mouse_position.x() - m_origin.x()).to_double();
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auto distance_y = (m_mouse_position.y() - m_origin.y()).to_double();
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if (auto distance = AK::hypot(distance_x, distance_y); distance < DEAD_ZONE_RADIUS)
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return;
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m_container_element->document().update_layout(DOM::UpdateLayoutReason::AutoScrollSelection);
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m_mouse_has_moved_beyond_dead_zone = true;
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auto paintable_box = AutoScrollHandler::auto_scroll_paintable(m_container_element);
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if (!paintable_box)
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return;
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auto speed_x = clamp(distance_x * SPEED_FACTOR, -MAX_SPEED_PER_SECOND, MAX_SPEED_PER_SECOND);
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auto speed_y = clamp(distance_y * SPEED_FACTOR, -MAX_SPEED_PER_SECOND, MAX_SPEED_PER_SECOND);
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auto elapsed_seconds = SCROLL_INTERVAL_MS / 1000.0;
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m_fractional_delta += CSSPixelPoint {
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CSSPixels(speed_x * elapsed_seconds),
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CSSPixels(speed_y * elapsed_seconds),
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};
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auto scroll_x = m_fractional_delta.x().to_int();
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auto scroll_y = m_fractional_delta.y().to_int();
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m_fractional_delta -= CSSPixelPoint { scroll_x, scroll_y };
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paintable_box->scroll_by(scroll_x, scroll_y);
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}
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}
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