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LibGUI: Keep scrollbar timer active while mouse is down

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Rather than disable and re-enable the timer, always keep it active
and make it do collision checks to decide if it should have an effect.

This is because set_automatic_scrolling_active(true) calls the
timeout callback immediately before starting the timer, and
when clicking the gutter this callback could disable the timer
again (if the first page scroll put the scrubber under the cursor).

Intead of making set_automatic_scrolling_active() work when it's
called reentrantly (which is easy: just swap the order of
on_automatic_scrolling_timer_fired() and timer->start() so that
on_automatic_scrolling_timer_fired() can immediately stop the
timer again, but it's confusing), make the timer check if it
should do anything.

This is keyed off m_last_mouse_position instead of
m_hovered_component because m_hovered_component is a visual state
and we arguably shouldn't modify it while the left mouse button
is down (as it indicated what part is activated on click).
This commit is contained in:
Nico Weber 2020-08-25 11:04:53 -04:00 • committed by Andreas Kling
parent b96759930d
commit 0a462dac14
2 changed files with 12 additions and 18 deletions
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29
Libraries/LibGUI/ScrollBar.cpp
View file

@ -261,11 +261,11 @@ void ScrollBar::paint_event(PaintEvent& event)
void ScrollBar::on_automatic_scrolling_timer_fired() void ScrollBar::on_automatic_scrolling_timer_fired()
{ {
if (m_automatic_scrolling_kind == AutomaticScrollingKind::DecrementButton) { if (m_automatic_scrolling_kind == AutomaticScrollingKind::DecrementButton && component_at_position(m_last_mouse_position) == Component::DecrementButton) {
set_value(value() - m_step); set_value(value() - m_step);
return; return;
} }
if (m_automatic_scrolling_kind == AutomaticScrollingKind::IncrementButton) { if (m_automatic_scrolling_kind == AutomaticScrollingKind::IncrementButton && component_at_position(m_last_mouse_position) == Component::IncrementButton) {
set_value(value() + m_step); set_value(value() + m_step);
return; return;
} }
@ -278,7 +278,8 @@ void ScrollBar::mousedown_event(MouseEvent& event)
if (!has_scrubber()) if (!has_scrubber())
return; return;
Component clicked_component = component_at_position(event.position()); m_last_mouse_position = event.position();
Component clicked_component = component_at_position(m_last_mouse_position);
if (clicked_component == Component::DecrementButton) { if (clicked_component == Component::DecrementButton) {
set_automatic_scrolling_active(true, AutomaticScrollingKind::DecrementButton); set_automatic_scrolling_active(true, AutomaticScrollingKind::DecrementButton);
@ -377,23 +378,15 @@ ScrollBar::Component ScrollBar::component_at_position(const Gfx::IntPoint& posit
return Component::Invalid; return Component::Invalid;
} }
void ScrollBar::update_hovered_component(const Gfx::IntPoint& position)
{
auto old_hovered_component = m_hovered_component;
m_hovered_component = component_at_position(event.position());
if (old_hovered_component != m_hovered_component) {
update();
if (m_automatic_scrolling_kind == AutomaticScrollingKind::DecrementButton)
set_automatic_scrolling_active(m_hovered_component == Component::DecrementButton, m_automatic_scrolling_kind);
else if (m_automatic_scrolling_kind == AutomaticScrollingKind::IncrementButton)
set_automatic_scrolling_active(m_hovered_component == Component::IncrementButton, m_automatic_scrolling_kind);
}
}
void ScrollBar::mousemove_event(MouseEvent& event) void ScrollBar::mousemove_event(MouseEvent& event)
{ {
update_hovered_component(event.position()); m_last_mouse_position = event.position();
auto old_hovered_component = m_hovered_component;
m_hovered_component = component_at_position(m_last_mouse_position);
if (old_hovered_component != m_hovered_component) {
update();
}
if (!m_scrubbing) if (!m_scrubbing)
return; return;
float delta = orientation() == Orientation::Vertical ? (event.y() - m_scrub_origin.y()) : (event.x() - m_scrub_origin.x()); float delta = orientation() == Orientation::Vertical ? (event.y() - m_scrub_origin.y()) : (event.x() - m_scrub_origin.x());

1
Libraries/LibGUI/ScrollBar.h
View file

@ -118,6 +118,7 @@ private:
Gfx::Orientation m_orientation { Gfx::Orientation::Vertical }; Gfx::Orientation m_orientation { Gfx::Orientation::Vertical };
Component m_hovered_component { Component::Invalid }; Component m_hovered_component { Component::Invalid };
Gfx::IntPoint m_last_mouse_position;
bool m_scrubber_in_use { false }; bool m_scrubber_in_use { false };
AutomaticScrollingKind m_automatic_scrolling_kind { AutomaticScrollingKind::None }; AutomaticScrollingKind m_automatic_scrolling_kind { AutomaticScrollingKind::None };