QuickShow: When zooming with the mouse wheel, keep image centered at cursor.

This commit is contained in:
Andreas Kling 2019-06-30 15:01:35 +02:00
parent e7ce4514ec
commit 038f99eeff
Notes: sideshowbarker 2024-07-19 13:26:01 +09:00
2 changed files with 8 additions and 1 deletions

View file

@ -72,12 +72,19 @@ void QSWidget::mousemove_event(GMouseEvent& event)
void QSWidget::mousewheel_event(GMouseEvent& event)
{
auto old_scale = m_scale;
auto old_scale_factor = (float)m_scale / 100.0f;
auto zoom_point = event.position().translated(-m_bitmap_rect.location());
zoom_point.set_x((float)zoom_point.x() / old_scale_factor);
zoom_point.set_y((float)zoom_point.y() / old_scale_factor);
m_scale += -event.wheel_delta() * 10;
if (m_scale < 10)
m_scale = 10;
if (m_scale > 1000)
m_scale = 1000;
relayout();
auto new_scale_factor = (float)m_scale / 100.0f;
auto scale_factor_change = new_scale_factor - old_scale_factor;
m_bitmap_rect.move_by(-Point((float)zoom_point.x() * scale_factor_change, (float)zoom_point.y() * scale_factor_change));
if (old_scale != m_scale) {
if (on_scale_change)
on_scale_change(m_scale);

View file

@ -56,7 +56,7 @@ int main(int argc, char** argv)
window->set_title(String::format("QuickShow: %s %s %d%%", path, bitmap->size().to_string().characters(), scale));
};
window->set_double_buffering_enabled(false);
window->set_double_buffering_enabled(true);
update_window_title(100);
window->set_rect(200, 200, bitmap->width(), bitmap->height());