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Mandelbrot: Add mousewheel zooming

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This allows the user to zoom in with a up scroll of the mousewheel and
zoom out with a down scroll.
This commit is contained in:
sin-ack 2021-08-08 13:40:39 +00:00 committed by Gunnar Beutner
parent a08dd5b99c
commit faec8bbe45
Notes: sideshowbarker 2024-07-18 07:09:59 +09:00 
Author: https://github.com/sin-ack
Commit: https://github.com/SerenityOS/serenity/commit/faec8bbe45d
Pull-request: https://github.com/SerenityOS/serenity/pull/9286
Reviewed-by: https://github.com/gunnarbeutner
1 changed files with 28 additions and 0 deletions
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28
Userland/Demos/Mandelbrot/Mandelbrot.cpp
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@ -147,6 +147,7 @@ private:
virtual void mousedown_event(GUI::MouseEvent& event) override;
virtual void mousemove_event(GUI::MouseEvent& event) override;
virtual void mouseup_event(GUI::MouseEvent& event) override;
virtual void mousewheel_event(GUI::MouseEvent& event) override;
virtual void resize_event(GUI::ResizeEvent& event) override;
bool m_dragging { false };
@ -217,6 +218,33 @@ void Mandelbrot::mouseup_event(GUI::MouseEvent& event)
return GUI::Widget::mouseup_event(event);
}
void Mandelbrot::mousewheel_event(GUI::MouseEvent& event)
{
static constexpr double zoom_in_multiplier = 0.8;
static constexpr double zoom_out_multiplier = 1.25;
bool zooming_in = event.wheel_delta() < 0;
double multiplier = zooming_in ? zoom_in_multiplier : zoom_out_multiplier;
auto relative_rect = this->relative_rect();
Gfx::IntRect zoomed_rect = relative_rect;
zoomed_rect.set_width(zoomed_rect.width() * multiplier);
zoomed_rect.set_height(zoomed_rect.height() * multiplier);
auto leftover_width = abs(relative_rect.width() - zoomed_rect.width());
auto leftover_height = abs(relative_rect.height() - zoomed_rect.height());
double cursor_x_percentage = static_cast<double>(event.position().x()) / relative_rect.width();
double cursor_y_percentage = static_cast<double>(event.position().y()) / relative_rect.height();
zoomed_rect.set_x((zooming_in ? 1 : -1) * leftover_width * cursor_x_percentage);
zoomed_rect.set_y((zooming_in ? 1 : -1) * leftover_height * cursor_y_percentage);
m_set.zoom(zoomed_rect);
update();
}
void Mandelbrot::resize_event(GUI::ResizeEvent& event)
{
m_set.resize(event.size());