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topola
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egui: implement zooming in/out to a point

This commit is contained in:
Mikolaj Wielgus 2024-03-05 20:02:16 +00:00
parent 4959f3512b
commit 8a56a16528
1 changed files with 17 additions and 1 deletions
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18
src/bin/topola-egui/app.rs
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@ -111,9 +111,25 @@ impl eframe::App for App {
let desired_size = ui.available_width() * egui::vec2(1.0, 0.5);
let (_id, viewport_rect) = ui.allocate_space(desired_size);
self.from_rect = self.from_rect.translate(ctx.input(|i| -i.raw_scroll_delta));
let old_transform =
egui::emath::RectTransform::from_to(self.from_rect, viewport_rect);
let latest_pos = old_transform
.inverse()
.transform_pos(ctx.input(|i| i.pointer.latest_pos().unwrap_or_default()));
let old_scale = old_transform.scale().x;
self.from_rect = self.from_rect / ctx.input(|i| i.zoom_delta());
let new_scale = egui::emath::RectTransform::from_to(self.from_rect, viewport_rect)
.scale()
.x;
self.from_rect = self.from_rect.translate(
ctx.input(|i| latest_pos.to_vec2() * (new_scale - old_scale) / new_scale),
);
self.from_rect = self.from_rect.translate(ctx.input(|i| -i.raw_scroll_delta));
let transform = egui::emath::RectTransform::from_to(self.from_rect, viewport_rect);
let mut painter = Painter::new(ui, transform);