Allow changing plot aspect ratio with scroll + cmd/ctrl + alt (#2742)

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### What

Wanted Shift+Cmd originally, but egui no longer see this as a scroll
then. Also, shift+scroll is already taken for translating along y.

Fixes #2148
* #2148



https://github.com/rerun-io/rerun/assets/1220815/bc078094-4bae-4980-8508-af0cff234614



### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested [demo.rerun.io](https://demo.rerun.io/pr/2742) (if
applicable)

- [PR Build Summary](https://build.rerun.io/pr/2742)
- [Docs
preview](https://rerun.io/preview/pr%3Aandreas%2Fsingle-axis-plot-zoom/docs)
- [Examples
preview](https://rerun.io/preview/pr%3Aandreas%2Fsingle-axis-plot-zoom/examples)

crates/re_space_view/src/controls.rs

@@ -1,6 +1,10 @@
 /// Modifier to press for scroll to zoom.
 pub const ZOOM_SCROLL_MODIFIER: egui::Modifiers = egui::Modifiers::COMMAND;
 
+/// Modifier to press for scroll to change aspect ratio.
+pub const ASPECT_SCROLL_MODIFIER: egui::Modifiers =
+    egui::Modifiers::ALT.plus(egui::Modifiers::COMMAND);
+
 /// Modifier to press for scroll to pan horizontally.
 pub const HORIZONTAL_SCROLL_MODIFIER: egui::Modifiers = egui::Modifiers::SHIFT;
 

crates/re_space_view_bar_chart/src/space_view_class.rs

@@ -35,6 +35,10 @@ impl SpaceViewClass for BarChartSpaceView {
         layout.add(controls::ZOOM_SCROLL_MODIFIER);
         layout.add(".\n");
 
+        layout.add("Scroll + ");
+        layout.add(controls::ASPECT_SCROLL_MODIFIER);
+        layout.add(" to change the aspect ratio.\n");
+
         layout.add("Drag ");
         layout.add(controls::SELECTION_RECT_ZOOM_BUTTON);
         layout.add(" to zoom in/out using a selection.\n\n");
@@ -84,10 +88,16 @@ impl SpaceViewClass for BarChartSpaceView {
 
         let charts = &parts.get::<BarChartViewPartSystem>()?.charts;
 
+        let zoom_both_axis = !ui.input(|i| i.modifiers.contains(controls::ASPECT_SCROLL_MODIFIER));
+
         ui.scope(|ui| {
             Plot::new("bar_chart_plot")
                 .legend(Legend::default())
                 .clamp_grid(true)
+                .allow_zoom(egui::plot::AxisBools {
+                    x: true,
+                    y: zoom_both_axis,
+                })
                 .show(ui, |plot_ui| {
                     fn create_bar_chart<N: Into<f64>>(
                         ent_path: &EntityPath,

crates/re_space_view_time_series/src/space_view_class.rs

@@ -40,6 +40,10 @@ impl SpaceViewClass for TimeSeriesSpaceView {
         layout.add(controls::ZOOM_SCROLL_MODIFIER);
         layout.add(".\n");
 
+        layout.add("Scroll + ");
+        layout.add(controls::ASPECT_SCROLL_MODIFIER);
+        layout.add(" to change the aspect ratio.\n");
+
         layout.add("Drag ");
         layout.add(controls::SELECTION_RECT_ZOOM_BUTTON);
         layout.add(" to zoom in/out using a selection.\n");
@@ -121,7 +125,13 @@ impl SpaceViewClass for TimeSeriesSpaceView {
         // use timeline_name as part of id, so that egui stores different pan/zoom for different timelines
         let plot_id_src = ("plot", &timeline_name);
 
+        let zoom_both_axis = !ui.input(|i| i.modifiers.contains(controls::ASPECT_SCROLL_MODIFIER));
+
         let mut plot = Plot::new(plot_id_src)
+            .allow_zoom(egui::plot::AxisBools {
+                x: true,
+                y: zoom_both_axis,
+            })
             .legend(Legend {
                 position: egui::plot::Corner::RightBottom,
                 ..Default::default()