Multiple visible GraphViews all zoom on Ctrl+Wheel — handle_zoom has no hover gate

[stergiotis]

Repro

Render two GraphView widgets simultaneously (e.g. side-by-side egui::SidePanels) with default SettingsNavigation (zoom + pan enabled). Hold Ctrl and scroll the wheel anywhere on the screen — including outside either
graph. Both graphs zoom in lockstep at the same rate. The examples/multiple example in this repo reproduces the symptom directly.

Expected vs actual

• Expected: only the graph whose response rect contains the pointer should zoom.
• Actual: every visible GraphView with zoom_and_pan_enabled = true zooms on every Ctrl+Wheel event, regardless of pointer position.

Cause

GraphView::handle_zoom (src/graph_view.rs, 0.30.0) reads ui.input(|i| i.zoom_delta()) whenever settings_navigation.zoom_and_pan_enabled is true, with no containment check on the passed &Response:

fn handle_zoom(&self, ui: &Ui, resp: &Response, ...) {
    if !self.settings_navigation.zoom_and_pan_enabled { return; }
    ui.input(|i| {
        let delta = i.zoom_delta();
        // ...
        let local_center = i.pointer.hover_pos().map(|p| self.local_pos(resp, p));
        // ...
        self.zoom(&local_rect, step, local_center, meta);
    });
}

resp is consulted only to compute the zoom centre, never to gate whether the delta applies. With multiple GraphViews sharing the same egui::Context, every visible graph reads the same global zoom delta on every
frame.

Proposed fix

Wrap the input read in a hover gate:

fn handle_zoom(...) {
    if !self.settings_navigation.zoom_and_pan_enabled { return; }
    if !resp.hovered() { return; }
    ui.input(|i| { /* existing body unchanged */ });
}

resp.hovered() already accounts for layer ordering and pointer occlusion, which matches user expectation. Two-line patch; happy to send a PR if the approach looks right.

Workaround today

Set settings_navigation.zoom_and_pan_enabled = false on every graph except the primary. The early-return at the top of handle_zoom/handle_pan suppresses input on secondaries. Acceptable when secondaries are read-only;
awkward when users expect multiple independently navigable graphs.

Versions

egui_graphs 0.30.0.

[blitzarx1]

Thanks for this finding. I will address it in the next release.