Make shift-scroll do horizontal scrolling on all platforms

Closes #1135

Author: emilk

eframe/CHANGELOG.md

@@ -10,6 +10,7 @@ NOTE: [`egui_web`](egui_web/CHANGELOG.md), [`egui-winit`](egui-winit/CHANGELOG.m
 * The default web painter is now `egui_glow` (instead of WebGL) ([#1020](https://github.com/emilk/egui/pull/1020)).
 * Fix horizontal scrolling direction on Linux.
 * Added `App::on_exit_event` ([#1038](https://github.com/emilk/egui/pull/1038))
+* Shift-scroll will now result in horizontal scrolling on all platforms ((#1136)[https://github.com/emilk/egui/pull/1136]).
 
 
 ## 0.16.0 - 2021-12-29

egui-winit/CHANGELOG.md

@@ -6,6 +6,7 @@ All notable changes to the `egui-winit` integration will be noted in this file.
 ## Unreleased
 * Fix horizontal scrolling direction on Linux.
 * Replaced `std::time::Instant` with `instant::Instant` for WebAssembly compatability ([#1023](https://github.com/emilk/egui/pull/1023))
+* Shift-scroll will now result in horizontal scrolling on all platforms ((#1136)[https://github.com/emilk/egui/pull/1136]).
 
 
 ## 0.16.0 - 2021-12-29

egui-winit/src/lib.rs

@@ -460,6 +460,12 @@ impl State {
             // Treat as zoom instead:
             let factor = (delta.y / 200.0).exp();
             self.egui_input.events.push(egui::Event::Zoom(factor));
+        } else if self.egui_input.modifiers.shift {
+            // Treat as horizontal scrolling.
+            // Note: one Mac we already get horizontal scroll events when shift is down.
+            self.egui_input
+                .events
+                .push(egui::Event::Scroll(egui::vec2(delta.x + delta.y, 0.0)));
         } else {
             self.egui_input.events.push(egui::Event::Scroll(delta));
         }

egui/src/data/input.rs

@@ -180,6 +180,8 @@ pub enum Event {
     /// The direction of the vector indicates how to move the _content_ that is being viewed.
     /// So if you get positive values, the content being viewed should move to the right and down,
     /// revealing new things to the left and up.
+    ///
+    /// Shift-scroll should result in horizontal scrolling (it is up to the integrations to do this).
     Scroll(Vec2),
 
     /// Zoom scale factor this frame (e.g. from ctrl-scroll or pinch gesture).

egui_web/CHANGELOG.md

@@ -7,6 +7,7 @@ All notable changes to the `egui_web` integration will be noted in this file.
 * The default painter is now glow instead of WebGL ([#1020](https://github.com/emilk/egui/pull/1020)).
 * Made the WebGL painter opt-in ([#1020](https://github.com/emilk/egui/pull/1020)).
 * Fix glow failure Chrome ((#1092)[https://github.com/emilk/egui/pull/1092]).
+* Shift-scroll will now result in horizontal scrolling on all platforms ((#1136)[https://github.com/emilk/egui/pull/1136]).
 
 
 ## 0.16.0 - 2021-12-29

egui_web/src/lib.rs

@@ -69,7 +69,7 @@ pub fn now_sec() -> f64 {
 
 pub fn screen_size_in_native_points() -> Option<egui::Vec2> {
     let window = web_sys::window()?;
-    Some(egui::Vec2::new(
+    Some(egui::vec2(
         window.inner_width().ok()?.as_f64()? as f32,
         window.inner_height().ok()?.as_f64()? as f32,
     ))
@@ -1022,11 +1022,11 @@ fn install_canvas_events(runner_ref: &AppRunnerRef) -> Result<(), JsValue> {
                     let points_per_scroll_line = 8.0; // Note that this is intentionally different from what we use in egui_glium / winit.
                     points_per_scroll_line
                 }
-                _ => 1.0,
+                _ => 1.0, // DOM_DELTA_PIXEL
             };
 
-            let delta = -scroll_multiplier
-                * egui::Vec2::new(event.delta_x() as f32, event.delta_y() as f32);
+            let mut delta =
+                -scroll_multiplier * egui::vec2(event.delta_x() as f32, event.delta_y() as f32);
 
             // Report a zoom event in case CTRL (on Windows or Linux) or CMD (on Mac) is pressed.
             // This if-statement is equivalent to how `Modifiers.command` is determined in
@@ -1035,6 +1035,12 @@ fn install_canvas_events(runner_ref: &AppRunnerRef) -> Result<(), JsValue> {
                 let factor = (delta.y / 200.0).exp();
                 runner_lock.input.raw.events.push(egui::Event::Zoom(factor));
             } else {
+                if event.shift_key() {
+                    // Treat as horizontal scrolling.
+                    // Note: one Mac we already get horizontal scroll events when shift is down.
+                    delta = egui::vec2(delta.x + delta.y, 0.0);
+                }
+
                 runner_lock
                     .input
                     .raw