From cd0f66b9ae661be737ce57f26fb305cf124f6b73 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Mon, 16 Jan 2023 14:40:19 +0100
Subject: [PATCH] eframe web: ctrl-P and cmd-P will not open the print dialog
 (#2598)

---
 crates/eframe/CHANGELOG.md      |  3 +++
 crates/eframe/src/web/events.rs | 24 +++++++++++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/crates/eframe/CHANGELOG.md b/crates/eframe/CHANGELOG.md
index bcabaeb7..0f67c3db 100644
--- a/crates/eframe/CHANGELOG.md
+++ b/crates/eframe/CHANGELOG.md
@@ -9,6 +9,9 @@ NOTE: [`egui-winit`](../egui-winit/CHANGELOG.md), [`egui_glium`](../egui_glium/C
 #### Desktop/Native:
 * `eframe::run_native` now returns a `Result` ([#2433](https://github.com/emilk/egui/pull/2433)).
 
+#### Web:
+* Prevent ctrl-P/cmd-P from opening the print dialog ([#2598](https://github.com/emilk/egui/pull/2598)).
+
 
 ## 0.20.1 - 2022-12-11
 * Fix docs.rs build ([#2420](https://github.com/emilk/egui/pull/2420)).
diff --git a/crates/eframe/src/web/events.rs b/crates/eframe/src/web/events.rs
index 6ac9e1e4..dcca886a 100644
--- a/crates/eframe/src/web/events.rs
+++ b/crates/eframe/src/web/events.rs
@@ -1,6 +1,9 @@
-use super::*;
 use std::sync::atomic::{AtomicBool, Ordering};
 
+use egui::Key;
+
+use super::*;
+
 struct IsDestroyed(pub bool);
 
 pub fn paint_and_schedule(
@@ -64,8 +67,9 @@ pub fn install_document_events(runner_container: &mut AppRunnerContainer) -> Res
             runner_lock.input.raw.modifiers = modifiers;
 
             let key = event.key();
+            let egui_key = translate_key(&key);
 
-            if let Some(key) = translate_key(&key) {
+            if let Some(key) = egui_key {
                 runner_lock.input.raw.events.push(egui::Event::Key {
                     key,
                     pressed: true,
@@ -85,10 +89,13 @@ pub fn install_document_events(runner_container: &mut AppRunnerContainer) -> Res
 
             let egui_wants_keyboard = runner_lock.egui_ctx().wants_keyboard_input();
 
-            let prevent_default = if matches!(event.key().as_str(), "Tab") {
+            #[allow(clippy::if_same_then_else)]
+            let prevent_default = if egui_key == Some(Key::Tab) {
                 // Always prevent moving cursor to url bar.
                 // egui wants to use tab to move to the next text field.
                 true
+            } else if egui_key == Some(Key::P) {
+                true // Prevent ctrl-P opening the print dialog. Users may want to use it for a command palette.
             } else if egui_wants_keyboard {
                 matches!(
                     event.key().as_str(),
@@ -112,6 +119,7 @@ pub fn install_document_events(runner_container: &mut AppRunnerContainer) -> Res
 
             if prevent_default {
                 event.prevent_default();
+                // event.stop_propagation();
             }
         },
     )?;
@@ -198,15 +206,21 @@ pub fn install_document_events(runner_container: &mut AppRunnerContainer) -> Res
 pub fn install_canvas_events(runner_container: &mut AppRunnerContainer) -> Result<(), JsValue> {
     let canvas = canvas_element(runner_container.runner.lock().canvas_id()).unwrap();
 
-    {
+    let prevent_default_events = [
         // By default, right-clicks open a context menu.
         // We don't want to do that (right clicks is handled by egui):
-        let event_name = "contextmenu";
+        "contextmenu",
+        // Allow users to use ctrl-p for e.g. a command palette
+        "afterprint",
+    ];
 
+    for event_name in prevent_default_events {
         let closure =
             move |event: web_sys::MouseEvent,
                   mut _runner_lock: egui::mutex::MutexGuard<'_, AppRunner>| {
                 event.prevent_default();
+                // event.stop_propagation();
+                // tracing::debug!("Preventing event {:?}", event_name);
             };
 
         runner_container.add_event_listener(&canvas, event_name, closure)?;