Handle standard text keyboard shortcuts without menu

The textbox will now receive copy/cut/paste/undo/redo/select-all
without a menu being present.

Several of these (select-all, undo/redo) do not currently have
implementations, but we will at least get the commands.

- progress on #1652
- closes #1030

CHANGELOG.md

@@ -41,6 +41,7 @@ You can find its changes [documented below](#070---2021-01-01).
 
 ### Fixed
 - `Notification`s will not be delivered to the widget that sends them ([#1640] by [@cmyr])
+- `TextBox` can handle standard keyboard shortcuts without needing menus ([#1660] by [@cmyr])
 
 
 - Fixed docs of derived Lens ([#1523] by [@Maan2003])
@@ -644,6 +645,7 @@ Last release without a changelog :(
 [#1640]: https://github.com/linebender/druid/pull/1640
 [#1641]: https://github.com/linebender/druid/pull/1641
 [#1647]: https://github.com/linebender/druid/pull/1647
+[#1660]: https://github.com/linebender/druid/pull/1660
 
 [Unreleased]: https://github.com/linebender/druid/compare/v0.7.0...master
 [0.7.0]: https://github.com/linebender/druid/compare/v0.6.0...v0.7.0

druid/src/command.rs

@@ -325,6 +325,9 @@ pub mod sys {
     /// Redo.
     pub const REDO: Selector = Selector::new("druid-builtin.menu-redo");
 
+    /// Select all.
+    pub const SELECT_ALL: Selector = Selector::new("druid-builtin.menu-select-all");
+
     /// Text input state has changed, and we need to notify the platform.
     pub(crate) const INVALIDATE_IME: Selector<ImeInvalidation> =
         Selector::new("druid-builtin.invalidate-ime");

druid/src/text/input_component.rs

@@ -202,6 +202,14 @@ impl<T> TextComponent<T> {
         self.lock.get() == ImeLock::None
     }
 
+    /// Returns `true` if the IME is actively composing (or the text is locked.)
+    ///
+    /// When text is composing, you should avoid doing things like modifying the
+    /// selection or copy/pasting text.
+    pub fn is_composing(&self) -> bool {
+        self.can_read() && self.borrow().composition_range.is_some()
+    }
+
     /// Attempt to mutably borrow the inner [`EditSession`].
     ///
     /// # Panics

druid/src/widget/textbox.rs

@@ -23,7 +23,8 @@ use crate::text::{EditableText, Selection, TextComponent, TextLayout, TextStorag
 use crate::widget::prelude::*;
 use crate::widget::{Padding, Scroll, WidgetWrapper};
 use crate::{
-    theme, Color, FontDescriptor, KeyOrValue, Point, Rect, TextAlignment, TimerToken, Vec2,
+    theme, Color, Command, FontDescriptor, HotKey, KeyEvent, KeyOrValue, Point, Rect, SysMods,
+    TextAlignment, TimerToken, Vec2,
 };
 
 const TEXTBOX_INSETS: Insets = Insets::new(4.0, 2.0, 4.0, 2.0);
@@ -328,6 +329,35 @@ impl<T: TextStorage + EditableText> TextBox<T> {
             self.inner.wrapped_mut().scroll_to(rect + SCROLL_TO_INSETS);
         }
     }
+
+    /// These commands may be supplied by menus; but if they aren't, we
+    /// inject them again, here.
+    fn fallback_do_builtin_command(
+        &mut self,
+        ctx: &mut EventCtx,
+        key: &KeyEvent,
+    ) -> Option<Command> {
+        use crate::commands as sys;
+        let our_id = ctx.widget_id();
+        match key {
+            key if HotKey::new(SysMods::Cmd, "c").matches(key) => Some(sys::COPY.to(our_id)),
+            key if HotKey::new(SysMods::Cmd, "x").matches(key) => Some(sys::CUT.to(our_id)),
+            // we have to send paste to the window, in order to get it converted into the `Paste`
+            // event
+            key if HotKey::new(SysMods::Cmd, "v").matches(key) => {
+                Some(sys::PASTE.to(ctx.window_id()))
+            }
+            key if HotKey::new(SysMods::Cmd, "z").matches(key) => Some(sys::UNDO.to(our_id)),
+            key if HotKey::new(SysMods::CmdShift, "Z").matches(key) && !cfg!(windows) => {
+                Some(sys::REDO.to(our_id))
+            }
+            key if HotKey::new(SysMods::Cmd, "y").matches(key) && cfg!(windows) => {
+                Some(sys::REDO.to(our_id))
+            }
+            key if HotKey::new(SysMods::Cmd, "a").matches(key) => Some(sys::SELECT_ALL.to(our_id)),
+            _ => None,
+        }
+    }
 }
 
 impl<T: TextStorage + EditableText> Widget<T> for TextBox<T> {
@@ -363,6 +393,12 @@ impl<T: TextStorage + EditableText> Widget<T> for TextBox<T> {
                 }
                 _ => (),
             },
+            Event::KeyDown(key) if !self.text().is_composing() => {
+                if let Some(cmd) = self.fallback_do_builtin_command(ctx, key) {
+                    ctx.submit_command(cmd);
+                    ctx.set_handled();
+                }
+            }
             Event::MouseDown(mouse) if self.text().can_write() => {
                 if !mouse.focus {
                     ctx.request_focus();
@@ -383,13 +419,17 @@ impl<T: TextStorage + EditableText> Widget<T> for TextBox<T> {
                 self.reset_cursor_blink(ctx.request_timer(CURSOR_BLINK_DURATION));
             }
             Event::Command(ref cmd)
-                if self.text().can_read() && ctx.is_focused() && cmd.is(crate::commands::COPY) =>
+                if !self.text().is_composing()
+                    && ctx.is_focused()
+                    && cmd.is(crate::commands::COPY) =>
             {
                 self.text().borrow().set_clipboard();
                 ctx.set_handled();
             }
             Event::Command(cmd)
-                if self.text().can_write() && ctx.is_focused() && cmd.is(crate::commands::CUT) =>
+                if !self.text().is_composing()
+                    && ctx.is_focused()
+                    && cmd.is(crate::commands::CUT) =>
             {
                 if self.text().borrow().set_clipboard() {
                     let inval = self.text_mut().borrow_mut().insert_text(data, "");