feat: implement selection across bounds with hacky copy solution

- This commit implements the selection across bounds, which is it allows
  a selection to start out of bounds and allows a selection that started
  on another widget to be dragged in bounds and select multiple
  different widgets. However in order to get the copy working on
  `ctrl/cmd + c` it resorts to a hacky solution where each widget clears
  the clipboard when a drag movement comes into its bounds and when the
  user presses `ctrl/cmd + c` it appends it's selected text to the
  clipboard.

2 files changed, 170 insertions, 8 deletions

diff --git a/src/text.rs b/src/text.rs
index 851e77b..acc7d2c 100644
--- a/src/text.rs
+++ b/src/text.rs
@@ -177,6 +177,8 @@ pub struct State {
     selection: Selection,
     dragging: Option<Dragging>,
     last_click: Option<mouse::Click>,
+    potential_click: Option<mouse::Click>,
+    has_cleared_clipboard: bool,
     keyboard_modifiers: keyboard::Modifiers,
     visual_lines_bounds: Vec<core::Rectangle>,
 }
@@ -434,6 +436,14 @@ where
 
                     shell.capture_event();
                 } else {
+                    if let Some(position) = cursor.land().position() {
+                        let potential_click = mouse::Click::new(
+                            position,
+                            mouse::Button::Left,
+                            state.potential_click,
+                        );
+                        state.potential_click = Some(potential_click);
+                    }
                     state.selection = Selection::default();
                 }
             }
@@ -441,6 +451,7 @@ where
             | Event::Touch(touch::Event::FingerLifted { .. })
             | Event::Touch(touch::Event::FingerLost { .. }) => {
                 state.dragging = None;
+                state.potential_click = None;
             }
             Event::Mouse(mouse::Event::CursorMoved { .. })
             | Event::Touch(touch::Event::FingerMoved { .. }) => {
@@ -472,6 +483,65 @@ where
                             );
                         }
                     };
+                } else if let Some(potential_click) = state.potential_click
+                    && let Some(position) = cursor.position_over(bounds)
+                {
+                    // We had a click outside of bounds that dragged inside bounds
+                    let (line, index) = state
+                        .grapheme_line_and_index(
+                            potential_click.position(),
+                            bounds,
+                        )
+                        .unwrap_or((0, 0));
+                    let new_start = SelectionEnd { line, index };
+                    state.selection.select_range(new_start, new_start);
+
+                    let (line, index) = state
+                        .grapheme_line_and_index(position, bounds)
+                        .unwrap_or((0, 0));
+
+                    match potential_click.kind() {
+                        click::Kind::Single => {
+                            let new_end = SelectionEnd { line, index };
+
+                            state.selection.change_selection(new_end);
+
+                            state.dragging = Some(Dragging::Grapheme);
+                        }
+                        click::Kind::Double => {
+                            let new_end = SelectionEnd { line, index };
+
+                            state.selection.select_word(
+                                new_start.line,
+                                new_start.index,
+                                &state.paragraph,
+                            );
+                            state.selection.change_selection_by_word(
+                                new_end,
+                                &state.paragraph,
+                            );
+
+                            state.dragging = Some(Dragging::Word);
+                        }
+                        click::Kind::Triple => {
+                            state
+                                .selection
+                                .select_line(new_start.line, &state.paragraph);
+                            state.selection.change_selection_by_line(
+                                line,
+                                &state.paragraph,
+                            );
+                            state.dragging = Some(Dragging::Line);
+                        }
+                    }
+
+                    state.last_click = Some(potential_click);
+                    state.potential_click = None;
+
+                    // Clear the clipboard so that we can append to it if the user presses the copy
+                    // shortcut to be able to include all selected texts.
+                    clipboard.write(clipboard::Kind::Standard, String::new());
+                    state.has_cleared_clipboard = true;
                 }
             }
             Event::Keyboard(keyboard::Event::KeyPressed { key, .. }) => {
@@ -480,10 +550,20 @@ where
                         if state.keyboard_modifiers.command()
                             && !state.selection.is_empty() =>
                     {
-                        clipboard.write(
-                            clipboard::Kind::Standard,
-                            state.selection.text(&state.paragraph),
-                        );
+                        let contents =
+                            if state.has_cleared_clipboard {
+                                state.has_cleared_clipboard = false;
+                                clipboard
+                                    .read(clipboard::Kind::Standard)
+                                    .map(|c| {
+                                        if !c.is_empty() { c + "\n" } else { c }
+                                    })
+                                    .unwrap_or_default()
+                                    + &state.selection.text(&state.paragraph)
+                            } else {
+                                state.selection.text(&state.paragraph)
+                            };
+                        clipboard.write(clipboard::Kind::Standard, contents);
 
                         shell.capture_event();
                     }
diff --git a/src/text/rich.rs b/src/text/rich.rs
index 865f64a..2285b4e 100644
--- a/src/text/rich.rs
+++ b/src/text/rich.rs
@@ -224,6 +224,8 @@ struct State<Link> {
     selection: Selection,
     dragging: Option<Dragging>,
     last_click: Option<mouse::Click>,
+    potential_click: Option<mouse::Click>,
+    has_cleared_clipboard: bool,
     keyboard_modifiers: keyboard::Modifiers,
     visual_lines_bounds: Vec<core::Rectangle>,
 }
@@ -364,6 +366,8 @@ where
             selection: Selection::default(),
             dragging: None,
             last_click: None,
+            potential_click: None,
+            has_cleared_clipboard: false,
             keyboard_modifiers: keyboard::Modifiers::default(),
             visual_lines_bounds: Vec::new(),
         })
@@ -628,6 +632,14 @@ where
 
                     shell.capture_event();
                 } else {
+                    if let Some(position) = cursor.land().position() {
+                        let potential_click = mouse::Click::new(
+                            position,
+                            mouse::Button::Left,
+                            state.potential_click,
+                        );
+                        state.potential_click = Some(potential_click);
+                    }
                     state.selection = Selection::default();
                 }
             }
@@ -635,6 +647,7 @@ where
             | Event::Touch(touch::Event::FingerLifted { .. })
             | Event::Touch(touch::Event::FingerLost { .. }) => {
                 state.dragging = None;
+                state.potential_click = None;
                 if !matches!(
                     event,
                     Event::Touch(touch::Event::FingerLost { .. })
@@ -689,6 +702,65 @@ where
                             );
                         }
                     };
+                } else if let Some(potential_click) = state.potential_click
+                    && let Some(position) = cursor.position_over(bounds)
+                {
+                    // We had a click outside of bounds that dragged inside bounds
+                    let (line, index) = state
+                        .grapheme_line_and_index(
+                            potential_click.position(),
+                            bounds,
+                        )
+                        .unwrap_or((0, 0));
+                    let new_start = SelectionEnd { line, index };
+                    state.selection.select_range(new_start, new_start);
+
+                    let (line, index) = state
+                        .grapheme_line_and_index(position, bounds)
+                        .unwrap_or((0, 0));
+
+                    match potential_click.kind() {
+                        mouse::click::Kind::Single => {
+                            let new_end = SelectionEnd { line, index };
+
+                            state.selection.change_selection(new_end);
+
+                            state.dragging = Some(Dragging::Grapheme);
+                        }
+                        mouse::click::Kind::Double => {
+                            let new_end = SelectionEnd { line, index };
+
+                            state.selection.select_word(
+                                new_start.line,
+                                new_start.index,
+                                &state.paragraph,
+                            );
+                            state.selection.change_selection_by_word(
+                                new_end,
+                                &state.paragraph,
+                            );
+
+                            state.dragging = Some(Dragging::Word);
+                        }
+                        mouse::click::Kind::Triple => {
+                            state
+                                .selection
+                                .select_line(new_start.line, &state.paragraph);
+                            state.selection.change_selection_by_line(
+                                line,
+                                &state.paragraph,
+                            );
+                            state.dragging = Some(Dragging::Line);
+                        }
+                    }
+
+                    state.last_click = Some(potential_click);
+                    state.potential_click = None;
+
+                    // Clear the clipboard so that we can append to it if the user presses the copy
+                    // shortcut to be able to include all selected texts.
+                    clipboard.write(clipboard::Kind::Standard, String::new());
+                    state.has_cleared_clipboard = true;
                 }
             }
             Event::Keyboard(keyboard::Event::KeyPressed { key, .. }) => {
@@ -697,10 +769,20 @@ where
                         if state.keyboard_modifiers.command()
                             && !state.selection.is_empty() =>
                     {
-                        clipboard.write(
-                            clipboard::Kind::Standard,
-                            state.selection.text(&state.paragraph),
-                        );
+                        let contents =
+                            if state.has_cleared_clipboard {
+                                state.has_cleared_clipboard = false;
+                                clipboard
+                                    .read(clipboard::Kind::Standard)
+                                    .map(|c| {
+                                        if !c.is_empty() { c + "\n" } else { c }
+                                    })
+                                    .unwrap_or_default()
+                                    + &state.selection.text(&state.paragraph)
+                            } else {
+                                state.selection.text(&state.paragraph)
+                            };
+                        clipboard.write(clipboard::Kind::Standard, contents);
 
                         shell.capture_event();
                     }