editor/editor/

pointer.rs

//! Presses, drags and clicks below the last block.

use super::*;

impl Editor {
    /// The task block whose checkbox `at` landed in, in window coordinates.
    ///
    /// The box that painted rather than the marker column: a press in the
    /// gutter beside it is a press on the row, and still places a caret.
    pub(super) fn checkbox_at(&self, at: gpui::Point<gpui::Pixels>) -> Option<usize> {
        let ix = self.layouts.block_at(at)?;
        self.layouts
            .checkbox_bounds(ix)
            .is_some_and(|bounds| bounds.contains(&at))
            .then_some(ix)
    }

    /// The paragraph a document ending in a fence, a table, a rule or an image
    /// has no other way to grow: a fence swallows Enter, a cell and a caption
    /// have nowhere to put one, and a rule holds no caret at all. `false` when
    /// the last block ends in a body, which can carry on by itself.
    pub(super) fn append_tail(&mut self, cx: &mut Context<Self>) -> bool {
        let Some(last) = self.doc.blocks.len().checked_sub(1) else {
            return false;
        };
        if !self.blocks() {
            return false;
        }
        if self.doc.blocks[last].parts().last() == Some(&Part::Body) {
            return false;
        }
        self.edit(EditKind::Structure, cx, |this| {
            this.doc
                .blocks
                .push(markdown::Block::new(BlockKind::Paragraph(Text::default())));
            let ix = this.doc.blocks.len() - 1;
            this.selection = Selection::at(Cursor::new(ix, Part::Body, 0).clamp(&this.doc));
            vec![]
        });
        true
    }

    /// Press at `position` as if on the document: menus close, the editor
    /// takes focus, and the caret goes to the nearest place a caret can be —
    /// below the last block, above the first, or beside a line.
    ///
    /// For a host whose own frame around the editor should behave as the page. A
    /// press the editor's box already took is marked with
    /// [`Window::prevent_default`], and this ignores one so marked.
    pub fn press(
        &mut self,
        position: gpui::Point<gpui::Pixels>,
        click_count: usize,
        modifiers: gpui::Modifiers,
        window: &mut Window,
        cx: &mut Context<Self>,
    ) {
        if window.default_prevented() {
            return;
        }
        window.prevent_default();
        self.pressed(position, click_count, modifiers, window, cx);
    }

    /// Whether a press is being dragged: a selection, a lifted block or an
    /// image resize.
    pub(super) fn in_drag(&self) -> bool {
        self.dragging || self.lifted.is_some() || self.resizing.is_some()
    }

    /// Follow a dragged pointer, wherever in the window it is.
    pub(super) fn drag_to(&mut self, position: gpui::Point<gpui::Pixels>, cx: &mut Context<Self>) {
        // A lifted block follows the pointer.
        if let Some((from, _)) = self.lifted {
            if let Some(to) = self.layouts.block_at(position) {
                self.lifted = Some((from, to));
                cx.notify();
            }
            return;
        }
        // An image being resized follows the pointer the same way — the
        // document holds nothing until the handle is released.
        if let Some((ix, _)) = self.resizing {
            if let Some(width) = self.dragged_width(ix, position.x) {
                self.resizing = Some((ix, Some(width)));
                cx.notify();
            }
            return;
        }
        if self.dragging
            && let Some(hit) = self.layouts.hit(position)
        {
            self.selection = self.selection.extend_to(hit).clamp(&self.doc);
            cx.notify();
        }
    }

    pub(super) fn pressed(
        &mut self,
        position: gpui::Point<gpui::Pixels>,
        click_count: usize,
        modifiers: gpui::Modifiers,
        window: &mut Window,
        cx: &mut Context<Self>,
    ) {
        ui::popover::close_popup(self, cx, |this| &mut this.block_menu);
        ui::popover::close_popup(self, cx, |this| &mut this.language_menu);
        self.pasted = None;
        self.focus_handle.clone().focus(window, cx);
        // Ahead of the hit test, and returning without one: the
        // box is a control, and a caret dropped into the row
        // behind it would move the caret on every check.
        if let Some(ix) = self.checkbox_at(position) {
            self.toggle_task(ix, cx);
            return;
        }
        if self.tail_click(position, cx) {
            return;
        }
        let Some(hit) = self.layouts.hit(position) else {
            return cx.notify();
        };
        self.selection = match click_count {
            // Shift extends from wherever the anchor already is,
            // which is what makes click-then-shift-click a range.
            _ if modifiers.shift => self.selection.extend_to(hit),
            1 => Selection::at(hit),
            2 => Selection::new(hit.word_left(&self.doc), hit.word_right(&self.doc)),
            _ => Selection::new(hit.home(), hit.end(&self.doc)),
        }
        .clamp(&self.doc);
        self.dragging = click_count == 1 && !modifiers.shift;
        self.history.interrupt();
        self.caret_moved();
        // Only the editor sees the press, so only the editor can
        // say which anchor it landed on.
        if let Some(id) = self.anchor_at(position) {
            cx.emit(EditorEvent::AnchorActivated(id));
        }
        cx.notify();
    }

    /// A click past the end of the document. Without this the document has no
    /// end: the click snaps back into the block above it, and what gets typed
    /// lands inside the code the reader was trying to escape.
    pub(super) fn tail_click(
        &mut self,
        at: gpui::Point<gpui::Pixels>,
        cx: &mut Context<Self>,
    ) -> bool {
        let Some(last) = self.doc.blocks.len().checked_sub(1) else {
            return false;
        };
        let Some(bounds) = self.layouts.block_bounds(last) else {
            return false;
        };
        at.y > bounds.origin.y + bounds.size.height && self.append_tail(cx)
    }
}