Function handleMouseEvent

src/ink/components/App.tsx:522–664

(app: App, m: ParsedMouse)

/** Exported for testing. Mutates app.props.selection and click/hover state. */
export function handleMouseEvent(app: App, m: ParsedMouse): void {
  // Allow disabling click handling while keeping wheel scroll (which goes
  // through the keybinding system as 'wheelup'/'wheeldown', not here).
  if (isMouseClicksDisabled()) return;
  const sel = app.props.selection;
  // Terminal coords are 1-indexed; screen buffer is 0-indexed
  const col = m.col - 1;
  const row = m.row - 1;
  const baseButton = m.button & 0x03;
  if (m.action === 'press') {
    if ((m.button & 0x20) !== 0 && baseButton === 3) {
      // Mode-1003 motion with no button held. Dispatch hover; skip the
      // rest of this handler (no selection, no click-count side effects).
      // Lost-release recovery: no-button motion while isDragging=true means
      // the release happened outside the terminal window (iTerm2 doesn't
      // capture the pointer past window bounds, so the SGR 'm' never
      // arrives). Finish the selection here so copy-on-select fires. The
      // FOCUS_OUT handler covers the "switched apps" case but not "released
      // past the edge, came back" — and tmux drops focus events unless
      // `focus-events on` is set, so this is the more reliable signal.
      if (sel.isDragging) {
        finishSelection(sel);
        app.props.onSelectionChange();
      }
      if (col === app.lastHoverCol && row === app.lastHoverRow) return;
      app.lastHoverCol = col;
      app.lastHoverRow = row;
      app.props.onHoverAt(col, row);
      return;
    }
    if (baseButton !== 0) {
      // Non-left press breaks the multi-click chain.
      app.clickCount = 0;
      return;
    }
    if ((m.button & 0x20) !== 0) {
      // Drag motion: mode-aware extension (char/word/line). onSelectionDrag
      // calls notifySelectionChange internally — no extra onSelectionChange.
      app.props.onSelectionDrag(col, row);
      return;
    }
    // Lost-release fallback for mode-1002-only terminals: a fresh press
    // while isDragging=true means the previous release was dropped (cursor
    // left the window). Finish that selection so copy-on-select fires
    // before startSelection/onMultiClick clobbers it. Mode-1003 terminals
    // hit the no-button-motion recovery above instead, so this is rare.
    if (sel.isDragging) {
      finishSelection(sel);
      app.props.onSelectionChange();
    }
    // Fresh left press. Detect multi-click HERE (not on release) so the
    // word/line highlight appears immediately and a subsequent drag can
    // extend by word/line like native macOS. Previously detected on
    // release, which meant (a) visible latency before the word highlights
    // and (b) double-click+drag fell through to char-mode selection.
    const now = Date.now();
    const nearLast = now - app.lastClickTime < MULTI_CLICK_TIMEOUT_MS && Math.abs(col - app.lastClickCol) <= MULTI_CLICK_DISTANCE && Math.abs(row - app.lastClickRow) <= MULTI_CLICK_DISTANCE;
    app.clickCount = nearLast ? app.clickCount + 1 : 1;