Function startOperation

src/codemirror.js:3010–3036

(cm)

  var nextOpId = 0;
  // Start a new operation.
  function startOperation(cm) {
    cm.curOp = {
      cm: cm,
      viewChanged: false,      // Flag that indicates that lines might need to be redrawn
      startHeight: cm.doc.height, // Used to detect need to update scrollbar
      forceUpdate: false,      // Used to force a redraw
      updateInput: null,       // Whether to reset the input textarea
      typing: false,           // Whether this reset should be careful to leave existing text (for compositing)
      changeObjs: null,        // Accumulated changes, for firing change events
      cursorActivityHandlers: null, // Set of handlers to fire cursorActivity on
      cursorActivityCalled: 0, // Tracks which cursorActivity handlers have been called already
      selectionChanged: false, // Whether the selection needs to be redrawn
      updateMaxLine: false,    // Set when the widest line needs to be determined anew
      scrollLeft: null, scrollTop: null, // Intermediate scroll position, not pushed to DOM yet
      scrollToPos: null,       // Used to scroll to a specific position
      focus: false,
      id: ++nextOpId           // Unique ID
    };
    if (operationGroup) {
      operationGroup.ops.push(cm.curOp);
    } else {
      cm.curOp.ownsGroup = operationGroup = {
        ops: [cm.curOp],
        delayedCallbacks: []
      };
    }
  }

  function fireCallbacksForOps(group) {
    // Calls delayed callbacks and cursorActivity handlers until no