field_label.js

/**
 * Visual Blocks Editor
 *
 * Copyright 2012 Google Inc.
 * http://code.google.com/p/blockly/
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @fileoverview Non-editable text field.  Used for titles, labels, etc.
 * @author fraser@google.com (Neil Fraser)
 */

/**
 * Class for a non-editable field.
 * @param {string} text The initial content of the field.
 * @constructor
 */
Blockly.FieldLabel = function(text) {
  this.sourceBlock_ = null;
  // Build the DOM.
  this.textElement_ = Blockly.createSvgElement('text',
      {'class': 'blocklyText'}, null);
  this.setText(text);
};

// Text is a subclass of Field.
Blockly.FieldLabel.prototype = new Blockly.Field(null);

/**
 * Editable fields are saved by the XML renderer, non-editable fields are not.
 */
Blockly.FieldLabel.prototype.EDITABLE = false;

/**
 * Install this text on a block.
 * @param {!Blockly.Block} block The block containing this text.
 */
Blockly.FieldLabel.prototype.init = function(block) {
  if (this.sourceBlock_) {
    throw 'Text has already been initialized once.';
  }
  this.sourceBlock_ = block;
  block.getSvgRoot().appendChild(this.textElement_);

  // Configure the field to be transparent with respect to tooltips.
  this.textElement_.tooltip = this.sourceBlock_;
  Blockly.Tooltip && Blockly.Tooltip.bindMouseEvents(this.textElement_);
};

/**
 * Destroy all DOM objects belonging to this text.
 */
Blockly.FieldLabel.prototype.destroy = function() {
  this.textElement_.parentNode.removeChild(this.textElement_);
  this.textElement_ = null;
};

/**
 * Gets the group element for this field.
 * Used for measuring the size and for positioning.
 * @return {!Element} The group element.
 */
Blockly.FieldLabel.prototype.getRootElement = function() {
  return this.textElement_;
};

/**
 * Returns the resulting bounding box.
 * @return {Object} Object containing width/height/x/y properties.
 */
Blockly.FieldLabel.prototype.render = function() {
  try {
    var bBox = this.textElement_.getBBox();
  } catch (e) {
    // Firefox has trouble with hidden elements (Bug 528969).
    return null;
  }
  if (bBox.height == 0) {
    bBox.height = 18;
  }
  return bBox;
};

/**
 * Change the tooltip text for this field.
 * @param {string|!Element} newTip Text for tooltip or a parent element to
 *     link to for its tooltip.
 */
Blockly.FieldLabel.prototype.setTooltip = function(newTip) {
  this.textElement_.tooltip = newTip;
};