blockly/demos/minimap/minimap.js

/**

 * Copyright 2017 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @fileoverview JavaScript for Blockly's Minimap demo.
 */
'use strict';

/**
 * Creating a separate namespace for minimap.
 */
var Minimap = {};

/**
 * Initialize the workspace and minimap.
 * @param {!Workspace} workspace The main workspace of the user.
 * @param {!Workspace} minimap The workspace that will be used as a minimap.
 */
Minimap.init = function(workspace, minimap) {
  this.workspace = workspace;
  this.minimap = minimap;

  // Adding scroll callback functionality to vScroll and hScroll just for this demo.
  // IMPORTANT: This should be changed when there is proper UI event handling
  //     API available and should be handled by workspace's event listeners.
  this.workspace.scrollbar.vScroll.setHandlePosition = function(newPosition) {
    this.handlePosition_ = newPosition;
    this.svgHandle_.setAttribute(this.positionAttribute_, this.handlePosition_);

    // Code above is same as the original setHandlePosition function in core/scrollbar.js.
    // New code starts from here.

    // Get the absolutePosition.
    var absolutePosition = (this.handlePosition_ / this.ratio);

    // Firing the scroll change listener.
    Minimap.onScrollChange(absolutePosition, this.horizontal_);
  };

  // Adding call back for horizontal scroll.
  this.workspace.scrollbar.hScroll.setHandlePosition = function(newPosition) {
    this.handlePosition_ = newPosition;
    this.svgHandle_.setAttribute(this.positionAttribute_, this.handlePosition_);

    // Code above is same as the original setHandlePosition function in core/scrollbar.js.
    // New code starts from here.

    // Get the absolutePosition.
    var absolutePosition = (this.handlePosition_ / this.ratio);

    // Firing the scroll change listener.
    Minimap.onScrollChange(absolutePosition, this.horizontal_);
  };


  // Required to stop a positive feedback loop when user clicks minimap
  // and the scroll changes, which in turn may change minimap.
  this.disableScrollChange = false;

  // Listen to events on the main workspace.
  this.workspace.addChangeListener(Minimap.mirrorEvent);

  //Get rectangle bounding the minimap div.
  this.rect = document.getElementById('mapDiv').getBoundingClientRect();

  // Create a svg overlay on the top of mapDiv for the minimap.
  this.svg = Blockly.utils.dom.createSvgElement('svg', {
    'xmlns': Blockly.utils.dom.SVG_NS,
    'xmlns:html': Blockly.utils.dom.HTML_NS,
    'xmlns:xlink': Blockly.utils.dom.XLINK_NS,
    'version': '1.1',
    'height': this.rect.bottom-this.rect.top,
    'width': this.rect.right-this.rect.left,
    'class': 'minimap',
  }, document.getElementById('mapDiv'));
  this.svg.style.top = this.rect.top + 'px';
  this.svg.style.left = this.rect.left + 'px';

  // Creating a rectangle in the minimap that represents current view.
  Blockly.utils.dom.createSvgElement('rect', {
    'width': 100,
    'height': 100,
    'class': 'mapDragger'
  }, this.svg);

  // Rectangle in the minimap that represents current view.
  this.mapDragger = this.svg.childNodes[0];

  // Adding mouse events to the rectangle, to make it Draggable.
  // Using Blockly.browserEvents.bind to attach mouse/touch listeners.
  Blockly.browserEvents.bind(
      this.mapDragger, 'mousedown', null, Minimap.mousedown);

  //When the window change, we need to resize the minimap window.
  window.addEventListener('resize', Minimap.repositionMinimap);

  // Mouse up event for the minimap.
  this.svg.addEventListener('mouseup', Minimap.updateMapDragger);

  //Boolean to check whether I am dragging the surface or not.
  this.isDragging = false;
};

Minimap.mousedown = function(e) {
  // Using Blockly.browserEvents.bind to attach mouse/touch listeners.
  Minimap.mouseMoveBindData = Blockly.browserEvents.bind(
      document, 'mousemove', null, Minimap.mousemove);
  Minimap.mouseUpBindData =
      Blockly.browserEvents.bind(document, 'mouseup', null, Minimap.mouseup);

  Minimap.isDragging = true;
  e.stopPropagation();
};

Minimap.mouseup = function(e) {
  Minimap.isDragging = false;
  // Removing listeners.
  Blockly.browserEvents.unbind(Minimap.mouseUpBindData);
  Blockly.browserEvents.unbind(Minimap.mouseMoveBindData);
  Minimap.updateMapDragger(e);
  e.stopPropagation();
};

Minimap.mousemove = function(e) {
  if (Minimap.isDragging) {
    Minimap.updateMapDragger(e);
    e.stopPropagation();
  }
};

/**
 * Run non-UI events from the main workspace on the minimap.
 * @param {!Blockly.Events.Abstract} event Event that triggered in the main
 *    workspace.
 */
Minimap.mirrorEvent = function(event) {
  if (event.isUiEvent) {
    return;  // Don't mirror UI events.
  }
  // Convert event to JSON.  This could then be transmitted across the net.
  var json = event.toJson();
  // Convert JSON back into an event, then execute it.
  var minimapEvent = Blockly.Events.fromJson(json, Minimap.minimap);
  minimapEvent.run(true);
  Minimap.scaleMinimap();
  Minimap.setDraggerHeight();
  Minimap.setDraggerWidth();
};

/**
 * Called when window is resized. Repositions the minimap overlay.
 */
Minimap.repositionMinimap = function() {
  Minimap.rect = document.getElementById('mapDiv').getBoundingClientRect();
  Minimap.svg.style.top = Minimap.rect.top + 'px';
  Minimap.svg.style.left = Minimap.rect.left + 'px';
};

/**
 * Updates the rectangle's height.
 */
Minimap.setDraggerHeight = function() {
  var workspaceMetrics = Minimap.workspace.getMetrics();
  var draggerHeight = (workspaceMetrics.viewHeight / Minimap.workspace.scale) *
      Minimap.minimap.scale;
  // It's zero when first block is placed.
  if (draggerHeight === 0) {
    return;
  }
  Minimap.mapDragger.setAttribute('height', draggerHeight);
};

/**
 * Updates the rectangle's width.
 */
Minimap.setDraggerWidth = function() {
  var workspaceMetrics = Minimap.workspace.getMetrics();
  var draggerWidth = (workspaceMetrics.viewWidth / Minimap.workspace.scale) *
      Minimap.minimap.scale;
  // It's zero when first block is placed.
  if (draggerWidth === 0) {
    return;
  }
  Minimap.mapDragger.setAttribute('width', draggerWidth);
};


/**
 * Updates the overall position of the viewport of the minimap by appropriately
 * using translate functions.
 */
Minimap.scaleMinimap = function() {
  var minimapBoundingBox = Minimap.minimap.getBlocksBoundingBox();
  var workspaceBoundingBox = Minimap.workspace.getBlocksBoundingBox();
  var workspaceMetrics = Minimap.workspace.getMetrics();
  var minimapMetrics = Minimap.minimap.getMetrics();

  // Scaling the mimimap such that all the blocks can be seen in the viewport.
  // This padding is default because this is how to scrollbar(in main workspace)
  // is implemented.
  var topPadding = (workspaceMetrics.viewHeight) * Minimap.minimap.scale /
      (2 * Minimap.workspace.scale);
  var sidePadding = (workspaceMetrics.viewWidth) * Minimap.minimap.scale /
      (2 * Minimap.workspace.scale);

  // If actual padding is more than half view ports height,
  // change it to actual padding.
  if ((workspaceBoundingBox.y * Minimap.workspace.scale -
      workspaceMetrics.contentTop) *
      Minimap.minimap.scale / Minimap.workspace.scale > topPadding) {
    topPadding = (workspaceBoundingBox.y * Minimap.workspace.scale -
        workspaceMetrics.contentTop) *
        Minimap.minimap.scale / Minimap.workspace.scale;
  }

  // If actual padding is more than half view ports height,
  // change it to actual padding.
  if ((workspaceBoundingBox.x * Minimap.workspace.scale -
      workspaceMetrics.contentLeft) *
      Minimap.minimap.scale / Minimap.workspace.scale > sidePadding) {
    sidePadding = (workspaceBoundingBox.x * Minimap.workspace.scale -
        workspaceMetrics.contentLeft) *
        Minimap.minimap.scale / Minimap.workspace.scale;
  }

  var scalex = (minimapMetrics.viewWidth - 2 * sidePadding) /
      minimapBoundingBox.width;
  var scaley = (minimapMetrics.viewHeight - 2 * topPadding) /
      minimapBoundingBox.height;
  Minimap.minimap.setScale(Math.min(scalex, scaley));

  // Translating the minimap.
  Minimap.minimap.translate(
      -minimapMetrics.contentLeft * Minimap.minimap.scale + sidePadding,
      -minimapMetrics.contentTop * Minimap.minimap.scale + topPadding);
};

/**
 * Handles the onclick event on the minimapBoundingBox.
 * Changes mapDraggers position.
 * @param {!Event} e Event from the mouse click.
 */
Minimap.updateMapDragger = function(e) {
  var y = e.clientY;
  var x = e.clientX;
  var draggerHeight = Minimap.mapDragger.getAttribute('height');
  var draggerWidth = Minimap.mapDragger.getAttribute('width');

  var finalY = y - Minimap.rect.top - draggerHeight / 2;
  var finalX = x - Minimap.rect.left - draggerWidth / 2;

  var maxValidY = (Minimap.workspace.getMetrics().contentHeight -
      Minimap.workspace.getMetrics().viewHeight) * Minimap.minimap.scale;
  var maxValidX = (Minimap.workspace.getMetrics().contentWidth -
      Minimap.workspace.getMetrics().viewWidth) * Minimap.minimap.scale;

  if (y + draggerHeight / 2 > Minimap.rect.bottom) {
    finalY = Minimap.rect.bottom - Minimap.rect.top - draggerHeight;
  } else if (y < Minimap.rect.top + draggerHeight / 2) {
    finalY = 0;
  }

  if (x + draggerWidth / 2 > Minimap.rect.right) {
    finalX = Minimap.rect.right - Minimap.rect.left - draggerWidth;
  } else if (x < Minimap.rect.left + draggerWidth / 2) {
    finalX = 0;
  }

  // Do not go below lower bound of scrollbar.
  if (finalY > maxValidY) {
    finalY = maxValidY;
  }
  if (finalX > maxValidX) {
    finalX = maxValidX;
  }
  Minimap.mapDragger.setAttribute('y', finalY);
  Minimap.mapDragger.setAttribute('x', finalX);
  // Required, otherwise creates a feedback loop.
  Minimap.disableScrollChange = true;
  Minimap.workspace.scrollbar.vScroll.set((finalY * Minimap.workspace.scale) /
                                          Minimap.minimap.scale);
  Minimap.workspace.scrollbar.hScroll.set((finalX * Minimap.workspace.scale) /
                                          Minimap.minimap.scale);
  Minimap.disableScrollChange = false;
};

/**
 * Handles the onclick event on the minimapBoundingBox, parameters are passed by
 * the event handler.
 * @param {number} position This is the absolute position of the scrollbar.
 * @param {boolean} horizontal Informs if the change event if for
 *     horizontal (true) or vertical (false) scrollbar.
 */
Minimap.onScrollChange = function(position, horizontal) {
  if (!Minimap.disableScrollChange) {
    Minimap.mapDragger.setAttribute(horizontal ? 'x' : 'y',
        position * Minimap.minimap.scale / Minimap.workspace.scale);
  }
};