gecko/browser/base/content/tabcandy/app/trench.js

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is trench.js.
 *
 * The Initial Developer of the Original Code is
 * Michael Yoshitaka Erlewine <mitcho@mitcho.com>.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 * Ian Gilman <ian@iangilman.com>
 *
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 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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 * the provisions above, a recipient may use your version of this file under
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 * ***** END LICENSE BLOCK ***** */

// **********
// Title: trench.js 

// ##########
// Class: Trench
// 
// Class for drag-snapping regions; called "trenches" as they are long and narrow.

// Constructor: Trench
// 
// Parameters:
//   element - the DOM element for Item (Group or TabItem) from which the trench is projected
//   xory - either "x" or "y": whether the trench's <position> is along the x- or y-axis.
//     In other words, if "x", the trench is vertical; if "y", the trench is horizontal.
//   type - either "border" or "guide". Border trenches mark the border of an Item.
//     Guide trenches extend out (unless they are intercepted) and act as "guides".
//   edge - which edge of the Item that this trench corresponds to. 
//     Either "top", "left", "bottom", or "right".
var Trench = function(element, xory, type, edge) {
  //----------
  // Variable: id
  // (integer) The id for the Trench. Set sequentially via <Trenches.nextId>
  this.id = Trenches.nextId++;

  // ---------
  // Variables: Initial parameters
  //   element - (DOMElement)
  //   xory - (string) "x" or "y"
  //   type - (string) "border" or "guide"
  //   edge - (string) "top", "left", "bottom", or "right"
  this.el = element;
  this.xory = xory; // either "x" or "y"
  this.type = type; // "border" or "guide"
  this.edge = edge; // "top", "left", "bottom", or "right"

  this.$el = iQ(this.el);

  //----------
  // Variable: active
  // (boolean) Whether this trench is currently active or not.
  // Basically every trench aside for those projected by the Item currently being dragged
  // all become active.
  this.active = false;
  this.gutter = Items.defaultGutter;

  //----------
  // Variable: position
  // (integer) position is the position that we should snap to.
  this.position = 0;

  //----------
  // Variable: radius
  // (integer) radius is how far away we should snap from
  this.radius = Trenches.defaultRadius;

  //----------
  // Variables: some Ranges
  //   range - (<Range>) explicit range; this is along the transverse axis
  //   minRange - (<Range>) the minimum active range
  //   activeRange - (<Range>) the currently active range
  this.range = new Range(0,10000);
  this.minRange = new Range(0,0);
  this.activeRange = new Range(0,10000);
};
Trench.prototype = {
  //----------
  // Function: setPosition
  // set the trench's position.
  // 
  // Parameters:
  //   position - (integer) px center position of the trench
  //   range - (<Range>) the explicit active range of the trench
  //   minRange - (<Range>) the minimum range of the trench
  setPosition: function Trench_setPos(position, range, minRange) {
    this.position = position;
    
    // optionally, set the range.
    if (isRange(range)) {
      this.range = range;
    }
    
    // if there's a minRange, set that too.
    if (isRange(minRange))
      this.minRange = minRange;
    
    // set the appropriate bounds as a rect.
    if ( this.xory == "x" ) // horizontal
      this.rect = new Rect ( this.position - this.radius, this.range.min, 2 * this.radius, this.range.extent );
    else
      this.rect = new Rect ( this.range.min, this.position - this.radius, this.range.extent, 2 * this.radius );
      
    this.show(); // DEBUG

  },
  
  //----------
  // Function: setActiveRange
  // set the trench's currently active range.
  // 
  // Parameters:
  //   activeRange - (<Range>)
  setActiveRange: function Trench_setActiveRect(activeRange) {
    if (!isRange(activeRange))
      return false;
    this.activeRange = activeRange;
    if ( this.xory == "x" ) // horizontal
      this.activeRect = new Rect ( this.position - this.radius, this.activeRange.min, 2 * this.radius, this.activeRange.extent );
    else
      this.activeRect = new Rect ( this.activeRange.min, this.position - this.radius, this.activeRange.extent, 2 * this.radius );    
  },
  
  //----------
  // Function: setWithRect
  // Set the trench's position using the given rect. We know which side of the rect we should match
  // because we've already recorded this information in <edge>.
  // 
  // Parameters:
  //   rect - (<Rect>)
  setWithRect: function Trench_setWithRect(rect) {
    
    if (!isRect(rect))
      Utils.error('argument must be Rect');
    
    // First, calculate the range for this trench.
    // Border trenches are always only active for the length of this range.
    // Guide trenches, however, still use this value as its minRange.
    if (this.xory == "x")
      var range = new Range(rect.top - this.gutter, rect.bottom + this.gutter);
    else
      var range = new Range(rect.left - this.gutter, rect.right + this.gutter);

    if (this.type == "border") {
      // border trenches have a range, so set that too.
      if (this.edge == "left")
        this.setPosition(rect.left - this.gutter, range);
      else if (this.edge == "right")
        this.setPosition(rect.right + this.gutter, range);
      else if (this.edge == "top")
        this.setPosition(rect.top - this.gutter, range);
      else if (this.edge == "bottom")
        this.setPosition(rect.bottom + this.gutter, range);
    } else if (this.type == "guide") {
      // guide trenches have no range, but do have a minRange.
      if (this.edge == "left")    
        this.setPosition(rect.left, false, range);
      else if (this.edge == "right")
        this.setPosition(rect.right, false, range);
      else if (this.edge == "top")
        this.setPosition(rect.top, false, range);
      else if (this.edge == "bottom")
        this.setPosition(rect.bottom, false, range);
    }
  },
  
  //----------
  // Function: show
  // If <Trenches.showDebug> is true, we will draw the trench.
  // 
  // Active portions are drawn with 0.5 opacity. If <active> is false, the entire trench will be
  // very translucent.
  show: function Trench_show() { // DEBUG
    if (!Trenches.showDebug) {
      this.hide();
      return;
    }

    if (!this.visibleTrench)
      this.visibleTrench = iQ("<div/>").css({position: 'absolute', zIndex:-102, opacity: 0.05, id: 'visibleTrench'+this.id});
    var visibleTrench = this.visibleTrench;

    if (!this.activeVisibleTrench) {
      this.activeVisibleTrench = iQ("<div/>").css({position: 'absolute', zIndex:-101, id: 'activeVisibleTrench'+this.id});
    }
    var activeVisibleTrench = this.activeVisibleTrench;

    if (this.active)
      activeVisibleTrench.css({opacity: 0.45});
    else
      activeVisibleTrench.css({opacity: 0});
      
    if (this.type == "border") {
      visibleTrench.css({backgroundColor:'red'});
      activeVisibleTrench.css({backgroundColor:'red'});      
    } else {
      visibleTrench.css({backgroundColor:'blue'});
      activeVisibleTrench.css({backgroundColor:'blue'});
    }

    visibleTrench.css(this.rect);
    activeVisibleTrench.css(this.activeRect || this.rect);
    iQ("body").append(visibleTrench);
    iQ("body").append(activeVisibleTrench);
  },
  
  //----------
  // Function: hide
  // Hide the trench.
  hide: function Trench_hide() {
    if (this.visibleTrench)
      this.visibleTrench.remove();
  },

  //----------
  // Function: rectOverlaps
  // Given a <Rect>, compute whether it overlaps with this trench. If it does, return an
  // adjusted ("snapped") <Rect>; if it does not overlap, simply return false.
  //
  // Note that simply overlapping is not all that is required to be affected by this function.
  // Trenches can only affect certain edges of rectangles... for example, a "left"-edge guide
  // trench should only affect left edges of rectangles. We don't snap right edges to left-edged
  // guide trenches. For border trenches, the logic is a bit different, so left snaps to right and
  // top snaps to bottom.
  // 
  // Parameters:
  //   rect - (<Rect>) the rectangle in question
  //   assumeConstantSize - (boolean) whether the rect's dimensions are sacred or not
  //   keepProportional - (boolean) if we are allowed to change the rect's size, whether the
  //                                dimensions should scaled proportionally or not.
  // 
  // Returns:
  //   false - if rect does not overlap with this trench
  //   newRect - (<Rect>) an adjusted version of rect, if it is affected by this trench
  rectOverlaps: function Trench_rectOverlaps(rect,assumeConstantSize,keepProportional) {
    var edgeToCheck;
    if (this.type == "border") {
      if (this.edge == "left")
        edgeToCheck = "right";
      else if (this.edge == "right")
        edgeToCheck = "left";
      else if (this.edge == "top")
        edgeToCheck = "bottom";
      else if (this.edge == "bottom")
        edgeToCheck = "top";
    } else { // if trench type is guide or barrier...
      edgeToCheck = this.edge;
    }

    rect.adjustedEdge = edgeToCheck;
    
    switch (edgeToCheck) {
      case "left":
        if (this.ruleOverlaps(rect.left, rect.yRange)) {
          rect.left = this.position;
          return rect;
        }
        break;
      case "right":
        if (this.ruleOverlaps(rect.right, rect.yRange)) {
          if (assumeConstantSize) {
            rect.left = this.position - rect.width;
          } else {
            var newWidth = this.position - rect.left;
            if (keepProportional)
              rect.height = rect.height * newWidth / rect.width;
            rect.width = newWidth;
          }
          return rect;
        }
        break;
      case "top":
        if (this.ruleOverlaps(rect.top, rect.xRange)) {
          rect.top = this.position;
          return rect;
        }
        break;
      case "bottom":
        if (this.ruleOverlaps(rect.bottom, rect.xRange)) {
          if (assumeConstantSize) {
            rect.top = this.position - rect.height;
          } else {
            var newHeight = this.position - rect.top;
            if (keepProportional)
              rect.width = rect.width * newHeight / rect.height;
            rect.height = newHeight;
          }
          return rect;
        }
    }
      
    return false;
  },
  
  //----------
  // Function: ruleOverlaps
  // Computes whether the given "rule" (a line segment, essentially), given by the position and
  // range arguments, overlaps with the current trench. Note that this function assumes that
  // the rule and the trench are in the same direction: both horizontal, or both vertical.
  // 
  // Parameters:
  //   position - (integer) a position in px
  //   range - (<Range>) the rule's range
  ruleOverlaps: function Trench_ruleOverlaps(position, range) {
    return (this.position - this.radius <= position && position <= this.position + this.radius
            && this.activeRange.contains(range));
  },
  
  //----------
  // Function: adjustRangeIfIntercept
  // Computes whether the given boundary (given as a position and its active range), perpendicular
  // to the trench, intercepts the trench or not. If it does, it returns an adjusted <Range> for 
  // the trench. If not, it returns false.
  // 
  // Parameters:
  //   position - (integer) the position of the boundary
  //   range - (<Range>) the target's range, on the trench's transverse axis
  adjustRangeIfIntercept: function Trench_adjustRangeIfIntercept(position, range) {
    if (this.position - this.radius > range.min && this.position + this.radius < range.max) {
      var activeRange = new Range(this.activeRange);
      
      // there are three ways this can go:
      // 1. position < minRange.min
      // 2. position > minRange.max
      // 3. position >= minRange.min && position <= minRange.max
      
      if (position < this.minRange.min) {
        activeRange.min = Math.min(this.minRange.min,position);        
      } else if (position > this.minRange.max) {
        activeRange.max = Math.max(this.minRange.max,position);
      } else {
        // this should be impossible because items can't overlap and we've already checked
        // that the range intercepts.
      }
      return activeRange;
    }
    return false;
  },
  
  //----------
  // Function: calculateActiveRange
  // Computes and sets the <activeRange> for the trench, based on the <Groups> around.
  // This makes it so trenches' active ranges don't extend through other groups.
  calculateActiveRange: function Trench_calculateActiveRange() {
    // only guide-type trenches need to set an active rect
    if (this.type != 'guide')
      return;

    // first, reset the activeRange
    this.setActiveRange(this.range);

    var groups = Groups.groups;
    var trench = this;
    groups.forEach(function( group ) {
      if (group.isDragging) // floating groups don't block trenches
        return;
      if (group.isNewTabsGroup())
        return;
      if (trench.el == group.container) // groups don't block their own trenches
        return;
      var bounds = group.getBounds();
      var activeRange = new Range();
      if (trench.xory == 'y') { // if this trench is horizontal...
        activeRange = trench.adjustRangeIfIntercept(bounds.left, bounds.yRange);
        if (activeRange)
          trench.setActiveRange(activeRange);
        activeRange = trench.adjustRangeIfIntercept(bounds.right, bounds.yRange);
        if (activeRange)
          trench.setActiveRange(activeRange);
      } else { // if this trench is vertical...
        activeRange = trench.adjustRangeIfIntercept(bounds.top, bounds.xRange);
        if (activeRange)
          trench.setActiveRange(activeRange);
        activeRange = trench.adjustRangeIfIntercept(bounds.bottom, bounds.xRange);
        if (activeRange)
          trench.setActiveRange(activeRange);
      }
    });
  }
};

// ##########
// Class: Trenches
// Singelton for managing all <Trench>es. 
var Trenches = {
  // ---------
  // Variables:
  //   nextId - (integer) a counter for the next <Trench>'s <Trench.id> value.
  //   showDebug - (boolean) whether to draw the <Trench>es or not.
  //   defaultRadius - (integer) the default radius for new <Trench>es.
  nextId: 0,
  showDebug: false,
  defaultRadius: 10,

  // ---------
  // Variables: snapping preferences; used to break ties in snapping.
  //   preferTop - (boolean) prefer snapping to the top to the bottom
  //   preferLeft - (boolean) prefer snapping to the left to the right
  preferTop: true,
  preferLeft: true,
  
  activeTrenches: {},
  trenches: [],

  // ---------
  // Function: getById
  // Return the specified <Trench>.
  // 
  // Parameters:
  //   id - (integer)
  getById: function Trenches_getById(id) {
    return this.trenches[id];
  },

  // ---------
  // Function: register
  // Register a new <Trench> and returns the resulting <Trench> ID.
  // 
  // Parameters:
  // See the constructor <Trench.Trench>'s parameters.
  // 
  // Returns:
  //   id - (boolean) the new <Trench>'s ID.
  register: function Trenches_register(element, xory, type, edge) {
    var trench = new Trench(element, xory, type, edge);
    this.trenches[trench.id] = trench;
    return trench.id;
  },

  // ---------
  // Function: unregister
  // Unregister one or more <Trench>es.
  // 
  // Parameters:
  //   ids - (integer) a single <Trench> ID or (array) a list of <Trench> IDs.
  unregister: function Trenches_unregister(ids) {
    if (!iQ.isArray(ids))
      ids = [ids];
    var self = this;
    ids.forEach(function(id){
      self.trenches[id].hide();
      delete self.trenches[id];
    });
  },

  // ---------
  // Function: activateOthersTrenches
  // Activate all <Trench>es other than those projected by the current element.
  // 
  // Parameters:
  //   element - (DOMElement) the DOM element of the Item being dragged or resized.
  activateOthersTrenches: function Trenches_activateOthersTrenches(element) {
    this.trenches.forEach(function(t) {
      if (t.el === element)
        return;
      t.active = true;
      t.calculateActiveRange();
      t.show(); // debug
    });
  },

  // ---------
  // Function: disactivate
  // After <activateOthersTrenches>, disactivates all the <Trench>es again.
  disactivate: function Trenches_disactivate() {
    this.trenches.forEach(function(t) {
      t.active = false;
      t.show();
    });
  },

  // ---------
  // Function: snap
  // Used to "snap" an object's bounds to active trenches and to the edge of the window.
  // If the meta key is down (<Key.meta>), it will not snap but will still enforce the rect
  // not leaving the safe bounds of the window.
  //
  // Parameters:
  //   rect - (<Rect>) the object's current bounds 
  //   assumeConstantSize - (boolean) whether the rect's dimensions are sacred or not
  //   keepProportional - (boolean) if we are allowed to change the rect's size, whether the
  //                                dimensions should scaled proportionally or not.
  //   
  // Returns:
  //   (<Rect>) - the updated bounds, if they were updated
  //   false - if the bounds were not updated
  snap: function Trenches_snap(rect,assumeConstantSize,keepProportional) {
    var aT = this.activeTrenches;
    
    var updated = false;
    var updatedX = false;
    var updatedY = false;
    
    for (let i in this.trenches) {
      var t = this.trenches[i];
      if (!t.active)
        continue;
      // newRect will be a new rect, or false
      var newRect = t.rectOverlaps(rect,assumeConstantSize,keepProportional);

      if (newRect) {
        if (assumeConstantSize && updatedX && updatedY)
          break;
        if (assumeConstantSize && updatedX && (newRect.adjustedEdge == "left"||newRect.adjustedEdge == "right"))
          continue;
        if (assumeConstantSize && updatedY && (newRect.adjustedEdge == "top"||newRect.adjustedEdge == "bottom"))
          continue;
         rect = newRect;
         updated = true;
  
        // if updatedX, we don't need to update x any more.
        if (newRect.adjustedEdge == "left" && this.preferLeft)
          updatedX = true;
        if (newRect.adjustedEdge == "right" && !this.preferLeft)
          updatedX = true;
  
        // if updatedY, we don't need to update x any more.
        if (newRect.adjustedEdge == "top" && this.preferTop)
          updatedY = true;
        if (newRect.adjustedEdge == "bottom" && !this.preferTop)
          updatedY = true;

      }
    }    

    if (updated)
      return rect;
    else
      return false;
  },

  // ---------
  // Function: show
  // <Trench.show> all <Trench>es.
  show: function Trenches_show() {
    this.trenches.forEach(function(t){
      t.show();
    });
  }, 

  // ---------
  // Function: toggleShown
  // Toggle <Trenches.showDebug> and trigger <Trenches.show>
  toggleShown: function Trenches_toggleShown() {
    this.showDebug = !this.showDebug;
    this.show();
  }
};