Print Preview: Making margin lines draggable.

chrome/browser/resources/print_preview/margins_ui_pair.js

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+cr.define('print_preview', function() {
+  'strict';
+
+  /**
+   * @constructor
+   * This class represents a margin line and a textbox corresponding to that
+   * margin.
+   */
+  function MarginsUIPair(groupName) {
+    var marginsUIPair = document.createElement('div');
+    marginsUIPair.__proto__ = MarginsUIPair.prototype;
+    marginsUIPair.className = MarginsUIPair.CSS_CLASS;
+    // @type {string} Specifies which margin this line refers to.
+    marginsUIPair.marginGroup = groupName;
+
+    marginsUIPair.isTop_() || marginsUIPair.isBottom_() ?
+        marginsUIPair.classList.add('top-bottom') :
+        marginsUIPair.classList.add('left-right');
+
+    // @type {print_preview.Rect} A rectangle describing the dimensions of
+    //     the draggable area.
+    marginsUIPair.rectangle = null;
+    // @type {print_preview.Rect} A rectangle describing the four margins.
+    marginsUIPair.marginsRectangle = null;
+    // @type {print_preview.MarginLine} The line representing the margin.
+    marginsUIPair.line_ = new print_preview.MarginLine(groupName);
+    // @type {print_preview.MarginTextbox} The textbox corresponding to this
+    //     margin.
+    marginsUIPair.box_ = new print_preview.MarginTextbox(groupName);
+    // @type {print_preview.Point} The point where mousedown occured within the
+    // draggable area with respect the top-left corner of |this|.
+    marginsUIPair.mousePointerOffset = null;
+    // @type {print_preview.Point} The position of the origin before any
+    //     dragging in progress occured.
+    marginsUIPair.originBeforeDragging = null;
+
+    marginsUIPair.appendChild(marginsUIPair.line_);
+    marginsUIPair.appendChild(marginsUIPair.box_);
+
+    marginsUIPair.addEventListeners_();
+    return marginsUIPair;
+  }
+
+  MarginsUIPair.CSS_CLASS = 'margins-ui-pair';
+  // Width of the clickable region around each margin line in screen pixels.
+  MarginsUIPair.CLICKABLE_REGION = 20;
+
+  MarginsUIPair.prototype = {
+    __proto__: HTMLDivElement.prototype,
+
+    /**
+     * Updates the state.
+     */
+    update: function(marginsRectangle, value, valueLimit, keepDisplayedValue,
+        valueLimitInPercent) {
+      this.marginsRectangle = marginsRectangle;
+      this.valueLimitInPercent = valueLimitInPercent;
+      this.rectangle = this.getCoordinates_(this.marginsRectangle);
+      this.box_.update(value, valueLimit, keepDisplayedValue);
+    },
+
+    /**
+     * Draws |this| based on the state.
+     */
+    draw: function() {
+      this.drawDraggableArea_();
+      this.line_.draw();
+      this.box_.draw();
+    },
+
+    /**
+     * Draws the area that can be clicked in order to start dragging.
+     * @private
+     */
+    drawDraggableArea_: function() {
+      var width = previewArea.pdfPlugin_.offsetWidth;
+      var height = previewArea.pdfPlugin_.offsetHeight;
+
+      this.style.left = Math.round(this.rectangle.x * width) + 'px';
+      this.style.top = Math.round(this.rectangle.y * height) + 'px';
+      this.style.width = Math.round(this.rectangle.width * width) + 'px';
+      this.style.height = Math.round(this.rectangle.height * height) + 'px';
+    },
+
+    /**
+     * Calculates the coordinates and size of |this|.
+     * @param {print_preview.Rect} marginsRectangle A rectangle describing the
+     *     selected margins values in percentages.
+     * @private
+     */
+    getCoordinates_: function(marginsRectangle) {
+      var pageLocation = previewArea.getPageLocationNormalized();
+      var totalWidth = previewArea.pdfPlugin_.offsetWidth;
+      var totalHeight = previewArea.pdfPlugin_.offsetHeight;
+      var offsetY = (MarginsUIPair.CLICKABLE_REGION / 2) / totalHeight;
+      var offsetX = (MarginsUIPair.CLICKABLE_REGION / 2) / totalWidth;
+
+      if (this.isTop_()) {
+        var lineCoordinates = new print_preview.Rect(
+            pageLocation.x,
+            marginsRectangle.y - offsetY,
+            pageLocation.width,
+            MarginsUIPair.CLICKABLE_REGION / totalHeight);
+      } else if (this.isBottom_()) {
+        var lineCoordinates = new print_preview.Rect(
+            pageLocation.x,
+            marginsRectangle.bottom - offsetY,
+            pageLocation.width,
+            MarginsUIPair.CLICKABLE_REGION / totalHeight);
+      } else if (this.isRight_()) {
+        var lineCoordinates = new print_preview.Rect(
+            marginsRectangle.right - offsetX,
+            pageLocation.y,
+            MarginsUIPair.CLICKABLE_REGION / totalWidth,
+            pageLocation.height);
+      } else if (this.isLeft_()) {
+        var lineCoordinates = new print_preview.Rect(
+            marginsRectangle.x - offsetX,
+            pageLocation.y,
+            MarginsUIPair.CLICKABLE_REGION / totalWidth,
+            pageLocation.height);
+      }
+      return lineCoordinates;
+    },
+
+    /**
+     * @return {boolean} True if |this| refers to the top margin.
+     * @private
+     */
+    isTop_: function() {
+      return this.marginGroup == print_preview.MarginSettings.TOP_GROUP;
+    },
+
+    /**
+     * @return {boolean} True if |this| refers to the bottom margin.
+     * @private
+     */
+    isBottom_: function() {
+      return this.marginGroup == print_preview.MarginSettings.BOTTOM_GROUP;
+    },
+
+    /**
+     * @return {boolean} True if |this| refers to the left margin.
+     * @private
+     */
+    isLeft_: function() {
+      return this.marginGroup == print_preview.MarginSettings.LEFT_GROUP;
+    },
+
+    /**
+     * @return {boolean} True if |this| refers to the bottom margin.
+     * @private
+     */
+    isRight_: function() {
+      return this.marginGroup == print_preview.MarginSettings.RIGHT_GROUP;
+    },
+
+    /**
+     * Adds event listeners for events related to dragging.
+     */
+    addEventListeners_: function() {
+      this.onmousedown = this.onMouseDown_.bind(this);
+    },
+
+    /**
+     * Executes whenever a mousedown event occurs on |this| or its child nodes.
+     * @parameter {MouseEvent} e The event that occured.
+     */
+    onMouseDown_: function(e) {
+      if (e.target != this)
+        return;
+      var point = print_preview.MarginsUI.convert({x: e.x, y: e.y});
+      this.originBeforeDragging =
+          new print_preview.Point(this.offsetLeft, this.offsetTop);
+
+      this.mousePointerOffset =
+          { x: point.x - this.offsetLeft, y: point.y - this.offsetTop };
+      cr.dispatchSimpleEvent(this, 'MarginsLineMouseDown');
+    },
+
+    /**
+     * Moves |this| including all its children to |point|.
+     * @param {print_preview.Point} point The point where |this| should be
+     *     moved.
+     */
+    moveTo: function(point) {
+      if (this.isTop_() || this.isBottom_())
+        this.style.top = point.y  - this.mousePointerOffset.y + 'px';
+      else
+        this.style.left = point.x - this.mousePointerOffset.x + 'px';
+    },
+
+    /**
+     * @param {print_preview.Point} rhs The point to compare with.
+     * @return {number} The horizontal or vertical displacement in pixels
+     *     between |this.originBeforeDragging| and |rhs|.
+     */
+    getDragDisplacementFrom: function(rhs) {
+      var dragDisplacement = 0;
+      if (this.isTop_() || this.isBottom_()) {
+        dragDisplacement = (rhs.y - this.originBeforeDragging.y -
+            this.mousePointerOffset.y) / previewArea.height;
+      } else {
+        dragDisplacement = (rhs.x - this.originBeforeDragging.x -
+            this.mousePointerOffset.x) / previewArea.width;
+      }
+
+      if (this.isBottom_() || this.isRight_())
+        dragDisplacement *= -1;

[Evan Stade, 2011/10/14 21:58:36]

my point was that it seems like if you take the bottom line and drag up, versus
if you take the top line and drag up, the signs will be different. So you're
using an inverted coordinate system in each case. I think the comment should
mention this somehow.

[dpapad, 2011/10/14 23:14:38]

Done.

+      return dragDisplacement;
+    },
+
+    /**
+     * Updates |this| while dragging is in progress. Takes care of rejecting
+     * invalid margin values.
+     * @param {number} dragDeltaInPoints The difference in points between the
+     *     currently applied margin and the margin indicated by
+     *     |destinationPoint|.
+     * @param {print_preview.Point} destinationPoint The point where the margin
+     *     line should be drawn if |dragDeltaInPoints| is applied.
+     */
+    updateWhileDragging: function(dragDeltaInPoints, destinationPoint) {
+      this.box_.updateWhileDragging(dragDeltaInPoints);
+      var validity = this.box_.validateDelta(dragDeltaInPoints);
+      if (validity == 0)
+        this.moveTo(destinationPoint);
+      else if (validity == -1)
+        this.snapToMinValue_();
+      else if (validity == 1)
+        this.snapToMaxValue_();
+    },
+
+    /**
+     * Snaps |this| to the minimum allowed margin value (0). Happens whenever
+     * the user drags the margin line to a smaller value than the minimum
+     * allowed.
+     * @private
+     */
+    snapToMinValue_: function() {
+      var pageInformation = previewArea.getPageLocationNormalized();
+      var newMarginsRectangle = this.marginsRectangle.clone();
+      if (this.isTop_()) {
+        newMarginsRectangle.y = pageInformation.y;
+      } else if (this.isLeft_()) {
+        newMarginsRectangle.x = pageInformation.x;
+      } else if (this.isRight_()) {
+        newMarginsRectangle.x = pageInformation.x;
+        newMarginsRectangle.width = pageInformation.width;
+      } else if (this.isBottom_()) {
+        newMarginsRectangle.y = pageInformation.y;
+        newMarginsRectangle.height = pageInformation.height;
+      }
+
+      this.rectangle = this.getCoordinates_(newMarginsRectangle);
+      this.drawDraggableArea_();
+    },
+
+    /**
+     * Snaps |this| to the maximum allowed margin value. Happens whenever
+     * the user drags the margin line to a larger value than the maximum
+     * allowed.
+     * @private
+     */
+    snapToMaxValue_: function() {
+      var newMarginsRectangle = this.marginsRectangle.clone();
+
+      if (this.isTop_()) {
+        newMarginsRectangle.y = this.valueLimitInPercent;
+      } else if (this.isLeft_()) {
+        newMarginsRectangle.x = this.valueLimitInPercent;
+      } else if (this.isRight_()) {
+        newMarginsRectangle.x = 0;
+        newMarginsRectangle.width = this.valueLimitInPercent;
+      } else if (this.isBottom_()) {
+        newMarginsRectangle.y = 0;
+        newMarginsRectangle.height = this.valueLimitInPercent;
+      }
+
+      this.rectangle = this.getCoordinates_(newMarginsRectangle);
+      this.drawDraggableArea_();
+    },
+

[Evan Stade, 2011/10/14 21:58:36]

don't need this newline

[dpapad, 2011/10/14 23:14:38]

Done.

+  };
+
+  return {
+    MarginsUIPair: MarginsUIPair
+  };
+});