forked from mirrors/gecko-dev
317 lines
11 KiB
JavaScript
317 lines
11 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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"use strict";
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var gManagers = new WeakMap();
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const kPaletteId = "customization-palette";
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var EXPORTED_SYMBOLS = ["DragPositionManager"];
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function AreaPositionManager(aContainer) {
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// Caching the direction and bounds of the container for quick access later:
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this._rtl = aContainer.ownerGlobal.RTL_UI;
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let containerRect = aContainer.getBoundingClientRect();
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this._containerInfo = {
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left: containerRect.left,
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right: containerRect.right,
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top: containerRect.top,
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width: containerRect.width,
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};
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this._horizontalDistance = null;
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this.update(aContainer);
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}
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AreaPositionManager.prototype = {
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_nodePositionStore: null,
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update(aContainer) {
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this._nodePositionStore = new WeakMap();
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let last = null;
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let singleItemHeight;
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for (let child of aContainer.children) {
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if (child.hidden) {
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continue;
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}
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let coordinates = this._lazyStoreGet(child);
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// We keep a baseline horizontal distance between nodes around
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// for use when we can't compare with previous/next nodes
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if (!this._horizontalDistance && last) {
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this._horizontalDistance = coordinates.left - last.left;
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}
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// We also keep the basic height of items for use below:
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if (!singleItemHeight) {
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singleItemHeight = coordinates.height;
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}
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last = coordinates;
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}
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this._heightToWidthFactor = this._containerInfo.width / singleItemHeight;
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},
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/**
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* Find the closest node in the container given the coordinates.
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* "Closest" is defined in a somewhat strange manner: we prefer nodes
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* which are in the same row over nodes that are in a different row.
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* In order to implement this, we use a weighted cartesian distance
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* where dy is more heavily weighted by a factor corresponding to the
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* ratio between the container's width and the height of its elements.
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*/
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find(aContainer, aX, aY) {
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let closest = null;
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let minCartesian = Number.MAX_VALUE;
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let containerX = this._containerInfo.left;
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let containerY = this._containerInfo.top;
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for (let node of aContainer.children) {
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let coordinates = this._lazyStoreGet(node);
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let offsetX = coordinates.x - containerX;
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let offsetY = coordinates.y - containerY;
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let hDiff = offsetX - aX;
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let vDiff = offsetY - aY;
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// Then compensate for the height/width ratio so that we prefer items
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// which are in the same row:
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hDiff /= this._heightToWidthFactor;
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let cartesianDiff = hDiff * hDiff + vDiff * vDiff;
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if (cartesianDiff < minCartesian) {
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minCartesian = cartesianDiff;
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closest = node;
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}
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}
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// Now correct this node based on what we're dragging
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if (closest) {
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let targetBounds = this._lazyStoreGet(closest);
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let farSide = this._rtl ? "left" : "right";
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let outsideX = targetBounds[farSide];
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// Check if we're closer to the next target than to this one:
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// Only move if we're not targeting a node in a different row:
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if (aY > targetBounds.top && aY < targetBounds.bottom) {
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if ((!this._rtl && aX > outsideX) || (this._rtl && aX < outsideX)) {
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return closest.nextElementSibling || aContainer;
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}
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}
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}
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return closest;
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},
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/**
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* "Insert" a "placeholder" by shifting the subsequent children out of the
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* way. We go through all the children, and shift them based on the position
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* they would have if we had inserted something before aBefore. We use CSS
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* transforms for this, which are CSS transitioned.
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*/
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insertPlaceholder(aContainer, aBefore, aSize, aIsFromThisArea) {
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let isShifted = false;
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for (let child of aContainer.children) {
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// Don't need to shift hidden nodes:
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if (child.hidden) {
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continue;
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}
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// If this is the node before which we're inserting, start shifting
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// everything that comes after. One exception is inserting at the end
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// of the menupanel, in which case we do not shift the placeholders:
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if (child == aBefore) {
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isShifted = true;
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}
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if (isShifted) {
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if (aIsFromThisArea && !this._lastPlaceholderInsertion) {
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child.setAttribute("notransition", "true");
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}
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// Determine the CSS transform based on the next node:
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child.style.transform = this._diffWithNext(child, aSize);
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} else {
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// If we're not shifting this node, reset the transform
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child.style.transform = "";
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}
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}
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if (
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aContainer.lastElementChild &&
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aIsFromThisArea &&
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!this._lastPlaceholderInsertion
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) {
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// Flush layout:
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aContainer.lastElementChild.getBoundingClientRect();
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// then remove all the [notransition]
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for (let child of aContainer.children) {
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child.removeAttribute("notransition");
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}
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}
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this._lastPlaceholderInsertion = aBefore;
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},
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/**
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* Reset all the transforms in this container, optionally without
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* transitioning them.
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* @param aContainer the container in which to reset transforms
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* @param aNoTransition if truthy, adds a notransition attribute to the node
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* while resetting the transform.
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*/
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clearPlaceholders(aContainer, aNoTransition) {
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for (let child of aContainer.children) {
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if (aNoTransition) {
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child.setAttribute("notransition", true);
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}
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child.style.transform = "";
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if (aNoTransition) {
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// Need to force a reflow otherwise this won't work.
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child.getBoundingClientRect();
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child.removeAttribute("notransition");
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}
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}
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// We snapped back, so we can assume there's no more
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// "last" placeholder insertion point to keep track of.
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if (aNoTransition) {
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this._lastPlaceholderInsertion = null;
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}
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},
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_diffWithNext(aNode, aSize) {
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let xDiff;
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let yDiff = null;
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let nodeBounds = this._lazyStoreGet(aNode);
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let side = this._rtl ? "right" : "left";
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let next = this._getVisibleSiblingForDirection(aNode, "next");
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// First we determine the transform along the x axis.
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// Usually, there will be a next node to base this on:
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if (next) {
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let otherBounds = this._lazyStoreGet(next);
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xDiff = otherBounds[side] - nodeBounds[side];
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// We set this explicitly because otherwise some strange difference
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// between the height and the actual difference between line creeps in
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// and messes with alignments
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yDiff = otherBounds.top - nodeBounds.top;
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} else {
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// We don't have a sibling whose position we can use. First, let's see
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// if we're also the first item (which complicates things):
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let firstNode = this._firstInRow(aNode);
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if (aNode == firstNode) {
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// Maybe we stored the horizontal distance between nodes,
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// if not, we'll use the width of the incoming node as a proxy:
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xDiff = this._horizontalDistance || (this._rtl ? -1 : 1) * aSize.width;
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} else {
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// If not, we should be able to get the distance to the previous node
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// and use the inverse, unless there's no room for another node (ie we
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// are the last node and there's no room for another one)
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xDiff = this._moveNextBasedOnPrevious(aNode, nodeBounds, firstNode);
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}
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}
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// If we've not determined the vertical difference yet, check it here
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if (yDiff === null) {
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// If the next node is behind rather than in front, we must have moved
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// vertically:
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if ((xDiff > 0 && this._rtl) || (xDiff < 0 && !this._rtl)) {
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yDiff = aSize.height;
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} else {
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// Otherwise, we haven't
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yDiff = 0;
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}
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}
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return "translate(" + xDiff + "px, " + yDiff + "px)";
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},
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/**
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* Helper function to find the transform a node if there isn't a next node
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* to base that on.
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* @param aNode the node to transform
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* @param aNodeBounds the bounding rect info of this node
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* @param aFirstNodeInRow the first node in aNode's row
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*/
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_moveNextBasedOnPrevious(aNode, aNodeBounds, aFirstNodeInRow) {
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let next = this._getVisibleSiblingForDirection(aNode, "previous");
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let otherBounds = this._lazyStoreGet(next);
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let side = this._rtl ? "right" : "left";
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let xDiff = aNodeBounds[side] - otherBounds[side];
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// If, however, this means we move outside the container's box
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// (i.e. the row in which this item is placed is full)
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// we should move it to align with the first item in the next row instead
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let bound = this._containerInfo[this._rtl ? "left" : "right"];
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if (
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(!this._rtl && xDiff + aNodeBounds.right > bound) ||
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(this._rtl && xDiff + aNodeBounds.left < bound)
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) {
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xDiff = this._lazyStoreGet(aFirstNodeInRow)[side] - aNodeBounds[side];
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}
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return xDiff;
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},
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/**
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* Get position details from our cache. If the node is not yet cached, get its position
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* information and cache it now.
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* @param aNode the node whose position info we want
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* @return the position info
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*/
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_lazyStoreGet(aNode) {
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let rect = this._nodePositionStore.get(aNode);
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if (!rect) {
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// getBoundingClientRect() returns a DOMRect that is live, meaning that
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// as the element moves around, the rects values change. We don't want
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// that - we want a snapshot of what the rect values are right at this
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// moment, and nothing else. So we have to clone the values.
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let clientRect = aNode.getBoundingClientRect();
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rect = {
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left: clientRect.left,
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right: clientRect.right,
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width: clientRect.width,
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height: clientRect.height,
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top: clientRect.top,
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bottom: clientRect.bottom,
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};
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rect.x = rect.left + rect.width / 2;
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rect.y = rect.top + rect.height / 2;
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Object.freeze(rect);
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this._nodePositionStore.set(aNode, rect);
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}
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return rect;
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},
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_firstInRow(aNode) {
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// XXXmconley: I'm not entirely sure why we need to take the floor of these
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// values - it looks like, periodically, we're getting fractional pixels back
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// from lazyStoreGet. I've filed bug 994247 to investigate.
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let bound = Math.floor(this._lazyStoreGet(aNode).top);
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let rv = aNode;
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let prev;
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while (rv && (prev = this._getVisibleSiblingForDirection(rv, "previous"))) {
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if (Math.floor(this._lazyStoreGet(prev).bottom) <= bound) {
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return rv;
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}
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rv = prev;
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}
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return rv;
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},
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_getVisibleSiblingForDirection(aNode, aDirection) {
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let rv = aNode;
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do {
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rv = rv[aDirection + "ElementSibling"];
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} while (rv && rv.hidden);
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return rv;
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},
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};
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var DragPositionManager = {
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start(aWindow) {
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let areas = [aWindow.document.getElementById(kPaletteId)];
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for (let areaNode of areas) {
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let positionManager = gManagers.get(areaNode);
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if (positionManager) {
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positionManager.update(areaNode);
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} else {
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gManagers.set(areaNode, new AreaPositionManager(areaNode));
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}
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}
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},
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stop() {
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gManagers = new WeakMap();
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},
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getManagerForArea(aArea) {
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return gManagers.get(aArea);
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},
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};
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Object.freeze(DragPositionManager);
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