@material-git/all/grid-list/tile-coordinator.js

Angular 2 Material

import { MdGridTileTooWideError } from './grid-list-errors';
/**
 * Class for determining, from a list of tiles, the (row, col) position of each of those tiles
 * in the grid. This is necessary (rather than just rendering the tiles in normal document flow)
 * because the tiles can have a rowspan.
 *
 * The positioning algorithm greedily places each tile as soon as it encounters a gap in the grid
 * large enough to accommodate it so that the tiles still render in the same order in which they
 * are given.
 *
 * The basis of the algorithm is the use of an array to track the already placed tiles. Each
 * element of the array corresponds to a column, and the value indicates how many cells in that
 * column are already occupied; zero indicates an empty cell. Moving "down" to the next row
 * decrements each value in the tracking array (indicating that the column is one cell closer to
 * being free).
 */
export var TileCoordinator = (function () {
    function TileCoordinator(numColumns, tiles) {
        var _this = this;
        /** Index at which the search for the next gap will start. */
        this.columnIndex = 0;
        /** The current row index. */
        this.rowIndex = 0;
        this.tracker = new Array(numColumns);
        this.tracker.fill(0, 0, this.tracker.length);
        this.positions = tiles.map(function (tile) { return _this._trackTile(tile); });
    }
    Object.defineProperty(TileCoordinator.prototype, "rowCount", {
        /** Gets the total number of rows occupied by tiles */
        get: function () { return this.rowIndex + 1; },
        enumerable: true,
        configurable: true
    });
    Object.defineProperty(TileCoordinator.prototype, "rowspan", {
        /** Gets the total span of rows occupied by tiles.
         * Ex: A list with 1 row that contains a tile with rowspan 2 will have a total rowspan of 2. */
        get: function () {
            var lastRowMax = Math.max.apply(Math, this.tracker);
            // if any of the tiles has a rowspan that pushes it beyond the total row count,
            // add the difference to the rowcount
            return lastRowMax > 1 ? this.rowCount + lastRowMax - 1 : this.rowCount;
        },
        enumerable: true,
        configurable: true
    });
    /** Calculates the row and col position of a tile. */
    TileCoordinator.prototype._trackTile = function (tile) {
        // Find a gap large enough for this tile.
        var gapStartIndex = this._findMatchingGap(tile.colspan);
        // Place tile in the resulting gap.
        this._markTilePosition(gapStartIndex, tile);
        // The next time we look for a gap, the search will start at columnIndex, which should be
        // immediately after the tile that has just been placed.
        this.columnIndex = gapStartIndex + tile.colspan;
        return new TilePosition(this.rowIndex, gapStartIndex);
    };
    /** Finds the next available space large enough to fit the tile. */
    TileCoordinator.prototype._findMatchingGap = function (tileCols) {
        if (tileCols > this.tracker.length) {
            throw new MdGridTileTooWideError(tileCols, this.tracker.length);
        }
        // Start index is inclusive, end index is exclusive.
        var gapStartIndex = -1;
        var gapEndIndex = -1;
        // Look for a gap large enough to fit the given tile. Empty spaces are marked with a zero.
        do {
            // If we've reached the end of the row, go to the next row.
            if (this.columnIndex + tileCols > this.tracker.length) {
                this._nextRow();
                continue;
            }
            gapStartIndex = this.tracker.indexOf(0, this.columnIndex);
            // If there are no more empty spaces in this row at all, move on to the next row.
            if (gapStartIndex == -1) {
                this._nextRow();
                continue;
            }
            gapEndIndex = this._findGapEndIndex(gapStartIndex);
            // If a gap large enough isn't found, we want to start looking immediately after the current
            // gap on the next iteration.
            this.columnIndex = gapStartIndex + 1;
        } while (gapEndIndex - gapStartIndex < tileCols);
        return gapStartIndex;
    };
    /** Move "down" to the next row. */
    TileCoordinator.prototype._nextRow = function () {
        this.columnIndex = 0;
        this.rowIndex++;
        // Decrement all spaces by one to reflect moving down one row.
        for (var i = 0; i < this.tracker.length; i++) {
            this.tracker[i] = Math.max(0, this.tracker[i] - 1);
        }
    };
    /**
     * Finds the end index (exclusive) of a gap given the index from which to start looking.
     * The gap ends when a non-zero value is found.
     */
    TileCoordinator.prototype._findGapEndIndex = function (gapStartIndex) {
        for (var i = gapStartIndex + 1; i < this.tracker.length; i++) {
            if (this.tracker[i] != 0) {
                return i;
            }
        }
        // The gap ends with the end of the row.
        return this.tracker.length;
    };
    /** Update the tile tracker to account for the given tile in the given space. */
    TileCoordinator.prototype._markTilePosition = function (start, tile) {
        for (var i = 0; i < tile.colspan; i++) {
            this.tracker[start + i] = tile.rowspan;
        }
    };
    return TileCoordinator;
}());
/** Simple data structure for tile position (row, col). */
export var TilePosition = (function () {
    function TilePosition(row, col) {
        this.row = row;
        this.col = col;
    }
    return TilePosition;
}());

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