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      1 package com.android.launcher3.util;
      2 
      3 import android.graphics.Rect;
      4 
      5 import com.android.launcher3.ItemInfo;
      6 
      7 /**
      8  * Utility object to manage the occupancy in a grid.
      9  */
     10 public class GridOccupancy {
     11 
     12     private final int mCountX;
     13     private final int mCountY;
     14 
     15     public final boolean[][] cells;
     16 
     17     public GridOccupancy(int countX, int countY) {
     18         mCountX = countX;
     19         mCountY = countY;
     20         cells = new boolean[countX][countY];
     21     }
     22 
     23     /**
     24      * Find the first vacant cell, if there is one.
     25      *
     26      * @param vacantOut Holds the x and y coordinate of the vacant cell
     27      * @param spanX Horizontal cell span.
     28      * @param spanY Vertical cell span.
     29      *
     30      * @return true if a vacant cell was found
     31      */
     32     public boolean findVacantCell(int[] vacantOut, int spanX, int spanY) {
     33         for (int y = 0; (y + spanY) <= mCountY; y++) {
     34             for (int x = 0; (x + spanX) <= mCountX; x++) {
     35                 boolean available = !cells[x][y];
     36                 out:
     37                 for (int i = x; i < x + spanX; i++) {
     38                     for (int j = y; j < y + spanY; j++) {
     39                         available = available && !cells[i][j];
     40                         if (!available) break out;
     41                     }
     42                 }
     43                 if (available) {
     44                     vacantOut[0] = x;
     45                     vacantOut[1] = y;
     46                     return true;
     47                 }
     48             }
     49         }
     50         return false;
     51     }
     52 
     53     public void copyTo(GridOccupancy dest) {
     54         for (int i = 0; i < mCountX; i++) {
     55             for (int j = 0; j < mCountY; j++) {
     56                 dest.cells[i][j] = cells[i][j];
     57             }
     58         }
     59     }
     60 
     61     public boolean isRegionVacant(int x, int y, int spanX, int spanY) {
     62         int x2 = x + spanX - 1;
     63         int y2 = y + spanY - 1;
     64         if (x < 0 || y < 0 || x2 >= mCountX || y2 >= mCountY) {
     65             return false;
     66         }
     67         for (int i = x; i <= x2; i++) {
     68             for (int j = y; j <= y2; j++) {
     69                 if (cells[i][j]) {
     70                     return false;
     71                 }
     72             }
     73         }
     74         return true;
     75     }
     76 
     77     public void markCells(int cellX, int cellY, int spanX, int spanY, boolean value) {
     78         if (cellX < 0 || cellY < 0) return;
     79         for (int x = cellX; x < cellX + spanX && x < mCountX; x++) {
     80             for (int y = cellY; y < cellY + spanY && y < mCountY; y++) {
     81                 cells[x][y] = value;
     82             }
     83         }
     84     }
     85 
     86     public void markCells(Rect r, boolean value) {
     87         markCells(r.left, r.top, r.width(), r.height(), value);
     88     }
     89 
     90     public void markCells(CellAndSpan cell, boolean value) {
     91         markCells(cell.cellX, cell.cellY, cell.spanX, cell.spanY, value);
     92     }
     93 
     94     public void markCells(ItemInfo item, boolean value) {
     95         markCells(item.cellX, item.cellY, item.spanX, item.spanY, value);
     96     }
     97 
     98     public void clear() {
     99         markCells(0, 0, mCountX, mCountY, false);
    100     }
    101 }
    102