Launcher 安装APK快捷方式出现在末尾空白位置

在做完仿小米桌面之后，客户又提了一个新需求，要求安装APK的时候，快捷方式要出现在末尾空白位置仿小米桌面方法请点击：Launcher3仿小米桌面

在代码中开始搜索之旅在这个位置packages\apps\Launcher3\src\com\android\launcher3\LauncherModel.java

发现了一个findNextAvailableIconSpace方法

  // Try adding to the workspace screens incrementally, starting at the default or center            // screen and alternating between +1, -1, +2, -2, etc. (using ~ ceil(i/2f)*(-1)^(i-1))            firstScreenIndex = Math.max(firstScreenIndex, workspaceScreens.size()); //czy min            int count = workspaceScreens.size();            for (int screen = firstScreenIndex - 1; screen < count && !found; screen++) { //czy 加-1                int[] tmpCoordinates = new int[2];                if (findNextAvailableIconSpaceInScreen(items, tmpCoordinates,                        workspaceScreens.get(screen))) {                    // Update the Launcher db                    return new Pairint[]>(workspaceScreens.get(screen), tmpCoordinates);                }            }        }        return null;    }

这里说明先for (int screen = firstScreenIndex - 1; screen < count && !found; screen++)在找第几屏，如果没有就新建一个具体增加快捷方式坐标得方法在这里
findNextAvailableIconSpaceInScreen(items, tmpCoordinates,workspaceScreens.get(screen)
tmpCoordinates这个参数就是快捷方式插入的位置
源代码原有的方法是从上到下从左到右的顺序去遍历每一个位置遇到空位就插进去具体方法如下

static boolean findNextAvailableIconSpaceInScreen(ArrayList items, int[] xy,                                 long screen) {        int a = 0;        int b = 0;        LauncherAppState app = LauncherAppState.getInstance();        DeviceProfile grid = app.getDynamicGrid().getDeviceProfile();        final int xCount = (int) grid.numColumns;        final int yCount = (int) grid.numRows;        boolean[][] occupied = new boolean[xCount][yCount];        //czy        ArrayList myX = new ArrayList();        ArrayList myY = new ArrayList();        //end        int cellX, cellY, spanX, spanY;        for (int i = 0; i < items.size(); ++i) {            final ItemInfo item = items.get(i);            if (item.container == LauncherSettings.Favorites.CONTAINER_DESKTOP) {                if (item.screenId == screen) {                    cellX = item.cellX;                    cellY = item.cellY;                    spanX = item.spanX;                    spanY = item.spanY;                    for (int x = cellX; 0 <= x && x < cellX + spanX && x < xCount; x++) {                        for (int y = cellY; 0 <= y && y < cellY + spanY && y < yCount; y++) {                            occupied[x][y] = true;                        }                    }                    //czy                    for (int y = 0; y < yCount; y++) {                        for (int x = 0; x < xCount; x++) {                            if(occupied[x][y]){                                 myX.add(x);                                 myY.add(y);                            }                        }                    }                    //end                }            }        }        return CellLayout.findVacantCellCzy(xy, 1, 1, xCount, yCount, occupied, myX, myY);//czy    }

可以看到返回的又是一个方法加参数这个方法是重写的，直接给出路径和具体代码
路径packages\apps\Launcher3\src\com\android\launcher3\CellLayout.java

static boolean findVacantCellCzy(int[] vacant, int spanX, int spanY,            int xCount, int yCount, boolean[][] occupied, ArrayList myX, ArrayList myY) {        ArrayList myXX = new ArrayList();        int xC = 0;        int yC = 0;        if(myX.size() >=1 && myY.size()>=1){            xC = myX.get(myX.size()-1);            yC = myY.get(myY.size()-1);        }                    for (int y = yC; y < yCount; y++) {            for (int x = xC; x < xCount; x++) {                boolean available = !occupied[x][y];out:            for (int i = x; i < x + spanX - 1 && x < xCount; i++) {                    for (int j = y; j < y + spanY - 1 && y < yCount; j++) {                        available = available && !occupied[i][j];                        if (!available) break out;                    }                }                if (available) {                    if(x == 3 /*&& occupied[x][y - 1]*/){                        for(int z = 0; z < xCount; z++){                            if(!occupied[z][y]){                                                            myXX.add(z);                                                        }                        }                        if(myXX.size() == 4){                            x = myXX.get(0);                        }else{                            if(myXX.size() != 0){                                x = myXX.get(myXX.size() - 1);                            }                        }                        Log.i("czy","-----x------"+x);                    }                    vacant[0] = x;                    vacant[1] = y;                    return true;                }            }        }        return false;    }    //end

最后把原生代码也贴出来，更直观

 static boolean findVacantCell(int[] vacant, int spanX, int spanY,            int xCount, int yCount, boolean[][] occupied) {        for (int y = 0; y < yCount; y++) {            for (int x = 0; x < xCount; x++) {                boolean available = !occupied[x][y];out:            for (int i = x; i < x + spanX - 1 && x < xCount; i++) {                    for (int j = y; j < y + spanY - 1 && y < yCount; j++) {                        available = available && !occupied[i][j];                        if (!available) break out;                    }                }                if (available) {                    vacant[0] = x;                    vacant[1] = y;                    return true;                }            }        }        return false;    }

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