Android Launcher3 修改行数和列数

packages\apps\Launcher3\src\com\android\launcher3\InvariantDeviceProfile.java

    ArrayList getPredefinedDeviceProfiles(Context context) {
        ArrayList profiles = new ArrayList<>();
        try (XmlResourceParser parser = context.getResources().getXml(R.xml.device_profiles)) {
            final int depth = parser.getDepth();
            int type;

            while (((type = parser.next()) != XmlPullParser.END_TAG ||
                    parser.getDepth() > depth) && type != XmlPullParser.END_DOCUMENT) {
                if ((type == XmlPullParser.START_TAG) && "profile".equals(parser.getName())) {
                    TypedArray a = context.obtainStyledAttributes(
                            Xml.asAttributeSet(parser), R.styleable.InvariantDeviceProfile);
                    int numRows = a.getInt(R.styleable.InvariantDeviceProfile_numRows, 0);
                    int numColumns = a.getInt(R.styleable.InvariantDeviceProfile_numColumns, 0);
                    float iconSize = a.getFloat(R.styleable.InvariantDeviceProfile_iconSize, 0);
                    profiles.add(new InvariantDeviceProfile(
                            a.getString(R.styleable.InvariantDeviceProfile_name),
                            a.getFloat(R.styleable.InvariantDeviceProfile_minWidthDps, 0),
                            a.getFloat(R.styleable.InvariantDeviceProfile_minHeightDps, 0),
                            numRows,
                            numColumns,
                            a.getInt(R.styleable.InvariantDeviceProfile_numFolderRows, numRows),
                            a.getInt(R.styleable.InvariantDeviceProfile_numFolderColumns, numColumns),
                            iconSize,
                            a.getFloat(R.styleable.InvariantDeviceProfile_landscapeIconSize, iconSize),
                            a.getFloat(R.styleable.InvariantDeviceProfile_iconTextSize, 0),
                            a.getInt(R.styleable.InvariantDeviceProfile_numHotseatIcons, numColumns),
                            a.getResourceId(R.styleable.InvariantDeviceProfile_defaultLayoutId, 0),
                            a.getResourceId(R.styleable.InvariantDeviceProfile_demoModeLayoutId, 0)));
                    a.recycle();
                }
            }
        } catch (IOException|XmlPullParserException e) {
            throw new RuntimeException(e);
        }
        return profiles;
    }

从R.xml.device_profiles这个文件中读取数据 

packages\apps\Launcher3\res\xml\device_profiles.xml

根据屏幕尺寸设置不同的布局

修改 numHotseatIcons的数量即可