Launcher3 定制桌面行列数

一.Launcher3默认显示行列数是通过device_profiles.xml这个文件配置的，文件内容是

<profiles xmlns:launcher="http://schemas.android.com/apk/res-auto" >

    <profile
        launcher:name="Super Short Stubby"
        launcher:minWidthDps="255"
        launcher:minHeightDps="300"
        launcher:numRows="2"
        launcher:numColumns="3"
        launcher:numFolderRows="2"
        launcher:numFolderColumns="3"
        launcher:minAllAppsPredictionColumns="3"
        launcher:iconSize="248"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="3"
        launcher:defaultLayoutId="@xml/default_workspace_3x3"
        />

    <profile
        launcher:name="Shorter Stubby"
        launcher:minWidthDps="255"
        launcher:minHeightDps="400"
        launcher:numRows="3"
        launcher:numColumns="3"
        launcher:numFolderRows="3"
        launcher:numFolderColumns="3"
        launcher:minAllAppsPredictionColumns="3"
        launcher:iconSize="48"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="3"
        launcher:defaultLayoutId="@xml/default_workspace_3x3"
        />

    <profile
        launcher:name="Short Stubby"
        launcher:minWidthDps="275"
        launcher:minHeightDps="420"
        launcher:numRows="3"
        launcher:numColumns="4"
        launcher:numFolderRows="3"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="48"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

    <profile
        launcher:name="Stubby"
        launcher:minWidthDps="255"
        launcher:minHeightDps="450"
        launcher:numRows="3"
        launcher:numColumns="4"
        launcher:numFolderRows="3"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="48"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

    <profile
        launcher:name="Nexus S"
        launcher:minWidthDps="296"
        launcher:minHeightDps="491.33"
        launcher:numRows="4"
        launcher:numColumns="4"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="48"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

    <profile
        launcher:name="Nexus 4"
        launcher:minWidthDps="359"
        launcher:minHeightDps="567"
        launcher:numRows="4"
        launcher:numColumns="4"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="54"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

    <profile
        launcher:name="Nexus 5"
        launcher:minWidthDps="335"
        launcher:minHeightDps="567"
        launcher:numRows="4"
        launcher:numColumns="4"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="54"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

    <profile
        launcher:name="Large Phone"
        launcher:minWidthDps="406"
        launcher:minHeightDps="694"
        launcher:numRows="5"
        launcher:numColumns="5"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="56"
        launcher:iconTextSize="14.4"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_5x5"
        />

    <profile
        launcher:name="Nexus 7"
        launcher:minWidthDps="575"
        launcher:minHeightDps="904"
        launcher:numRows="5"
        launcher:numColumns="6"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="5"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="64"
        launcher:iconTextSize="14.4"
        launcher:numHotseatIcons="7"
        launcher:defaultLayoutId="@xml/default_workspace_5x6"
        />

    <profile
        launcher:name="Nexus 10"
        launcher:minWidthDps="727"
        launcher:minHeightDps="1207"
        launcher:numRows="2"
        launcher:numColumns="3"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="5"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="76"
        launcher:iconTextSize="14.4"
        launcher:numHotseatIcons="7"
        launcher:defaultLayoutId="@xml/default_workspace_5x6"
        />

    <profile
        launcher:name="20-inch Tablet"
        launcher:minWidthDps="1527"
        launcher:minHeightDps="2527"
        launcher:numRows="7"
        launcher:numColumns="7"
        launcher:numFolderRows="6"
        launcher:numFolderColumns="6"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="100"
        launcher:iconTextSize="20.0"
        launcher:numHotseatIcons="7"
        launcher:defaultLayoutId="@xml/default_workspace_5x6"
        />

</profiles>

二.该配置文件是在InvariantDeviceProfile类的getPredefinedDeviceProfiles方法加载

 ArrayList<InvariantDeviceProfile> getPredefinedDeviceProfiles(Context context) {
        ArrayList<InvariantDeviceProfile> 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);        Log.e("TAG", ">>>>>>>>>>>3>>>>"+numColumns+"#"+a.getString(R.styleable.InvariantDeviceProfile_name));
                    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),
                            a.getInt(R.styleable.InvariantDeviceProfile_minAllAppsPredictionColumns, 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;
    }