src/com/android/launcher3/graphics/GridCustomizationsProvider.java

package com.android.launcher3.graphics;

import static com.android.launcher3.Utilities.getPrefs;
import static com.android.launcher3.util.Executors.UI_HELPER_EXECUTOR;
import static com.android.launcher3.util.Themes.KEY_THEMED_ICONS;
import static com.android.launcher3.util.Themes.isThemedIconEnabled;

import android.annotation.TargetApi;
import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.net.Uri;
import android.os.Binder;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.IBinder.DeathRecipient;
import android.os.Message;
import android.os.Messenger;
import android.util.ArrayMap;
import android.util.Log;

import com.android.launcher3.InvariantDeviceProfile;
import com.android.launcher3.InvariantDeviceProfile.GridOption;
import com.android.launcher3.Utilities;
import com.android.launcher3.config.FeatureFlags;
import com.android.launcher3.util.Executors;

/**
 * Exposes various launcher grid options and allows the caller to change them.
 * APIs:
 *      /list_options: List the various available grip options, has following columns
 *          name: name of the grid
 *          rows: number of rows in the grid
 *          cols: number of columns in the grid
 *          preview_count: number of previews available for this grid option. The preview uri
 *                         looks like /preview/<grid-name>/<preview index starting with 0>
 *          is_default: true if this grid is currently active
 *
 *     /preview: Opens a file stream for the grid preview
 *
 *     /default_grid: Call update to set the current grid, with values
 *          name: name of the grid to apply
 */
public class GridCustomizationsProvider extends ContentProvider {

    private static final String TAG = "GridCustomizationsProvider";

    private static final String KEY_NAME = "name";
    private static final String KEY_ROWS = "rows";
    private static final String KEY_COLS = "cols";
    private static final String KEY_PREVIEW_COUNT = "preview_count";
    private static final String KEY_IS_DEFAULT = "is_default";

    private static final String KEY_LIST_OPTIONS = "/list_options";
    private static final String KEY_DEFAULT_GRID = "/default_grid";

    private static final String METHOD_GET_PREVIEW = "get_preview";

    private static final String GET_ICON_THEMED = "/get_icon_themed";
    private static final String SET_ICON_THEMED = "/set_icon_themed";
    private static final String ICON_THEMED = "/icon_themed";
    private static final String BOOLEAN_VALUE = "boolean_value";

    private static final String KEY_SURFACE_PACKAGE = "surface_package";
    private static final String KEY_CALLBACK = "callback";

    private final ArrayMap<IBinder, PreviewLifecycleObserver> mActivePreviews = new ArrayMap<>();

    @Override
    public boolean onCreate() {
        return true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection,
            String[] selectionArgs, String sortOrder) {
        switch (uri.getPath()) {
            case KEY_LIST_OPTIONS: {
                MatrixCursor cursor = new MatrixCursor(new String[] {
                        KEY_NAME, KEY_ROWS, KEY_COLS, KEY_PREVIEW_COUNT, KEY_IS_DEFAULT});
                InvariantDeviceProfile idp = InvariantDeviceProfile.INSTANCE.get(getContext());
                for (GridOption gridOption : idp.parseAllGridOptions(getContext())) {
                    cursor.newRow()
                            .add(KEY_NAME, gridOption.name)
                            .add(KEY_ROWS, gridOption.numRows)
                            .add(KEY_COLS, gridOption.numColumns)
                            .add(KEY_PREVIEW_COUNT, 1)
                            .add(KEY_IS_DEFAULT, idp.numColumns == gridOption.numColumns
                                    && idp.numRows == gridOption.numRows);
                }
                return cursor;
            }
            case GET_ICON_THEMED:
            case ICON_THEMED: {
                MatrixCursor cursor = new MatrixCursor(new String[] {BOOLEAN_VALUE});
                cursor.newRow().add(BOOLEAN_VALUE, isThemedIconEnabled(getContext()) ? 1 : 0);
                return cursor;
            }
            default:
                return null;
        }
    }

    @Override
    public String getType(Uri uri) {
        return "vnd.android.cursor.dir/launcher_grid";
    }

    @Override
    public Uri insert(Uri uri, ContentValues initialValues) {
        return null;
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        return 0;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        switch (uri.getPath()) {
            case KEY_DEFAULT_GRID: {
                String gridName = values.getAsString(KEY_NAME);
                InvariantDeviceProfile idp = InvariantDeviceProfile.INSTANCE.get(getContext());
                // Verify that this is a valid grid option
                GridOption match = null;
                for (GridOption option : idp.parseAllGridOptions(getContext())) {
                    if (option.name.equals(gridName)) {
                        match = option;
                        break;
                    }
                }
                if (match == null) {
                    return 0;
                }

                idp.setCurrentGrid(getContext(), gridName);
                return 1;
            }
            case ICON_THEMED:
            case SET_ICON_THEMED: {
                if (FeatureFlags.ENABLE_THEMED_ICONS.get()) {
                    getPrefs(getContext()).edit()
                            .putBoolean(KEY_THEMED_ICONS, values.getAsBoolean(BOOLEAN_VALUE))
                            .apply();
                }
                return 1;
            }
            default:
                return 0;
        }
    }

    @Override
    public Bundle call(String method, String arg, Bundle extras) {
        if (getContext().checkPermission("android.permission.BIND_WALLPAPER",
                Binder.getCallingPid(), Binder.getCallingUid())
                != PackageManager.PERMISSION_GRANTED) {
            return null;
        }

        if (!Utilities.ATLEAST_R || !METHOD_GET_PREVIEW.equals(method)) {
            return null;
        }
        return getPreview(extras);
    }

    @TargetApi(Build.VERSION_CODES.R)
    private synchronized Bundle getPreview(Bundle request) {
        PreviewLifecycleObserver observer = null;
        try {
            PreviewSurfaceRenderer renderer = new PreviewSurfaceRenderer(getContext(), request);

            // Destroy previous
            destroyObserver(mActivePreviews.get(renderer.getHostToken()));

            observer = new PreviewLifecycleObserver(renderer);
            mActivePreviews.put(renderer.getHostToken(), observer);

            renderer.loadAsync();
            renderer.getHostToken().linkToDeath(observer, 0);

            Bundle result = new Bundle();
            result.putParcelable(KEY_SURFACE_PACKAGE, renderer.getSurfacePackage());

            Messenger messenger =
                    new Messenger(new Handler(UI_HELPER_EXECUTOR.getLooper(), observer));
            Message msg = Message.obtain();
            msg.replyTo = messenger;
            result.putParcelable(KEY_CALLBACK, msg);
            return result;
        } catch (Exception e) {
            Log.e(TAG, "Unable to generate preview", e);
            if (observer != null) {
                destroyObserver(observer);
            }
            return null;
        }
    }

    private synchronized void destroyObserver(PreviewLifecycleObserver observer) {
        if (observer == null || observer.destroyed) {
            return;
        }
        observer.destroyed = true;
        observer.renderer.getHostToken().unlinkToDeath(observer, 0);
        Executors.MAIN_EXECUTOR.execute(observer.renderer::destroy);
        PreviewLifecycleObserver cached = mActivePreviews.get(observer.renderer.getHostToken());
        if (cached == observer) {
            mActivePreviews.remove(observer.renderer.getHostToken());
        }
    }

    private class PreviewLifecycleObserver implements Handler.Callback, DeathRecipient {

        public final PreviewSurfaceRenderer renderer;
        public boolean destroyed = false;

        PreviewLifecycleObserver(PreviewSurfaceRenderer renderer) {
            this.renderer = renderer;
        }

        @Override
        public boolean handleMessage(Message message) {
            destroyObserver(this);
            return true;
        }

        @Override
        public void binderDied() {
            destroyObserver(this);
        }
    }
}