Android example source code file (AppWidgetHostView.java)

This example Android source code file (AppWidgetHostView.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, appwidgethostview, appwidgetproviderinfo, context, crossfade, drawing, graphics, layoutinflater, logd, os, override, paint, parcelablesparsearray, runtimeexception, string, ui, view, view_mode_default, view_mode_error, view_mode_noinit

The AppWidgetHostView.java Android example source code

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.appwidget;

import android.content.Context;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.SystemClock;
import android.os.Parcelable;
import android.os.Parcel;
import android.util.AttributeSet;
import android.util.Log;
import android.util.SparseArray;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.RemoteViews;
import android.widget.TextView;

/**
 * Provides the glue to show AppWidget views. This class offers automatic animation
 * between updates, and will try recycling old views for each incoming
 * {@link RemoteViews}.
 */
public class AppWidgetHostView extends FrameLayout {
    static final String TAG = "AppWidgetHostView";
    static final boolean LOGD = false;
    static final boolean CROSSFADE = false;

    static final int UPDATE_FLAGS_RESET = 0x00000001;

    static final int VIEW_MODE_NOINIT = 0;
    static final int VIEW_MODE_CONTENT = 1;
    static final int VIEW_MODE_ERROR = 2;
    static final int VIEW_MODE_DEFAULT = 3;

    static final int FADE_DURATION = 1000;

    // When we're inflating the initialLayout for a AppWidget, we only allow
    // views that are allowed in RemoteViews.
    static final LayoutInflater.Filter sInflaterFilter = new LayoutInflater.Filter() {
        public boolean onLoadClass(Class clazz) {
            return clazz.isAnnotationPresent(RemoteViews.RemoteView.class);
        }
    };

    Context mContext;
    Context mRemoteContext;

    int mAppWidgetId;
    AppWidgetProviderInfo mInfo;
    View mView;
    int mViewMode = VIEW_MODE_NOINIT;
    int mLayoutId = -1;
    long mFadeStartTime = -1;
    Bitmap mOld;
    Paint mOldPaint = new Paint();
    
    /**
     * Create a host view.  Uses default fade animations.
     */
    public AppWidgetHostView(Context context) {
        this(context, android.R.anim.fade_in, android.R.anim.fade_out);
    }

    /**
     * Create a host view. Uses specified animations when pushing
     * {@link #updateAppWidget(RemoteViews)}.
     * 
     * @param animationIn Resource ID of in animation to use
     * @param animationOut Resource ID of out animation to use
     */
    @SuppressWarnings({"UnusedDeclaration"})
    public AppWidgetHostView(Context context, int animationIn, int animationOut) {
        super(context);
        mContext = context;
    }
    
    /**
     * Set the AppWidget that will be displayed by this view.
     */
    public void setAppWidget(int appWidgetId, AppWidgetProviderInfo info) {
        mAppWidgetId = appWidgetId;
        mInfo = info;
    }
    
    public int getAppWidgetId() {
        return mAppWidgetId;
    }
    
    public AppWidgetProviderInfo getAppWidgetInfo() {
        return mInfo;
    }

    @Override
    protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) {
        final ParcelableSparseArray jail = new ParcelableSparseArray();
        super.dispatchSaveInstanceState(jail);
        container.put(generateId(), jail);
    }

    private int generateId() {
        final int id = getId();
        return id == View.NO_ID ? mAppWidgetId : id;
    }

    @Override
    protected void dispatchRestoreInstanceState(SparseArray<Parcelable> container) {
        final Parcelable parcelable = container.get(generateId());

        ParcelableSparseArray jail = null;
        if (parcelable != null && parcelable instanceof ParcelableSparseArray) {
            jail = (ParcelableSparseArray) parcelable;
        }

        if (jail == null) jail = new ParcelableSparseArray();

        super.dispatchRestoreInstanceState(jail);
    }

    /** {@inheritDoc} */
    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        // We're being asked to inflate parameters, probably by a LayoutInflater
        // in a remote Context. To help resolve any remote references, we
        // inflate through our last mRemoteContext when it exists.
        final Context context = mRemoteContext != null ? mRemoteContext : mContext;
        return new FrameLayout.LayoutParams(context, attrs);
    }

    /**
     * Process a set of {@link RemoteViews} coming in as an update from the
     * AppWidget provider. Will animate into these new views as needed
     */
    public void updateAppWidget(RemoteViews remoteViews) {
        updateAppWidget(remoteViews, 0);
    }

    void updateAppWidget(RemoteViews remoteViews, int flags) {
        if (LOGD) Log.d(TAG, "updateAppWidget called mOld=" + mOld + " flags=0x"
                + Integer.toHexString(flags));

        if ((flags & UPDATE_FLAGS_RESET) != 0) {
            mViewMode = VIEW_MODE_NOINIT;
        }
        
        boolean recycled = false;
        View content = null;
        Exception exception = null;
        
        // Capture the old view into a bitmap so we can do the crossfade.
        if (CROSSFADE) {
            if (mFadeStartTime < 0) {
                if (mView != null) {
                    final int width = mView.getWidth();
                    final int height = mView.getHeight();
                    try {
                        mOld = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
                    } catch (OutOfMemoryError e) {
                        // we just won't do the fade
                        mOld = null;
                    }
                    if (mOld != null) {
                        //mView.drawIntoBitmap(mOld);
                    }
                }
            }
        }
        
        if (remoteViews == null) {
            if (mViewMode == VIEW_MODE_DEFAULT) {
                // We've already done this -- nothing to do.
                return;
            }
            content = getDefaultView();
            mLayoutId = -1;
            mViewMode = VIEW_MODE_DEFAULT;
        } else {
            // Prepare a local reference to the remote Context so we're ready to
            // inflate any requested LayoutParams.
            mRemoteContext = getRemoteContext(remoteViews);
            int layoutId = remoteViews.getLayoutId();

            // If our stale view has been prepared to match active, and the new
            // layout matches, try recycling it
            if (content == null && layoutId == mLayoutId) {
                try {
                    remoteViews.reapply(mContext, mView);
                    content = mView;
                    recycled = true;
                    if (LOGD) Log.d(TAG, "was able to recycled existing layout");
                } catch (RuntimeException e) {
                    exception = e;
                }
            }
            
            // Try normal RemoteView inflation
            if (content == null) {
                try {
                    content = remoteViews.apply(mContext, this);
                    if (LOGD) Log.d(TAG, "had to inflate new layout");
                } catch (RuntimeException e) {
                    exception = e;
                }
            }

            mLayoutId = layoutId;
            mViewMode = VIEW_MODE_CONTENT;
        }
        
        if (content == null) {
            if (mViewMode == VIEW_MODE_ERROR) {
                // We've already done this -- nothing to do.
                return ;
            }
            Log.w(TAG, "updateAppWidget couldn't find any view, using error view", exception);
            content = getErrorView();
            mViewMode = VIEW_MODE_ERROR;
        }
        
        if (!recycled) {
            prepareView(content);
            addView(content);
        }

        if (mView != content) {
            removeView(mView);
            mView = content;
        }

        if (CROSSFADE) {
            if (mFadeStartTime < 0) {
                // if there is already an animation in progress, don't do anything --
                // the new view will pop in on top of the old one during the cross fade,
                // and that looks okay.
                mFadeStartTime = SystemClock.uptimeMillis();
                invalidate();
            }
        }
    }

    /**
     * Build a {@link Context} cloned into another package name, usually for the
     * purposes of reading remote resources.
     */
    private Context getRemoteContext(RemoteViews views) {
        // Bail if missing package name
        final String packageName = views.getPackage();
        if (packageName == null) return mContext;

        try {
            // Return if cloned successfully, otherwise default
            return mContext.createPackageContext(packageName, Context.CONTEXT_RESTRICTED);
        } catch (NameNotFoundException e) {
            Log.e(TAG, "Package name " + packageName + " not found");
            return mContext;
        }
    }

    protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
        if (CROSSFADE) {
            int alpha;
            int l = child.getLeft();
            int t = child.getTop();
            if (mFadeStartTime > 0) {
                alpha = (int)(((drawingTime-mFadeStartTime)*255)/FADE_DURATION);
                if (alpha > 255) {
                    alpha = 255;
                }
                Log.d(TAG, "drawChild alpha=" + alpha + " l=" + l + " t=" + t
                        + " w=" + child.getWidth());
                if (alpha != 255 && mOld != null) {
                    mOldPaint.setAlpha(255-alpha);
                    //canvas.drawBitmap(mOld, l, t, mOldPaint);
                }
            } else {
                alpha = 255;
            }
            int restoreTo = canvas.saveLayerAlpha(l, t, child.getWidth(), child.getHeight(), alpha,
                    Canvas.HAS_ALPHA_LAYER_SAVE_FLAG | Canvas.CLIP_TO_LAYER_SAVE_FLAG);
            boolean rv = super.drawChild(canvas, child, drawingTime);
            canvas.restoreToCount(restoreTo);
            if (alpha < 255) {
                invalidate();
            } else {
                mFadeStartTime = -1;
                if (mOld != null) {
                    mOld.recycle();
                    mOld = null;
                }
            }
            return rv;
        } else {
            return super.drawChild(canvas, child, drawingTime);
        }
    }
    
    /**
     * Prepare the given view to be shown. This might include adjusting
     * {@link FrameLayout.LayoutParams} before inserting.
     */
    protected void prepareView(View view) {
        // Take requested dimensions from child, but apply default gravity.
        FrameLayout.LayoutParams requested = (FrameLayout.LayoutParams)view.getLayoutParams();
        if (requested == null) {
            requested = new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT,
                    LayoutParams.MATCH_PARENT);
        }

        requested.gravity = Gravity.CENTER;
        view.setLayoutParams(requested);
    }
    
    /**
     * Inflate and return the default layout requested by AppWidget provider.
     */
    protected View getDefaultView() {
        if (LOGD) {
            Log.d(TAG, "getDefaultView");
        }
        View defaultView = null;
        Exception exception = null;
        
        try {
            if (mInfo != null) {
                Context theirContext = mContext.createPackageContext(
                        mInfo.provider.getPackageName(), Context.CONTEXT_RESTRICTED);
                mRemoteContext = theirContext;
                LayoutInflater inflater = (LayoutInflater)
                        theirContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                inflater = inflater.cloneInContext(theirContext);
                inflater.setFilter(sInflaterFilter);
                defaultView = inflater.inflate(mInfo.initialLayout, this, false);
            } else {
                Log.w(TAG, "can't inflate defaultView because mInfo is missing");
            }
        } catch (PackageManager.NameNotFoundException e) {
            exception = e;
        } catch (RuntimeException e) {
            exception = e;
        }
        
        if (exception != null) {
            Log.w(TAG, "Error inflating AppWidget " + mInfo + ": " + exception.toString());
        }
        
        if (defaultView == null) {
            if (LOGD) Log.d(TAG, "getDefaultView couldn't find any view, so inflating error");
            defaultView = getErrorView();
        }
        
        return defaultView;
    }
    
    /**
     * Inflate and return a view that represents an error state.
     */
    protected View getErrorView() {
        TextView tv = new TextView(mContext);
        tv.setText(com.android.internal.R.string.gadget_host_error_inflating);
        // TODO: get this color from somewhere.
        tv.setBackgroundColor(Color.argb(127, 0, 0, 0));
        return tv;
    }

    private static class ParcelableSparseArray extends SparseArray<Parcelable> implements Parcelable {
        public int describeContents() {
            return 0;
        }

        public void writeToParcel(Parcel dest, int flags) {
            final int count = size();
            dest.writeInt(count);
            for (int i = 0; i < count; i++) {
                dest.writeInt(keyAt(i));
                dest.writeParcelable(valueAt(i), 0);
            }
        }

        public static final Parcelable.Creator<ParcelableSparseArray> CREATOR =
                new Parcelable.Creator<ParcelableSparseArray>() {
                    public ParcelableSparseArray createFromParcel(Parcel source) {
                        final ParcelableSparseArray array = new ParcelableSparseArray();
                        final ClassLoader loader = array.getClass().getClassLoader();
                        final int count = source.readInt();
                        for (int i = 0; i < count; i++) {
                            array.put(source.readInt(), source.readParcelable(loader));
                        }
                        return array;
                    }

                    public ParcelableSparseArray[] newArray(int size) {
                        return new ParcelableSparseArray[size];
                    }
                };
    }
}