https://source.android.com/ 
/*
 * Copyright (C) 2007 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.widget;

import android.annotation.IntDef;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.StringRes;
import android.app.INotificationManager;
import android.app.ITransientNotification;
import android.content.Context;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.graphics.PixelFormat;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.Message;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.WindowManager;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityManager;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;


A toast is a view containing a quick little message for the user.  The toast class
helps you create and show those.
{@more}


When the view is shown to the user, appears as a floating view over the
application.  It will never receive focus.  The user will probably be in the
middle of typing something else.  The idea is to be as unobtrusive as
possible, while still showing the user the information you want them to see.
Two examples are the volume control, and the brief message saying that your
settings have been saved.


The easiest way to use this class is to call one of the static methods that constructs
everything you need and returns a new Toast object.



Developer Guides


For information about creating Toast notifications, read the
Toast Notifications developer
guide.




/**
 * A toast is a view containing a quick little message for the user.  The toast class
 * helps you create and show those.
 * {@more}
 *
 * <p>
 * When the view is shown to the user, appears as a floating view over the
 * application.  It will never receive focus.  The user will probably be in the
 * middle of typing something else.  The idea is to be as unobtrusive as
 * possible, while still showing the user the information you want them to see.
 * Two examples are the volume control, and the brief message saying that your
 * settings have been saved.
 * <p>
 * The easiest way to use this class is to call one of the static methods that constructs
 * everything you need and returns a new Toast object.
 *
 * <div class="special reference">
 * <h3>Developer Guides</h3>
 * <p>For information about creating Toast notifications, read the
 * <a href="{@docRoot}guide/topics/ui/notifiers/toasts.html">Toast Notifications</a> developer
 * guide.</p>
 * </div>
 */
public class Toast {
    static final String TAG = "Toast";
    static final boolean localLOGV = false;

    
@hide
/** @hide */
    @IntDef(prefix = { "LENGTH_" }, value = {
            LENGTH_SHORT,
            LENGTH_LONG
    })
    @Retention(RetentionPolicy.SOURCE)
    public @interface Duration {}

    
Show the view or text notification for a short period of time.  This time
could be user-definable.  This is the default.

See Also:
  • setDuration
/**
     * Show the view or text notification for a short period of time.  This time
     * could be user-definable.  This is the default.
     * @see #setDuration
     */
    public static final int LENGTH_SHORT = 0;

    
Show the view or text notification for a long period of time.  This time
could be user-definable.

See Also:
  • setDuration
/**
     * Show the view or text notification for a long period of time.  This time
     * could be user-definable.
     * @see #setDuration
     */
    public static final int LENGTH_LONG = 1;

    final Context mContext;
    final TN mTN;
    int mDuration;
    View mNextView;

    
Construct an empty Toast object. You must call setView before you can call show. 
Params:
/**
     * Construct an empty Toast object.  You must call {@link #setView} before you
     * can call {@link #show}.
     *
     * @param context  The context to use.  Usually your {@link android.app.Application}
     *                 or {@link android.app.Activity} object.
     */
    public Toast(Context context) {
        this(context, null);
    }

    
Constructs an empty Toast object.  If looper is null, Looper.myLooper() is used.

@hide
/**
     * Constructs an empty Toast object.  If looper is null, Looper.myLooper() is used.
     * @hide
     */
    public Toast(@NonNull Context context, @Nullable Looper looper) {
        mContext = context;
        mTN = new TN(context.getPackageName(), looper);
        mTN.mY = context.getResources().getDimensionPixelSize(
                com.android.internal.R.dimen.toast_y_offset);
        mTN.mGravity = context.getResources().getInteger(
                com.android.internal.R.integer.config_toastDefaultGravity);
    }

    
Show the view for the specified duration.

/**
     * Show the view for the specified duration.
     */
    public void show() {
        if (mNextView == null) {
            throw new RuntimeException("setView must have been called");
        }

        INotificationManager service = getService();
        String pkg = mContext.getOpPackageName();
        TN tn = mTN;
        tn.mNextView = mNextView;

        try {
            service.enqueueToast(pkg, tn, mDuration);
        } catch (RemoteException e) {
            // Empty
        }
    }

    
Close the view if it's showing, or don't show it if it isn't showing yet.
You do not normally have to call this.  Normally view will disappear on its own
after the appropriate duration.

/**
     * Close the view if it's showing, or don't show it if it isn't showing yet.
     * You do not normally have to call this.  Normally view will disappear on its own
     * after the appropriate duration.
     */
    public void cancel() {
        mTN.cancel();
    }

    
Set the view to show.

See Also:
  • getView
/**
     * Set the view to show.
     * @see #getView
     */
    public void setView(View view) {
        mNextView = view;
    }

    
Return the view.

See Also:
  • setView
/**
     * Return the view.
     * @see #setView
     */
    public View getView() {
        return mNextView;
    }

    
Set how long to show the view for.

See Also:
/**
     * Set how long to show the view for.
     * @see #LENGTH_SHORT
     * @see #LENGTH_LONG
     */
    public void setDuration(@Duration int duration) {
        mDuration = duration;
        mTN.mDuration = duration;
    }

    
Return the duration.

See Also:
  • setDuration
/**
     * Return the duration.
     * @see #setDuration
     */
    @Duration
    public int getDuration() {
        return mDuration;
    }

    
Set the margins of the view.

Params:
  • horizontalMargin – The horizontal margin, in percentage of the
       container width, between the container's edges and the
       notification
  • verticalMargin – The vertical margin, in percentage of the
       container height, between the container's edges and the
       notification
/**
     * Set the margins of the view.
     *
     * @param horizontalMargin The horizontal margin, in percentage of the
     *        container width, between the container's edges and the
     *        notification
     * @param verticalMargin The vertical margin, in percentage of the
     *        container height, between the container's edges and the
     *        notification
     */
    public void setMargin(float horizontalMargin, float verticalMargin) {
        mTN.mHorizontalMargin = horizontalMargin;
        mTN.mVerticalMargin = verticalMargin;
    }

    
Return the horizontal margin.

/**
     * Return the horizontal margin.
     */
    public float getHorizontalMargin() {
        return mTN.mHorizontalMargin;
    }

    
Return the vertical margin.

/**
     * Return the vertical margin.
     */
    public float getVerticalMargin() {
        return mTN.mVerticalMargin;
    }

    
Set the location at which the notification should appear on the screen.

See Also:
/**
     * Set the location at which the notification should appear on the screen.
     * @see android.view.Gravity
     * @see #getGravity
     */
    public void setGravity(int gravity, int xOffset, int yOffset) {
        mTN.mGravity = gravity;
        mTN.mX = xOffset;
        mTN.mY = yOffset;
    }

     
Get the location at which the notification should appear on the screen.

See Also:
/**
     * Get the location at which the notification should appear on the screen.
     * @see android.view.Gravity
     * @see #getGravity
     */
    public int getGravity() {
        return mTN.mGravity;
    }

    
Return the X offset in pixels to apply to the gravity's location.

/**
     * Return the X offset in pixels to apply to the gravity's location.
     */
    public int getXOffset() {
        return mTN.mX;
    }

    
Return the Y offset in pixels to apply to the gravity's location.

/**
     * Return the Y offset in pixels to apply to the gravity's location.
     */
    public int getYOffset() {
        return mTN.mY;
    }

    
Gets the LayoutParams for the Toast window.

@hide
/**
     * Gets the LayoutParams for the Toast window.
     * @hide
     */
    public WindowManager.LayoutParams getWindowParams() {
        return mTN.mParams;
    }

    
Make a standard toast that just contains a text view.

Params:
/**
     * Make a standard toast that just contains a text view.
     *
     * @param context  The context to use.  Usually your {@link android.app.Application}
     *                 or {@link android.app.Activity} object.
     * @param text     The text to show.  Can be formatted text.
     * @param duration How long to display the message.  Either {@link #LENGTH_SHORT} or
     *                 {@link #LENGTH_LONG}
     *
     */
    public static Toast makeText(Context context, CharSequence text, @Duration int duration) {
        return makeText(context, null, text, duration);
    }

    
Make a standard toast to display using the specified looper.
If looper is null, Looper.myLooper() is used.

@hide
/**
     * Make a standard toast to display using the specified looper.
     * If looper is null, Looper.myLooper() is used.
     * @hide
     */
    public static Toast makeText(@NonNull Context context, @Nullable Looper looper,
            @NonNull CharSequence text, @Duration int duration) {
        Toast result = new Toast(context, looper);

        LayoutInflater inflate = (LayoutInflater)
                context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View v = inflate.inflate(com.android.internal.R.layout.transient_notification, null);
        TextView tv = (TextView)v.findViewById(com.android.internal.R.id.message);
        tv.setText(text);

        result.mNextView = v;
        result.mDuration = duration;

        return result;
    }

    
Make a standard toast that just contains a text view with the text from a resource.

Params:
  • context –  The context to use. Usually your Application or Activity object.
  • resId –    The resource id of the string resource to use.  Can be formatted text.
  • duration – How long to display the message. Either LENGTH_SHORT or LENGTH_LONG
Throws:
/**
     * Make a standard toast that just contains a text view with the text from a resource.
     *
     * @param context  The context to use.  Usually your {@link android.app.Application}
     *                 or {@link android.app.Activity} object.
     * @param resId    The resource id of the string resource to use.  Can be formatted text.
     * @param duration How long to display the message.  Either {@link #LENGTH_SHORT} or
     *                 {@link #LENGTH_LONG}
     *
     * @throws Resources.NotFoundException if the resource can't be found.
     */
    public static Toast makeText(Context context, @StringRes int resId, @Duration int duration)
                                throws Resources.NotFoundException {
        return makeText(context, context.getResources().getText(resId), duration);
    }

    
Update the text in a Toast that was previously created using one of the makeText() methods.

Params:
  • resId – The new text for the Toast.
/**
     * Update the text in a Toast that was previously created using one of the makeText() methods.
     * @param resId The new text for the Toast.
     */
    public void setText(@StringRes int resId) {
        setText(mContext.getText(resId));
    }

    
Update the text in a Toast that was previously created using one of the makeText() methods.

Params:
  • s – The new text for the Toast.
/**
     * Update the text in a Toast that was previously created using one of the makeText() methods.
     * @param s The new text for the Toast.
     */
    public void setText(CharSequence s) {
        if (mNextView == null) {
            throw new RuntimeException("This Toast was not created with Toast.makeText()");
        }
        TextView tv = mNextView.findViewById(com.android.internal.R.id.message);
        if (tv == null) {
            throw new RuntimeException("This Toast was not created with Toast.makeText()");
        }
        tv.setText(s);
    }

    // =======================================================================================
    // All the gunk below is the interaction with the Notification Service, which handles
    // the proper ordering of these system-wide.
    // =======================================================================================

    private static INotificationManager sService;

    static private INotificationManager getService() {
        if (sService != null) {
            return sService;
        }
        sService = INotificationManager.Stub.asInterface(ServiceManager.getService("notification"));
        return sService;
    }

    private static class TN extends ITransientNotification.Stub {
        private final WindowManager.LayoutParams mParams = new WindowManager.LayoutParams();

        private static final int SHOW = 0;
        private static final int HIDE = 1;
        private static final int CANCEL = 2;
        final Handler mHandler;

        int mGravity;
        int mX, mY;
        float mHorizontalMargin;
        float mVerticalMargin;


        View mView;
        View mNextView;
        int mDuration;

        WindowManager mWM;

        String mPackageName;

        static final long SHORT_DURATION_TIMEOUT = 4000;
        static final long LONG_DURATION_TIMEOUT = 7000;

        TN(String packageName, @Nullable Looper looper) {
            // XXX This should be changed to use a Dialog, with a Theme.Toast
            // defined that sets up the layout params appropriately.
            final WindowManager.LayoutParams params = mParams;
            params.height = WindowManager.LayoutParams.WRAP_CONTENT;
            params.width = WindowManager.LayoutParams.WRAP_CONTENT;
            params.format = PixelFormat.TRANSLUCENT;
            params.windowAnimations = com.android.internal.R.style.Animation_Toast;
            params.type = WindowManager.LayoutParams.TYPE_TOAST;
            params.setTitle("Toast");
            params.flags = WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
                    | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                    | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE;

            mPackageName = packageName;

            if (looper == null) {
                // Use Looper.myLooper() if looper is not specified.
                looper = Looper.myLooper();
                if (looper == null) {
                    throw new RuntimeException(
                            "Can't toast on a thread that has not called Looper.prepare()");
                }
            }
            mHandler = new Handler(looper, null) {
                @Override
                public void handleMessage(Message msg) {
                    switch (msg.what) {
                        case SHOW: {
                            IBinder token = (IBinder) msg.obj;
                            handleShow(token);
                            break;
                        }
                        case HIDE: {
                            handleHide();
                            // Don't do this in handleHide() because it is also invoked by
                            // handleShow()
                            mNextView = null;
                            break;
                        }
                        case CANCEL: {
                            handleHide();
                            // Don't do this in handleHide() because it is also invoked by
                            // handleShow()
                            mNextView = null;
                            try {
                                getService().cancelToast(mPackageName, TN.this);
                            } catch (RemoteException e) {
                            }
                            break;
                        }
                    }
                }
            };
        }

        
schedule handleShow into the right thread

/**
         * schedule handleShow into the right thread
         */
        @Override
        public void show(IBinder windowToken) {
            if (localLOGV) Log.v(TAG, "SHOW: " + this);
            mHandler.obtainMessage(SHOW, windowToken).sendToTarget();
        }

        
schedule handleHide into the right thread

/**
         * schedule handleHide into the right thread
         */
        @Override
        public void hide() {
            if (localLOGV) Log.v(TAG, "HIDE: " + this);
            mHandler.obtainMessage(HIDE).sendToTarget();
        }

        public void cancel() {
            if (localLOGV) Log.v(TAG, "CANCEL: " + this);
            mHandler.obtainMessage(CANCEL).sendToTarget();
        }

        public void handleShow(IBinder windowToken) {
            if (localLOGV) Log.v(TAG, "HANDLE SHOW: " + this + " mView=" + mView
                    + " mNextView=" + mNextView);
            // If a cancel/hide is pending - no need to show - at this point
            // the window token is already invalid and no need to do any work.
            if (mHandler.hasMessages(CANCEL) || mHandler.hasMessages(HIDE)) {
                return;
            }
            if (mView != mNextView) {
                // remove the old view if necessary
                handleHide();
                mView = mNextView;
                Context context = mView.getContext().getApplicationContext();
                String packageName = mView.getContext().getOpPackageName();
                if (context == null) {
                    context = mView.getContext();
                }
                mWM = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
                // We can resolve the Gravity here by using the Locale for getting
                // the layout direction
                final Configuration config = mView.getContext().getResources().getConfiguration();
                final int gravity = Gravity.getAbsoluteGravity(mGravity, config.getLayoutDirection());
                mParams.gravity = gravity;
                if ((gravity & Gravity.HORIZONTAL_GRAVITY_MASK) == Gravity.FILL_HORIZONTAL) {
                    mParams.horizontalWeight = 1.0f;
                }
                if ((gravity & Gravity.VERTICAL_GRAVITY_MASK) == Gravity.FILL_VERTICAL) {
                    mParams.verticalWeight = 1.0f;
                }
                mParams.x = mX;
                mParams.y = mY;
                mParams.verticalMargin = mVerticalMargin;
                mParams.horizontalMargin = mHorizontalMargin;
                mParams.packageName = packageName;
                mParams.hideTimeoutMilliseconds = mDuration ==
                    Toast.LENGTH_LONG ? LONG_DURATION_TIMEOUT : SHORT_DURATION_TIMEOUT;
                mParams.token = windowToken;
                if (mView.getParent() != null) {
                    if (localLOGV) Log.v(TAG, "REMOVE! " + mView + " in " + this);
                    mWM.removeView(mView);
                }
                if (localLOGV) Log.v(TAG, "ADD! " + mView + " in " + this);
                // Since the notification manager service cancels the token right
                // after it notifies us to cancel the toast there is an inherent
                // race and we may attempt to add a window after the token has been
                // invalidated. Let us hedge against that.
                try {
                    mWM.addView(mView, mParams);
                    trySendAccessibilityEvent();
                } catch (WindowManager.BadTokenException e) {
                    /* ignore */
                }
            }
        }

        private void trySendAccessibilityEvent() {
            AccessibilityManager accessibilityManager =
                    AccessibilityManager.getInstance(mView.getContext());
            if (!accessibilityManager.isEnabled()) {
                return;
            }
            // treat toasts as notifications since they are used to
            // announce a transient piece of information to the user
            AccessibilityEvent event = AccessibilityEvent.obtain(
                    AccessibilityEvent.TYPE_NOTIFICATION_STATE_CHANGED);
            event.setClassName(getClass().getName());
            event.setPackageName(mView.getContext().getPackageName());
            mView.dispatchPopulateAccessibilityEvent(event);
            accessibilityManager.sendAccessibilityEvent(event);
        }

        public void handleHide() {
            if (localLOGV) Log.v(TAG, "HANDLE HIDE: " + this + " mView=" + mView);
            if (mView != null) {
                // note: checking parent() just to make sure the view has
                // been added...  i have seen cases where we get here when
                // the view isn't yet added, so let's try not to crash.
                if (mView.getParent() != null) {
                    if (localLOGV) Log.v(TAG, "REMOVE! " + mView + " in " + this);
                    mWM.removeViewImmediate(mView);
                }


                // Now that we've removed the view it's safe for the server to release
                // the resources.
                try {
                    getService().finishToken(mPackageName, this);
                } catch (RemoteException e) {
                }

                mView = null;
            }
        }
    }
}