android/app/DialogFragment.java

/*
 * Copyright (C) 2010 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.app;

import android.content.DialogInterface;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;

/**
 * A fragment that displays a dialog window, floating on top of its
 * activity's window.  This fragment contains a Dialog object, which it
 * displays as appropriate based on the fragment's state.  Control of
 * the dialog (deciding when to show, hide, dismiss it) should be done through
 * the API here, not with direct calls on the dialog.
 *
 * <p>Implementations should override this class and implement
 * {@link #onCreateView(LayoutInflater, ViewGroup, Bundle)} to supply the
 * content of the dialog.  Alternatively, they can override
 * {@link #onCreateDialog(Bundle)} to create an entirely custom dialog, such
 * as an AlertDialog, with its own content.
 *
 * <p>Topics covered here:
 * <ol>
 * <li><a href="#Lifecycle">Lifecycle</a>
 * <li><a href="#BasicDialog">Basic Dialog</a>
 * <li><a href="#AlertDialog">Alert Dialog</a>
 * <li><a href="#DialogOrEmbed">Selecting Between Dialog or Embedding</a>
 * </ol>
 *
 * <a name="Lifecycle"></a>
 * <h3>Lifecycle</h3>
 *
 * <p>DialogFragment does various things to keep the fragment's lifecycle
 * driving it, instead of the Dialog.  Note that dialogs are generally
 * autonomous entities -- they are their own window, receiving their own
 * input events, and often deciding on their own when to disappear (by
 * receiving a back key event or the user clicking on a button).
 *
 * <p>DialogFragment needs to ensure that what is happening with the Fragment
 * and Dialog states remains consistent.  To do this, it watches for dismiss
 * events from the dialog and takes are of removing its own state when they
 * happen.  This means you should use {@link #show(FragmentManager, String)}
 * or {@link #show(FragmentTransaction, String)} to add an instance of
 * DialogFragment to your UI, as these keep track of how DialogFragment should
 * remove itself when the dialog is dismissed.
 *
 * <a name="BasicDialog"></a>
 * <h3>Basic Dialog</h3>
 *
 * <p>The simplest use of DialogFragment is as a floating container for the
 * fragment's view hierarchy.  A simple implementation may look like this:
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentDialog.java
 *      dialog}
 *
 * <p>An example showDialog() method on the Activity could be:
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentDialog.java
 *      add_dialog}
 *
 * <p>This removes any currently shown dialog, creates a new DialogFragment
 * with an argument, and shows it as a new state on the back stack.  When the
 * transaction is popped, the current DialogFragment and its Dialog will be
 * destroyed, and the previous one (if any) re-shown.  Note that in this case
 * DialogFragment will take care of popping the transaction of the Dialog
 * is dismissed separately from it.
 *
 * <a name="AlertDialog"></a>
 * <h3>Alert Dialog</h3>
 *
 * <p>Instead of (or in addition to) implementing {@link #onCreateView} to
 * generate the view hierarchy inside of a dialog, you may implement
 * {@link #onCreateDialog(Bundle)} to create your own custom Dialog object.
 *
 * <p>This is most useful for creating an {@link AlertDialog}, allowing you
 * to display standard alerts to the user that are managed by a fragment.
 * A simple example implementation of this is:
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentAlertDialog.java
 *      dialog}
 *
 * <p>The activity creating this fragment may have the following methods to
 * show the dialog and receive results from it:
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentAlertDialog.java
 *      activity}
 *
 * <p>Note that in this case the fragment is not placed on the back stack, it
 * is just added as an indefinitely running fragment.  Because dialogs normally
 * are modal, this will still operate as a back stack, since the dialog will
 * capture user input until it is dismissed.  When it is dismissed, DialogFragment
 * will take care of removing itself from its fragment manager.
 *
 * <a name="DialogOrEmbed"></a>
 * <h3>Selecting Between Dialog or Embedding</h3>
 *
 * <p>A DialogFragment can still optionally be used as a normal fragment, if
 * desired.  This is useful if you have a fragment that in some cases should
 * be shown as a dialog and others embedded in a larger UI.  This behavior
 * will normally be automatically selected for you based on how you are using
 * the fragment, but can be customized with {@link #setShowsDialog(boolean)}.
 *
 * <p>For example, here is a simple dialog fragment:
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentDialogOrActivity.java
 *      dialog}
 *
 * <p>An instance of this fragment can be created and shown as a dialog:
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentDialogOrActivity.java
 *      show_dialog}
 *
 * <p>It can also be added as content in a view hierarchy:
 *
 * {@sample development/samples/ApiDemos/src/com/example/android/apis/app/FragmentDialogOrActivity.java
 *      embed}
 */
public class DialogFragment extends Fragment
        implements DialogInterface.OnCancelListener, DialogInterface.OnDismissListener {

    /**
     * Style for {@link #setStyle(int, int)}: a basic,
     * normal dialog.
     */
    public static final int STYLE_NORMAL = 0;

    /**
     * Style for {@link #setStyle(int, int)}: don't include
     * a title area.
     */
    public static final int STYLE_NO_TITLE = 1;

    /**
     * Style for {@link #setStyle(int, int)}: don't draw
     * any frame at all; the view hierarchy returned by {@link #onCreateView}
     * is entirely responsible for drawing the dialog.
     */
    public static final int STYLE_NO_FRAME = 2;

    /**
     * Style for {@link #setStyle(int, int)}: like
     * {@link #STYLE_NO_FRAME}, but also disables all input to the dialog.
     * The user can not touch it, and its window will not receive input focus.
     */
    public static final int STYLE_NO_INPUT = 3;

    private static final String SAVED_DIALOG_STATE_TAG = "android:savedDialogState";
    private static final String SAVED_STYLE = "android:style";
    private static final String SAVED_THEME = "android:theme";
    private static final String SAVED_CANCELABLE = "android:cancelable";
    private static final String SAVED_SHOWS_DIALOG = "android:showsDialog";
    private static final String SAVED_BACK_STACK_ID = "android:backStackId";

    int mStyle = STYLE_NORMAL;
    int mTheme = 0;
    boolean mCancelable = true;
    boolean mShowsDialog = true;
    int mBackStackId = -1;

    Dialog mDialog;
    boolean mDestroyed;
    boolean mRemoved;

    public DialogFragment() {
    }

    /**
     * Call to customize the basic appearance and behavior of the
     * fragment's dialog.  This can be used for some common dialog behaviors,
     * taking care of selecting flags, theme, and other options for you.  The
     * same effect can be achieve by manually setting Dialog and Window
     * attributes yourself.  Calling this after the fragment's Dialog is
     * created will have no effect.
     *
     * @param style Selects a standard style: may be {@link #STYLE_NORMAL},
     * {@link #STYLE_NO_TITLE}, {@link #STYLE_NO_FRAME}, or
     * {@link #STYLE_NO_INPUT}.
     * @param theme Optional custom theme.  If 0, an appropriate theme (based
     * on the style) will be selected for you.
     */
    public void setStyle(int style, int theme) {
        mStyle = style;
        if (mStyle == STYLE_NO_FRAME || mStyle == STYLE_NO_INPUT) {
            mTheme = com.android.internal.R.style.Theme_Holo_Dialog_NoFrame;
        }
        if (theme != 0) {
            mTheme = theme;
        }
    }

    /**
     * Display the dialog, adding the fragment to the given FragmentManager.  This
     * is a convenience for explicitly creating a transaction, adding the
     * fragment to it with the given tag, and committing it.  This does
     * <em>not</em> add the transaction to the back stack.  When the fragment
     * is dismissed, a new transaction will be executed to remove it from
     * the activity.
     * @param manager The FragmentManager this fragment will be added to.
     * @param tag The tag for this fragment, as per
     * {@link FragmentTransaction#add(Fragment, String) FragmentTransaction.add}.
     */
    public void show(FragmentManager manager, String tag) {
        FragmentTransaction ft = manager.beginTransaction();
        ft.add(this, tag);
        ft.commit();
    }

    /**
     * Display the dialog, adding the fragment using an existing transaction
     * and then committing the transaction.
     * @param transaction An existing transaction in which to add the fragment.
     * @param tag The tag for this fragment, as per
     * {@link FragmentTransaction#add(Fragment, String) FragmentTransaction.add}.
     * @return Returns the identifier of the committed transaction, as per
     * {@link FragmentTransaction#commit() FragmentTransaction.commit()}.
     */
    public int show(FragmentTransaction transaction, String tag) {
        transaction.add(this, tag);
        mRemoved = false;
        mBackStackId = transaction.commit();
        return mBackStackId;
    }

    /**
     * Dismiss the fragment and its dialog.  If the fragment was added to the
     * back stack, all back stack state up to and including this entry will
     * be popped.  Otherwise, a new transaction will be committed to remove
     * the fragment.
     */
    public void dismiss() {
        dismissInternal(false);
    }

    void dismissInternal(boolean allowStateLoss) {
        if (mDialog != null) {
            mDialog.dismiss();
            mDialog = null;
        }
        mRemoved = true;
        if (mBackStackId >= 0) {
            getFragmentManager().popBackStack(mBackStackId,
                    FragmentManager.POP_BACK_STACK_INCLUSIVE);
            mBackStackId = -1;
        } else {
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.remove(this);
            if (allowStateLoss) {
                ft.commitAllowingStateLoss();
            } else {
                ft.commit();
            }
        }
    }

    public Dialog getDialog() {
        return mDialog;
    }

    public int getTheme() {
        return mTheme;
    }

    /**
     * Control whether the shown Dialog is cancelable.  Use this instead of
     * directly calling {@link Dialog#setCancelable(boolean)
     * Dialog.setCancelable(boolean)}, because DialogFragment needs to change
     * its behavior based on this.
     *
     * @param cancelable If true, the dialog is cancelable.  The default
     * is true.
     */
    public void setCancelable(boolean cancelable) {
        mCancelable = cancelable;
        if (mDialog != null) mDialog.setCancelable(cancelable);
    }

    /**
     * Return the current value of {@link #setCancelable(boolean)}.
     */
    public boolean isCancelable() {
        return mCancelable;
    }

    /**
     * Controls whether this fragment should be shown in a dialog.  If not
     * set, no Dialog will be created in {@link #onActivityCreated(Bundle)},
     * and the fragment's view hierarchy will thus not be added to it.  This
     * allows you to instead use it as a normal fragment (embedded inside of
     * its activity).
     *
     * <p>This is normally set for you based on whether the fragment is
     * associated with a container view ID passed to
     * {@link FragmentTransaction#add(int, Fragment) FragmentTransaction.add(int, Fragment)}.
     * If the fragment was added with a container, setShowsDialog will be
     * initialized to false; otherwise, it will be true.
     *
     * @param showsDialog If true, the fragment will be displayed in a Dialog.
     * If false, no Dialog will be created and the fragment's view hierarchly
     * left undisturbed.
     */
    public void setShowsDialog(boolean showsDialog) {
        mShowsDialog = showsDialog;
    }

    /**
     * Return the current value of {@link #setShowsDialog(boolean)}.
     */
    public boolean getShowsDialog() {
        return mShowsDialog;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mShowsDialog = mContainerId == 0;

        if (savedInstanceState != null) {
            mStyle = savedInstanceState.getInt(SAVED_STYLE, STYLE_NORMAL);
            mTheme = savedInstanceState.getInt(SAVED_THEME, 0);
            mCancelable = savedInstanceState.getBoolean(SAVED_CANCELABLE, true);
            mShowsDialog = savedInstanceState.getBoolean(SAVED_SHOWS_DIALOG, mShowsDialog);
            mBackStackId = savedInstanceState.getInt(SAVED_BACK_STACK_ID, -1);
        }
    }

    public Dialog onCreateDialog(Bundle savedInstanceState) {
        return new Dialog(getActivity(), getTheme());
    }

    public void onCancel(DialogInterface dialog) {
    }

    public void onDismiss(DialogInterface dialog) {
        if (!mRemoved) {
            // Note: we need to use allowStateLoss, because the dialog
            // dispatches this asynchronously so we can receive the call
            // after the activity is paused.  Worst case, when the user comes
            // back to the activity they see the dialog again.
            dismissInternal(true);
        }
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        if (!mShowsDialog) {
            return;
        }

        mDialog = onCreateDialog(savedInstanceState);
        mDestroyed = false;
        switch (mStyle) {
            case STYLE_NO_INPUT:
                mDialog.getWindow().addFlags(
                        WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE |
                        WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE);
                // fall through...
            case STYLE_NO_FRAME:
            case STYLE_NO_TITLE:
                mDialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
        }
        View view = getView();
        if (view != null) {
            if (view.getParent() != null) {
                throw new IllegalStateException("DialogFragment can not be attached to a container view");
            }
            mDialog.setContentView(view);
        }
        mDialog.setOwnerActivity(getActivity());
        mDialog.setCancelable(mCancelable);
        mDialog.setOnCancelListener(this);
        mDialog.setOnDismissListener(this);
        if (savedInstanceState != null) {
            Bundle dialogState = savedInstanceState.getBundle(SAVED_DIALOG_STATE_TAG);
            if (dialogState != null) {
                mDialog.onRestoreInstanceState(dialogState);
            }
        }
    }

    @Override
    public void onStart() {
        super.onStart();
        if (mDialog != null) {
            mRemoved = false;
            mDialog.show();
        }
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        if (mDialog != null) {
            Bundle dialogState = mDialog.onSaveInstanceState();
            if (dialogState != null) {
                outState.putBundle(SAVED_DIALOG_STATE_TAG, dialogState);
            }
        }
        if (mStyle != STYLE_NORMAL) {
            outState.putInt(SAVED_STYLE, mStyle);
        }
        if (mTheme != 0) {
            outState.putInt(SAVED_THEME, mTheme);
        }
        if (!mCancelable) {
            outState.putBoolean(SAVED_CANCELABLE, mCancelable);
        }
        if (!mShowsDialog) {
            outState.putBoolean(SAVED_SHOWS_DIALOG, mShowsDialog);
        }
        if (mBackStackId != -1) {
            outState.putInt(SAVED_BACK_STACK_ID, mBackStackId);
        }
    }

    @Override
    public void onStop() {
        super.onStop();
        if (mDialog != null) {
            mDialog.hide();
        }
    }

    /**
     * Remove dialog.
     */
    @Override
    public void onDestroyView() {
        super.onDestroyView();
        mDestroyed = true;
        if (mDialog != null) {
            // Set removed here because this dismissal is just to hide
            // the dialog -- we don't want this to cause the fragment to
            // actually be removed.
            mRemoved = true;
            mDialog.dismiss();
            mDialog = null;
        }
    }
}