1/*
2 * Copyright (C) 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.view;
18
19import android.graphics.Canvas;
20import android.graphics.Rect;
21
22/**
23 * Abstract interface to someone holding a display surface.  Allows you to
24 * control the surface size and format, edit the pixels in the surface, and
25 * monitor changes to the surface.  This interface is typically available
26 * through the {@link SurfaceView} class.
27 *
28 * <p>When using this interface from a thread other than the one running
29 * its {@link SurfaceView}, you will want to carefully read the
30 * methods
31 * {@link #lockCanvas} and {@link Callback#surfaceCreated Callback.surfaceCreated()}.
32 */
33public interface SurfaceHolder {
34
35    /** @deprecated this is ignored, this value is set automatically when needed. */
36    @Deprecated
37    public static final int SURFACE_TYPE_NORMAL = 0;
38    /** @deprecated this is ignored, this value is set automatically when needed. */
39    @Deprecated
40    public static final int SURFACE_TYPE_HARDWARE = 1;
41    /** @deprecated this is ignored, this value is set automatically when needed. */
42    @Deprecated
43    public static final int SURFACE_TYPE_GPU = 2;
44    /** @deprecated this is ignored, this value is set automatically when needed. */
45    @Deprecated
46    public static final int SURFACE_TYPE_PUSH_BUFFERS = 3;
47
48    /**
49     * Exception that is thrown from {@link #lockCanvas} when called on a Surface
50     * whose type is SURFACE_TYPE_PUSH_BUFFERS.
51     */
52    public static class BadSurfaceTypeException extends RuntimeException {
53        public BadSurfaceTypeException() {
54        }
55
56        public BadSurfaceTypeException(String name) {
57            super(name);
58        }
59    }
60
61    /**
62     * A client may implement this interface to receive information about
63     * changes to the surface.  When used with a {@link SurfaceView}, the
64     * Surface being held is only available between calls to
65     * {@link #surfaceCreated(SurfaceHolder)} and
66     * {@link #surfaceDestroyed(SurfaceHolder)}.  The Callback is set with
67     * {@link SurfaceHolder#addCallback SurfaceHolder.addCallback} method.
68     */
69    public interface Callback {
70        /**
71         * This is called immediately after the surface is first created.
72         * Implementations of this should start up whatever rendering code
73         * they desire.  Note that only one thread can ever draw into
74         * a {@link Surface}, so you should not draw into the Surface here
75         * if your normal rendering will be in another thread.
76         *
77         * @param holder The SurfaceHolder whose surface is being created.
78         */
79        public void surfaceCreated(SurfaceHolder holder);
80
81        /**
82         * This is called immediately after any structural changes (format or
83         * size) have been made to the surface.  You should at this point update
84         * the imagery in the surface.  This method is always called at least
85         * once, after {@link #surfaceCreated}.
86         *
87         * @param holder The SurfaceHolder whose surface has changed.
88         * @param format The new PixelFormat of the surface.
89         * @param width The new width of the surface.
90         * @param height The new height of the surface.
91         */
92        public void surfaceChanged(SurfaceHolder holder, int format, int width,
93                int height);
94
95        /**
96         * This is called immediately before a surface is being destroyed. After
97         * returning from this call, you should no longer try to access this
98         * surface.  If you have a rendering thread that directly accesses
99         * the surface, you must ensure that thread is no longer touching the
100         * Surface before returning from this function.
101         *
102         * @param holder The SurfaceHolder whose surface is being destroyed.
103         */
104        public void surfaceDestroyed(SurfaceHolder holder);
105    }
106
107    /**
108     * Additional callbacks that can be received for {@link Callback}.
109     */
110    public interface Callback2 extends Callback {
111        /**
112         * Called when the application needs to redraw the content of its
113         * surface, after it is resized or for some other reason.  By not
114         * returning from here until the redraw is complete, you can ensure that
115         * the user will not see your surface in a bad state (at its new
116         * size before it has been correctly drawn that way).  This will
117         * typically be preceeded by a call to {@link #surfaceChanged}.
118         *
119         * @param holder The SurfaceHolder whose surface has changed.
120         */
121        public void surfaceRedrawNeeded(SurfaceHolder holder);
122    }
123
124    /**
125     * Add a Callback interface for this holder.  There can several Callback
126     * interfaces associated with a holder.
127     *
128     * @param callback The new Callback interface.
129     */
130    public void addCallback(Callback callback);
131
132    /**
133     * Removes a previously added Callback interface from this holder.
134     *
135     * @param callback The Callback interface to remove.
136     */
137    public void removeCallback(Callback callback);
138
139    /**
140     * Use this method to find out if the surface is in the process of being
141     * created from Callback methods. This is intended to be used with
142     * {@link Callback#surfaceChanged}.
143     *
144     * @return true if the surface is in the process of being created.
145     */
146    public boolean isCreating();
147
148    /**
149     * Sets the surface's type.
150     *
151     * @deprecated this is ignored, this value is set automatically when needed.
152     */
153    @Deprecated
154    public void setType(int type);
155
156    /**
157     * Make the surface a fixed size.  It will never change from this size.
158     * When working with a {@link SurfaceView}, this must be called from the
159     * same thread running the SurfaceView's window.
160     *
161     * @param width The surface's width.
162     * @param height The surface's height.
163     */
164    public void setFixedSize(int width, int height);
165
166    /**
167     * Allow the surface to resized based on layout of its container (this is
168     * the default).  When this is enabled, you should monitor
169     * {@link Callback#surfaceChanged} for changes to the size of the surface.
170     * When working with a {@link SurfaceView}, this must be called from the
171     * same thread running the SurfaceView's window.
172     */
173    public void setSizeFromLayout();
174
175    /**
176     * Set the desired PixelFormat of the surface.  The default is OPAQUE.
177     * When working with a {@link SurfaceView}, this must be called from the
178     * same thread running the SurfaceView's window.
179     *
180     * @param format A constant from PixelFormat.
181     *
182     * @see android.graphics.PixelFormat
183     */
184    public void setFormat(int format);
185
186    /**
187     * Enable or disable option to keep the screen turned on while this
188     * surface is displayed.  The default is false, allowing it to turn off.
189     * This is safe to call from any thread.
190     *
191     * @param screenOn Set to true to force the screen to stay on, false
192     * to allow it to turn off.
193     */
194    public void setKeepScreenOn(boolean screenOn);
195
196    /**
197     * Start editing the pixels in the surface.  The returned Canvas can be used
198     * to draw into the surface's bitmap.  A null is returned if the surface has
199     * not been created or otherwise cannot be edited.  You will usually need
200     * to implement {@link Callback#surfaceCreated Callback.surfaceCreated}
201     * to find out when the Surface is available for use.
202     *
203     * <p>The content of the Surface is never preserved between unlockCanvas() and
204     * lockCanvas(), for this reason, every pixel within the Surface area
205     * must be written. The only exception to this rule is when a dirty
206     * rectangle is specified, in which case, non-dirty pixels will be
207     * preserved.
208     *
209     * <p>If you call this repeatedly when the Surface is not ready (before
210     * {@link Callback#surfaceCreated Callback.surfaceCreated} or after
211     * {@link Callback#surfaceDestroyed Callback.surfaceDestroyed}), your calls
212     * will be throttled to a slow rate in order to avoid consuming CPU.
213     *
214     * <p>If null is not returned, this function internally holds a lock until
215     * the corresponding {@link #unlockCanvasAndPost} call, preventing
216     * {@link SurfaceView} from creating, destroying, or modifying the surface
217     * while it is being drawn.  This can be more convenient than accessing
218     * the Surface directly, as you do not need to do special synchronization
219     * with a drawing thread in {@link Callback#surfaceDestroyed
220     * Callback.surfaceDestroyed}.
221     *
222     * @return Canvas Use to draw into the surface.
223     */
224    public Canvas lockCanvas();
225
226
227    /**
228     * Just like {@link #lockCanvas()} but allows specification of a dirty rectangle.
229     * Every
230     * pixel within that rectangle must be written; however pixels outside
231     * the dirty rectangle will be preserved by the next call to lockCanvas().
232     *
233     * @see android.view.SurfaceHolder#lockCanvas
234     *
235     * @param dirty Area of the Surface that will be modified.
236     * @return Canvas Use to draw into the surface.
237     */
238    public Canvas lockCanvas(Rect dirty);
239
240    /**
241     * Finish editing pixels in the surface.  After this call, the surface's
242     * current pixels will be shown on the screen, but its content is lost,
243     * in particular there is no guarantee that the content of the Surface
244     * will remain unchanged when lockCanvas() is called again.
245     *
246     * @see #lockCanvas()
247     *
248     * @param canvas The Canvas previously returned by lockCanvas().
249     */
250    public void unlockCanvasAndPost(Canvas canvas);
251
252    /**
253     * Retrieve the current size of the surface.  Note: do not modify the
254     * returned Rect.  This is only safe to call from the thread of
255     * {@link SurfaceView}'s window, or while inside of
256     * {@link #lockCanvas()}.
257     *
258     * @return Rect The surface's dimensions.  The left and top are always 0.
259     */
260    public Rect getSurfaceFrame();
261
262    /**
263     * Direct access to the surface object.  The Surface may not always be
264     * available -- for example when using a {@link SurfaceView} the holder's
265     * Surface is not created until the view has been attached to the window
266     * manager and performed a layout in order to determine the dimensions
267     * and screen position of the Surface.    You will thus usually need
268     * to implement {@link Callback#surfaceCreated Callback.surfaceCreated}
269     * to find out when the Surface is available for use.
270     *
271     * <p>Note that if you directly access the Surface from another thread,
272     * it is critical that you correctly implement
273     * {@link Callback#surfaceCreated Callback.surfaceCreated} and
274     * {@link Callback#surfaceDestroyed Callback.surfaceDestroyed} to ensure
275     * that thread only accesses the Surface while it is valid, and that the
276     * Surface does not get destroyed while the thread is using it.
277     *
278     * <p>This method is intended to be used by frameworks which often need
279     * direct access to the Surface object (usually to pass it to native code).
280     * When designing APIs always use SurfaceHolder to pass surfaces around
281     * as opposed to the Surface object itself. A rule of thumb is that
282     * application code should never have to call this method.
283     *
284     * @return Surface The surface.
285     */
286    public Surface getSurface();
287}
288