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         * As of O, {@link #surfaceRedrawNeededAsync} may be implemented
120         * to provide a non-blocking implementation. If {@link #surfaceRedrawNeededAsync}
121         * is not implemented, then this will be called instead.
122         *
123         * @param holder The SurfaceHolder whose surface has changed.
124         */
125        void surfaceRedrawNeeded(SurfaceHolder holder);
126
127        /**
128         * An alternative to surfaceRedrawNeeded where it is not required to block
129         * until the redraw is complete. You should initiate the redraw, and return,
130         * later invoking drawingFinished when your redraw is complete.
131         *
132         * This can be useful to avoid blocking your main application thread on rendering.
133         *
134         * As of O, if this is implemented {@link #surfaceRedrawNeeded} will not be called.
135         * However it is still recommended to implement {@link #surfaceRedrawNeeded} for
136         * compatibility with older versions of the platform.
137         *
138         * @param holder The SurfaceHolder which needs redrawing.
139         * @param drawingFinished A runnable to signal completion. This may be invoked
140         * from any thread.
141         *
142         */
143        default void surfaceRedrawNeededAsync(SurfaceHolder holder, Runnable drawingFinished) {
144            surfaceRedrawNeeded(holder);
145            drawingFinished.run();
146        }
147    }
148
149    /**
150     * Add a Callback interface for this holder.  There can several Callback
151     * interfaces associated with a holder.
152     *
153     * @param callback The new Callback interface.
154     */
155    public void addCallback(Callback callback);
156
157    /**
158     * Removes a previously added Callback interface from this holder.
159     *
160     * @param callback The Callback interface to remove.
161     */
162    public void removeCallback(Callback callback);
163
164    /**
165     * Use this method to find out if the surface is in the process of being
166     * created from Callback methods. This is intended to be used with
167     * {@link Callback#surfaceChanged}.
168     *
169     * @return true if the surface is in the process of being created.
170     */
171    public boolean isCreating();
172
173    /**
174     * Sets the surface's type.
175     *
176     * @deprecated this is ignored, this value is set automatically when needed.
177     */
178    @Deprecated
179    public void setType(int type);
180
181    /**
182     * Make the surface a fixed size.  It will never change from this size.
183     * When working with a {@link SurfaceView}, this must be called from the
184     * same thread running the SurfaceView's window.
185     *
186     * @param width The surface's width.
187     * @param height The surface's height.
188     */
189    public void setFixedSize(int width, int height);
190
191    /**
192     * Allow the surface to resized based on layout of its container (this is
193     * the default).  When this is enabled, you should monitor
194     * {@link Callback#surfaceChanged} for changes to the size of the surface.
195     * When working with a {@link SurfaceView}, this must be called from the
196     * same thread running the SurfaceView's window.
197     */
198    public void setSizeFromLayout();
199
200    /**
201     * Set the desired PixelFormat of the surface.  The default is OPAQUE.
202     * When working with a {@link SurfaceView}, this must be called from the
203     * same thread running the SurfaceView's window.
204     *
205     * @param format A constant from PixelFormat.
206     *
207     * @see android.graphics.PixelFormat
208     */
209    public void setFormat(int format);
210
211    /**
212     * Enable or disable option to keep the screen turned on while this
213     * surface is displayed.  The default is false, allowing it to turn off.
214     * This is safe to call from any thread.
215     *
216     * @param screenOn Set to true to force the screen to stay on, false
217     * to allow it to turn off.
218     */
219    public void setKeepScreenOn(boolean screenOn);
220
221    /**
222     * Start editing the pixels in the surface.  The returned Canvas can be used
223     * to draw into the surface's bitmap.  A null is returned if the surface has
224     * not been created or otherwise cannot be edited.  You will usually need
225     * to implement {@link Callback#surfaceCreated Callback.surfaceCreated}
226     * to find out when the Surface is available for use.
227     *
228     * <p>The content of the Surface is never preserved between unlockCanvas() and
229     * lockCanvas(), for this reason, every pixel within the Surface area
230     * must be written. The only exception to this rule is when a dirty
231     * rectangle is specified, in which case, non-dirty pixels will be
232     * preserved.
233     *
234     * <p>If you call this repeatedly when the Surface is not ready (before
235     * {@link Callback#surfaceCreated Callback.surfaceCreated} or after
236     * {@link Callback#surfaceDestroyed Callback.surfaceDestroyed}), your calls
237     * will be throttled to a slow rate in order to avoid consuming CPU.
238     *
239     * <p>If null is not returned, this function internally holds a lock until
240     * the corresponding {@link #unlockCanvasAndPost} call, preventing
241     * {@link SurfaceView} from creating, destroying, or modifying the surface
242     * while it is being drawn.  This can be more convenient than accessing
243     * the Surface directly, as you do not need to do special synchronization
244     * with a drawing thread in {@link Callback#surfaceDestroyed
245     * Callback.surfaceDestroyed}.
246     *
247     * @return Canvas Use to draw into the surface.
248     */
249    public Canvas lockCanvas();
250
251
252    /**
253     * Just like {@link #lockCanvas()} but allows specification of a dirty rectangle.
254     * Every
255     * pixel within that rectangle must be written; however pixels outside
256     * the dirty rectangle will be preserved by the next call to lockCanvas().
257     *
258     * @see android.view.SurfaceHolder#lockCanvas
259     *
260     * @param dirty Area of the Surface that will be modified.
261     * @return Canvas Use to draw into the surface.
262     */
263    public Canvas lockCanvas(Rect dirty);
264
265    /**
266     * <p>Just like {@link #lockCanvas()} but the returned canvas is hardware-accelerated.
267     *
268     * <p>See the <a href="{@docRoot}guide/topics/graphics/hardware-accel.html#unsupported">
269     * unsupported drawing operations</a> for a list of what is and isn't
270     * supported in a hardware-accelerated canvas.
271     *
272     * @return Canvas Use to draw into the surface.
273     * @throws IllegalStateException If the canvas cannot be locked.
274     */
275    default Canvas lockHardwareCanvas() {
276        throw new IllegalStateException("This SurfaceHolder doesn't support lockHardwareCanvas");
277    }
278
279    /**
280     * Finish editing pixels in the surface.  After this call, the surface's
281     * current pixels will be shown on the screen, but its content is lost,
282     * in particular there is no guarantee that the content of the Surface
283     * will remain unchanged when lockCanvas() is called again.
284     *
285     * @see #lockCanvas()
286     *
287     * @param canvas The Canvas previously returned by lockCanvas().
288     */
289    public void unlockCanvasAndPost(Canvas canvas);
290
291    /**
292     * Retrieve the current size of the surface.  Note: do not modify the
293     * returned Rect.  This is only safe to call from the thread of
294     * {@link SurfaceView}'s window, or while inside of
295     * {@link #lockCanvas()}.
296     *
297     * @return Rect The surface's dimensions.  The left and top are always 0.
298     */
299    public Rect getSurfaceFrame();
300
301    /**
302     * Direct access to the surface object.  The Surface may not always be
303     * available -- for example when using a {@link SurfaceView} the holder's
304     * Surface is not created until the view has been attached to the window
305     * manager and performed a layout in order to determine the dimensions
306     * and screen position of the Surface.    You will thus usually need
307     * to implement {@link Callback#surfaceCreated Callback.surfaceCreated}
308     * to find out when the Surface is available for use.
309     *
310     * <p>Note that if you directly access the Surface from another thread,
311     * it is critical that you correctly implement
312     * {@link Callback#surfaceCreated Callback.surfaceCreated} and
313     * {@link Callback#surfaceDestroyed Callback.surfaceDestroyed} to ensure
314     * that thread only accesses the Surface while it is valid, and that the
315     * Surface does not get destroyed while the thread is using it.
316     *
317     * <p>This method is intended to be used by frameworks which often need
318     * direct access to the Surface object (usually to pass it to native code).
319     *
320     * @return Surface The surface.
321     */
322    public Surface getSurface();
323}
324