/*
* Copyright (C) 2006 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.view;
import android.graphics.Canvas;
import android.graphics.Rect;
import static android.view.WindowManager.LayoutParams.MEMORY_TYPE_NORMAL;
import static android.view.WindowManager.LayoutParams.MEMORY_TYPE_HARDWARE;
import static android.view.WindowManager.LayoutParams.MEMORY_TYPE_GPU;
import static android.view.WindowManager.LayoutParams.MEMORY_TYPE_PUSH_BUFFERS;
/**
* Abstract interface to someone holding a display surface. Allows you to
* control the surface size and format, edit the pixels in the surface, and
* monitor changes to the surface. This interface is typically available
* through the {@link SurfaceView} class.
*
* <p>When using this interface from a thread different than the one running
* its {@link SurfaceView}, you will want to carefully read the
* {@link #lockCanvas} and {@link Callback#surfaceCreated Callback.surfaceCreated}.
*/
public interface SurfaceHolder {
/**
* Surface type.
*
* @see #SURFACE_TYPE_NORMAL
* @see #SURFACE_TYPE_HARDWARE
* @see #SURFACE_TYPE_GPU
* @see #SURFACE_TYPE_PUSH_BUFFERS
*/
/** Surface type: creates a regular surface, usually in main, non
* contiguous, cached/buffered RAM. */
public static final int SURFACE_TYPE_NORMAL = MEMORY_TYPE_NORMAL;
/** Surface type: creates a suited to be used with DMA engines and
* hardware accelerators. */
public static final int SURFACE_TYPE_HARDWARE = MEMORY_TYPE_HARDWARE;
/** Surface type: creates a surface suited to be used with the GPU */
public static final int SURFACE_TYPE_GPU = MEMORY_TYPE_GPU;
/** Surface type: creates a "push" surface, that is a surface that
* doesn't owns its buffers. With such a surface lockCanvas will fail. */
public static final int SURFACE_TYPE_PUSH_BUFFERS = MEMORY_TYPE_PUSH_BUFFERS;
/**
* Exception that is thrown from {@link #lockCanvas} when called on a Surface
* whose is SURFACE_TYPE_PUSH_BUFFERS.
*/
public static class BadSurfaceTypeException extends RuntimeException {
public BadSurfaceTypeException() {
}
public BadSurfaceTypeException(String name) {
super(name);
}
}
/**
* A client may implement this interface to receive information about
* changes to the surface. When used with a {@link SurfaceView}, the
* Surface being held is only available between calls to
* {@link #surfaceCreated(SurfaceHolder)} and
* {@link #surfaceDestroyed(SurfaceHolder). The Callback is set with
* {@link SurfaceHolder#addCallback SurfaceHolder.addCallback} method.
*/
public interface Callback {
/**
* This is called immediately after the surface is first created.
* Implementations of this should start up whatever rendering code
* they desire. Note that only one thread can ever draw into
* a {@link Surface}, so you should not draw into the Surface here
* if your normal rendering will be in another thread.
*
* @param holder The SurfaceHolder whose surface is being created.
*/
public void surfaceCreated(SurfaceHolder holder);
/**
* This is called immediately after any structural changes (format or
* size) have been made to the surface. You should at this point update
* the imagery in the surface. This method is always called at least
* once, after {@link #surfaceCreated}.
*
* @param holder The SurfaceHolder whose surface has changed.
* @param format The new PixelFormat of the surface.
* @param width The new width of the surface.
* @param height The new height of the surface.
*/
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height);
/**
* This is called immediately before a surface is being destroyed. After
* returning from this call, you should no longer try to access this
* surface. If you have a rendering thread that directly accesses
* the surface, you must ensure that thread is no longer touching the
* Surface before returning from this function.
*
* @param holder The SurfaceHolder whose surface is being destroyed.
*/
public void surfaceDestroyed(SurfaceHolder holder);
}
/**
* Add a Callback interface for this holder. There can several Callback
* interfaces associated to a holder.
*
* @param callback The new Callback interface.
*/
public void addCallback(Callback callback);
/**
* Removes a previously added Callback interface from this holder.
*
* @param callback The Callback interface to remove.
*/
public void removeCallback(Callback callback);
/**
* Use this method to find out if the surface is in the process of being
* created from Callback methods. This is intended to be used with
* {@link Callback#surfaceChanged}.
*
* @return true if the surface is in the process of being created.
*/
public boolean isCreating();
/**
* Sets the surface's type. Surfaces intended to be used with OpenGL ES
* should be of SURFACE_TYPE_GPU, surfaces accessed by DMA engines and
* hardware accelerators should be of type SURFACE_TYPE_HARDWARE.
* Failing to set the surface's type appropriately could result in
* degraded performance or failure.
*
* @param type The surface's memory type.
*/
public void setType(int type);
/**
* Make the surface a fixed size. It will never change from this size.
* When working with a {link SurfaceView}, this must be called from the
* same thread running the SurfaceView's window.
*
* @param width The surface's width.
* @param height The surface's height.
*/
public void setFixedSize(int width, int height);
/**
* Allow the surface to resized based on layout of its container (this is
* the default). When this is enabled, you should monitor
* {@link Callback#surfaceChanged} for changes to the size of the surface.
* When working with a {link SurfaceView}, this must be called from the
* same thread running the SurfaceView's window.
*/
public void setSizeFromLayout();
/**
* Set the desired PixelFormat of the surface. The default is OPAQUE.
* When working with a {link SurfaceView}, this must be called from the
* same thread running the SurfaceView's window.
*
* @param format A constant from PixelFormat.
*
* @see android.graphics.PixelFormat
*/
public void setFormat(int format);
/**
* Enable or disable option to keep the screen turned on while this
* surface is displayed. The default is false, allowing it to turn off.
* Enabling the option effectivelty.
* This is safe to call from any thread.
*
* @param screenOn Supply to true to force the screen to stay on, false
* to allow it to turn off.
*/
public void setKeepScreenOn(boolean screenOn);
/**
* Start editing the pixels in the surface. The returned Canvas can be used
* to draw into the surface's bitmap. A null is returned if the surface has
* not been created or otherwise can not be edited. You will usually need
* to implement {@link Callback#surfaceCreated Callback.surfaceCreated}
* to find out when the Surface is available for use.
*
* <p>The content of the Surface is never preserved between unlockCanvas() and
* lockCanvas(), for this reason, every pixel within the Surface area
* must be written. The only exception to this rule is when a dirty
* rectangle is specified, in which case, non dirty pixels will be
* preserved.
*
* <p>If you call this repeatedly when the Surface is not ready (before
* {@link Callback#surfaceCreated Callback.surfaceCreated} or after
* {@link Callback#surfaceDestroyed Callback.surfaceDestroyed}), your calls
* will be throttled to a slow rate in order to avoid consuming CPU.
*
* <p>If null is not returned, this function internally holds a lock until
* the corresponding {@link #unlockCanvasAndPost} call, preventing
* {@link SurfaceView} from creating, destroying, or modifying the surface
* while it is being drawn. This can be more convenience than accessing
* the Surface directly, as you do not need to do special synchronization
* with a drawing thread in {@link Callback#surfaceDestroyed
* Callback.surfaceDestroyed}.
*
* @return Canvas Use to draw into the surface.
*/
public Canvas lockCanvas();
/**
* Just like {@link #lockCanvas()} but allows to specify a dirty rectangle.
* Every
* pixel within that rectangle must be written; however pixels outside
* the dirty rectangle will be preserved by the next call to lockCanvas().
*
* @see android.view.SurfaceHolder#lockCanvas
*
* @param dirty Area of the Surface that will be modified.
* @return Canvas Use to draw into the surface.
*/
public Canvas lockCanvas(Rect dirty);
/**
* Finish editing pixels in the surface. After this call, the surface's
* current pixels will be shown on the screen, but its content is lost,
* in particular there is no guarantee that the content of the Surface
* will remain unchanged when lockCanvas() is called again.
*
* @see #lockCanvas()
*
* @param canvas The Canvas previously returned by lockCanvas().
*/
public void unlockCanvasAndPost(Canvas canvas);
/**
* Retrieve the current size of the surface. Note: do not modify the
* returned Rect. This is only safe to call from the thread of
* {@link SurfaceView}'s window, or while inside of
* {@link #lockCanvas()}.
*
* @return Rect The surface's dimensions. The left and top are always 0.
*/
public Rect getSurfaceFrame();
/**
* Direct access to the surface object. The Surface may not always be
* available -- for example when using a {@link SurfaceView} the holder's
* Surface is not created until the view has been attached to the window
* manager and performed a layout in order to determine the dimensions
* and screen position of the Surface. You will thus usually need
* to implement {@link Callback#surfaceCreated Callback.surfaceCreated}
* to find out when the Surface is available for use.
*
* <p>Note that if you directly access the Surface from another thread,
* it is critical that you correctly implement
* {@link Callback#surfaceCreated Callback.surfaceCreated} and
* {@link Callback#surfaceDestroyed Callback.surfaceDestroyed} to ensure
* that thread only accesses the Surface while it is valid, and that the
* Surface does not get destroyed while the thread is using it.
*
* <p>This method is intended to be used by frameworks which often need
* direct access to the Surface object (usually to pass it to native code).
* When designing APIs always use SurfaceHolder to pass surfaces around
* as opposed to the Surface object itself. A rule of thumb is that
* application code should never have to call this method.
*
* @return Surface The surface.
*/
public Surface getSurface();
}