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GLSurfaceView.javaAPI DocAndroid 1.5 API40916Wed May 06 22:42:00 BST 2009android.opengl

GLSurfaceView

public class GLSurfaceView extends android.view.SurfaceView implements SurfaceHolder.Callback
An implementation of SurfaceView that uses the dedicated surface for displaying OpenGL rendering.

A GLSurfaceView provides the following features:

  • Manages a surface, which is a special piece of memory that can be composited into the Android view system.
  • Manages an EGL display, which enables OpenGL to render into a surface.
  • Accepts a user-provided Renderer object that does the actual rendering.
  • Renders on a dedicated thread to decouple rendering performance from the UI thread.
  • Supports both on-demand and continuous rendering.
  • Optionally wraps, traces, and/or error-checks the renderer's OpenGL calls.

Using GLSurfaceView

Typically you use GLSurfaceView by subclassing it and overriding one or more of the View system input event methods. If your application does not need to override event methods then GLSurfaceView can be used as-is. For the most part GLSurfaceView behavior is customized by calling "set" methods rather than by subclassing. For example, unlike a regular View, drawing is delegated to a separate Renderer object which is registered with the GLSurfaceView using the {@link #setRenderer(Renderer)} call.

Initializing GLSurfaceView

All you have to do to initialize a GLSurfaceView is call {@link #setRenderer(Renderer)}. However, if desired, you can modify the default behavior of GLSurfaceView by calling one or more of these methods before calling setRenderer:
  • {@link #setDebugFlags(int)}
  • {@link #setEGLConfigChooser(boolean)}
  • {@link #setEGLConfigChooser(EGLConfigChooser)}
  • {@link #setEGLConfigChooser(int, int, int, int, int, int)}
  • {@link #setGLWrapper(GLWrapper)}

Choosing an EGL Configuration

A given Android device may support multiple possible types of drawing surfaces. The available surfaces may differ in how may channels of data are present, as well as how many bits are allocated to each channel. Therefore, the first thing GLSurfaceView has to do when starting to render is choose what type of surface to use.

By default GLSurfaceView chooses an available surface that's closest to a 16-bit R5G6B5 surface with a 16-bit depth buffer and no stencil. If you would prefer a different surface (for example, if you do not need a depth buffer) you can override the default behavior by calling one of the setEGLConfigChooser methods.

Debug Behavior

You can optionally modify the behavior of GLSurfaceView by calling one or more of the debugging methods {@link #setDebugFlags(int)}, and {@link #setGLWrapper}. These methods may be called before and/or after setRenderer, but typically they are called before setRenderer so that they take effect immediately.

Setting a Renderer

Finally, you must call {@link #setRenderer} to register a {@link Renderer}. The renderer is responsible for doing the actual OpenGL rendering.

Rendering Mode

Once the renderer is set, you can control whether the renderer draws continuously or on-demand by calling {@link #setRenderMode}. The default is continuous rendering.

Activity Life-cycle

A GLSurfaceView must be notified when the activity is paused and resumed. GLSurfaceView clients are required to call {@link #onPause()} when the activity pauses and {@link #onResume()} when the activity resumes. These calls allow GLSurfaceView to pause and resume the rendering thread, and also allow GLSurfaceView to release and recreate the OpenGL display.

Handling events

To handle an event you will typically subclass GLSurfaceView and override the appropriate method, just as you would with any other View. However, when handling the event, you may need to communicate with the Renderer object that's running in the rendering thread. You can do this using any standard Java cross-thread communication mechanism. In addition, one relatively easy way to communicate with your renderer is to call {@link #queueEvent(Runnable)}. For example: 

class MyGLSurfaceView extends GLSurfaceView {

private MyRenderer mMyRenderer;

public void start() {
mMyRenderer = ...;
setRenderer(mMyRenderer);
}

public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
queueEvent(new Runnable() {
// This method will be called on the rendering
// thread:
public void run() {
mMyRenderer.handleDpadCenter();
}});
return true;
}
return super.onKeyDown(keyCode, event);
}
}

Fields Summary
public static final int
RENDERMODE_WHEN_DIRTY
The renderer only renders when the surface is created, or when {@link #requestRender} is called.
public static final int
RENDERMODE_CONTINUOUSLY
The renderer is called continuously to re-render the scene.
public static final int
DEBUG_CHECK_GL_ERROR
Check glError() after every GL call and throw an exception if glError indicates that an error has occurred. This can be used to help track down which OpenGL ES call is causing an error.
public static final int
DEBUG_LOG_GL_CALLS
Log GL calls to the system log at "verbose" level with tag "GLSurfaceView".
private static final Semaphore
sEglSemaphore
private boolean
mSizeChanged
private GLThread
mGLThread
private EGLConfigChooser
mEGLConfigChooser
private GLWrapper
mGLWrapper
private int
mDebugFlags
Constructors Summary
public GLSurfaceView(android.content.Context context)
Standard View constructor. In order to render something, you must call {@link #setRenderer} to register a renderer.


                          
       
        super(context);
        init();
public GLSurfaceView(android.content.Context context, android.util.AttributeSet attrs)
Standard View constructor. In order to render something, you must call {@link #setRenderer} to register a renderer.

        super(context, attrs);
        init();
Methods Summary
public intgetDebugFlags()
Get the current value of the debug flags.

return
the current value of the debug flags.

        return mDebugFlags;
public intgetRenderMode()
Get the current rendering mode. May be called from any thread. Must not be called before a renderer has been set.

return
the current rendering mode.
see
#RENDERMODE_CONTINUOUSLY
see
#RENDERMODE_WHEN_DIRTY

        return mGLThread.getRenderMode();
private voidinit()

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed
        SurfaceHolder holder = getHolder();
        holder.addCallback(this);
        holder.setType(SurfaceHolder.SURFACE_TYPE_GPU);
protected voidonDetachedFromWindow()
This method is used as part of the View class and is not normally called or subclassed by clients of GLSurfaceView. Must not be called before a renderer has been set.

        super.onDetachedFromWindow();
        mGLThread.requestExitAndWait();
public voidonPause()
Inform the view that the activity is paused. The owner of this view must call this method when the activity is paused. Calling this method will pause the rendering thread. Must not be called before a renderer has been set.

        mGLThread.onPause();
public voidonResume()
Inform the view that the activity is resumed. The owner of this view must call this method when the activity is resumed. Calling this method will recreate the OpenGL display and resume the rendering thread. Must not be called before a renderer has been set.

        mGLThread.onResume();
public voidqueueEvent(java.lang.Runnable r)
Queue a runnable to be run on the GL rendering thread. This can be used to communicate with the Renderer on the rendering thread. Must not be called before a renderer has been set.

param
r the runnable to be run on the GL rendering thread.

        mGLThread.queueEvent(r);
public voidrequestRender()
Request that the renderer render a frame. This method is typically used when the render mode has been set to {@link #RENDERMODE_WHEN_DIRTY}, so that frames are only rendered on demand. May be called from any thread. Must not be called before a renderer has been set.

        mGLThread.requestRender();
public voidsetDebugFlags(int debugFlags)
Set the debug flags to a new value. The value is constructed by OR-together zero or more of the DEBUG_CHECK_* constants. The debug flags take effect whenever a surface is created. The default value is zero.

param
debugFlags the new debug flags
see
#DEBUG_CHECK_GL_ERROR
see
#DEBUG_LOG_GL_CALLS

        mDebugFlags = debugFlags;
public voidsetEGLConfigChooser(int redSize, int greenSize, int blueSize, int alphaSize, int depthSize, int stencilSize)
Install a config chooser which will choose a config with at least the specified component sizes, and as close to the specified component sizes as possible.

If this method is called, it must be called before {@link #setRenderer(Renderer)} is called.

If no setEGLConfigChooser method is called, then by default the view will choose a config as close to 16-bit RGB as possible, with a depth buffer as close to 16 bits as possible.

        setEGLConfigChooser(new ComponentSizeChooser(redSize, greenSize,
                blueSize, alphaSize, depthSize, stencilSize));
public voidsetEGLConfigChooser(android.opengl.GLSurfaceView$EGLConfigChooser configChooser)
Install a custom EGLConfigChooser.

If this method is called, it must be called before {@link #setRenderer(Renderer)} is called.

If no setEGLConfigChooser method is called, then by default the view will choose a config as close to 16-bit RGB as possible, with a depth buffer as close to 16 bits as possible.

param
configChooser

        if (mGLThread != null) {
            throw new IllegalStateException(
                    "setRenderer has already been called for this instance.");
        }
        mEGLConfigChooser = configChooser;
public voidsetEGLConfigChooser(boolean needDepth)
Install a config chooser which will choose a config as close to 16-bit RGB as possible, with or without an optional depth buffer as close to 16-bits as possible.

If this method is called, it must be called before {@link #setRenderer(Renderer)} is called.

If no setEGLConfigChooser method is called, then by default the view will choose a config as close to 16-bit RGB as possible, with a depth buffer as close to 16 bits as possible.

param
needDepth

        setEGLConfigChooser(new SimpleEGLConfigChooser(needDepth));
public voidsetGLWrapper(android.opengl.GLSurfaceView$GLWrapper glWrapper)
Set the glWrapper. If the glWrapper is not null, its {@link GLWrapper#wrap(GL)} method is called whenever a surface is created. A GLWrapper can be used to wrap the GL object that's passed to the renderer. Wrapping a GL object enables examining and modifying the behavior of the GL calls made by the renderer.

Wrapping is typically used for debugging purposes.

The default value is null.

param
glWrapper the new GLWrapper

        mGLWrapper = glWrapper;
public voidsetRenderMode(int renderMode)
Set the rendering mode. When renderMode is RENDERMODE_CONTINUOUSLY, the renderer is called repeatedly to re-render the scene. When renderMode is RENDERMODE_WHEN_DIRTY, the renderer only rendered when the surface is created, or when {@link #requestRender} is called. Defaults to RENDERMODE_CONTINUOUSLY.

Using RENDERMODE_WHEN_DIRTY can improve battery life and overall system performance by allowing the GPU and CPU to idle when the view does not need to be updated.

This method can only be called after {@link #setRenderer(Renderer)}

param
renderMode one of the RENDERMODE_X constants
see
#RENDERMODE_CONTINUOUSLY
see
#RENDERMODE_WHEN_DIRTY

        mGLThread.setRenderMode(renderMode);
public voidsetRenderer(android.opengl.GLSurfaceView$Renderer renderer)
Set the renderer associated with this view. Also starts the thread that will call the renderer, which in turn causes the rendering to start.

This method should be called once and only once in the life-cycle of a GLSurfaceView.

The following GLSurfaceView methods can only be called before setRenderer is called:

  • {@link #setEGLConfigChooser(boolean)}
  • {@link #setEGLConfigChooser(EGLConfigChooser)}
  • {@link #setEGLConfigChooser(int, int, int, int, int, int)}

The following GLSurfaceView methods can only be called after setRenderer is called:

  • {@link #getRenderMode()}
  • {@link #onPause()}
  • {@link #onResume()}
  • {@link #queueEvent(Runnable)}
  • {@link #requestRender()}
  • {@link #setRenderMode(int)}

param
renderer the renderer to use to perform OpenGL drawing.

        if (mGLThread != null) {
            throw new IllegalStateException(
                    "setRenderer has already been called for this instance.");
        }
        if (mEGLConfigChooser == null) {
            mEGLConfigChooser = new SimpleEGLConfigChooser(true);
        }
        mGLThread = new GLThread(renderer);
        mGLThread.start();
public voidsurfaceChanged(android.view.SurfaceHolder holder, int format, int w, int h)
This method is part of the SurfaceHolder.Callback interface, and is not normally called or subclassed by clients of GLSurfaceView.

        mGLThread.onWindowResize(w, h);
public voidsurfaceCreated(android.view.SurfaceHolder holder)
This method is part of the SurfaceHolder.Callback interface, and is not normally called or subclassed by clients of GLSurfaceView.

        mGLThread.surfaceCreated();
public voidsurfaceDestroyed(android.view.SurfaceHolder holder)
This method is part of the SurfaceHolder.Callback interface, and is not normally called or subclassed by clients of GLSurfaceView.

        // Surface will be destroyed when we return
        mGLThread.surfaceDestroyed();