https://source.android.com/ 
/*
 * 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.graphics;

import android.annotation.Nullable;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.view.Surface;

import java.lang.ref.WeakReference;


Captures frames from an image stream as an OpenGL ES texture.

The image stream may come from either camera preview or video decode. A Surface created from a SurfaceTexture can be used as an output destination for the camera2, MediaCodec, MediaPlayer, and Allocation APIs. When updateTexImage is called, the contents of the texture object specified when the SurfaceTexture was created are updated to contain the most recent image from the image stream. This may cause some frames of the stream to be skipped. 
A SurfaceTexture may also be used in place of a SurfaceHolder when specifying the output destination of the older Camera API. Doing so will cause all the frames from the image stream to be sent to the SurfaceTexture object rather than to the device's display. 
When sampling from the texture one should first transform the texture coordinates using the matrix queried via getTransformMatrix(float[]). The transform matrix may change each time updateTexImage is called, so it should be re-queried each time the texture image is updated. This matrix transforms traditional 2D OpenGL ES texture coordinate column vectors of the form (s, t, 0, 1) where s and t are on the inclusive interval [0, 1] to the proper sampling location in the streamed texture. This transform compensates for any properties of the image stream source that cause it to appear different from a traditional OpenGL ES texture. For example, sampling from the bottom left corner of the image can be accomplished by transforming the column vector (0, 0, 0, 1) using the queried matrix, while sampling from the top right corner of the image can be done by transforming (1, 1, 0, 1). 
The texture object uses the GL_TEXTURE_EXTERNAL_OES texture target, which is defined by the

GL_OES_EGL_image_external OpenGL ES extension.  This limits how the texture may be used.
Each time the texture is bound it must be bound to the GL_TEXTURE_EXTERNAL_OES target rather than
the GL_TEXTURE_2D target.  Additionally, any OpenGL ES 2.0 shader that samples from the texture
must declare its use of this extension using, for example, an "#extension
GL_OES_EGL_image_external : require" directive.  Such shaders must also access the texture using
the samplerExternalOES GLSL sampler type.

SurfaceTexture objects may be created on any thread. updateTexImage may only be called on the thread with the OpenGL ES context that contains the texture object. The frame-available callback is called on an arbitrary thread, so unless special care is taken updateTexImage should not be called directly from the callback. 
/**
 * Captures frames from an image stream as an OpenGL ES texture.
 *
 * <p>The image stream may come from either camera preview or video decode. A
 * {@link android.view.Surface} created from a SurfaceTexture can be used as an output
 * destination for the {@link android.hardware.camera2}, {@link android.media.MediaCodec},
 * {@link android.media.MediaPlayer}, and {@link android.renderscript.Allocation} APIs.
 * When {@link #updateTexImage} is called, the contents of the texture object specified
 * when the SurfaceTexture was created are updated to contain the most recent image from the image
 * stream.  This may cause some frames of the stream to be skipped.
 *
 * <p>A SurfaceTexture may also be used in place of a SurfaceHolder when specifying the output
 * destination of the older {@link android.hardware.Camera} API. Doing so will cause all the
 * frames from the image stream to be sent to the SurfaceTexture object rather than to the device's
 * display.
 *
 * <p>When sampling from the texture one should first transform the texture coordinates using the
 * matrix queried via {@link #getTransformMatrix(float[])}.  The transform matrix may change each
 * time {@link #updateTexImage} is called, so it should be re-queried each time the texture image
 * is updated.
 * This matrix transforms traditional 2D OpenGL ES texture coordinate column vectors of the form (s,
 * t, 0, 1) where s and t are on the inclusive interval [0, 1] to the proper sampling location in
 * the streamed texture.  This transform compensates for any properties of the image stream source
 * that cause it to appear different from a traditional OpenGL ES texture.  For example, sampling
 * from the bottom left corner of the image can be accomplished by transforming the column vector
 * (0, 0, 0, 1) using the queried matrix, while sampling from the top right corner of the image can
 * be done by transforming (1, 1, 0, 1).
 *
 * <p>The texture object uses the GL_TEXTURE_EXTERNAL_OES texture target, which is defined by the
 * <a href="http://www.khronos.org/registry/gles/extensions/OES/OES_EGL_image_external.txt">
 * GL_OES_EGL_image_external</a> OpenGL ES extension.  This limits how the texture may be used.
 * Each time the texture is bound it must be bound to the GL_TEXTURE_EXTERNAL_OES target rather than
 * the GL_TEXTURE_2D target.  Additionally, any OpenGL ES 2.0 shader that samples from the texture
 * must declare its use of this extension using, for example, an "#extension
 * GL_OES_EGL_image_external : require" directive.  Such shaders must also access the texture using
 * the samplerExternalOES GLSL sampler type.
 *
 * <p>SurfaceTexture objects may be created on any thread.  {@link #updateTexImage} may only be
 * called on the thread with the OpenGL ES context that contains the texture object.  The
 * frame-available callback is called on an arbitrary thread, so unless special care is taken {@link
 * #updateTexImage} should not be called directly from the callback.
 */
public class SurfaceTexture {
    private final Looper mCreatorLooper;
    private Handler mOnFrameAvailableHandler;

    
These fields are used by native code, do not access or modify.

/**
     * These fields are used by native code, do not access or modify.
     */
    private long mSurfaceTexture;
    private long mProducer;
    private long mFrameAvailableListener;

    private boolean mIsSingleBuffered;

    
Callback interface for being notified that a new stream frame is available.

/**
     * Callback interface for being notified that a new stream frame is available.
     */
    public interface OnFrameAvailableListener {
        void onFrameAvailable(SurfaceTexture surfaceTexture);
    }

    
Exception thrown when a SurfaceTexture couldn't be created or resized.

Deprecated:No longer thrown. OutOfResourcesException is used instead.
/**
     * Exception thrown when a SurfaceTexture couldn't be created or resized.
     *
     * @deprecated No longer thrown. {@link android.view.Surface.OutOfResourcesException}
     * is used instead.
     */
    @SuppressWarnings("serial")
    @Deprecated
    public static class OutOfResourcesException extends Exception {
        public OutOfResourcesException() {
        }
        public OutOfResourcesException(String name) {
            super(name);
        }
    }

    
Construct a new SurfaceTexture to stream images to a given OpenGL texture.

Params:
  • texName – the OpenGL texture object name (e.g. generated via glGenTextures)
Throws:
/**
     * Construct a new SurfaceTexture to stream images to a given OpenGL texture.
     *
     * @param texName the OpenGL texture object name (e.g. generated via glGenTextures)
     *
     * @throws android.view.Surface.OutOfResourcesException If the SurfaceTexture cannot be created.
     */
    public SurfaceTexture(int texName) {
        this(texName, false);
    }

    
Construct a new SurfaceTexture to stream images to a given OpenGL texture. In single buffered mode the application is responsible for serializing access to the image content buffer. Each time the image content is to be updated, the releaseTexImage() method must be called before the image content producer takes ownership of the buffer. For example, when producing image content with the NDK ANativeWindow_lock and ANativeWindow_unlockAndPost functions, releaseTexImage() must be called before each ANativeWindow_lock, or that call will fail. When producing image content with OpenGL ES, releaseTexImage() must be called before the first OpenGL ES function call each frame. 
Params:
  • texName – the OpenGL texture object name (e.g. generated via glGenTextures)
  • singleBufferMode – whether the SurfaceTexture will be in single buffered mode.
Throws:
/**
     * Construct a new SurfaceTexture to stream images to a given OpenGL texture.
     *
     * In single buffered mode the application is responsible for serializing access to the image
     * content buffer. Each time the image content is to be updated, the
     * {@link #releaseTexImage()} method must be called before the image content producer takes
     * ownership of the buffer. For example, when producing image content with the NDK
     * ANativeWindow_lock and ANativeWindow_unlockAndPost functions, {@link #releaseTexImage()}
     * must be called before each ANativeWindow_lock, or that call will fail. When producing
     * image content with OpenGL ES, {@link #releaseTexImage()} must be called before the first
     * OpenGL ES function call each frame.
     *
     * @param texName the OpenGL texture object name (e.g. generated via glGenTextures)
     * @param singleBufferMode whether the SurfaceTexture will be in single buffered mode.
     *
     * @throws android.view.Surface.OutOfResourcesException If the SurfaceTexture cannot be created.
     */
    public SurfaceTexture(int texName, boolean singleBufferMode) {
        mCreatorLooper = Looper.myLooper();
        mIsSingleBuffered = singleBufferMode;
        nativeInit(false, texName, singleBufferMode, new WeakReference<SurfaceTexture>(this));
    }

    
Construct a new SurfaceTexture to stream images to a given OpenGL texture. In single buffered mode the application is responsible for serializing access to the image content buffer. Each time the image content is to be updated, the releaseTexImage() method must be called before the image content producer takes ownership of the buffer. For example, when producing image content with the NDK ANativeWindow_lock and ANativeWindow_unlockAndPost functions, releaseTexImage() must be called before each ANativeWindow_lock, or that call will fail. When producing image content with OpenGL ES, releaseTexImage() must be called before the first OpenGL ES function call each frame. Unlike SurfaceTexture(int, boolean), which takes an OpenGL texture object name, this constructor creates the SurfaceTexture in detached mode. A texture name must be passed in using attachToGLContext before calling releaseTexImage() and producing image content using OpenGL ES. 
Params:
  • singleBufferMode – whether the SurfaceTexture will be in single buffered mode.
Throws:
/**
     * Construct a new SurfaceTexture to stream images to a given OpenGL texture.
     *
     * In single buffered mode the application is responsible for serializing access to the image
     * content buffer. Each time the image content is to be updated, the
     * {@link #releaseTexImage()} method must be called before the image content producer takes
     * ownership of the buffer. For example, when producing image content with the NDK
     * ANativeWindow_lock and ANativeWindow_unlockAndPost functions, {@link #releaseTexImage()}
     * must be called before each ANativeWindow_lock, or that call will fail. When producing
     * image content with OpenGL ES, {@link #releaseTexImage()} must be called before the first
     * OpenGL ES function call each frame.
     *
     * Unlike {@link #SurfaceTexture(int, boolean)}, which takes an OpenGL texture object name,
     * this constructor creates the SurfaceTexture in detached mode. A texture name must be passed
     * in using {@link #attachToGLContext} before calling {@link #releaseTexImage()} and producing
     * image content using OpenGL ES.
     *
     * @param singleBufferMode whether the SurfaceTexture will be in single buffered mode.
     *
     * @throws android.view.Surface.OutOfResourcesException If the SurfaceTexture cannot be created.
     */
    public SurfaceTexture(boolean singleBufferMode) {
        mCreatorLooper = Looper.myLooper();
        mIsSingleBuffered = singleBufferMode;
        nativeInit(true, 0, singleBufferMode, new WeakReference<SurfaceTexture>(this));
    }

    
Register a callback to be invoked when a new image frame becomes available to the
SurfaceTexture.

 The callback may be called on an arbitrary thread, so it is not safe to call updateTexImage without first binding the OpenGL ES context to the thread invoking the callback. 


Params:
  • listener – The listener to use, or null to remove the listener.
/**
     * Register a callback to be invoked when a new image frame becomes available to the
     * SurfaceTexture.
     * <p>
     * The callback may be called on an arbitrary thread, so it is not
     * safe to call {@link #updateTexImage} without first binding the OpenGL ES context to the
     * thread invoking the callback.
     * </p>
     *
     * @param listener The listener to use, or null to remove the listener.
     */
    public void setOnFrameAvailableListener(@Nullable OnFrameAvailableListener listener) {
        setOnFrameAvailableListener(listener, null);
    }

    
Register a callback to be invoked when a new image frame becomes available to the
SurfaceTexture.

 If a handler is specified, the callback will be invoked on that handler's thread. If no handler is specified, then the callback may be called on an arbitrary thread, so it is not safe to call updateTexImage without first binding the OpenGL ES context to the thread invoking the callback. 


Params:
  • listener – The listener to use, or null to remove the listener.
  • handler – The handler on which the listener should be invoked, or null
to use an arbitrary thread.
/**
     * Register a callback to be invoked when a new image frame becomes available to the
     * SurfaceTexture.
     * <p>
     * If a handler is specified, the callback will be invoked on that handler's thread.
     * If no handler is specified, then the callback may be called on an arbitrary thread,
     * so it is not safe to call {@link #updateTexImage} without first binding the OpenGL ES
     * context to the thread invoking the callback.
     * </p>
     *
     * @param listener The listener to use, or null to remove the listener.
     * @param handler The handler on which the listener should be invoked, or null
     * to use an arbitrary thread.
     */
    public void setOnFrameAvailableListener(@Nullable final OnFrameAvailableListener listener,
            @Nullable Handler handler) {
        if (listener != null) {
            // Although we claim the thread is arbitrary, earlier implementation would
            // prefer to send the callback on the creating looper or the main looper
            // so we preserve this behavior here.
            Looper looper = handler != null ? handler.getLooper() :
                    mCreatorLooper != null ? mCreatorLooper : Looper.getMainLooper();
            mOnFrameAvailableHandler = new Handler(looper, null, true /*async*/) {
                @Override
                public void handleMessage(Message msg) {
                    listener.onFrameAvailable(SurfaceTexture.this);
                }
            };
        } else {
            mOnFrameAvailableHandler = null;
        }
    }

    
Set the default size of the image buffers. The image producer may override the buffer size, in which case the producer-set buffer size will be used, not the default size set by this method. Both video and camera based image producers do override the size. This method may be used to set the image size when producing images with Canvas (via Surface.lockCanvas), or OpenGL ES (via an EGLSurface). The new default buffer size will take effect the next time the image producer requests a buffer to fill. For Canvas this will be the next time Surface.lockCanvas is called. For OpenGL ES, the EGLSurface should be destroyed (via eglDestroySurface), made not-current (via eglMakeCurrent), and then recreated (via eglCreateWindowSurface) to ensure that the new default size has taken effect. The width and height parameters must be no greater than the minimum of GL_MAX_VIEWPORT_DIMS and GL_MAX_TEXTURE_SIZE (see glGetIntegerv). An error due to invalid dimensions might not be reported until updateTexImage() is called. 
/**
     * Set the default size of the image buffers.  The image producer may override the buffer size,
     * in which case the producer-set buffer size will be used, not the default size set by this
     * method.  Both video and camera based image producers do override the size.  This method may
     * be used to set the image size when producing images with {@link android.graphics.Canvas} (via
     * {@link android.view.Surface#lockCanvas}), or OpenGL ES (via an EGLSurface).
     *
     * The new default buffer size will take effect the next time the image producer requests a
     * buffer to fill.  For {@link android.graphics.Canvas} this will be the next time {@link
     * android.view.Surface#lockCanvas} is called.  For OpenGL ES, the EGLSurface should be
     * destroyed (via eglDestroySurface), made not-current (via eglMakeCurrent), and then recreated
     * (via eglCreateWindowSurface) to ensure that the new default size has taken effect.
     *
     * The width and height parameters must be no greater than the minimum of
     * GL_MAX_VIEWPORT_DIMS and GL_MAX_TEXTURE_SIZE (see
     * {@link javax.microedition.khronos.opengles.GL10#glGetIntegerv glGetIntegerv}).
     * An error due to invalid dimensions might not be reported until
     * updateTexImage() is called.
     */
    public void setDefaultBufferSize(int width, int height) {
        nativeSetDefaultBufferSize(width, height);
    }

    
Update the texture image to the most recent frame from the image stream.  This may only be
called while the OpenGL ES context that owns the texture is current on the calling thread.
It will implicitly bind its texture to the GL_TEXTURE_EXTERNAL_OES texture target.

/**
     * Update the texture image to the most recent frame from the image stream.  This may only be
     * called while the OpenGL ES context that owns the texture is current on the calling thread.
     * It will implicitly bind its texture to the GL_TEXTURE_EXTERNAL_OES texture target.
     */
    public void updateTexImage() {
        nativeUpdateTexImage();
    }

    
Releases the the texture content. This is needed in single buffered mode to allow the image content producer to take ownership of the image buffer. For more information see SurfaceTexture(int, boolean). 
/**
     * Releases the the texture content. This is needed in single buffered mode to allow the image
     * content producer to take ownership of the image buffer.
     * For more information see {@link #SurfaceTexture(int, boolean)}.
     */
    public void releaseTexImage() {
        nativeReleaseTexImage();
    }

    
Detach the SurfaceTexture from the OpenGL ES context that owns the OpenGL ES texture object. This call must be made with the OpenGL ES context current on the calling thread. The OpenGL ES texture object will be deleted as a result of this call. After calling this method all calls to updateTexImage will throw an IllegalStateException until a successful call to attachToGLContext is made. This can be used to access the SurfaceTexture image contents from multiple OpenGL ES contexts. Note, however, that the image contents are only accessible from one OpenGL ES context at a time. 
/**
     * Detach the SurfaceTexture from the OpenGL ES context that owns the OpenGL ES texture object.
     * This call must be made with the OpenGL ES context current on the calling thread.  The OpenGL
     * ES texture object will be deleted as a result of this call.  After calling this method all
     * calls to {@link #updateTexImage} will throw an {@link java.lang.IllegalStateException} until
     * a successful call to {@link #attachToGLContext} is made.
     *
     * This can be used to access the SurfaceTexture image contents from multiple OpenGL ES
     * contexts.  Note, however, that the image contents are only accessible from one OpenGL ES
     * context at a time.
     */
    public void detachFromGLContext() {
        int err = nativeDetachFromGLContext();
        if (err != 0) {
            throw new RuntimeException("Error during detachFromGLContext (see logcat for details)");
        }
    }

    
Attach the SurfaceTexture to the OpenGL ES context that is current on the calling thread. A new OpenGL ES texture object is created and populated with the SurfaceTexture image frame that was current at the time of the last call to detachFromGLContext. This new texture is bound to the GL_TEXTURE_EXTERNAL_OES texture target. This can be used to access the SurfaceTexture image contents from multiple OpenGL ES contexts. Note, however, that the image contents are only accessible from one OpenGL ES context at a time. 
Params:
  • texName – The name of the OpenGL ES texture that will be created.  This texture name
must be unusued in the OpenGL ES context that is current on the calling thread.
/**
     * Attach the SurfaceTexture to the OpenGL ES context that is current on the calling thread.  A
     * new OpenGL ES texture object is created and populated with the SurfaceTexture image frame
     * that was current at the time of the last call to {@link #detachFromGLContext}.  This new
     * texture is bound to the GL_TEXTURE_EXTERNAL_OES texture target.
     *
     * This can be used to access the SurfaceTexture image contents from multiple OpenGL ES
     * contexts.  Note, however, that the image contents are only accessible from one OpenGL ES
     * context at a time.
     *
     * @param texName The name of the OpenGL ES texture that will be created.  This texture name
     * must be unusued in the OpenGL ES context that is current on the calling thread.
     */
    public void attachToGLContext(int texName) {
        int err = nativeAttachToGLContext(texName);
        if (err != 0) {
            throw new RuntimeException("Error during attachToGLContext (see logcat for details)");
        }
    }

    
Retrieve the 4x4 texture coordinate transform matrix associated with the texture image set by
the most recent call to updateTexImage.
This transform matrix maps 2D homogeneous texture coordinates of the form (s, t, 0, 1) with s
and t in the inclusive range [0, 1] to the texture coordinate that should be used to sample
that location from the texture.  Sampling the texture outside of the range of this transform
is undefined.
The matrix is stored in column-major order so that it may be passed directly to OpenGL ES via
the glLoadMatrixf or glUniformMatrix4fv functions.

Params:
  • mtx – the array into which the 4x4 matrix will be stored.  The array must have exactly
    16 elements.
/**
     * Retrieve the 4x4 texture coordinate transform matrix associated with the texture image set by
     * the most recent call to updateTexImage.
     *
     * This transform matrix maps 2D homogeneous texture coordinates of the form (s, t, 0, 1) with s
     * and t in the inclusive range [0, 1] to the texture coordinate that should be used to sample
     * that location from the texture.  Sampling the texture outside of the range of this transform
     * is undefined.
     *
     * The matrix is stored in column-major order so that it may be passed directly to OpenGL ES via
     * the glLoadMatrixf or glUniformMatrix4fv functions.
     *
     * @param mtx the array into which the 4x4 matrix will be stored.  The array must have exactly
     *     16 elements.
     */
    public void getTransformMatrix(float[] mtx) {
        // Note we intentionally don't check mtx for null, so this will result in a
        // NullPointerException. But it's safe because it happens before the call to native.
        if (mtx.length != 16) {
            throw new IllegalArgumentException();
        }
        nativeGetTransformMatrix(mtx);
    }

    
Retrieve the timestamp associated with the texture image set by the most recent call to
updateTexImage.

This timestamp is in nanoseconds, and is normally monotonically increasing. The timestamp
should be unaffected by time-of-day adjustments. The specific meaning and zero point of the
timestamp depends on the source providing images to the SurfaceTexture. Unless otherwise
specified by the image source, timestamps cannot generally be compared across SurfaceTexture
instances, or across multiple program invocations. It is mostly useful for determining time
offsets between subsequent frames.


For camera sources, timestamps should be strictly monotonic. Timestamps from MediaPlayer
sources may be reset when the playback position is set. For EGL and Vulkan producers, the
timestamp is the desired present time set with the EGL_ANDROID_presentation_time or
VK_GOOGLE_display_timing extensions.


/**
     * Retrieve the timestamp associated with the texture image set by the most recent call to
     * updateTexImage.
     *
     * <p>This timestamp is in nanoseconds, and is normally monotonically increasing. The timestamp
     * should be unaffected by time-of-day adjustments. The specific meaning and zero point of the
     * timestamp depends on the source providing images to the SurfaceTexture. Unless otherwise
     * specified by the image source, timestamps cannot generally be compared across SurfaceTexture
     * instances, or across multiple program invocations. It is mostly useful for determining time
     * offsets between subsequent frames.</p>
     *
     * <p>For camera sources, timestamps should be strictly monotonic. Timestamps from MediaPlayer
     * sources may be reset when the playback position is set. For EGL and Vulkan producers, the
     * timestamp is the desired present time set with the EGL_ANDROID_presentation_time or
     * VK_GOOGLE_display_timing extensions.</p>
     */

    public long getTimestamp() {
        return nativeGetTimestamp();
    }

    
release() frees all the buffers and puts the SurfaceTexture into the
'abandoned' state. Once put in this state the SurfaceTexture can never
leave it. When in the 'abandoned' state, all methods of the
IGraphicBufferProducer interface will fail with the NO_INIT error.
Note that while calling this method causes all the buffers to be freed
from the perspective of the the SurfaceTexture, if there are additional
references on the buffers (e.g. if a buffer is referenced by a client or
by OpenGL ES as a texture) then those buffer will remain allocated.
Always call this method when you are done with SurfaceTexture. Failing
to do so may delay resource deallocation for a significant amount of
time.

See Also:
  • isReleased()
/**
     * release() frees all the buffers and puts the SurfaceTexture into the
     * 'abandoned' state. Once put in this state the SurfaceTexture can never
     * leave it. When in the 'abandoned' state, all methods of the
     * IGraphicBufferProducer interface will fail with the NO_INIT error.
     *
     * Note that while calling this method causes all the buffers to be freed
     * from the perspective of the the SurfaceTexture, if there are additional
     * references on the buffers (e.g. if a buffer is referenced by a client or
     * by OpenGL ES as a texture) then those buffer will remain allocated.
     *
     * Always call this method when you are done with SurfaceTexture. Failing
     * to do so may delay resource deallocation for a significant amount of
     * time.
     *
     * @see #isReleased()
     */
    public void release() {
        nativeRelease();
    }

    
Returns true if the SurfaceTexture was released.

See Also:
  • release()
/**
     * Returns true if the SurfaceTexture was released.
     *
     * @see #release()
     */
    public boolean isReleased() {
        return nativeIsReleased();
    }

    @Override
    protected void finalize() throws Throwable {
        try {
            nativeFinalize();
        } finally {
            super.finalize();
        }
    }

    
This method is invoked from native code only.

/**
     * This method is invoked from native code only.
     */
    @SuppressWarnings({"UnusedDeclaration"})
    private static void postEventFromNative(WeakReference<SurfaceTexture> weakSelf) {
        SurfaceTexture st = weakSelf.get();
        if (st != null) {
            Handler handler = st.mOnFrameAvailableHandler;
            if (handler != null) {
                handler.sendEmptyMessage(0);
            }
        }
    }

    
Returns true if the SurfaceTexture is single-buffered

@hide
/**
     * Returns true if the SurfaceTexture is single-buffered
     * @hide
     */
    public boolean isSingleBuffered() {
        return mIsSingleBuffered;
    }

    private native void nativeInit(boolean isDetached, int texName,
            boolean singleBufferMode, WeakReference<SurfaceTexture> weakSelf)
            throws Surface.OutOfResourcesException;
    private native void nativeFinalize();
    private native void nativeGetTransformMatrix(float[] mtx);
    private native long nativeGetTimestamp();
    private native void nativeSetDefaultBufferSize(int width, int height);
    private native void nativeUpdateTexImage();
    private native void nativeReleaseTexImage();
    private native int nativeDetachFromGLContext();
    private native int nativeAttachToGLContext(int texName);
    private native void nativeRelease();
    private native boolean nativeIsReleased();
}