mSurfaceView.init(surfaceTexture -> { mSurfaceTexture = surfaceTexture; initMediaPlayer(surfaceTexture); }); 代码解析

这段代码是一个使用Lambda表达式的初始化SurfaceView的示例。让我们逐行解析它：

1. `mSurfaceView.init()`：这是一个自定义方法，用于初始化SurfaceView。它接受一个函数式接口作为参数，该函数式接口的唯一抽象方法是`onSurfaceTextureAvailable`。

2. `surfaceTexture -> { ... }`：这是一个Lambda表达式，用于实现函数式接口的抽象方法。它使用参数`surfaceTexture`，并在箭头后面的代码块中定义了对该参数的处理逻辑。

3. `mSurfaceTexture = surfaceTexture;`：将传递给Lambda表达式的`surfaceTexture`赋值给类成员变量`mSurfaceTexture`，以便在后续的代码中使用。

4. `initMediaPlayer(surfaceTexture);`：调用一个名为`initMediaPlayer`的方法，并将`surfaceTexture`作为参数传递给该方法。这个方法可能用于初始化MediaPlayer并将其与SurfaceTexture关联起来。

总的来说，这段代码的目的是在初始化SurfaceView时，通过Lambda表达式获取SurfaceTexture对象，并将其用于后续的MediaPlayer初始化和配置过程。具体的逻辑和功能可能需要查看其他部分的代码才能完全理解。

相关问题

将一个SurfaceTexture内容复制到另一个SurfaceTexture中

可以使用OpenGL ES在Android中将一个SurfaceTexture的内容复制到另一个SurfaceTexture中。以下是实现此操作的基本步骤：

1.创建一个新的SurfaceTexture和相关的Surface。

SurfaceTexture surfaceTexture1 = new SurfaceTexture(0);
Surface surface1 = new Surface(surfaceTexture1);

SurfaceTexture surfaceTexture2 = new SurfaceTexture(0);
Surface surface2 = new Surface(surfaceTexture2);

2.使用第一个SurfaceTexture作为纹理绑定到OpenGL ES程序中。

int textureId;
GLES20.glGenTextures(1, textureId, 0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE);
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE);

surfaceTexture1.setDefaultBufferSize(width, height);
surfaceTexture1.setOnFrameAvailableListener(new MyOnFrameAvailableListener());

Surface surface = new Surface(surfaceTexture1);

3.创建一个OpenGL ES程序，并将第一个SurfaceTexture作为输入纹理。

int program = GLES20.glCreateProgram();
int vertexShader = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);
int fragmentShader = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);

GLES20.glAttachShader(program, vertexShader);
GLES20.glAttachShader(program, fragmentShader);
GLES20.glLinkProgram(program);
GLES20.glUseProgram(program);

int aPosition = GLES20.glGetAttribLocation(program, "aPosition");
int aTextureCoordinates = GLES20.glGetAttribLocation(program, "aTextureCoordinates");
int uTextureMatrix = GLES20.glGetUniformLocation(program, "uTextureMatrix");
int uTextureSampler = GLES20.glGetUniformLocation(program, "uTextureSampler");

FloatBuffer vertexBuffer = ByteBuffer.allocateDirect(4 * 2 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
vertexBuffer.put(new float[]{-1, -1, 1, -1, -1, 1, 1, 1}).position(0);

FloatBuffer textureCoordinatesBuffer = ByteBuffer.allocateDirect(4 * 2 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
textureCoordinatesBuffer.put(new float[]{0, 0, 1, 0, 0, 1, 1, 1}).position(0);

GLES20.glVertexAttribPointer(aPosition, 2, GLES20.GL_FLOAT, false, 0, vertexBuffer);
GLES20.glVertexAttribPointer(aTextureCoordinates, 2, GLES20.GL_FLOAT, false, 0, textureCoordinatesBuffer);
GLES20.glEnableVertexAttribArray(aPosition);
GLES20.glEnableVertexAttribArray(aTextureCoordinates);

Matrix.setIdentityM(textureMatrix, 0);
GLES20.glUniformMatrix4fv(uTextureMatrix, 1, false, textureMatrix, 0);

GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);
GLES20.glUniform1i(uTextureSampler, 0);

4.在onFrameAvailable回调中更新第一个SurfaceTexture并将数据复制到第二个SurfaceTexture中。

class MyOnFrameAvailableListener implements SurfaceTexture.OnFrameAvailableListener {

    @Override
    public void onFrameAvailable(SurfaceTexture surfaceTexture) {
        surfaceTexture.updateTexImage();
        surfaceTexture.getTransformMatrix(textureMatrix);

        GLES20.glViewport(0, 0, width, height);
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

        surface2.attachToGLContext(textureId);
        surfaceTexture2.updateTexImage();
        surface2.detachFromGLContext();
    }
}

5.最后，您可以使用第二个SurfaceTexture来显示输出图像。

mRenderer = new MyRenderer(surfaceTexture2);
mSurfaceView = new GLSurfaceView(this);
mSurfaceView.setEGLContextClientVersion(2);
mSurfaceView.setRenderer(mRenderer);
setContentView(mSurfaceView);

Android 录制surface

您好！要在Android上录制Surface，您可以使用MediaRecorder类来实现。下面是一个简单的示例代码，展示了如何录制SurfaceView的内容：

import android.Manifest;
import android.content.pm.PackageManager;
import android.media.CamcorderProfile;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Environment;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import java.io.File;
import java.io.IOException;

public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback {

    private static final int REQUEST_PERMISSIONS = 100;
    private static final String[] PERMISSIONS = {
            Manifest.permission.WRITE_EXTERNAL_STORAGE,
            Manifest.permission.RECORD_AUDIO,
            Manifest.permission.CAMERA
    };

    private SurfaceView mSurfaceView;
    private Button mRecordButton;

    private MediaRecorder mMediaRecorder;
    private boolean isRecording = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mSurfaceView = findViewById(R.id.surface_view);
        mRecordButton = findViewById(R.id.record_button);

        mSurfaceView.getHolder().addCallback(this);

        mRecordButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isRecording) {
                    stopRecording();
                } else {
                    startRecording();
                }
            }
        });

        if (!hasPermissions()) {
            ActivityCompat.requestPermissions(this, PERMISSIONS, REQUEST_PERMISSIONS);
        }
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        prepareMediaRecorder();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        releaseMediaRecorder();
    }

    private boolean hasPermissions() {
        for (String permission : PERMISSIONS) {
            if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
                return false;
            }
        }
        return true;
    }

    private void prepareMediaRecorder() {
        mMediaRecorder = new MediaRecorder();
        mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.DEFAULT);
        mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.DEFAULT);
        mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);

        String outputPath = Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "output.mp4";
        mMediaRecorder.setOutputFile(outputPath);

        CamcorderProfile profile = CamcorderProfile.get(CamcorderProfile.QUALITY_HIGH);
        mMediaRecorder.setVideoSize(profile.videoFrameWidth, profile.videoFrameHeight);
        mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
        mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);

        mMediaRecorder.setPreviewDisplay(mSurfaceView.getHolder().getSurface());

        try {
            mMediaRecorder.prepare();
        } catch (IOException e) {
            Toast.makeText(this, "录制准备失败: " + e.getMessage(), Toast.LENGTH_SHORT).show();
        }
    }

    private void startRecording() {
        mMediaRecorder.start();
        isRecording = true;
        mRecordButton.setText(R.string.stop_recording);
    }

    private void stopRecording() {
        mMediaRecorder.stop();
        isRecording = false;
        mRecordButton.setText(R.string.start_recording);
        releaseMediaRecorder();
    }

    private void releaseMediaRecorder() {
        if (mMediaRecorder != null) {
            mMediaRecorder.reset();
            mMediaRecorder.release();
            mMediaRecorder = null;
        }
    }
}

请确保在AndroidManifest.xml文件中添加必要的权限，并在布局文件中添加一个SurfaceView和一个Button，用于启动/停止录制。

这是一个简单的示例，您可以根据您的需求进行扩展和优化。希望对您有所帮助！如果您有任何问题，请随时提问。