Android使用Opengl录像时添加水印

最近需要开发一个类似行车记录仪的app，其中需要给录制的视频添加动态水印。我使用的是OpenGL开发的，刚开始实现的是静态水印，后面才实现的动态水印。

先上效果图，左下角的是静态水印，中间偏下的是时间水印（动态水印）：

一、静态水印

实现原理：录像时是通过OpenGL把图像渲染到GLSurfaceView上的，通俗的讲，就是把图片画到一块画布上，然后展示出来。添加图片水印，就是把水印图片跟录制的图像一起画到画布上。

这是加载纹理跟阴影的Java类

package com.audiovideo.camera.blog;

import android.opengl.GLES20;

/**
* Created by fenghaitao on 2019/9/12.
*/

public class WaterSignSProgram{

private static int programId;
private static final String VERTEX_SHADER =
"uniform mat4 uMVPMatrix;\n" +
"attribute vec4 aPosition;\n" +
"attribute vec4 aTextureCoord;\n" +
"varying vec2 vTextureCoord;\n" +
"void main() {\n" +
"  gl_Position = uMVPMatrix * aPosition;\n" +
"  vTextureCoord = aTextureCoord.xy;\n" +
"}\n";

private static final String FRAGMENT_SHADER =
"precision mediump float;\n" +
"varying vec2 vTextureCoord;\n" +
"uniform sampler2D sTexture;\n" +
"void main() {\n" +
"  gl_FragColor = texture2D(sTexture, vTextureCoord);\n" +
"}\n";

public WaterSignSProgram() {
programId = loadShader(VERTEX_SHADER, FRAGMENT_SHADER);

uMVPMatrixLoc = GLES20.glGetUniformLocation(programId, "uMVPMatrix");
checkLocation(uMVPMatrixLoc, "uMVPMatrix");
aPositionLoc = GLES20.glGetAttribLocation(programId, "aPosition");
checkLocation(aPositionLoc, "aPosition");
aTextureCoordLoc = GLES20.glGetAttribLocation(programId, "aTextureCoord");
checkLocation(aTextureCoordLoc, "aTextureCoord");
sTextureLoc = GLES20.glGetUniformLocation(programId, "sTexture");
checkLocation(sTextureLoc, "sTexture");
}

public int uMVPMatrixLoc;
public int aPositionLoc;
public int aTextureCoordLoc;
public int sTextureLoc;

public static void checkLocation(int location, String label) {
if (location < 0) {
throw new RuntimeException("Unable to locate '" + label + "' in program");
}
}

/**
* 加载编译连接阴影
* @param vss source of vertex shader
* @param fss source of fragment shader
* @return
*/
public static int loadShader(final String vss, final String fss) {
Log.v(TAG, "loadShader:");
int vs = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);
GLES20.glShaderSource(vs, vss);
GLES20.glCompileShader(vs);
final int[] compiled = new int[1];
GLES20.glGetShaderiv(vs, GLES20.GL_COMPILE_STATUS, compiled, 0);
if (compiled[0] == 0) {
Log.e(TAG, "Failed to compile vertex shader:"
+ GLES20.glGetShaderInfoLog(vs));
GLES20.glDeleteShader(vs);
vs = 0;
}

int fs = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);
GLES20.glShaderSource(fs, fss);
GLES20.glCompileShader(fs);
GLES20.glGetShaderiv(fs, GLES20.GL_COMPILE_STATUS, compiled, 0);
if (compiled[0] == 0) {
Log.w(TAG, "Failed to compile fragment shader:"
+ GLES20.glGetShaderInfoLog(fs));
GLES20.glDeleteShader(fs);
fs = 0;
}

final int program = GLES20.glCreateProgram();
GLES20.glAttachShader(program, vs);
GLES20.glAttachShader(program, fs);
GLES20.glLinkProgram(program);

return program;
}

/**
* terminatinng, this should be called in GL context
*/
public static void release() {
if (programId >= 0)
GLES20.glDeleteProgram(programId);
programId = -1;
}
}

package com.audiovideo.camera.blog;

import android.opengl.GLES20;
import android.opengl.Matrix;

import com.audiovideo.camera.glutils.GLDrawer2D;
import com.audiovideo.camera.utils.LogUtil;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

这是画水印的Java类
/**
* Created by fenghaitao on 2019/9/12.
*/

public class WaterSignature {

private static final String VERTEX_SHADER =
"uniform mat4 uMVPMatrix;\n" +
"attribute vec4 aPosition;\n" +
"attribute vec4 aTextureCoord;\n" +
"varying vec2 vTextureCoord;\n" +
"void main() {\n" +
"  gl_Position = uMVPMatrix * aPosition;\n" +
"  vTextureCoord = aTextureCoord.xy;\n" +
"}\n";

private static final String FRAGMENT_SHADER =
"precision mediump float;\n" +
"varying vec2 vTextureCoord;\n" +
"uniform sampler2D sTexture;\n" +
"void main() {\n" +
"  gl_FragColor = texture2D(sTexture, vTextureCoord);\n" +
"}\n";

public static final int SIZE_OF_FLOAT = 4;
/**
* 一个“完整”的正方形，从两维延伸到-1到1。
* 当 模型/视图/投影矩阵是都为单位矩阵的时候，这将完全覆盖视口。
* 纹理坐标相对于矩形是y反的。
* (This seems to work out right with external textures from SurfaceTexture.)
*/
private static final float FULL_RECTANGLE_COORDS[] = {
-1.0f, -1.0f,  // 0 bottom left
1.0f, -1.0f,  // 1 bottom right
-1.0f, 1.0f,  // 2 top left
1.0f, 1.0f,  // 3 top right
};
private static final float FULL_RECTANGLE_TEX_COORDS[] = {
0.0f, 1.0f,   //0 bottom left   //0.0f, 0.0f, // 0 bottom left
1.0f, 1.0f,   //1 bottom right  //1.0f, 0.0f, // 1 bottom right
0.0f, 0.0f,   //2 top left    //0.0f, 1.0f, // 2 top left
1.0f, 0.0f,   //3 top right    //1.0f, 1.0f, // 3 top right
};

private FloatBuffer mVertexArray;
private FloatBuffer mTexCoordArray;
private int mCoordsPerVertex;
private int mCoordsPerTexture;
private int mVertexCount;
private int mVertexStride;
private int mTexCoordStride;
private int hProgram;

public float[] mProjectionMatrix = new float[16];// 投影矩阵
public float[] mViewMatrix = new float[16]; // 摄像机位置朝向9参数矩阵
public float[] mModelMatrix = new float[16];// 模型变换矩阵
public float[] mMVPMatrix = new float[16];// 获取具体物体的总变换矩阵
private float[] getFinalMatrix() {
Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0);
Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);
return mMVPMatrix;
}

public WaterSignature() {
mVertexArray = createFloatBuffer(FULL_RECTANGLE_COORDS);
mTexCoordArray = createFloatBuffer(FULL_RECTANGLE_TEX_COORDS);
mCoordsPerVertex = 2;
mCoordsPerTexture = 2;
mVertexCount = FULL_RECTANGLE_COORDS.length / mCoordsPerVertex; // 4
mTexCoordStride = 2 * SIZE_OF_FLOAT;
mVertexStride = 2 * SIZE_OF_FLOAT;

Matrix.setIdentityM(mProjectionMatrix, 0);
Matrix.setIdentityM(mViewMatrix, 0);
Matrix.setIdentityM(mModelMatrix, 0);
Matrix.setIdentityM(mMVPMatrix, 0);
hProgram = GLDrawer2D.loadShader(VERTEX_SHADER, FRAGMENT_SHADER);
GLES20.glUseProgram(hProgram);
}

private FloatBuffer createFloatBuffer(float[] coords) {
ByteBuffer bb = ByteBuffer.allocateDirect(coords.length * SIZE_OF_FLOAT);
bb.order(ByteOrder.nativeOrder());
FloatBuffer fb = bb.asFloatBuffer();
fb.put(coords);
fb.position(0);
return fb;
}

private WaterSignSProgram mProgram;

public void setShaderProgram(WaterSignSProgram mProgram) {
this.mProgram = mProgram;
}

public void drawFrame(int mTextureId) {
GLES20.glUseProgram(hProgram);
// 设置纹理
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextureId);
GLES20.glUniform1i(mProgram.sTextureLoc, 0);
GlUtil.checkGlError("GL_TEXTURE_2D sTexture");
// 设置 model / view / projection 矩阵
GLES20.glUniformMatrix4fv(mProgram.uMVPMatrixLoc, 1, false, getFinalMatrix(), 0);
GlUtil.checkGlError("glUniformMatrix4fv uMVPMatrixLoc");
// 使用简单的VAO 设置顶点坐标数据
GLES20.glEnableVertexAttribArray(mProgram.aPositionLoc);
GLES20.glVertexAttribPointer(mProgram.aPositionLoc, mCoordsPerVertex,
GLES20.GL_FLOAT, false, mVertexStride, mVertexArray);
GlUtil.checkGlError("VAO aPositionLoc");
// 使用简单的VAO 设置纹理坐标数据
GLES20.glEnableVertexAttribArray(mProgram.aTextureCoordLoc);
GLES20.glVertexAttribPointer(mProgram.aTextureCoordLoc, mCoordsPerTexture,
GLES20.GL_FLOAT, false, mTexCoordStride, mTexCoordArray);
GlUtil.checkGlError("VAO aTextureCoordLoc");
// GL_TRIANGLE_STRIP三角形带，这就为啥只需要指出4个坐标点，就能画出两个三角形了。
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, mVertexCount);
// Done -- 解绑~
GLES20.glDisableVertexAttribArray(mProgram.aPositionLoc);
GLES20.glDisableVertexAttribArray(mProgram.aTextureCoordLoc);
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
GLES20.glUseProgram(0);
}

/**
* terminatinng, this should be called in GL context
*/
public void release() {
if (hProgram >= 0)
GLES20.glDeleteProgram(hProgram);
hProgram = -1;
}

/**
* 删除texture
*/
public static void deleteTex(final int hTex) {
LogUtil.v("WaterSignature", "deleteTex:");
final int[] tex = new int[] {hTex};
GLES20.glDeleteTextures(1, tex, 0);
}

}

没时间了。先写到这，后面是调用，迟点再写。

下面是如何把水印绘制到画布上：

1、在SurfaceTexture的onSurfaceCreated方法中初始化并设置阴影；

@Override
public void onSurfaceCreated(final GL10 unused, final EGLConfig config) {
LogUtil.v(TAG, "onSurfaceCreated:");
// This renderer required OES_EGL_image_external extension
final String extensions = GLES20.glGetString(GLES20.GL_EXTENSIONS);  // API >= 8
// 使用黄色清除界面
GLES20.glClearColor(1.0f, 1.0f, 0.0f, 1.0f);
//设置水印
if (mWaterSign == null) {
mWaterSign = new WaterSignature();
}
//设置阴影
mWaterSign.setShaderProgram(new WaterSignSProgram());
mSignTexId = loadTexture(MyApplication.getContext(), R.mipmap.watermark);
}

这里是生成mSignTexId 的方法，把该图像与纹理id绑定并返回：

public static int loadTexture(Context context, int resourceId) {
final int[] textureObjectIds = new int[1];
GLES20.glGenTextures(1, textureObjectIds, 0);
if(textureObjectIds[0] == 0){
Log.e(TAG,"Could not generate a new OpenGL texture object!");
return 0;
}
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inScaled = false;  //指定需要的是原始数据，非压缩数据
final Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), resourceId, options);
if(bitmap == null){
Log.e(TAG, "Resource ID "+resourceId + "could not be decode");
GLES20.glDeleteTextures(1, textureObjectIds, 0);
return 0;
}
//告诉OpenGL后面纹理调用应该是应用于哪个纹理对象
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureObjectIds[0]);
//设置缩小的时候（GL_TEXTURE_MIN_FILTER）使用mipmap三线程过滤
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR_MIPMAP_LINEAR);
//设置放大的时候（GL_TEXTURE_MAG_FILTER）使用双线程过滤
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
//Android设备y坐标是反向的，正常图显示到设备上是水平颠倒的，解决方案就是设置纹理包装，纹理T坐标（y）设置镜面重复
//ball读取纹理的时候 t范围坐标取正常值+1
//GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_MIRRORED_REPEAT);
GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);
bitmap.recycle();
//快速生成mipmap贴图
GLES20.glGenerateMipmap(GLES20.GL_TEXTURE_2D);
//解除纹理操作的绑定
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
return textureObjectIds[0];
}

2、在绘制方法onDrawFrame中绘制画面的同时把水印绘制进去；

/**
* 绘图到glsurface
* 我们将rendermode设置为glsurfaceview.rendermode_when_dirty，
* 仅当调用requestrender时调用此方法（=需要更新纹理时）
* 如果不在脏时设置rendermode，则此方法的最大调用速度为60fps。
*/
@Override
public void onDrawFrame(final GL10 unused) {
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
GLES20.glEnable(GLES20.GL_BLEND);//开启GL的混合模式，即图像叠加
GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA)；
/**
*中间这里是你绘制的预览画面
*/
//画水印（非动态）
GLES20.glViewport(20, 20, 288, 120);
mWaterSign.drawFrame(mSignTexId);
}

这里最重要的是要开启GL的混合模式，即图像叠加，不然你绘制的水印会覆盖原先的预览画面

//开启GL的混合模式，即图像叠加
GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA)；

以上就是本文的全部内容，希望对大家的学习有所帮助

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