Android使用Opengl录像时添加(动态)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)     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)；

二、动态水印（时间水印）
原理：把时间字符单个转化为图片，然后再把它一个个的绘制在画布上。如2020-02-14 10:24:30这种时间格式总共包含0123456789 - ：这12个字符，全部先转成图片，再去匹配绘制到画布。
下面是一点的相关的代码：
注意：时间格式必须为 yyyy-MM-dd HH:mm:ss ，因为下面是截取文字，格式不对的话会抛异常。

/** * 添加时间水印 * 原理：将文字转成图片，使用OpenGL将图片画到视频上 * 实现方法：将时间水印所需的文字转化为图片（避免每次实时转换导致大量内存被消耗），如：2019-09-05 16:52:18  共16张图片。 * 每张图片绑定一个纹理；获取当前时间切出单个字符，使用OpenGL将对应的字符纹理画上去。 * @param time * @param x * @param y    位于屏幕的（x,y）坐标点 */private void drawWaterSign(String time, int x, int y) {   if ("".equals(time)) {      return;   }   //画水印   GLES20.glViewport(x, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(0, 1))]);   GLES20.glViewport(x + 15, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(1, 2))]);   GLES20.glViewport(x + 15 * 2, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(2, 3))]);   GLES20.glViewport(x + 15 * 3, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(3, 4))]);   GLES20.glViewport(x + 15 * 4, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[10]); // -   GLES20.glViewport(x + 15 * 5, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(5, 6))]);   GLES20.glViewport(x + 15 * 6, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(6, 7))]);   GLES20.glViewport(x + 15 * 7, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[10]); // -   GLES20.glViewport(x + 15 * 8, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(8, 9))]);   GLES20.glViewport(x + 15 * 9, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(9, 10))]);   GLES20.glViewport(x + 15 * 11, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(11, 12))]);   GLES20.glViewport(x + 15 * 12, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(12, 13))]);   GLES20.glViewport(x + 15 * 13, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[11]); // :   GLES20.glViewport(x + 15 * 14, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(14, 15))]);   GLES20.glViewport(x + 15 * 15, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(15, 16))]);   GLES20.glViewport(x + 15 * 16, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[11]); // :   GLES20.glViewport(x + 15 * 17, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(17, 18))]);   GLES20.glViewport(x + 15 * 18, y, 220, 60);   mWaterSign.drawFrame(mWaterTexId[Integer.parseInt(time.substring(18, 19))]);}

调用方法：

最近把添加水印的代码抽出来做成demo，需要的可以私信，这边有偿提供demo。