最近需要開發一個類似行車記錄儀的app，其中需要給錄制的視頻添加動態水印。我使用的是OpenGL開發的，剛開始實現的是靜態水印，后面才實現的動態水印。

先上效果圖，左下角的是靜態水印，中間偏下的是時間水印（動態水印）：

一、靜態水印

實現原理：錄像時是通過OpenGL把圖像渲染到GLSurfaceView上的，通俗的講，就是把圖片畫到一塊畫布上，然后展示出來。添加圖片水印，就是把水印圖片跟錄制的圖像一起畫到畫布上。

這是加載紋理跟陰影的Java類

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'); } }/** * 加載編譯連接陰影 * @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;這是畫水印的Java類/** * 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; /** * 一個“完整”的正方形，從兩維延伸到-1到1。 * 當 模型/視圖/投影矩陣是都為單位矩陣的時候，這將完全覆蓋視口。 * 紋理坐標相對于矩形是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];// 投影矩陣 public float[] mViewMatrix = new float[16]; // 攝像機位置朝向9參數矩陣 public float[] mModelMatrix = new float[16];// 模型變換矩陣 public float[] mMVPMatrix = new float[16];// 獲取具體物體的總變換矩陣 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); // 設置紋理 GLES20.glActiveTexture(GLES20.GL_TEXTURE0); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextureId); GLES20.glUniform1i(mProgram.sTextureLoc, 0); GlUtil.checkGlError('GL_TEXTURE_2D sTexture'); // 設置 model / view / projection 矩陣 GLES20.glUniformMatrix4fv(mProgram.uMVPMatrixLoc, 1, false, getFinalMatrix(), 0); GlUtil.checkGlError('glUniformMatrix4fv uMVPMatrixLoc'); // 使用簡單的VAO 設置頂點坐標數據 GLES20.glEnableVertexAttribArray(mProgram.aPositionLoc); GLES20.glVertexAttribPointer(mProgram.aPositionLoc, mCoordsPerVertex,GLES20.GL_FLOAT, false, mVertexStride, mVertexArray); GlUtil.checkGlError('VAO aPositionLoc'); // 使用簡單的VAO 設置紋理坐標數據 GLES20.glEnableVertexAttribArray(mProgram.aTextureCoordLoc); GLES20.glVertexAttribPointer(mProgram.aTextureCoordLoc, mCoordsPerTexture,GLES20.GL_FLOAT, false, mTexCoordStride, mTexCoordArray); GlUtil.checkGlError('VAO aTextureCoordLoc'); // GL_TRIANGLE_STRIP三角形帶，這就為啥只需要指出4個坐標點，就能畫出兩個三角形了。 GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, mVertexCount); // Done -- 解綁~ 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; } /** * 刪除texture */ public static void deleteTex(final int hTex) { LogUtil.v('WaterSignature', 'deleteTex:'); final int[] tex = new int[] {hTex}; GLES20.glDeleteTextures(1, tex, 0); }}

沒時間了。先寫到這，后面是調用，遲點再寫。

下面是如何把水印繪制到畫布上：

1、在SurfaceTexture的onSurfaceCreated方法中初始化并設置陰影；

@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 // 使用黃色清除界面 GLES20.glClearColor(1.0f, 1.0f, 0.0f, 1.0f); //設置水印 if (mWaterSign == null) {mWaterSign = new WaterSignature(); } //設置陰影 mWaterSign.setShaderProgram(new WaterSignSProgram()); mSignTexId = loadTexture(MyApplication.getContext(), R.mipmap.watermark); }

這里是生成mSignTexId 的方法，把該圖像與紋理id綁定并返回：

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; //指定需要的是原始數據，非壓縮數據 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; } //告訴OpenGL后面紋理調用應該是應用于哪個紋理對象 GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureObjectIds[0]); //設置縮小的時候（GL_TEXTURE_MIN_FILTER）使用mipmap三線程過濾 GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR_MIPMAP_LINEAR); //設置放大的時候（GL_TEXTURE_MAG_FILTER）使用雙線程過濾 GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR); //Android設備y坐標是反向的，正常圖顯示到設備上是水平顛倒的，解決方案就是設置紋理包裝，紋理T坐標（y）設置鏡面重復 //ball讀取紋理的時候 t范圍坐標取正常值+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貼圖 GLES20.glGenerateMipmap(GLES20.GL_TEXTURE_2D); //解除紋理操作的綁定 GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0); return textureObjectIds[0];}

2、在繪制方法onDrawFrame中繪制畫面的同時把水印繪制進去；

/** * 繪圖到glsurface * 我們將rendermode設置為glsurfaceview.rendermode_when_dirty， * 僅當調用requestrender時調用此方法（=需要更新紋理時） * 如果不在臟時設置rendermode，則此方法的最大調用速度為60fps。 */ @Override public void onDrawFrame(final GL10 unused) { GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT); GLES20.glEnable(GLES20.GL_BLEND); //開啟GL的混合模式，即圖像疊加 GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA)； /** *中間這里是你繪制的預覽畫面 */ //畫水印（非動態） GLES20.glViewport(20, 20, 288, 120); mWaterSign.drawFrame(mSignTexId); }

這里最重要的是要開啟GL的混合模式，即圖像疊加，不然你繪制的水印會覆蓋原先的預覽畫面

//開啟GL的混合模式，即圖像疊加GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA)；

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持好吧啦網。