第三十一节 录制视频时添加水印

image.png
image.png
image.png
image.png

由于我们使用了FBO，绘制水印的工作就放在了FBO中
主要逻辑代码：
WlCameraFboRender.java

package com.ywl5320.wllivepusher.camera;

import android.content.Context;
import android.graphics.Bitmap;
import android.opengl.GLES20;

import com.ywl5320.wllivepusher.R;
import com.ywl5320.wllivepusher.egl.WlShaderUtil;

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

public class WlCameraFboRender {

    private Context context;

    private float[] vertexData = {
            -1f, -1f,
            1f, -1f,
            -1f, 1f,
            1f, 1f,

            0f, 0f,
            0f, 0f,
            0f, 0f,
            0f, 0f
    };
    private FloatBuffer vertexBuffer;

    private float[] fragmentData = {
            0f, 1f,
            1f, 1f,
            0f, 0f,
            1f, 0f
    };
    private FloatBuffer fragmentBuffer;

    private int program;
    private int vPosition;
    private int fPosition;
    private int textureid;
    private int sampler;

    private int vboId;

    private Bitmap bitmap;

    private int bitmapTextureid;

    public WlCameraFboRender(Context context) {
        this.context = context;

        bitmap = WlShaderUtil.createTextImage("视频直播和推流：ywl5320", 50, "#ff0000", "#00000000", 0);


        float r = 1.0f * bitmap.getWidth() / bitmap.getHeight();
        float w = r * 0.1f;

        vertexData[8] = 0.8f - w;
        vertexData[9] = -0.8f;

        vertexData[10] = 0.8f;
        vertexData[11] = -0.8f;

        vertexData[12] = 0.8f - w;
        vertexData[13] = -0.7f;

        vertexData[14] = 0.8f;
        vertexData[15] = -0.7f;

        vertexBuffer = ByteBuffer.allocateDirect(vertexData.length * 4)
                .order(ByteOrder.nativeOrder())
                .asFloatBuffer()
                .put(vertexData);
        vertexBuffer.position(0);

        fragmentBuffer = ByteBuffer.allocateDirect(fragmentData.length * 4)
                .order(ByteOrder.nativeOrder())
                .asFloatBuffer()
                .put(fragmentData);
        fragmentBuffer.position(0);

    }

    public void onCreate()
    {

        GLES20.glEnable (GLES20.GL_BLEND);
        GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA);

        String vertexSource = WlShaderUtil.getRawResource(context, R.raw.vertex_shader_screen);
        String fragmentSource = WlShaderUtil.getRawResource(context, R.raw.fragment_shader_screen);

        program = WlShaderUtil.createProgram(vertexSource, fragmentSource);

        vPosition = GLES20.glGetAttribLocation(program, "v_Position");
        fPosition = GLES20.glGetAttribLocation(program, "f_Position");
        sampler = GLES20.glGetUniformLocation(program, "sTexture");

        int [] vbos = new int[1];
        GLES20.glGenBuffers(1, vbos, 0);
        vboId = vbos[0];

        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);
        GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, vertexData.length * 4 + fragmentData.length * 4, null, GLES20. GL_STATIC_DRAW);
        GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER, 0, vertexData.length * 4, vertexBuffer);
        GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER, vertexData.length * 4, fragmentData.length * 4, fragmentBuffer);
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);

        bitmapTextureid = WlShaderUtil.loadBitmapTexture(bitmap);
    }

    public void onChange(int width, int height)
    {
        GLES20.glViewport(0, 0, width, height);
    }

    public void onDraw(int textureId)
    {
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
        GLES20.glClearColor(1f,0f, 0f, 1f);

        GLES20.glUseProgram(program);
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);

        //fbo
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);

        GLES20.glEnableVertexAttribArray(vPosition);
        GLES20.glVertexAttribPointer(vPosition, 2, GLES20.GL_FLOAT, false, 8,
                0);

        GLES20.glEnableVertexAttribArray(fPosition);
        GLES20.glVertexAttribPointer(fPosition, 2, GLES20.GL_FLOAT, false, 8,
                vertexData.length * 4);

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

        //bitmap
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, bitmapTextureid);

        GLES20.glEnableVertexAttribArray(vPosition);
        GLES20.glVertexAttribPointer(vPosition, 2, GLES20.GL_FLOAT, false, 8,
                32);

        GLES20.glEnableVertexAttribArray(fPosition);
        GLES20.glVertexAttribPointer(fPosition, 2, GLES20.GL_FLOAT, false, 8,
                vertexData.length * 4);

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



        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
    }
}

需要注意的地方：
1、在顶点数组中定义好水印的位置

private float[] vertexData = {
            -1f, -1f,
            1f, -1f,
            -1f, 1f,
            1f, 1f,

            0f, 0f,
            0f, 0f,
            0f, 0f,
            0f, 0f
    };

2、初始化水印bitmap，如果是文字也要转化为bitmap

public static Bitmap createTextImage(String text, int textSize, String textColor, String bgColor, int padding) {

        Paint paint = new Paint();
        paint.setColor(Color.parseColor(textColor));
        paint.setTextSize(textSize);
        paint.setStyle(Paint.Style.FILL);
        paint.setAntiAlias(true);

        float width = paint.measureText(text, 0, text.length());

        float top = paint.getFontMetrics().top;
        float bottom = paint.getFontMetrics().bottom;

        Bitmap bm = Bitmap.createBitmap((int) (width + padding * 2), (int) ((bottom - top) + padding * 2), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bm);

        canvas.drawColor(Color.parseColor(bgColor));
        canvas.drawText(text, padding, - top + padding, paint);
        return bm;
    }

3、得到水印的纹理id

public static int loadBitmapTexture(Bitmap bitmap)
    {
        int[] textureIds = new int[1];
        GLES20.glGenTextures(1, textureIds, 0);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureIds[0]);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_REPEAT);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_REPEAT);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);

        ByteBuffer bitmapBuffer = ByteBuffer.allocate(bitmap.getHeight() * bitmap.getWidth() * 4);
        bitmap.copyPixelsToBuffer(bitmapBuffer);
        bitmapBuffer.flip();

        GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, bitmap.getWidth(),
            bitmap.getHeight(), 0, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, bitmapBuffer);
        return textureIds[0];
    }

4、在绘制玩视频画面后绘制水印纹理

 //bitmap
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, bitmapTextureid);

        GLES20.glEnableVertexAttribArray(vPosition);
        GLES20.glVertexAttribPointer(vPosition, 2, GLES20.GL_FLOAT, false, 8,
                32);

        GLES20.glEnableVertexAttribArray(fPosition);
        GLES20.glVertexAttribPointer(fPosition, 2, GLES20.GL_FLOAT, false, 8,
                vertexData.length * 4);

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

5、注意水印坐标的归一化

//因为顶点坐标范围都是在-1到1之间的，我们规定水印的高度是0.1   那么水印的宽度怎么算呢？
        float r = 1.0f * bitmap.getWidth() / bitmap.getHeight();  //   15/5=3
        float w = r * 0.1f;   //  3*0.1=0.3   这就是水印高度为0.1的时候，水印的宽度大小

        vertexData[8] = 0.8f - w;
        vertexData[9] = -0.8f;

        vertexData[10] = 0.8f;
        vertexData[11] = -0.8f;

        vertexData[12] = 0.8f - w;
        vertexData[13] = -0.7f;

        vertexData[14] = 0.8f;
        vertexData[15] = -0.7f;