public void adjustImageScaling(int width, int height) {
        float outputWidth = width;
        float outputHeight = height;
        if (mBitmap != null) {
            int framewidth = mBitmap.getWidth();
            int frameheight = mBitmap.getHeight();
            int rotation = (matrixAngle + bitmapAngle) % 360;
            if ((rotation == 90 || rotation == 270)) {
                framewidth = mBitmap.getHeight();
                frameheight = mBitmap.getWidth();
            float ratio1 = outputWidth / framewidth;
            float ratio2 = outputHeight / frameheight;
            float ratioMax = Math.min(ratio1, ratio2);
            // 居中后图片显示的大小
            int imageWidthNew = Math.round(framewidth * ratioMax);
            int imageHeightNew = Math.round(frameheight * ratioMax);
            Log.i(TAG, "outputWidth:" + outputWidth + ",outputHeight:" + outputHeight + ",imageWidthNew:" + imageWidthNew + ",imageHeightNew:" + imageHeightNew);
            // 图片被拉伸的比例,以及显示比例时的偏移量
            float ratioWidth = outputWidth / imageWidthNew;
            float ratioHeight = outputHeight / imageHeightNew;
            Log.i(TAG, "isDoRotate:" + isDoRotate + ",ratioWidth:" + ratioWidth + ",ratioHeight:" + ratioHeight);
            // 根据拉伸比例还原顶点
            cube = new float[]{
                    pos[0] / ratioWidth, pos[1] / ratioHeight,
                    pos[2] / ratioWidth, pos[3] / ratioHeight,
                    pos[4] / ratioWidth, pos[5] / ratioHeight,
                    pos[6] / ratioWidth, pos[7] / ratioHeight,
            mVerBuffer.clear();
            mVerBuffer.put(cube).position(0);
2、对图片、视频帧进行模糊、暗化操作

模糊算法用的是高斯模糊，只是说自己遍历操作在java跑，用cpu跑逻辑，计算完之后再用gpu进行渲染，比起直接用opengl中遍历，就相对快了一点。然后背景的顶点位置是填充整个显示比例的，模糊的算法借鉴如下：

我只是在里面重新添加了暗度降低的算法：
https://github.com/Martin20150405/In77Camera/blob/e0b2ab455985db43e850244d5c789ce4ebcb49c3/In77Camera/omoshiroilib/src/main/java/com/martin/ads/omoshiroilib/filter/imgproc/CustomizedGaussianBlurFilter.java
    const vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
    vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
    return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
vec3 rgb2hsv(vec3 c) {
    const vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
    vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
    vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
    float d = q.x - min(q.w, q.y);
    return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + 0.001)), d / (q.x + 0.001), q.x);
  vec3 a = rgb2hsv(color);
    vec3 m = a-vec3(0.0f, 0.0f, 0.04f);
    gl_FragColor = vec4(hsv2rgb(m), orAlpha);
3、显示原始的图片和帧，按照第一步计算的顶点绘画该图片

整体调用如下：

//黑色背景
        GLES20.glViewport(0, 0, ConstantMediaSize.currentScreenWidth, ConstantMediaSize.currentScreenHeight);
        GLES20.glClearColor(0, 0, 0, 1.0f);
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
        //显示区背景
        GLES20.glViewport(0, 0, ConstantMediaSize.showViewWidth, ConstantMediaSize.showViewHeight);
        if (currentMediaItem == null) {
            return;
        int cornor = currentMediaItem.getRotation();
        imageBackgroundFilter.setmBitmap(currentMediaItem.getFirstFrame(), cornor);
        imageBackgroundFilter.initTexture();