Android OpenGLES如何给相机添加滤镜详解

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我是靠谱客的博主拉长老鼠，最近开发中收集的这篇文章主要介绍Android OpenGLES如何给相机添加滤镜详解，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

滤镜介绍

目前市面上的滤镜有很多，但整体归类也就几样，都是在fragment shader中进行处理。目前滤镜最常用的就是 lut滤镜以及调整RGB曲线的滤镜了。其他的类型变更大同小异。

动态滤镜的构建

为了实现动态下载的滤镜，我们接下来实现一套滤镜的json参数，主要包括滤镜类型、滤镜名称、vertex shader、fragment shader 文件、统一变量列表、与统一变量绑定的纹理图片、默认滤镜强度、是否带纹理宽高偏移量、音乐路径、音乐是否循环播放等参数。

json 以及各个字段的介绍如下：

{
 "filterList": [{
  "type": "filter", // 表明滤镜类型，目前filter是只普通滤镜，后续还会加入其它类型的滤镜
  "name": "amaro", // 滤镜名称
  "vertexShader": "", // vertex shader 文件名
  "fragmentShader": "fragment.glsl", // fragment shader 文件名
  "uniformList":["blowoutTexture", "overlayTexture", "mapTexture"], // 统一变量
  "uniformData": { // 与统一变量绑定的纹理图片
   "blowoutTexture": "blowout.png",
   "overlayTexture": "overlay.png",
   "mapTexture": "map.png"
  },
  "strength": 1.0,  // 默认滤镜强度 0.0 ~ 1.0之间
  "texelOffset": 0,  // 是否需要支持宽高偏移值，即需要传递 1.0f/width, 1.0f/height到shader中
  "audioPath": "",  // 音乐路径
  "audioLooping": 1  // 是否循环播放音乐
 }]
}

有了json 之后，我们需要解码得到滤镜参数对象，解码如下：

/**
  * 解码滤镜数据
  * @param folderPath
  * @return
  */
 public static DynamicColor decodeFilterData(String folderPath)
   throws IOException, JSONException {

  File file = new File(folderPath, "json");
  String filterJson = FileUtils.convertToString(new FileInputStream(file));

  JSONObject jsonObject = new JSONObject(filterJson);
  DynamicColor dynamicColor = new DynamicColor();
  dynamicColor.unzipPath = folderPath;
  if (dynamicColor.filterList == null) {
   dynamicColor.filterList = new ArrayList<>();
  }

  JSONArray filterList = jsonObject.getJSONArray("filterList");
  for (int filterIndex = 0; filterIndex < filterList.length(); filterIndex++) {
   DynamicColorData filterData = new DynamicColorData();
   JSONObject jsonData = filterList.getJSONObject(filterIndex);
   String type = jsonData.getString("type");
   // TODO 目前滤镜只做普通的filter，其他复杂的滤镜类型后续在做处理
   if ("filter".equals(type)) {
    filterData.name = jsonData.getString("name");
    filterData.vertexShader = jsonData.getString("vertexShader");
    filterData.fragmentShader = jsonData.getString("fragmentShader");
    // 获取统一变量字段
    JSONArray uniformList = jsonData.getJSONArray("uniformList");
    for (int uniformIndex = 0; uniformIndex < uniformList.length(); uniformIndex++) {
     String uniform = uniformList.getString(uniformIndex);
     filterData.uniformList.add(uniform);
    }

    // 获取统一变量字段绑定的图片资源
    JSONObject uniformData = jsonData.getJSONObject("uniformData");
    if (uniformData != null) {
     Iterator<String> dataIterator = uniformData.keys();
     while (dataIterator.hasNext()) {
      String key = dataIterator.next();
      String value = uniformData.getString(key);
      filterData.uniformDataList.add(new DynamicColorData.UniformData(key, value));
     }
    }
    filterData.strength = (float) jsonData.getDouble("strength");
    filterData.texelOffset = (jsonData.getInt("texelOffset") == 1);
    filterData.audioPath = jsonData.getString("audioPath");
    filterData.audioLooping = (jsonData.getInt("audioLooping") == 1);
   }
   dynamicColor.filterList.add(filterData);
  }

  return dynamicColor;
 }

滤镜的实现

在解码得到滤镜参数之后，我们接下来实现动态滤镜渲染过程。为了方便构建滤镜，我们创建一个滤镜资源加载器，代码如下：

/**
 * 滤镜资源加载器
 */
public class DynamicColorLoader {

 private static final String TAG = "DynamicColorLoader";

 // 滤镜所在的文件夹
 private String mFolderPath;
 // 动态滤镜数据
 private DynamicColorData mColorData;
 // 资源索引加载器
 private ResourceDataCodec mResourceCodec;
 // 动态滤镜
 private final WeakReference<DynamicColorBaseFilter> mWeakFilter;
 // 统一变量列表
 private HashMap<String, Integer> mUniformHandleList = new HashMap<>();
 // 纹理列表
 private int[] mTextureList;

 // 句柄
 private int mTexelWidthOffsetHandle = OpenGLUtils.GL_NOT_INIT;
 private int mTexelHeightOffsetHandle = OpenGLUtils.GL_NOT_INIT;
 private int mStrengthHandle = OpenGLUtils.GL_NOT_INIT;
 private float mStrength = 1.0f;
 private float mTexelWidthOffset = 1.0f;
 private float mTexelHeightOffset = 1.0f;

 public DynamicColorLoader(DynamicColorBaseFilter filter, DynamicColorData colorData, String folderPath) {
  mWeakFilter = new WeakReference<>(filter);
  mFolderPath = folderPath.startsWith("file://") ? folderPath.substring("file://".length()) : folderPath;
  mColorData = colorData;
  mStrength = (colorData == null) ? 1.0f : colorData.strength;
  Pair pair = ResourceCodec.getResourceFile(mFolderPath);
  if (pair != null) {
   mResourceCodec = new ResourceDataCodec(mFolderPath + "/" + (String) pair.first, mFolderPath + "/" + pair.second);
  }
  if (mResourceCodec != null) {
   try {
    mResourceCodec.init();
   } catch (IOException e) {
    Log.e(TAG, "DynamicColorLoader: ", e);
    mResourceCodec = null;
   }
  }
  if (!TextUtils.isEmpty(mColorData.audioPath)) {
   if (mWeakFilter.get() != null) {
    mWeakFilter.get().setAudioPath(Uri.parse(mFolderPath + "/" + mColorData.audioPath));
    mWeakFilter.get().setLooping(mColorData.audioLooping);
   }
  }
  loadColorTexture();
 }

 /**
  * 加载纹理
  */
 private void loadColorTexture() {
  if (mColorData.uniformDataList == null || mColorData.uniformDataList.size() <= 0) {
   return;
  }
  mTextureList = new int[mColorData.uniformDataList.size()];
  for (int dataIndex = 0; dataIndex < mColorData.uniformDataList.size(); dataIndex++) {
   Bitmap bitmap = null;
   if (mResourceCodec != null) {
    bitmap = mResourceCodec.loadBitmap(mColorData.uniformDataList.get(dataIndex).value);
   }
   if (bitmap == null) {
    bitmap = BitmapUtils.getBitmapFromFile(mFolderPath + "/" + String.format(mColorData.uniformDataList.get(dataIndex).value));
   }
   if (bitmap != null) {
    mTextureList[dataIndex] = OpenGLUtils.createTexture(bitmap);
    bitmap.recycle();
   } else {
    mTextureList[dataIndex] = OpenGLUtils.GL_NOT_TEXTURE;
   }
  }
 }


 /**
  * 绑定统一变量句柄
  * @param programHandle
  */
 public void onBindUniformHandle(int programHandle) {
  if (programHandle == OpenGLUtils.GL_NOT_INIT || mColorData == null) {
   return;
  }
  mStrengthHandle = GLES30.glGetUniformLocation(programHandle, "strength");
  if (mColorData.texelOffset) {
   mTexelWidthOffsetHandle = GLES30.glGetUniformLocation(programHandle, "texelWidthOffset");
   mTexelHeightOffsetHandle = GLES30.glGetUniformLocation(programHandle, "texelHeightOffset");
  } else {
   mTexelWidthOffsetHandle = OpenGLUtils.GL_NOT_INIT;
   mTexelHeightOffsetHandle = OpenGLUtils.GL_NOT_INIT;
  }
  for (int uniformIndex = 0; uniformIndex < mColorData.uniformList.size(); uniformIndex++) {
   String uniformString = mColorData.uniformList.get(uniformIndex);
   int handle = GLES30.glGetUniformLocation(programHandle, uniformString);
   mUniformHandleList.put(uniformString, handle);
  }
 }

 /**
  * 输入纹理大小
  * @param width
  * @param height
  */
 public void onInputSizeChange(int width, int height) {
  mTexelWidthOffset = 1.0f / width;
  mTexelHeightOffset = 1.0f / height;
 }

 /**
  * 绑定滤镜纹理，只需要绑定一次就行，不用重复绑定，减少开销
  */
 public void onDrawFrameBegin() {
  if (mStrengthHandle != OpenGLUtils.GL_NOT_INIT) {
   GLES30.glUniform1f(mStrengthHandle, mStrength);
  }
  if (mTexelWidthOffsetHandle != OpenGLUtils.GL_NOT_INIT) {
   GLES30.glUniform1f(mTexelWidthOffsetHandle, mTexelWidthOffset);
  }
  if (mTexelHeightOffsetHandle != OpenGLUtils.GL_NOT_INIT) {
   GLES30.glUniform1f(mTexelHeightOffsetHandle, mTexelHeightOffset);
  }

  if (mTextureList == null || mColorData == null) {
   return;
  }
  // 逐个绑定纹理
  for (int dataIndex = 0; dataIndex < mColorData.uniformDataList.size(); dataIndex++) {
   for (int uniformIndex = 0; uniformIndex < mUniformHandleList.size(); uniformIndex++) {
    // 如果统一变量存在，则直接绑定纹理
    Integer handle = mUniformHandleList.get(mColorData.uniformDataList.get(dataIndex).uniform);
    if (handle != null && mTextureList[dataIndex] != OpenGLUtils.GL_NOT_TEXTURE) {
     OpenGLUtils.bindTexture(handle, mTextureList[dataIndex], dataIndex + 1);
    }
   }
  }
 }

 /**
  * 释放资源
  */
 public void release() {
  if (mTextureList != null && mTextureList.length > 0) {
   GLES30.glDeleteTextures(mTextureList.length, mTextureList, 0);
   mTextureList = null;
  }
  if (mWeakFilter.get() != null) {
   mWeakFilter.clear();
  }
 }

 /**
  * 设置强度
  * @param strength
  */
 public void setStrength(float strength) {
  mStrength = strength;
 }
}

然后我们构建一个DynamicColorFilter的基类，方便后续添加其他类型的滤镜，代码如下：

public class DynamicColorBaseFilter extends GLImageAudioFilter {

 // 颜色滤镜参数
 protected DynamicColorData mDynamicColorData;
 protected DynamicColorLoader mDynamicColorLoader;

 public DynamicColorBaseFilter(Context context, DynamicColorData dynamicColorData, String unzipPath) {
  super(context, (dynamicColorData == null || TextUtils.isEmpty(dynamicColorData.vertexShader)) ? VERTEX_SHADER
      : getShaderString(context, unzipPath, dynamicColorData.vertexShader),
    (dynamicColorData == null || TextUtils.isEmpty(dynamicColorData.fragmentShader)) ? FRAGMENT_SHADER_2D
      : getShaderString(context, unzipPath, dynamicColorData.fragmentShader));
  mDynamicColorData = dynamicColorData;
  mDynamicColorLoader = new DynamicColorLoader(this, mDynamicColorData, unzipPath);
  mDynamicColorLoader.onBindUniformHandle(mProgramHandle);
 }

 @Override
 public void onInputSizeChanged(int width, int height) {
  super.onInputSizeChanged(width, height);
  if (mDynamicColorLoader != null) {
   mDynamicColorLoader.onInputSizeChange(width, height);
  }
 }

 @Override
 public void onDrawFrameBegin() {
  super.onDrawFrameBegin();
  if (mDynamicColorLoader != null) {
   mDynamicColorLoader.onDrawFrameBegin();
  }
 }

 @Override
 public void release() {
  super.release();
  if (mDynamicColorLoader != null) {
   mDynamicColorLoader.release();
  }
 }

 /**
  * 设置强度，调节滤镜的轻重程度
  * @param strength
  */
 public void setStrength(float strength) {
  if (mDynamicColorLoader != null) {
   mDynamicColorLoader.setStrength(strength);
  }
 }

 /**
  * 根据解压路径和shader名称读取shader的字符串内容
  * @param unzipPath
  * @param shaderName
  * @return
  */
 protected static String getShaderString(Context context, String unzipPath, String shaderName) {
  if (TextUtils.isEmpty(unzipPath) || TextUtils.isEmpty(shaderName)) {
   throw new IllegalArgumentException("shader is empty!");
  }
  String path = unzipPath + "/" + shaderName;
  if (path.startsWith("assets://")) {
   return OpenGLUtils.getShaderFromAssets(context, path.substring("assets://".length()));
  } else if (path.startsWith("file://")) {
   return OpenGLUtils.getShaderFromFile(path.substring("file://".length()));
  }
  return OpenGLUtils.getShaderFromFile(path);
 }

}

接下来我们构建动态滤镜组，因为动态滤镜有可能有多个滤镜组合而成。代码如下：

public class GLImageDynamicColorFilter extends GLImageGroupFilter {

 public GLImageDynamicColorFilter(Context context, DynamicColor dynamicColor) {
  super(context);
  // 判断数据是否存在
  if (dynamicColor == null || dynamicColor.filterList == null
    || TextUtils.isEmpty(dynamicColor.unzipPath)) {
   return;
  }
  // 添加滤镜
  for (int i = 0; i < dynamicColor.filterList.size(); i++) {
   mFilters.add(new DynamicColorFilter(context, dynamicColor.filterList.get(i), dynamicColor.unzipPath));
  }
 }

 /**
  * 设置滤镜强度
  * @param strength
  */
 public void setStrength(float strength) {
  for (int i = 0; i < mFilters.size(); i++) {
   if (mFilters.get(i) != null && mFilters.get(i) instanceof DynamicColorBaseFilter) {
    ((DynamicColorBaseFilter) mFilters.get(i)).setStrength(strength);
   }
  }
 }
}

总结

基本的动态滤镜实现起来比较简单，总的来说就是简单的json参数、shader、统一变量和纹理绑定需要做成动态构建的过程而已。

效果如下：

动态滤镜效果