手机相机的使用

手机相机的使用步骤:
1.打开相机,一般会有前置和后置摄像头。

 camera = Camera.open(cameId);

2.设置相机的参数，预览和图片尺寸。

//先获取相机参数
Camera.Parameters param=camera.getParameters();

获得相机支持的大小参数，然后通过参数去选择一个合适的尺寸。一般选择的是高度大于最小宽度，缩放比相近的参数。

    private Camera.Size getPropPreviewSize(List<Camera.Size> list, float th, int minWidth){
        Collections.sort(list, sizeComparator);
        int i = 0;
        for(Camera.Size s:list){
            if((s.height >= minWidth) && equalRate(s, th)){
                break;
            }
            i++;
        }
        if(i == list.size()){
            i = 0;
        }
        return list.get(i);
    }

将它们设置到参数中，一般设置预览和图片尺寸即可。

param.setPictureSize(picSize.width,picSize.height);
param.setPreviewSize(preSize.width,preSize.height);
camera.setParames(param);

将相机结果绘制到纹理，使用SurfaceTexture.

    public void setPreviewTexture(SurfaceTexture texture){
        if(camera!=null){
            try {
                camera.setPreviewTexture(texture);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

3.预览

    public boolean preview() {
        if(camera!=null){
            camera.startPreview();
        }
        return false;
    }

加入权限

<uses-permission android:name="android.permission.CAMERA" />

检测是不是成功得到权限

    public static void askPermission(Activity context, String[] permissions, int req, Runnable
            runnable){
        if(Build.VERSION.SDK_INT>=Build.VERSION_CODES.M){
            int result= ActivityCompat.checkSelfPermission(context,permissions[0]);
            if(result== PackageManager.PERMISSION_GRANTED){
                runnable.run();
            }else{
                ActivityCompat.requestPermissions(context,new String[]{Manifest.permission.CAMERA
                        ,Manifest.permission.WRITE_EXTERNAL_STORAGE},req);
            }
        }else{
            runnable.run();
        }
    }

绘制

一般的我们通过纹理将相机的数据放入到纹理中，然后通过绘制纹理达到绘制相机的效果。我们的所有操作都是基于这个纹理进行的。
简单绘制绘制代码。

public class MyCameraDrawer implements GLSurfaceView.Renderer {
    private SurfaceTexture surfaceTexture;
    private float[] matrix=new float[16];
    private int width,height
    private int dataWidth,dataHeight;
    private AFilter mOesFilter;
    private int cameraId=1;

    public MyCameraDrawer(Resources  resources){
        mOesFilter=new OesFilter(resources);
    }

    @Override
    public void onSurfaceCreated(GL10 gl10, EGLConfig eglConfig) {
        int texture = createTextureID();
        surfaceTexture=new SurfaceTexture(texture);
        mOesFilter.create();
        mOesFilter.setTextureId(texture);
    }

    @Override
    public void onSurfaceChanged(GL10 gl10, int i, int i1) {
        setViewSize(width,height);
    }

    @Override
    public void onDrawFrame(GL10 gl10) {
        if(surfaceTexture!=null){
            surfaceTexture.updateTexImage();
        }
        mOesFilter.draw();
    }

    public void setDataSize(int dataWidth,int dataHeight){
        this.dataWidth=dataWidth;
        this.dataHeight=dataHeight;
        calculateMatrix();
    }

    public void setViewSize(int width,int height){
        this.width=width;
        this.height=height;
        calculateMatrix();
    }

    private void calculateMatrix(){
        Gl2Utils.getShowMatrix(matrix,this.dataWidth,this.dataHeight,this.width,this.height);
        if(cameraId==1){
            Gl2Utils.flip(matrix,true,false);
            Gl2Utils.rotate(matrix,90);
        }else{
            Gl2Utils.rotate(matrix,270);
        }
        mOesFilter.setMatrix(matrix);
    }

    public SurfaceTexture getSurfaceTexture(){
        return surfaceTexture;
    }

    public void setCameraId(int id){
        this.cameraId=id;
        calculateMatrix();
    }


    private int createTextureID(){
        int[] texture = new int[1];
        GLES20.glGenTextures(1, texture, 0);
        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, texture[0]);
        GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,
                GL10.GL_TEXTURE_MIN_FILTER,GL10.GL_LINEAR);
        GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,
                GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,
                GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE);
        GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,
                GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE);
        return texture[0];
    }
}