在第 23 版的 android API 中引入了类 ImageWriter . 我需要在应在 api 19 上运行的应用程序中使用此类。 我怎样才能重新实现类(class)？是否有一些等效的代码(我有一个 Image 实例需要绘制到表面上)？

最佳答案

这里有一段代码，可以让您拍照并在 Surface 上预览。我相信您可以根据您的目的调整代码。

这是 XML 代码:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent">
  <SurfaceView
    android:id="@+id/preview"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
  />
  <RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="100dip"
    android:layout_alignParentBottom="true"
    android:gravity="center_vertical"
    android:background="#A000">
    <Button
      android:layout_width="100dip"
      android:layout_height="wrap_content"
      android:text="Cancel"
      android:onClick="onCancelClick"
    />
    <Button
      android:layout_width="100dip"
      android:layout_height="wrap_content"
      android:layout_alignParentRight="true"
      android:text="Snap Photo"
      android:onClick="onSnapClick"
    />
  </RelativeLayout>
</RelativeLayout>

这里是 Java 代码:

package app.test;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;

import android.app.Activity;
import android.hardware.Camera;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Toast;


public class PreviewActivity extends Activity implements SurfaceHolder.Callback, Camera.ShutterCallback, Camera.PictureCallback {

    Camera mCamera;
    SurfaceView mPreview;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mPreview = (SurfaceView)findViewById(R.id.preview);
        mPreview.getHolder().addCallback(this);
        mPreview.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

        mCamera = Camera.open();
    }

    @Override
    public void onPause() {
        super.onPause();
        mCamera.stopPreview();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mCamera.release();
        Log.d("CAMERA","Destroy");
    }

    public void onCancelClick(View v) {
        finish();
    }

    public void onSnapClick(View v) {
        mCamera.takePicture(this, null, null, this);
    }

    @Override
    public void onShutter() {
        Toast.makeText(this, "Click!", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onPictureTaken(byte[] data, Camera camera) {
        //Here, we chose internal storage
        try {
            FileOutputStream out = openFileOutput("picture.jpg", Activity.MODE_PRIVATE);
            out.write(data);
            out.flush();
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        camera.startPreview();
    }
    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        Camera.Parameters params = mCamera.getParameters();
        List<Camera.Size> sizes = params.getSupportedPreviewSizes();
        Camera.Size selected = sizes.get(0);
        params.setPreviewSize(selected.width,selected.height);
        mCamera.setParameters(params);

        mCamera.setDisplayOrientation(90);
        mCamera.startPreview();
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        try {
            mCamera.setPreviewDisplay(mPreview.getHolder());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        Log.i("PREVIEW","surfaceDestroyed");
    }
}

关于android - Android 19-22 的 ImageWriter 替代品？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32251722/