Question

好的，我在我的应用程序中使用ViewPager，我想在ViewPager的最后一页添加一个Camera Preview。我面临一些问题，因为为了开始预览，我将它分配给我的ViewPager的最后一页内的FrameLayout。但是出于某种原因，在调用整个onCreate（）和onResume（）方法之前，ViewPager不会对其页面进行充气。这是有问题的，因为当我尝试通过ID找到FrameLayout时，它返回null，因为该页面尚未膨胀。无论如何我可以解决这个问题吗？

以下是camerapreview的代码。我有一个if检查，看我的预览是否为空，它是。

package me.bionicsheep.aegis;

import com.qualcomm.snapdragon.sdk.face.FacialProcessing;

import android.os.Bundle;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.hardware.Camera.PreviewCallback;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.Display;
import android.view.Surface;
import android.view.WindowManager;
import android.widget.FrameLayout;
import android.widget.RelativeLayout.LayoutParams;

public class Setup extends FragmentActivity implements Camera.PreviewCallback{

    private ViewPager mPager;
    private PagerAdapter mPagerAdapter;

    CameraActivationFragment CAF;
    Camera cameraObj;
    FrameLayout preview;
    private CameraSurfacePreview mPreview;
    private int FRONT_CAMERA_INDEX = 1;

    private boolean qCommHardware;
    public static FacialProcessing facialProc;

    LayoutParams mParams;

    Parameters cParams;
    int cWidth;
    int cHeight;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.setup_layout);

        hideActionBar();

        mPager = (ViewPager) findViewById(R.id.pager);
        mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
        mPager.setAdapter(mPagerAdapter);

        checkForHardware();
    }

    private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
        public ScreenSlidePagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            switch (position){
            case 0:
                CAF = new CameraActivationFragment();
                return CAF;
            case 1:
                return new ScreenSlidePageFragment();
            }

            return null;

        }

        @Override
        public int getCount() {
            return 2;
        }
    }

    private void hideActionBar(){
        getActionBar().hide();
    }

    @Override
    public void onPreviewFrame(byte[] data, Camera camera) {
        // TODO Auto-generated method stub

    }

    private void checkForHardware(){
        qCommHardware = FacialProcessing.isFeatureSupported(FacialProcessing.
                FEATURE_LIST.FEATURE_FACIAL_RECOGNITION);
        if(qCommHardware){
            facialProc = (FacialProcessing) FacialProcessing.getInstance();
            facialProc.setRecognitionConfidence(85);
        }else{
            finish();
        }
    }

    public void startCamera(){
        try{
            cameraObj = Camera.open(FRONT_CAMERA_INDEX);
        }
        catch (Exception ex){
            finish();
            Log.d("Aegis", "failed to open front facing camera " + ex.getMessage());
        }

        setRotation();

        mPreview = new CameraSurfacePreview(Setup.this, cameraObj);
        preview = (FrameLayout) findViewById(R.id.camera_activation_preview);

        if(preview == null){
            Log.d("Aegis","preview is null");
            return;
        }

        cParams = cameraObj.getParameters();
        cWidth = cParams.getPictureSize().width;
        cHeight = cParams.getPictureSize().height;

        mParams = (LayoutParams) preview.getLayoutParams();
        mParams.width = (int) (getResources().getDisplayMetrics().widthPixels / 1.5);
        mParams.height = (int) (mParams.width * ((double) cWidth / cHeight));

        preview.addView(mPreview, mParams);
        cameraObj.setPreviewCallback((PreviewCallback) Setup.this);
    }

    @Override
    protected void onPause() {
        super.onPause();
        preview.removeView(mPreview);
    }

    @Override
    protected void onResume() {
        super.onResume();


        //startCamera();
    }

    private void setRotation(){
        Display display = ((WindowManager)getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();

        if(display.getRotation() == Surface.ROTATION_0)
        {                         
            cameraObj.setDisplayOrientation(90);
        }
        if(display.getRotation() == Surface.ROTATION_270)
        {
            cameraObj.setDisplayOrientation(180);
        }
    }

}

这是片段本身：

package me.bionicsheep.aegis;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class CameraActivationFragment extends Fragment {


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.camera_activation_layout, container, false);
        return rootView;
    }

}

最后是片段的xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <FrameLayout
        android:id="@+id/camera_activation_preview"
        android:scaleType="fitXY"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true" >
    </FrameLayout>

</RelativeLayout>

Answer 1

好的，我通过将以下内容添加到我的片段类

来解决这个问题

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    ((Setup) getActivity()).startCamera();
}

在视图正确创建并充气后启动相机。退出应用程序并重新进入（恢复）时，这就会导致问题，因为onResume没有启动startCamera命令。为了解决这个问题，我将这段代码包含在我的主类

中

@Override
protected void onResume() {
    super.onResume();
    if(preview != null){
        startCamera();
    }
}

ViewPager中的FrameLayout在调用Activity onResume后膨胀

1 个答案: