surfaceCreated()从不调用

Question

我已经看到了类似的问题,但我仍然无法找到解决方案.我对Android开发很新,所以我无法追踪我的问题.无论如何,我正在尝试使用我创建的CameraSurfaceView类来创建相机预览,该类扩展了SurfaceView并实现了SurfaceHolder.Callback.无论我在StartCamera类中尝试什么,都不会调用surfaceCreated()方法,因此我的相机永远不会启动.任何帮助都会很棒,谢谢!

StartCamera.java

import net.peterd.zombierun.R;
import android.hardware.Camera;
import android.os.Bundle;
import android.widget.FrameLayout;

public class StartCamera extends BaseActivity {

    private Camera mCamera;
    private CameraSurfaceView mView;

    public void onCreate(Bundle state) {
        // TODO Auto-generated constructor stub
        super.onCreate(state);
        setContentView(R.layout.start_camera);
    }

    public void onResume() {
        super.onResume();

        mView = new CameraSurfaceView(this);
        FrameLayout preview = (FrameLayout) findViewById(R.id.cPreview);
        preview.addView(mView);
    }

    public void onPause() {
        mCamera.stopPreview();
        mCamera.release();
    }

}

CameraSurfaceView.java

import java.io.IOException;
import android.content.Context;
import android.hardware.Camera;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class CameraSurfaceView extends SurfaceView implements SurfaceHolder.Callback
{
        private SurfaceHolder holder;
        private Camera camera;

        public CameraSurfaceView(Context context) 
        {
                super(context);

                //Initiate the Surface Holder properly
                this.holder = this.getHolder();
                this.holder.addCallback(this);
                this.holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        }

        @Override
        public void surfaceCreated(SurfaceHolder holder) 
        {
                try
                {
                        //Open the Camera in preview mode
                        this.camera = Camera.open();
                        this.camera.setPreviewDisplay(this.holder);
                }
                catch(IOException ioe)
                {
                        ioe.printStackTrace(System.out);
                }
        }

        @Override
        public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) 
        {
                // Now that the size is known, set up the camera parameters and begin
                // the preview.
                Camera.Parameters parameters = camera.getParameters();
                parameters.setPreviewSize(width, height);
                camera.setParameters(parameters);
                camera.startPreview();
        }

        @Override
        public void surfaceDestroyed(SurfaceHolder holder) 
        {
                // Surface will be destroyed when replaced with a new screen
                //Always make sure to release the Camera instance
                camera.stopPreview();
                camera.release();
                camera = null;
        }

        public Camera getCamera() {
            return camera;
        }
}

start_camera.xml

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

    <FrameLayout android:id="@+id/cPreview"
        android:layout_weight="1" android:layout_width="fill_parent"
        android:layout_height="fill_parent">
    </FrameLayout>

</LinearLayout>

Answer 1

显然这是因为FrameLayout是空的,因此不会创建任何类型的SurfaceView.您可以尝试手动强制父LinearLayout设置高度和宽度,或者只是在FrameLayout中添加imageView.由于FrameLayout可能包含许多小部件,但它只显示最后一个小部件,您可以在FrameLayout中放置一个ImageView,仅显示要创建的SurfaceView的小图像.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">

<FrameLayout android:id="@+id/cPreview"
    android:layout_weight="1" android:layout_width="fill_parent"
    android:layout_height="fill_parent">

<!-- Adding small dummy image -->
<ImageView android:layout_width="wrap_content"
    android:layout_height="wrap_content" 
    src="@drawable/small_picture">

</FrameLayout>

</LinearLayout>

Answer 2

我曾经也有过一样的问题.对我来说,这是因为视图大小设置为0,因此从未创建表面.我通过设置一个特定的大小来检查这一点,并且突然调用了回调.(如果View在屏幕外布局,显然也是如此).