我有一个带有开始按钮的简单屏幕。当按下开始按钮时，我想转到一个带有SurfaceView的新屏幕以显示“相机”。
一切正常，但是相机需要一段时间才能加载，这给了我黑屏。
我想加载新的布局。而不是在加载后启动相机...
因此，我将所有Camera都加载到后台线程中，但是仍然出现黑屏...
这是我的布局:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout android:id="@+id/RelativeLayout1"
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@drawable/blue_bg">
<SurfaceView
android:id="@+id/surface_camera"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_marginLeft="25dp"
android:layout_marginRight="25dp"
android:layout_below="@id/scan_header"
android:layout_above="@id/scan_footer">
</SurfaceView>
</RelativeLayout>
这是我的Activity中的方法，该方法将加载新 View :
private void setContent()
{
setContentView(R.layout.scan)
Thread t = new Thread()
{
public void run()
{
final SurfaceView mSurfaceView = (SurfaceView)findViewById(R.id.surface_camera);
final SurfaceHolder mSurfaceHolder = mSurfaceView.getHolder();
try
{
cameraView = new CameraView();
mSurfaceHolder.addCallback(cameraView);
cameraView.setPictureListener(SunpluggedActivity.this);
mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
} catch(Exception e)
{
Log.d(TAG, "Another exception");
e.printStackTrace();
}
}
};
t.start();
}
为什么直到线程完成加载相机后才显示新的布局？
编辑:我已经尝试在线程内的Thread.sleep(200) sleep 了一段时间。
最佳答案
好吧，问题是我在xml布局中使用了SurfaceView。
调用的时刻:setContentView(your_layout)-> XML文件膨胀。
这意味着SurfaceView也会膨胀。再次，这意味着调用了SurfaceView onSurfaceCreated方法，这将触发打开Camera等。
因此，整个过程需要一段时间，因此，您以前的Activity(例如，使用SurfaceView启动Activity的 Activity )似乎没有响应...
我的解决方案是在BG线程中创建CameraView，从而解决了无响应问题。但是未能在SurfaceView中显示Camera输出。
解决方案是从xml中删除SurfaceView。这将立即开始您的 Activity (因为未实例化SurfaceView和相机)。
加载新的“Activity ”布局后，可以以编程方式向屏幕添加新的SurfaceView。当然，这也需要时间，但是您的UI会快速切换到新 Activity ，并且可以在SurfaceView和Camera加载时显示加载器!
因此:从XML删除SURFACEVIEW->按程序添加:
启动 Activity :
public class Launch extends Activity implements OnClickListener
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btn = (Button)findViewById(R.id.button1);
btn.setOnClickListener(this);
}
@Override
public void onClick(View v) {
Intent intent = new Intent(Launch.this, SurfaceTestActivity.class);
startActivity(intent);
}
}
Main.xml(仅是启动新 Activity 的按钮)
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout android:id="@+id/RelativeLayout1"
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#ff6600">
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
</RelativeLayout>
这是第二个 Activity (其中包含SurfaceView)
public class SurfaceTestActivity extends Activity {
private Context mContext;
private CameraView cameraView;
private Handler mHandler = new Handler();
private final Runnable mLoadCamera = new Runnable()
{
public void run()
{
startCamera();
}
};
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContent();
mContext = getApplicationContext();
}
private void startCamera()
{
RelativeLayout rl = (RelativeLayout)findViewById(R.id.surface_camera);
SurfaceView surfaceView = new SurfaceView(mContext);
final SurfaceHolder mSurfaceHolder = surfaceView.getHolder();
try
{
cameraView = new CameraView();
mSurfaceHolder.addCallback(cameraView);
mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
} catch(Exception e)
{
Log.d("debug", "Another exception");
e.printStackTrace();
}
if(rl != null && surfaceView != null)
rl.addView(surfaceView);
}
private void setContent()
{
setContentView(R.layout.scan);
// Post the Runnable with a Slight delay -> than your layout will be
// shown. Without the delay -> your UI will feel inresponsive
mHandler.postDelayed(mLoadCamera, 100);
}
}
这是第二个Activity的布局(没有SURFACEVIEW)
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout android:id="@+id/RelativeLayout1"
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#ff6600">
<RelativeLayout
android:id="@+id/header"
android:layout_width="fill_parent" android:layout_height="wrap_content">
<TextView
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:text="Explanation Txt"></TextView>
</RelativeLayout>
<RelativeLayout
android:id="@+id/footer"
android:layout_width="fill_parent" android:layout_height="wrap_content"
android:layout_alignParentBottom="true">
<TextView
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:text="Explanation Txt"></TextView>
</RelativeLayout>
<RelativeLayout
android:id="@+id/surface_camera"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:layout_above="@+id/footer"
android:layout_below="@+id/header"
android:background="#ff0066">
</RelativeLayout>
</RelativeLayout>
最后，为了完成答案，这是CameraView()的代码。打开相机并显示内容实际上只是一个简单的实现:
public class CameraView implements SurfaceHolder.Callback{
// Variables
private Camera mCamera = null;
private boolean mPreviewRunning = false;
private boolean mProcessing = false;
private int mWidth = 0;
private int mHeight = 0;
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height)
{
if(mPreviewRunning )
{
mCamera.stopPreview();
}
// Store width and height
mWidth = width;
mHeight = height;
// Set camera parameters
Camera.Parameters p = mCamera.getParameters();
mCamera.setParameters(p);
if(android.os.Build.VERSION.SDK_INT >= 8)
{ // If API >= 8 -> rotate display...
mCamera.setDisplayOrientation(90);
}
try
{
mCamera.setPreviewDisplay(holder);
} catch(IOException e)
{
e.printStackTrace();
}
mCamera.startPreview();
mPreviewRunning = true;
}
@Override
public void surfaceCreated(final SurfaceHolder holder)
{
try {
mCamera = Camera.open();
mCamera.setPreviewDisplay(holder);
} catch (IOException e)
{
mCamera.release();
mCamera = null;
e.printStackTrace();
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder)
{
if(mCamera != null)
{
mCamera.setPreviewCallback(null);
mCamera.stopPreview();
mCamera.setPreviewCallback(null);
mPreviewRunning = false;
mCamera.release();
mCamera = null;
}
}
}