我有一个带开始按钮的简单屏幕.按下“开始”按钮后,我想转到带有SurfaceView的新屏幕以显示摄像机.
一切正常,但相机需要一段时间才能加载,这给了我一个黑屏.
我想加载新的布局.并且在装载后启动相机…
因此,我在后台线程中完成所有相机加载,但仍然,我得到一个黑屏……
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,它加载新视图：
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();
}
为什么新的布局没有显示,直到线程完成加载相机？
编辑：我已经尝试Thread中的Thread.sleep(200)睡了一段时间…当我这样做时,新的布局显示出来,但相机永远不会启动…
解决方法
好吧,问题是我在xml布局中使用了SurfaceView.
你打电话的那一刻：setContentView(your_layout) – > XML文件被夸大了.
这意味着,SurfaceView也会膨胀.这再次意味着调用SurfaceView onSurfaceCreated方法,触发打开相机等.
你打电话的那一刻：setContentView(your_layout) – > XML文件被夸大了.
这意味着,SurfaceView也会膨胀.这再次意味着调用SurfaceView onSurfaceCreated方法,触发打开相机等.
因此,整个过程需要一段时间,因此,您之前的Activity(例如,使用SurfaceView启动Activity的那个)似乎没有响应……
我在BG线程中创建Cameraview的解决方案解决了无响应问题.但未能在SurfaceView中显示Camera输出.
解决方案是从xml中删除SurfaceView.这将立即启动您的活动(因为SurfaceView& Camera未实例化).
加载新的“活动”布局后,可以以编程方式将新的SurfaceView添加到屏幕上.当然,这也需要时间,但您的UI会快速切换到新活动,并且您可以在SurfaceView和Camera加载时显示加载程序！
所以：从XML中删除SURFACEVIEW – >在程序上添加它：
发布活动：
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(只是一个启动新活动的按钮)
<?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>
这是第二个活动(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,这里是Cameraview()的代码.打开相机并显示内容真的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; } } }
原文地址：https://www.jb51.cc/android/317425.html
版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 dio@foxmail.com 举报，一经查实，本站将立刻删除。
