我正在努力实现一个类似扫描线的动画（上下），在一个我编写的Android运动应用程序中的相机预览活动上。
我已经成功地使动画代码在单个活动中工作 - 没有相机预览。无论我如何尝试这里在stackoverflow上读到的一切或搜索网络，我总是得到相机预览，而不是动画叠加。
这是我的XML文件：
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/container"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="horizontal"
android:background="@android:color/transparent"
android:layout_centerInParent="true">
<SurfaceView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/imageView"
android:src="@drawable/scanline"
android:contentDescription="@string/scanline"
android:layout_gravity="left|center_vertical"
android:layout_alignParentStart="true"
android:layout_alignParentEnd="true"
android:background="@android:color/transparent"
android:baselineAlignBottom="false"/>
<com.app.arsinoe.ui.widget.CameraPreview
android:id="@+id/camera_preview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@android:color/transparent" />
<Button
android:layout_width="156dp"
android:layout_height="27dp"
android:text="@string/exit_button"
android:id="@+id/aboardButton2"
android:layout_gravity="bottom|left"
android:clickable="true"
android:background="#4e0612"
android:textColor="@android:color/white"
android:textStyle="bold"
android:alpha="1"
android:paddingEnd="@dimen/activity_horizontal_margin"
android:paddingStart="@dimen/activity_vertical_margin"
android:onClick="exitButton"/>
<Button
android:layout_width="310dp"
android:layout_height="27dp"
android:text="@string/scan_button"
android:id="@+id/scanButton"
android:layout_gravity="bottom|right"
android:clickable="true"
android:textColor="@android:color/white"
android:textStyle="bold"
android:alpha="1"
android:background="#1b4a6c"
android:paddingEnd="@dimen/activity_horizontal_margin"
android:paddingStart="@dimen/activity_vertical_margin"
android:onClick="scanButton"/>
</FrameLayout>
这是我用于扫描线动画活动的工作代码：
public class ScanActivity extends Activity{
private View view;
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.scan_activity);
final Context readySnanner = this;
Handler mHandler = new Handler();
Runnable
makeToast = new Runnable() {
public void run() {
Toast.makeText(readySnanner,
"Bla bla bla...", Toast.LENGTH_LONG).show();
}
};
mHandler.postDelayed(makeToast, 4000);
Toast.makeText(ScanActivity.this,"Bla bla... Please wait", Toast.LENGTH_SHORT).show();
ImageView animatedImage = (ImageView) findViewById(R.id.imageView);
Animation animation
= AnimationUtils.loadAnimation(this, R.anim.topdown);
if (animation != null) {
animatedImage.startAnimation(animation);}
final int SPLASH_TIME;// 4 seconds
SPLASH_TIME = 4 * 1000;
boolean b;
b = new Handler().postDelayed(new Runnable() {
@Override
public void run() {
}
}, SPLASH_TIME);
}
public void exitButton(View view) {
this.finish();
System.exit(0);
}
public void scanButton(View view) {
Intent intent = new Intent(ScanActivity.this,
B.class);
startActivity(intent);
ScanActivity.this.finish();
}
这是我的相机活动的工作代码：
public class CameraActivity extends Activity {
private Camera camera;
private View view;
SurfaceView animatedImage;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.scan_activity);
setResult(RESULT_CANCELED);
// Camera may be in use by another activity or the system or not available at all
try {
camera = getCameraInstance();
} catch (Exception e) {
e.printStackTrace();
}
if(cameraAvailable(camera)){
initCameraPreview();
} else {
finish();
}
}
// Show the camera view on the activity
private void initCameraPreview() {
CameraPreview cameraPreview = (CameraPreview) findViewById(R.id.camera_preview);
cameraPreview.init(camera);}
我不知道如何使用提供的xml文件将这两个活动组合成单个活动。请帮助一个新手，因为我已经被这个问题卡了5天！
很抱歉我没有提供一个图片来描述我的编码目标，但是我的声誉很低。任何回复，最好附有一个可工作的示例。
编辑：
以下图片显示了活动的布局：
红色线应该在动画中上下移动，覆盖相机预览。这在ImageView中编码并且有效，但在CameraPreview中却无效。
这是我的CameraPreview活动，如Juan-devtopia.coop建议的编辑：
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private Context context;
private Camera camera;
public CameraPreview(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public CameraPreview(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CameraPreview(Context context, Camera camera) {
super(context);
this.context = context;
this.camera = camera;
}
public void init(Camera camera) {
this.camera = camera;
initSurfaceHolder();
}
@SuppressWarnings("deprecation") // needed for < 3.0
private void initSurfaceHolder() {
SurfaceHolder holder = getHolder();
if (holder != null) {
holder.addCallback(this);
}
if (holder != null) {
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
initCamera(holder);
}
private void initCamera(SurfaceHolder holder) {
try {
camera.setPreviewDisplay(holder);
camera.startPreview();
} catch (Exception ignored) {
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
public void setContext(Context context) {
this.context = context;
}
public class Animation extends Activity {
ImageView animatedImage = (ImageView) findViewById(R.id.imageView);
android.view.animation.Animation animation;
{
animatedImage.startAnimation(animation);
animation = AnimationUtils.loadAnimation(this, R.anim.topdown);
}
}
在编译并在设备上运行时，我在logcat中得到了一个"java.lang.RuntimeException: Unable to instantiate activity"错误，由"Caused by: java.lang.InstantiationException: com.app.myapp.ui.widget.CameraPreview"引起。有什么建议吗？
在我的示例代码中（我已经上传到github，请查看