所以我实现了一个TextureView直通代码。但是现在没有显示按钮，并且 onclick 侦听器给了我一个空指针异常。我究竟做错了什么
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera);
mTextureView = new TextureView(this);
mTextureView.setSurfaceTextureListener(this);
setContentView(mTextureView);
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
Toast.makeText(this, "No camera on device", Toast.LENGTH_LONG).show();
}else {
cameraId = findFrontFacingCamera();
if (cameraId<0){
Toast.makeText(this, "no front camera", Toast.LENGTH_LONG).show();
}else{
camera = Camera.open(cameraId);
Toast.makeText(this, "We have camera", Toast.LENGTH_LONG).show();
}
}
findViewById(R.id.buttonMenu).setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View v) {
// No account, load new account view
Intent intent = new Intent(CameraActivity.this,
MenuActivity.class);
startActivityForResult(intent, 0);
}
});
}
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width,
int height) {
camera = Camera.open();
Camera.Size previewSize = camera.getParameters().getPreviewSize();
mTextureView.setLayoutParams(new FrameLayout.LayoutParams(
30, 30, Gravity.CENTER));
try {
camera.setPreviewTexture(surface);
} catch (IOException t) {
}
camera.startPreview();
mTextureView.setAlpha(0.8f);
mTextureView.setRotation(45.0f);
}
public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width,
int height) {
// Ignored, the Camera does all the work for us
}
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
camera.stopPreview();
camera.release();
return true;
}
public void onSurfaceTextureUpdated(SurfaceTexture surface) {
// Called whenever a new frame is available and displayed in the
rotation += 1.0f;
if (rotation > 360) {
rotation = 0;
}
mTextureView.setRotation(rotation);
}
@Override
protected void onPause() {
if (camera != null) {
camera.release();
camera = null;
}
super.onPause();
}
public void onClick(View view) {
if (camera == null){
Toast.makeText(this, "Camera is null", Toast.LENGTH_LONG).show();
}else{
camera.takePicture(null, null,
new PhotoHandler(getApplicationContext(), mPreferences ));
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.camera, menu);
return true;
}
}
xml文件：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".CameraActivity" >
<Button
android:id="@+id/buttonMenu"
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/capture"
android:layout_alignBottom="@+id/capture"
android:layout_alignParentLeft="true"
android:layout_marginLeft="22dp"
android:text="menu" />
<Button
android:id="@+id/capture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="24dp"
android:onClick="onClick"
android:text="Take pic" />
</RelativeLayout>