WINDOW_SERVICE nicht gelöst werden können, um eine variable
Dachte ich WINDOW_SERVICE
sein sollte, war eine Konstante definiert, die in android.content.Context
.
http://developer.android.com/reference/android/content/Context.html#WINDOW_SERVICE
Wenn ich es in dem folgenden Codesegment wird eine Fehlermeldung besagt, dass es nicht aufgelöst werden kann wie eine variable.
Display display = ((WindowManager)getSystemService(WINDOW_SERVICE)).getDefaultDisplay();
Hier ist der vollständige code:
package com.commonsware.android.skeleton;
import android.app.Activity;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.*;
import android.os.Bundle;
import android.view.Display;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;
import android.widget.FrameLayout;
import java.io.IOException;
import java.util.List;
//----------------------------------------------------------------------
public class SimpleBulbActivity extends Activity {
private Preview mPreview;
FrameLayout preview;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Hide the window title.
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.main);
}
protected void onResume() {
super.onResume();
//Setup the FrameLayout with the Camera Preview Screen
mPreview = new Preview(this);
preview = (FrameLayout)findViewById(R.id.preview);
preview.addView(mPreview);
}
}
//----------------------------------------------------------------------
class Preview extends SurfaceView implements SurfaceHolder.Callback {
SurfaceHolder mHolder;
Camera mCamera;
Preview(Context context) {
super(context);
//Install a SurfaceHolder.Callback so we get notified when the
//underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
//The Surface has been created, acquire the camera and tell it where
//to draw.
mCamera = Camera.open();
try {
mCamera.setPreviewDisplay(holder);
} catch (IOException exception) {
mCamera.release();
mCamera = null;
//TODO: add more exception handling logic here
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
//Surface will be destroyed when we return, so stop the preview.
//Because the CameraDevice object is not a shared resource, it's very
//important to release it when the activity is paused.
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
final double ASPECT_TOLERANCE = 0.05;
double targetRatio = (double) w / h;
if (sizes == null) return null;
Size optimalSize = null;
double minDiff = Double.MAX_VALUE;
int targetHeight = h;
//Try to find an size match aspect ratio and size
for (Size size : sizes) {
double ratio = (double) size.width / size.height;
if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
//Cannot find the one match the aspect ratio, ignore the requirement
if (optimalSize == null) {
minDiff = Double.MAX_VALUE;
for (Size size : sizes) {
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
}
return optimalSize;
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
//Now that the size is known, set up the camera parameters and begin
//the preview.
Camera.Parameters parameters = mCamera.getParameters();
List<Size> sizes = parameters.getSupportedPreviewSizes();
Size optimalSize = getOptimalPreviewSize(sizes, w, h);
parameters.setPreviewSize(optimalSize.width, optimalSize.height);
Display display = ((WindowManager)getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
if(display.getRotation() == Surface.ROTATION_0)
{
parameters.setPreviewSize(h, w);
mCamera.setDisplayOrientation(90);
}
if(display.getRotation() == Surface.ROTATION_90)
{
parameters.setPreviewSize(w, h);
}
if(display.getRotation() == Surface.ROTATION_180)
{
parameters.setPreviewSize(h, w);
}
if(display.getRotation() == Surface.ROTATION_270)
{
parameters.setPreviewSize(w, h);
mCamera.setDisplayOrientation(180);
}
mCamera.setParameters(parameters);
mCamera.startPreview();
}
}
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The method getSystemService(String) is undefined for the type Preview
das macht für mich keinen Sinn.getSystemService(...)
ist eine Methode derContext
ist eine indirekte super-KlasseActivity
. Wenn Sie möchten, um IhrePreview
Klasse aus IhremActivity
wieder, Sie können immer mitgetContext().getSystemService(...)...
etc. AlleView
wieSurfaceView
könnengetContext()
zu finden, dieContext
in dem es ausgeführt wird, z.B., seine ElternActivity
.