Thứ Ba, 17 tháng 7, 2012

Error of getLocationInWindow() and getLocationOnScreen()

0
12:27
The View class provide the methods to computes the coordinates:

In my experience, the returned x location is correct, but the y location is always error with a fixed offset. The offset various depends on devices and configuration.

To correct it, we can get the offset using the code, after view displayed:
DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
int offsetY = displayMetrics.heightPixels - mainScreen.getMeasuredHeight();


offset of getLocationInWindow() and getLocationOnScreen()


package com.example.androidoffsetgetlocation;

import android.os.Bundle;
import android.app.Activity;
import android.util.DisplayMetrics;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainActivity extends Activity {

LinearLayout mainScreen;
ImageView object;
TextView textOnCreate, textOnWindowFocusChanged;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

mainScreen = (LinearLayout)findViewById(R.id.mainscreen);
object = (ImageView)findViewById(R.id.object);
textOnCreate = (TextView)findViewById(R.id.textview1);
textOnWindowFocusChanged = (TextView)findViewById(R.id.textview2);

readLocation(textOnCreate, "onCreate()");
}

@Override
public void onWindowFocusChanged(boolean hasFocus) {
// TODO Auto-generated method stub
super.onWindowFocusChanged(hasFocus);

readLocation(textOnWindowFocusChanged, "onWindowFocusChanged()");
}

private void readLocation(TextView tv, String status){
DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
int offsetX = displayMetrics.widthPixels - mainScreen.getMeasuredWidth();
int offsetY = displayMetrics.heightPixels - mainScreen.getMeasuredHeight();

int[] locationInWindow = new int[2];
object.getLocationInWindow(locationInWindow);
int[] locationOnScreen = new int[2];
object.getLocationOnScreen(locationOnScreen);

tv.setText(
"\n" + status +"\n"
+ "getLocationInWindow() - " + locationInWindow[0] + " : " + locationInWindow[1] + "\n"
+ "getLocationOnScreen() - " + locationOnScreen[0] + " : " + locationOnScreen[1] + "\n"
+ "Offset x: y - " + offsetX + " : " + offsetY);

}

}


<LinearLayout 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:orientation="vertical"
android:id="@+id/mainscreen">

<ImageView
android:id="@+id/object"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/ic_launcher"/>
<TextView
android:id="@+id/textview1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView
android:id="@+id/textview2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>

</LinearLayout>



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