我创建了一些自定义元素,并希望以编程方式将它们放置在右上角(距离上边缘n个像素,距离右边缘m个像素)。因此,我需要获得屏幕宽度和屏幕高度,然后设置位置:
int px = screenWidth - m;
int py = screenHeight - n;
如何在主活动中获取screenWidth和screenHeight?
我创建了一些自定义元素,并希望以编程方式将它们放置在右上角(距离上边缘n个像素,距离右边缘m个像素)。因此,我需要获得屏幕宽度和屏幕高度,然后设置位置:
int px = screenWidth - m;
int py = screenHeight - n;
如何在主活动中获取screenWidth和screenHeight?
当前回答
有一种使用DisplayMetrics(API 1)来实现这一点的方法并不过时,它可以避免try/catch混乱:
// initialize the DisplayMetrics object
DisplayMetrics deviceDisplayMetrics = new DisplayMetrics();
// populate the DisplayMetrics object with the display characteristics
getWindowManager().getDefaultDisplay().getMetrics(deviceDisplayMetrics);
// get the width and height
screenWidth = deviceDisplayMetrics.widthPixels;
screenHeight = deviceDisplayMetrics.heightPixels;
其他回答
这是我用于任务的代码:
// `activity` is an instance of Activity class.
Display display = activity.getWindowManager().getDefaultDisplay();
Point screen = new Point();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
display.getSize(screen);
} else {
screen.x = display.getWidth();
screen.y = display.getHeight();
}
看起来很干净,但要注意贬低。
只是补充弗朗西斯科的答案。如果你想找出窗口中的位置或屏幕中的位置,另一个更合适的观察者是ViewTreeObserver.OnPreDrawListener()
这也可用于查找在onCreate()时大部分未知的视图的其他属性,例如滚动位置、缩放位置。
在“活动”中使用以下代码。
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
int height = metrics.heightPixels;
int wwidth = metrics.widthPixels;
为了访问Android设备的状态栏高度,我们更喜欢一种编程方式:
示例代码
int resId = getResources().getIdentifier("status_bar_height", "dimen", "android");
if (resId > 0) {
result = getResources().getDimensionPixelSize(resId);
}
变量结果给出像素的高度。
用于快速访问
有关标题栏、导航栏和内容视图高度的更多信息,请查看Android设备屏幕大小。
在活动的onCreate中,有时需要知道布局可用空间的精确尺寸。经过一番思考,我想出了这种方法。
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
startActivityForResult(new Intent(this, Measure.class), 1);
// Return without setting the layout, that will be done in onActivityResult.
}
@Override
protected void onActivityResult (int requestCode, int resultCode, Intent data) {
// Probably can never happen, but just in case.
if (resultCode == RESULT_CANCELED) {
finish();
return;
}
int width = data.getIntExtra("Width", -1);
// Width is now set to the precise available width, and a layout can now be created. ...
}
}
public final class Measure extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// Create a LinearLayout with a MeasureFrameLayout in it.
// Just putting a subclass of LinearLayout in works fine, but to future proof things, I do it this way.
LinearLayout linearLayout = new LinearLayout(this);
LinearLayout.LayoutParams matchParent = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT);
MeasureFrameLayout measureFrameLayout = new MeasureFrameLayout(this);
measureFrameLayout.setLayoutParams(matchParent);
linearLayout.addView(measureFrameLayout);
this.addContentView(linearLayout, matchParent);
// measureFrameLayout will now request this second activity to finish, sending back the width.
}
class MeasureFrameLayout extends FrameLayout {
boolean finished = false;
public MeasureFrameLayout(Context context) {
super(context);
}
@SuppressLint("DrawAllocation")
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (finished) {
return;
}
finished = true;
// Send the width back as the result.
Intent data = new Intent().putExtra("Width", MeasureSpec.getSize(widthMeasureSpec));
Measure.this.setResult(Activity.RESULT_OK, data);
// Tell this activity to finish, so the result is passed back.
Measure.this.finish();
}
}
}
如果出于某种原因,您不想将另一个活动添加到Android清单中,可以这样做:
public class MainActivity extends Activity {
static Activity measuringActivity;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Bundle extras = getIntent().getExtras();
if (extras == null) {
extras = new Bundle();
}
int width = extras.getInt("Width", -2);
if (width == -2) {
// First time in, just start another copy of this activity.
extras.putInt("Width", -1);
startActivityForResult(new Intent(this, MainActivity.class).putExtras(extras), 1);
// Return without setting the layout, that will be done in onActivityResult.
return;
}
if (width == -1) {
// Second time in, here is where the measurement takes place.
// Create a LinearLayout with a MeasureFrameLayout in it.
// Just putting a subclass of LinearLayout in works fine, but to future proof things, I do it this way.
LinearLayout linearLayout = new LinearLayout(measuringActivity = this);
LinearLayout.LayoutParams matchParent = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
MeasureFrameLayout measureFrameLayout = new MeasureFrameLayout(this);
measureFrameLayout.setLayoutParams(matchParent);
linearLayout.addView(measureFrameLayout);
this.addContentView(linearLayout, matchParent);
// measureFrameLayout will now request this second activity to finish, sending back the width.
}
}
@Override
protected void onActivityResult (int requestCode, int resultCode, Intent data) {
// Probably can never happen, but just in case.
if (resultCode == RESULT_CANCELED) {
finish();
return;
}
int width = data.getIntExtra("Width", -3);
// Width is now set to the precise available width, and a layout can now be created.
...
}
class MeasureFrameLayout extends FrameLayout {
boolean finished = false;
public MeasureFrameLayout(Context context) {
super(context);
}
@SuppressLint("DrawAllocation")
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (finished) {
return;
}
finished = true;
// Send the width back as the result.
Intent data = new Intent().putExtra("Width", MeasureSpec.getSize(widthMeasureSpec));
MainActivity.measuringActivity.setResult(Activity.RESULT_OK, data);
// Tell the (second) activity to finish.
MainActivity.measuringActivity.finish();
}
}