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
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();
}
}
其他回答
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。
首先获取视图(例如,通过findViewById()),然后可以对视图本身使用getWidth()。
科特林牌手表
fun getScreenHeight(activity: Activity): Int {
val metrics = DisplayMetrics()
activity.windowManager.defaultDisplay.getMetrics(metrics)
return metrics.heightPixels
}
fun getScreenWidth(activity: Activity): Int {
val metrics = DisplayMetrics()
activity.windowManager.defaultDisplay.getMetrics(metrics)
return metrics.widthPixels
}
JAVA
DisplayMetrics dimension = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dimension);
int w = dimension.widthPixels;
int h = dimension.heightPixels;
我有两个函数,一个用于发送上下文,另一个用于获取像素的高度和宽度:
public static int getWidth(Context mContext){
int width=0;
WindowManager wm = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
if(Build.VERSION.SDK_INT>12){
Point size = new Point();
display.getSize(size);
width = size.x;
}
else{
width = display.getWidth(); // Deprecated
}
return width;
}
and
public static int getHeight(Context mContext){
int height=0;
WindowManager wm = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
if(Build.VERSION.SDK_INT>12){
Point size = new Point();
display.getSize(size);
height = size.y;
}
else{
height = display.getHeight(); // Deprecated
}
return height;
}
对于使用XML进行动态缩放,有一个名为“android:layout_weight”的属性
下面的示例是根据synic在这个线程上的响应修改的,显示了一个占屏幕75%的按钮(权重=.25)和一个占剩余25%的文本视图(权重=.75)。
<LinearLayout android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight=".25"
android:text="somebutton">
<TextView android:layout_width="fill_parent"
android:layout_height="Wrap_content"
android:layout_weight=".75">
</LinearLayout>