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
以上代码已在API级别30中弃用。现在您可以使用以下代码
val width = windowManager.currentWindowMetrics.bounds.width()
val height = windowManager.currentWindowMetrics.bounds.height()
此方法报告包括所有系统栏区域的窗口大小，而Display#getSize（Point）报告不包括导航栏和显示剪切区域的区域。Display#getSize（Point）报告的值可通过以下方式获得：
val metrics = windowManager.currentWindowMetrics
// Gets all excluding insets
val windowInsets = metrics.windowInsets
var insets: Insets = windowInsets.getInsets(WindowInsets.Type.navigationBars())
val cutout = windowInsets.displayCutout
if (cutout != null) {
val cutoutSafeInsets = Insets.of(cutout.safeInsetLeft, cutout.safeInsetTop, cutout.safeInsetRight, cutout.safeInsetBottom)
insets = Insets.max(insets, cutoutSafeInsets)
}
val insetsWidth = insets.right + insets.left
val insetsHeight = insets.top + insets.bottom
// Legacy size that Display#getSize reports
val legacySize = Size(metrics.bounds.width() - insetsWidth, metrics.bounds.height() - insetsHeight)
来源：WindowManager#getCurrentWindowMetrics（）
它可能无法回答您的问题，但如果你需要一个视图的维度，但你的代码在尚未布局时（例如在onCreate（）中）正在执行，你可以使用View.getViewTreeObserver（）.addOnGlobalLayoutListener（）设置一个ViewTreeObserver.OnGlobalLayout侦听器，并将需要该视图的相关代码放入尺寸。布局布局完成后，将调用侦听器的回调。
以下是低于/高于API 30代码的Kotlin扩展函数：
fun Activity.getScreenWidth(): Int {
return if (Build.VERSION.SDK_INT < 30) {
val displayMetrics = DisplayMetrics()
windowManager.defaultDisplay.getMetrics(displayMetrics)
displayMetrics.widthPixels
} else {
val metrics = windowManager.currentWindowMetrics
val insets = metrics.windowInsets
.getInsetsIgnoringVisibility(WindowInsets.Type.systemBars())
metrics.bounds.width() - insets.left - insets.right
}
}
fun Activity.getScreenHeight(): Int {
return if (Build.VERSION.SDK_INT < 30) {
val displayMetrics = DisplayMetrics()
windowManager.defaultDisplay.getMetrics(displayMetrics)
displayMetrics.heightPixels
} else {
val metrics = windowManager.currentWindowMetrics
val insets = metrics.windowInsets
.getInsetsIgnoringVisibility(WindowInsets.Type.systemBars())
metrics.bounds.height() - insets.top - insets.bottom
}
}
对应的Java助手方法：
public int getScreenWidth(Activity activity) {
if (Build.VERSION.SDK_INT < 30) {
DisplayMetrics displayMetrics = new DisplayMetrics();
activity.getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
return displayMetrics.widthPixels;
} else {
WindowMetrics metrics = activity.getWindowManager().getCurrentWindowMetrics();
Insets insets = metrics.getWindowInsets()
.getInsetsIgnoringVisibility(WindowInsets.Type.systemBars());
return metrics.getBounds().width() - insets.left - insets.right;
}
}
public int getScreenHeight(Activity activity) {
if (Build.VERSION.SDK_INT < 30) {
DisplayMetrics displayMetrics = new DisplayMetrics();
activity.getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
return displayMetrics.heightPixels;
} else {
WindowMetrics metrics = activity.getWindowManager().getCurrentWindowMetrics();
Insets insets = metrics.getWindowInsets()
.getInsetsIgnoringVisibility(WindowInsets.Type.systemBars());
return metrics.getBounds().height() - insets.bottom - insets.top;
}
}
public class AndroidScreenActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
String str_ScreenSize = "The Android Screen is: "
+ dm.widthPixels
+ " x "
+ dm.heightPixels;
TextView mScreenSize = (TextView) findViewById(R.id.strScreenSize);
mScreenSize.setText(str_ScreenSize);
}
}
•Kotlin版本通过扩展属性
在android中有多种实现屏幕尺寸的方法，但我认为最好的解决方案可以独立于Context实例，因此您可以在代码中的任何地方使用它。在这里，我通过kotlin扩展属性提供了一个解决方案，它可以很容易地知道以像素为单位的屏幕大小以及dp：
尺寸Utils.kt
import android.content.res.Resources
import android.graphics.Rect
import android.graphics.RectF
import android.util.DisplayMetrics
import kotlin.math.roundToInt
/**
* @author aminography
*/
private val displayMetrics: DisplayMetrics by lazy { Resources.getSystem().displayMetrics }
val screenRectPx: Rect
get() = displayMetrics.run { Rect(0, 0, widthPixels, heightPixels) }
val screenRectDp: RectF
get() = displayMetrics.run { RectF(0f, 0f, widthPixels.px2dp, heightPixels.px2dp) }
val Number.px2dp: Float
get() = this.toFloat() / displayMetrics.density
val Number.dp2px: Int
get() = (this.toFloat() * displayMetrics.density).roundToInt()
用法：
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val widthPx = screenRectPx.width()
val heightPx = screenRectPx.height()
println("[PX] screen width: $widthPx , height: $heightPx")
val widthDp = screenRectDp.width()
val heightDp = screenRectDp.height()
println("[DP] screen width: $widthDp , height: $heightDp")
}
}
结果：
当设备处于纵向时：
[PX] screen width: 1440 , height: 2392
[DP] screen width: 360.0 , height: 598.0
当设备处于横向时：
[PX] screen width: 2392 , height: 1440
[DP] screen width: 598.0 , height: 360.0
如果您不是kotlin的粉丝，请使用java版本：
import android.content.res.Resources;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.DisplayMetrics;
/**
* @author aminography
*/
public class DimensionUtils {
private static DisplayMetrics displayMetrics;
private static DisplayMetrics getDisplayMetrics() {
if (displayMetrics == null) {
displayMetrics = Resources.getSystem().getDisplayMetrics();
}
return displayMetrics;
}
public static Rect screenRectPx() {
return new Rect(0, 0, getDisplayMetrics().widthPixels, getDisplayMetrics().heightPixels);
}
public static RectF screenRectDp() {
return new RectF(0f, 0f, px2dp(getDisplayMetrics().widthPixels), px2dp(getDisplayMetrics().heightPixels));
}
public static float px2dp(int value) {
return value / getDisplayMetrics().density;
}
public static int dp2px(float value) {
return (int) (value * getDisplayMetrics().density);
}
}
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