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ContextExtensions.cs
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ContextExtensions.cs
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using System;
using System.Runtime.CompilerServices;
using Android.Content;
using Android.Util;
using Android.Views.InputMethods;
using AApplicationInfoFlags = Android.Content.PM.ApplicationInfoFlags;
using AActivity = Android.App.Activity;
namespace Xamarin.Forms.Platform.Android
{
public static class ContextExtensions
{
// Caching this display density here means that all pixel calculations are going to be based on the density
// of the first Context these extensions are run against. That's probably fine, but if we run into a
// situation where subsequent activities can be launched with a different display density from the intial
// activity, we'll need to remove this cached value or cache it in a Dictionary<Context, float>
static float s_displayDensity = float.MinValue;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static double FromPixels(this Context self, double pixels)
{
SetupMetrics(self);
return pixels / s_displayDensity;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static Size FromPixels(this Context context, double width, double height)
{
return new Size(context.FromPixels(width), context.FromPixels(height));
}
public static void HideKeyboard(this Context self, global::Android.Views.View view)
{
var service = (InputMethodManager)self.GetSystemService(Context.InputMethodService);
// service may be null in the context of the Android Designer
if (service != null)
service.HideSoftInputFromWindow(view.WindowToken, HideSoftInputFlags.None);
}
public static void ShowKeyboard(this Context self, global::Android.Views.View view)
{
var service = (InputMethodManager)self.GetSystemService(Context.InputMethodService);
// Can happen in the context of the Android Designer
if (service != null)
service.ShowSoftInput(view, ShowFlags.Implicit);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static float ToPixels(this Context self, double dp)
{
SetupMetrics(self);
return (float)Math.Round(dp * s_displayDensity);
}
public static bool HasRtlSupport(this Context self) =>
(self.ApplicationInfo.Flags & AApplicationInfoFlags.SupportsRtl) == AApplicationInfoFlags.SupportsRtl;
public static int TargetSdkVersion(this Context self) =>
(int)self.ApplicationInfo.TargetSdkVersion;
internal static double GetThemeAttributeDp(this Context self, int resource)
{
using (var value = new TypedValue())
{
if (!self.Theme.ResolveAttribute(resource, value, true))
return -1;
var pixels = (double)TypedValue.ComplexToDimension(value.Data, self.Resources.DisplayMetrics);
return self.FromPixels(pixels);
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
static void SetupMetrics(Context context)
{
if (s_displayDensity != float.MinValue)
return;
using (DisplayMetrics metrics = context.Resources.DisplayMetrics)
s_displayDensity = metrics.Density;
}
public static AActivity GetActivity(this Context context)
{
if (context == null)
return null;
if (context is AActivity activity)
return activity;
if (context is ContextWrapper contextWrapper)
return contextWrapper.BaseContext.GetActivity();
return null;
}
}
}