您好，我需要知道 Windows 10/8/8.1 和 iOS 中的屏幕密度。 我使用 DisplayMetrics 在 Android 中获得了屏幕密度，但我发现 UWP 和 iOS 中没有这样的选项/属性。 那么是否有任何属性可以让我在 UWP 和 IOS 中获得屏幕密度。
【问题讨论】：
标签： xamarin.ios uwp xamarin.forms portable-class-library
更新 - 2018 年 6 月 8 日
Xamarin.Essentials 为开发人员的移动应用程序提供跨平台 API。
Android、iOS 和 UWP 提供独特的操作系统和平台 API，开发人员可以利用 Xamarin 在 C# 中访问所有这些 API。 Xamarin.Essentials 提供了一个单一的跨平台 API，它适用于任何 Xamarin.Forms、Android、iOS 或 UWP 应用程序，无论用户界面是如何创建的，都可以从共享代码访问这些应用程序。 https://github.com/xamarin/Essentials
您现在可以查询设备的显示信息，而无需管理所有单独的平台代码片段。
设备显示信息 - https://docs.microsoft.com/en-us/xamarin/essentials/device-display
在您的类中添加对 Xamarin.Essentials 的引用：
using Xamarin.Essentials;
以下信息通过 API 公开：
// Get Metrics
var mainDisplayInfo = DeviceDisplay.MainDisplayInfo;
// Orientation (Landscape, Portrait, Square, Unknown)
var orientation = mainDisplayInfo.Orientation;
// Rotation (0, 90, 180, 270)
var rotation = mainDisplayInfo.Rotation;
// Width (in pixels)
var width = mainDisplayInfo.Width;
// Height (in pixels)
var height = mainDisplayInfo.Height;
// Screen density
var density = mainDisplayInfo.Density;
(Github) Xamarin.Essentials - https://github.com/xamarin/Essentials
（博客）Xamarin.Essentials - https://blog.xamarin.com/xamarin-essentials-cross-platform-apis-mobile-apps/
（文档）Essentials 入门 - https://docs.microsoft.com/en-us/xamarin/essentials/get-started
下面，我将特定操作系统的屏幕详细信息存储在位于 Xamarin Forms App 类中的 static 变量中
这些似乎都适用于我的测试。
（从我的 github 页面复制/粘贴 - https://github.com/mattregul/Xamarin_Screensize）
// Store off the device sizes, so we can access them within Xamarin Forms
// Screen Width = WidthPixels / Density
// Screen Height = HeightPixels / Density
App.DisplayScreenWidth = (double)Resources.DisplayMetrics.WidthPixels / (double)Resources.DisplayMetrics.Density;
App.DisplayScreenHeight = (double)Resources.DisplayMetrics.HeightPixels / (double)Resources.DisplayMetrics.Density;
App.DisplayScaleFactor = (double)Resources.DisplayMetrics.Density;
// Store off the device sizes, so we can access them within Xamarin Forms
App.DisplayScreenWidth = (double)UIScreen.MainScreen.Bounds.Width;
App.DisplayScreenHeight = (double)UIScreen.MainScreen.Bounds.Height;
App.DisplayScaleFactor = (double)UIScreen.MainScreen.Scale;
screensize 是根项目命名空间// You decided which is best for you...
// Do you want Size of the App's View
// or
// Do you want the Display's resolution
// ######################################
// Size of App's view
screensize.App.DisplayScreenHeight = Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().VisibleBounds.Height;
screensize.App.DisplayScreenWidth = Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().VisibleBounds.Width;
// Size of screen's resolution
//screensize.App.DisplayScreenWidth = Windows.Graphics.Display.DisplayInformation.GetForCurrentView().ScreenHeightInRawPixels;
//screensize.App.DisplayScreenHeight = Windows.Graphics.Display.DisplayInformation.GetForCurrentView().ScreenWidthInRawPixels;
// Pixels per View Pixel
// - https://msdn.microsoft.com/en-us/windows/uwp/layout/design-and-ui-intro#effective-pixels-and-scaling
// - https://msdn.microsoft.com/en-us/windows/uwp/layout/screen-sizes-and-breakpoints-for-responsive-design
screensize.App.DisplayScaleFactor = Windows.Graphics.Display.DisplayInformation.GetForCurrentView().RawPixelsPerViewPixel;
// Size of App's view
screensize.App.DisplayScreenHeight = Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().VisibleBounds.Height;
screensize.App.DisplayScreenWidth = Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().VisibleBounds.Width;
// Pixels per View Pixel
// - https://msdn.microsoft.com/en-us/windows/uwp/layout/design-and-ui-intro#effective-pixels-and-scaling
// - https://msdn.microsoft.com/en-us/windows/uwp/layout/screen-sizes-and-breakpoints-for-responsive-design
screensize.App.DisplayScaleFactor = Windows.Graphics.Display.DisplayInformation.GetForCurrentView().RawPixelsPerViewPixel;
// Size of App's view
screensize.App.DisplayScreenHeight = Window.Current.Bounds.Height;
screensize.App.DisplayScreenWidth = Window.Current.Bounds.Width;
screensize.App.DisplayScaleFactor = 1; // No scaling here? If you find a scaling for Windows 8.1, please let me know :)
namespace screensize
{
public class App : Application
{
public static double DisplayScreenWidth = 0f;
public static double DisplayScreenHeight = 0f;
public static double DisplayScaleFactor = 0f;
public App()
{
string ScreenDetails = Device.OS.ToString() + " Device Screen Size:\n" +
$"Width: {DisplayScreenWidth}\n" +
$"Height: {DisplayScreenHeight}\n" +
$"Scale Factor: {DisplayScaleFactor}";
// The root page of your application
var content = new ContentPage
{
Title = "Xamarin_GetDeviceScreensize",
Content = new StackLayout
{
VerticalOptions = LayoutOptions.Center,
Children = {
new Label {
HorizontalTextAlignment = TextAlignment.Center,
FontSize = Device.GetNamedSize (NamedSize.Large, typeof(Label)),
Text = ScreenDetails
}
}
}
};
MainPage = new NavigationPage(content);
}
}
}
【讨论】：
此列表列出了 ios 设备 dpi 信息。你也可以使用GBDeviceInfo第三方工具来获取IOS设备的屏幕密度，比如[GBDeviceInfo deviceInfo].displayInfo.pixelsPerInch;
IOS：
iPhones
iPhone 1/3G/3GS 320 x 480 163 ppi
iPhone 4/4S 640 x 940 326 ppi
iPhone 5/5C/5S 640 x 1136 326 ppi
iPhone 6/6S 750 x 1334 326 ppi
iPhone 6 Plus/6S Plus 1080 x 1920 401 ppi
Without downsampling: 1242 x 2208 461 ppi
Except for the 6th generation (= 5th) iPod touch,
all the models are equal to their iPhone counterparts
iPads
iPad 1/2 768 x 1024 132 ppi
iPad 3/4/Air/Air 2 1536 x 2048 264 ppi
iPad Mini 1 768 x 1024 163 ppi
iPad Mini 2/3/4 1536 x 2048 326 ppi
iPad Pro 2737 x 2048 264 ppi
Apple Watches
Apple Watch 38 mm 272 x 340 326 ppi
Apple Watch 42 mm 312 x 390 326 ppi
我在 UWP 中找到了API 以检索设备 dpi。 Windows.Graphics.Display.DisplayInformation。你可以试试看。
【讨论】：
(double)UIScreen.MainScreen.Scale;，它总是返回一个。为什么？？
MainScreen.Scale 的值始终为 1，因为您设备的原始显示设置。
[GBDeviceInfo deviceInfo].displayInfo.pixelsPerInch api。