如何以xamarin形式检测设备是大还是小

Question

如何检测设备是小还是大？我不需要检测是否是平板电脑。

这个概念取自https://devblogs.microsoft.com/xamarin/styling-for-multiple-device-resolutions/

我们使用下面的方法并相应地加载适当的样式，但是因为我没有考虑密度，所以它不准确。

我怎样才能改进或重写这个方法，以便它给我一个更好的结果，并更准确地检测设备是大还是小。

当前的

const int smallWightResolution = 768;
const int smallHeightResolution = 1280;

public static bool IsASmallDevice()
{
        // Get Metrics
        var mainDisplayInfo = Xamarin.Essentials.DeviceDisplay.MainDisplayInfo;

        // Width (in pixels)
        var width = mainDisplayInfo.Width;

        // Height (in pixels)
        var height = mainDisplayInfo.Height;
        return (width <= smallWightResolution && height <= smallHeightResolution);
  }

尝试使用密度但不知道公式是什么

public static bool IsSmallDevice()
{ 
    //we don't support tablet so tablet don't apply.

    int smallWidthResolution = 768;
    int smallHeightResolution = 1280;
    double screenWidth;
    double screenHeight;
    bool isSmallDevice;
    
    var metrics = Xamarin.Essentials.DeviceDisplay.MainDisplayInfo;
    
    switch (Xamarin.Forms.Device.RuntimePlatform)
    {
        case Xamarin.Forms.Device.Android:
            //Android not sure how to sort of correctly detect if is a small device
            screenWidth = (metrics.Width - 0.5f) / metrics.Density;
            screenHeight = (metrics.Height - 0.5f) / metrics.Density;
            isSmallDevice = "???????";
            break;
        case Xamarin.Forms.Device.iOS:
            //ios no changes 
            isSmallDevice = metrics.Width <= smallWidthResolution
                            && metrics.Height <= smallHeightResolution;
            break;
    }

    return isSmallDevice;
}

更新

Huawei P9 Android 7.0
    Density=2.5
    Width=1080
    Height=2160
    ScreenHeight(Calculated)=864
    ScreenWidth(Calculated)=432


    Samsung A20 Android (new phone)
    Density=2
    Width=720
    Height=1560
    ScreenHeight(Calculated)=780
    ScreenWidth(Calculated)=360

有什么建议么？

Answer 1

回答

我建议使用Xamarin.Essentials NuGet 包来检索屏幕的宽度、高度和密度，然后使用以下公式：

• 屏幕宽度 = 宽度 / 密度
• 屏幕高度 = 高度 / 密度

代码

using Xamarin.Essentials;

// **** Example Screen Sizes ****
// iPhone SE 2nd Gen (aka iPhone 8), Width 750, Density 2, Width/Density 375
// iPhone 11, Width 828, Density 2, Width/Density 414
// Pixel 3, Width 1080, Density 2.75, Width/Density 392.7
// Galaxy S5, Width 1080, Density 3, Width/Density 360
// Galaxy Nexus, Width 720, Density 2, Width/Density 360
public static double ScreenWidth { get; } = DeviceDisplay.MainDisplayInfo.Width / DeviceDisplay.MainDisplayInfo.Density;
public static double ScreenHeight { get; } = DeviceDisplay.MainDisplayInfo.Height / DeviceDisplay.MainDisplayInfo.Density;

public static bool IsSmallScreen { get; } = ScreenWidth <= 360;

示例应用程序

以下是我在GitTrends应用程序中使用上述代码的方式： https: //github.com/brminnick/GitTrends/blob/aa0c0a2d53dab7306514287533330b4a3bfbf609/GitTrends/Services/XamarinFormsService.cs#L11-L18