以xamarin形式的字体大小

Question

我正在使用xamarin表单并面临布局问题.现在,使用fontsize ..我有两个标签,其中一个是Micro.我需要另一个得到Micro标签/ 2的大小作为它的大小...我正在阅读相关布局,但我不知道这是否是最好的方式...有人有任何想法帮我？这是我的标签:

   <StackLayout Spacing="0">
        <Label x:Name="menu_lbl_promocoes" Text="0000" FontAttributes="Bold" TextColor="Black" HorizontalOptions="Center" Style="{Binding labelsfont}"/>
        <Label x:Name="menu_lbl_disponiveis" Text="Disponíveis" TextColor="Black" HorizontalOptions="Center" FontSize="Small" Style="{Binding labelsfont}"/>
   </StackLayout>

       </StackLayout> //yeah, there is another stacklayout 

       <Label Text="Promoções" FontSize="Micro" TextColor="White" HorizontalOptions="Center" Style="{Binding labelsfont}"/>

我需要第二个标签获得第三个标签的半尺寸(具有微尺寸)...

Answer 1

只需扩展Label为具有两个可绑定属性 - FontSizeFactor并NamedFontSize- 让它们为您计算字体大小:

public class MyLabel : Label
{
    public static readonly BindableProperty FontSizeFactorProperty =
        BindableProperty.Create(
        "FontSizeFactor", typeof(double), typeof(MyLabel),
        defaultValue: 1.0, propertyChanged: OnFontSizeFactorChanged);

    public double FontSizeFactor
    {
        get { return (double)GetValue(FontSizeFactorProperty); }
        set { SetValue(FontSizeFactorProperty, value); }
    }

    private static void OnFontSizeFactorChanged(BindableObject bindable, object oldValue, object newValue)
    {
        ((MyLabel)bindable).OnFontSizeChangedImpl();
    }

    public static readonly BindableProperty NamedFontSizeProperty =
        BindableProperty.Create(
        "NamedFontSize", typeof(NamedSize), typeof(MyLabel),
        defaultValue: NamedSize.Small, propertyChanged: OnNamedFontSizeChanged);

    public NamedSize NamedFontSize
    {
        get { return (NamedSize)GetValue(NamedFontSizeProperty); }
        set { SetValue(NamedFontSizeProperty, value); }
    }

    private static void OnNamedFontSizeChanged(BindableObject bindable, object oldValue, object newValue)
    {
        ((MyLabel)bindable).OnFontSizeChangedImpl();
    }

    protected virtual void OnFontSizeChangedImpl()
    {
        if (this.FontSizeFactor != 1)
            this.FontSize = (this.FontSizeFactor * Device.GetNamedSize(NamedFontSize, typeof(Label)));
    }
}

样品用法:

    <Label FontSize="Large" Text="Large Size" />
    <local:MyLabel NamedFontSize="Large" FontSizeFactor="0.9" Text="90% Large Size" />

    <Label FontSize="Medium" Text="Medium Size" />
    <local:MyLabel NamedFontSize="Medium" FontSizeFactor="0.75" Text="75% Medium Size" />

    <Label FontSize="Micro" Text="Micro Size" />
    <local:MyLabel NamedFontSize="Micro" FontSizeFactor="0.5" Text="50% Micro Size" />