如何在 Xamarin 表单 pcl 的网格中插入背景图像

Question

我需要将背景放置到网格中，即 PNG 图像。我在网上找不到具体的解决方案，你可以从xaml中添加吗？还是一定要通过c#来操作？

谢谢你。

    <StackLayout VerticalOptions="FillAndExpand" x:Name="allContent" HorizontalOptions="FillAndExpand" Orientation="Vertical" Spacing="0">    
<Grid Grid.Row="1">
              <Grid.ColumnDefinitions>
                <ColumnDefinition Width="2*"></ColumnDefinition>
                <ColumnDefinition Width="6*"></ColumnDefinition>
                <ColumnDefinition Width="2*"></ColumnDefinition>
              </Grid.ColumnDefinitions>
              <Grid.RowDefinitions>
                <RowDefinition Height="1*"></RowDefinition>
                <RowDefinition Height="2*"></RowDefinition>
                <RowDefinition Height="2*"></RowDefinition>
                <RowDefinition Height="2*"></RowDefinition>
                <RowDefinition Height="2*"></RowDefinition>
              </Grid.RowDefinitions>
              <ActivityIndicator x:Name="loading" Grid.Row="0" Grid.Column="1" IsVisible="false" Color="#008ECC" IsRunning="true" />
              <Label TextColor="#fff" Grid.Row="1" Grid.Column="1" Text="" />
              <Entry FontSize="24" Grid.Row="1" Grid.Column="1" Placeholder="Username" x:Name="UsernameEntry" Text="" />
              <Label TextColor="#fff" Grid.Row="2" Grid.Column="1" Text="" />
              <Entry FontSize="24" Grid.Row="2" Grid.Column="1" Placeholder="Password" IsPassword="True" x:Name="PasswordEntry" Text="" />
              <Button x:Name="LoginButton" Grid.Row="3" Grid.Column="1" Text="Accedi" Clicked="Login_OnClicked"/>
              <Label TextColor="#fff" Text="Ricorda accesso" Grid.Row="3" Grid.Column="1"></Label>
              <Switch x:Name="switchRememberPassword" Grid.Row="4" Grid.Column="1"></Switch>              
              <Label x:Name="recuperaPassword" Grid.Row="4" Grid.Column="1" TextColor="#fff" Text="Recupera credenziali di accesso" FontSize="12"></Label>
            </Grid>
</StackLayout>

Answer 1

您可以将其添加为 Grid 的子项，并添加 Grid.ColumnSpan 和 Grid.RowSpan 属性以跨越所有网格。例如：

     <Grid>
        <Image HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" Aspect="AspectFill" Source="" Grid.Row="6" Grid.Column="4" Grid.RowSpan="2" Grid.ColumnSpan="2"/>
            <!-- My other properties here code here-->
     </Grid>

（此外，如果您的网格位于 ContentPage 上并且它占据全屏，您可以使用页面的 BackgroundImage 属性）

Answer 2

您可以为此使用RelativeLayout

    <RelativeLayout>
       <Image Source="backgroundimage"   RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=1}" 
     RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=1}" />
       <Grid RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=1}" 
     RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=1}"> 

//Your grid content


       </Grid>
    </RelativeLayout>