Xamarin+Prism开发详解五：页面布局基础知识

说实在的研究Xamarin到现在，自己就没设计出一款好的UI，基本都在研究后台逻辑之类的！作为Xamarin爱好者，一些简单的页面布局知识还是必备的。

布局常见标签：

• StackLayout 
• AbsoluteLayout
• RelativeLayout 
• Grid 
• ScrollView

主要拿个人最喜欢的StackLayout和Grid做说明。

1、StackLayout

通过它可以设置内部子元素的纵向或者横向布局，默认为纵向。

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <StackLayout> <BoxView Color="Red"/> <BoxView Color="Green"/> <BoxView Color="Blue"/> <BoxView Color="Aqua"/> </StackLayout> </ContentPage>

显示结果

1.1、通过设置Orientation的属性可以切换纵向Vertical（默认）与横向Horizontal显示。

设置Horizontal(横向)看看效果：

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <StackLayout Orientation="Horizontal"> <BoxView Color="Red"/> <BoxView Color="Green"/> <BoxView Color="Blue"/> <BoxView Color="Aqua"/> </StackLayout> </ContentPage>

显示结果

1.2、通过Spacing可以设置子元素间的间隔空白大小。

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <StackLayout Orientation="Horizontal"

Spacing

="30"> <BoxView Color="Red"/> <BoxView Color="Green"/> <BoxView Color="Blue"/> <BoxView Color="Aqua"/> </StackLayout> </ContentPage>

显示结果

1.3、通过HorizontalOptions和VerticalOptions可以设置子元素在Stacklayout里面的布局位置。

HorizontalOptions和VerticalOptions可以指定如下值：

• Start: 开始位置布局元素
• Center: 居中布局元素
• End: 结束位置布局元素
• Fill: 扩展元素占用整个布局宽带 （默认设置）
• StartAndExpand: 开始位置布局元素并填充空白
• CenterAndExpand: 居中布局元素并填充空白
• EndAndExpand: 结束位置布局元素并填充空白
• FillAndExpand: 填充所有空白

首先看看Start，End，Center，Fill的效果：

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <StackLayout Orientation="Horizontal"

Spacing

="30"> <BoxView Color="Red" VerticalOptions="Start"/> <BoxView Color="Green" VerticalOptions="End"/> <BoxView Color="Blue" VerticalOptions="Center"/> <BoxView Color="Aqua" VerticalOptions="Fill"/> </StackLayout> </ContentPage>

显示结果

接下来看看AndExpand相关的设置。

首先设置StartAndExpand

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <StackLayout> <BoxView Color="Red" VerticalOptions="StartAndExpand"/> <BoxView Color="Blue"/> </StackLayout> </ContentPage>

显示结果

EndAndExpand情况

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <StackLayout> <BoxView Color="Red" VerticalOptions="EndAndExpand"/> <BoxView Color="Blue"/> </StackLayout> </ContentPage>

显示结果

FillAndExpand情况

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <StackLayout> <BoxView Color="Red" VerticalOptions="FillAndExpand"/> <BoxView Color="Blue"/> </StackLayout> </ContentPage>

显示结果

多个AndExpand设置的时候，空白大小是均等分配。比如下面两个控件分别设置为FillAndExpand与StartAndExpand，上半部分全是红色填充，后半部分开始位置为蓝色。

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <StackLayout> <BoxView Color="Red" VerticalOptions="FillAndExpand"/> <BoxView Color="Blue" VerticalOptions="StartAndExpand"/> </StackLayout> </ContentPage>

显示结果

通过多个StackLayout配合也可以实现复杂的布局

代码

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <ContentPage.Padding> <OnPlatform x:TypeArguments="Thickness"

iOS

="0, 20, 0, 0"/> </ContentPage.Padding> <StackLayout> <!-- 第1个项目 --> <StackLayout Orientation="Horizontal"

VerticalOptions

="Start"> <BoxView Color="Red"/> <StackLayout HorizontalOptions="FillAndExpand"> <StackLayout Orientation="Horizontal"> <StackLayout Orientation="Vertical"

VerticalOptions

="FillAndExpand"> <StackLayout Orientation="Horizontal"> <Label Text="@lxb"/> <Label Text="@Xamarin" HorizontalOptions="FillAndExpand" /> </StackLayout> <Label Text="xxxxxxxxxxxxxx"/> </StackLayout> </StackLayout> <StackLayout Orientation="Horizontal"

HorizontalOptions

="EndAndExpand"> <Button Text="Like" HorizontalOptions="End"/> <Button Text="RT" HorizontalOptions="End"/> <Button Text="Quote" HorizontalOptions="End"/> </StackLayout> </StackLayout> </StackLayout> <!-- 第2个项目 --> <StackLayout Orientation="Horizontal"

VerticalOptions

="Start"> <BoxView Color="Red"/> <StackLayout HorizontalOptions="FillAndExpand"> <StackLayout Orientation="Horizontal"> <StackLayout Orientation="Vertical"

VerticalOptions

="FillAndExpand"> <StackLayout Orientation="Horizontal"> <Label Text="@lxb"/> <Label Text="@Xamarin" HorizontalOptions="FillAndExpand" /> </StackLayout> <Label Text="xxxxxxxxxxxxxx"/> </StackLayout> </StackLayout> <StackLayout Orientation="Horizontal"

HorizontalOptions

="EndAndExpand"> <Button Text="Like" HorizontalOptions="End"/> <Button Text="RT" HorizontalOptions="End"/> <Button Text="Quote" HorizontalOptions="End"/> </StackLayout> </StackLayout> </StackLayout> </StackLayout> </ContentPage>

2、Grid

Grid相当于表格布局，这在网页布局用的最多。通过RowDefinitions属性的RowDefinition定义一行，通过ColumnDefinitions属性的ColumnDefinition定义一列。默认情况下是平均分配各个单元格大小。各个控件通过设置Grid.Row和Grid.Colum可以指定显示在哪个单元格。

比如下面三行三列的例子：

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <ContentPage.Padding> <OnPlatform x:TypeArguments="Thickness" iOS="20" /> </ContentPage.Padding> <Grid> <Grid.RowDefinitions> <RowDefinition /> <RowDefinition /> <RowDefinition /> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition /> <ColumnDefinition /> <ColumnDefinition /> </Grid.ColumnDefinitions> <BoxView Color="Red" /> <BoxView Color="Blue" Grid.Row="0" Grid.Column="1" /> <BoxView Color="Aqua" Grid.Row="0" Grid.Column="2" /> <BoxView Color="Maroon" Grid.Row="1" Grid.Column="0" /> <BoxView Color="Navy" Grid.Row="1" Grid.Column="1" /> <BoxView Color="Silver" Grid.Row="1" Grid.Column="2" /> <BoxView Color="Purple" Grid.Row="2" Grid.Column="0" /> <BoxView Color="Lime" Grid.Row="2" Grid.Column="1" /> <BoxView Color="Yellow" Grid.Row="2" Grid.Column="2" /> </Grid> </ContentPage>

显示结果

2.1、大小设置

RowDefinition可以设置行高度Height，ColumnDefinition可以设置列宽度Width。设置的值可以为数字（固定大小），也可以为1*，2*之类带*的（按比例分配大小），也可以设置为Auto（自动调整大小）。比如下面的例子：

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <ContentPage.Padding> <OnPlatform x:TypeArguments="Thickness"

iOS

="0, 20, 0, 0"/> </ContentPage.Padding> <Grid> <!-- 行定义 --> <Grid.RowDefinitions> <RowDefinition Height="15" /> <!-- 固定 --> <RowDefinition Height="1*" /> <!-- 1比2分配 --> <RowDefinition Height="2*" /> </Grid.RowDefinitions> <!-- 列定义 --> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto" /> <!-- 根据布局自动设置 --> <ColumnDefinition Width="*" /> <!-- 默认值*(和1*一样) --> <ColumnDefinition /> </Grid.ColumnDefinitions> <BoxView Color="Red" /> <!-- 默认设置在0,0单元格 --> <BoxView Color="Blue" Grid.Row="0"

Grid.Column

="1" /> <BoxView Color="Aqua" Grid.Row="0"

Grid.Column

="2" /> <BoxView Color="Maroon" Grid.Row="1"

Grid.Column

="0" /> <BoxView Color="Navy" Grid.Row="1"

Grid.Column

="1" /> <BoxView Color="Silver" Grid.Row="1"

Grid.Column

="2" /> <BoxView Color="Purple" Grid.Row="2"

Grid.Column

="0" /> <BoxView Color="Lime" Grid.Row="2"

Grid.Column

="1" /> <BoxView Color="Yellow" Grid.Row="2"

Grid.Column

="2" /> </Grid> </ContentPage>

显示结果

2.2、复数行，复数列设置

Grid.RowSpan设置复数行，Grid.ColumnSpan设置复数列。

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <ContentPage.Padding> <OnPlatform x:TypeArguments="Thickness"

iOS

="0, 20, 0, 0"/> </ContentPage.Padding> <Grid> <!-- 行定义 --> <Grid.RowDefinitions> <RowDefinition /> <RowDefinition /> <RowDefinition /> </Grid.RowDefinitions> <!-- 列定义 --> <Grid.ColumnDefinitions> <ColumnDefinition /> <ColumnDefinition /> <ColumnDefinition /> </Grid.ColumnDefinitions> <BoxView Color="Red" Grid.RowSpan="2" Grid.ColumnSpan="3" /> <BoxView Color="Blue" Grid.Row="2" Grid.Column="1" Grid.ColumnSpan="2"/> </Grid> </ContentPage>

显示效果

同样可以简单实现上面StackLayout的布局。

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <ContentPage.Padding> <OnPlatform x:TypeArguments="Thickness" iOS="0, 20, 0, 0" /> </ContentPage.Padding> <StackLayout VerticalOptions="Start"> <Grid> <!-- 行定义 --> <Grid.RowDefinitions> <RowDefinition Height="Auto" /> <RowDefinition Height="Auto" /> <RowDefinition Height="Auto" /> </Grid.RowDefinitions> <!-- 列定义 --> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto" /> <ColumnDefinition /> <ColumnDefinition Width="Auto" /> <ColumnDefinition Width="Auto" /> <ColumnDefinition Width="Auto" /> </Grid.ColumnDefinitions> <BoxView Color="Red" Grid.RowSpan="3" /> <StackLayout Orientation="Horizontal" Grid.Column="1" Grid.ColumnSpan="4"> <Label Text="@lxb" /> <Label Text="@Xamarin" /> </StackLayout> <Label Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="4" Text="xxxxxxxxxx" /> <Button Grid.Row="2" Grid.Column="2" Text="Like" /> <Button Grid.Row="2" Grid.Column="3" Text="RT" /> <Button Grid.Row="2" Grid.Column="4" Text="Quote" /> </Grid> <Grid> <!-- 行定义 --> <Grid.RowDefinitions> <RowDefinition Height="Auto" /> <RowDefinition Height="Auto" /> <RowDefinition Height="Auto" /> </Grid.RowDefinitions> <!-- 列定义 --> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto" /> <ColumnDefinition /> <ColumnDefinition Width="Auto" /> <ColumnDefinition Width="Auto" /> <ColumnDefinition Width="Auto" /> </Grid.ColumnDefinitions> <BoxView Color="Red" Grid.RowSpan="3" /> <StackLayout Orientation="Horizontal" Grid.Column="1" Grid.ColumnSpan="4"> <Label Text="@lxb" /> <Label Text="@Xamarin" /> </StackLayout> <Label Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="4" Text="xxxxxxxxxx" /> <Button Grid.Row="2" Grid.Column="2" Text="Like" /> <Button Grid.Row="2" Grid.Column="3" Text="RT" /> <Button Grid.Row="2" Grid.Column="4" Text="Quote" /> </Grid> </StackLayout> </ContentPage>

显示效果

3、余白设置

余白通过使用Padding和Margin进行设置。Padding是设置控件外侧余白，Margin是设置控件内侧余白。

3.1、设置方法

• 四个方向一个值设置
• 左右和上下两个值设置
• 四个方向不同值设置

（比如：

【20】：四个方向都自为20；

【20，10】左右为20，上下为10；

【10，15，20，25】左部余白为10，上部余白15，右余白为20，下部余白25。）

<?xml version="1.0" encoding="utf-8"?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" prism:ViewModelLocator.AutowireViewModel="True" x:Class="LayoutTest.Views.MainPage" Title="MainPage"> <ContentPage.Padding> <OnPlatform x:TypeArguments="Thickness" iOS="20" /> </ContentPage.Padding> <Grid Margin="20,10"> <BoxView Color="Red"/> </Grid> </ContentPage>

页面距离边框20，Grid左右距离页面20，上下距离页面10。

总结

使用xamarin.forms开发应用，只要掌握使用StackLayout与Grid布局，基本上可以实现各种想要的布局。当然要想UI很漂亮，图片设计是必须的。