Xamarin 简明教程

Xamarin - Layouts

Linear Layout

在线性布局中，内容水平或垂直排列。

Linear Layout ─ Horizontal

此布局的内容水平排列。对于此演示，我们将创建 3 个按钮并将它们水平排列在线性布局中。

<?xml version = "1.0" encoding = "utf-8"?>
<LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"
   android:orientation = "horizontal"
   android:layout_width = "fill_parent"
   android:layout_height = "fill_parent"
   android:background = "#d3d3d3"
   android:minWidth="25px"
   android:minHeight="25px">
   <Button
      android:id="@+id/MyButton1"
      android:layout_width="wrap_content"
      android:layout_margin="10dp"
      android:layout_height="wrap_content"
      android:text="Button 1"
      android:background="@android:color/holo_green_dark" />
   <Button
      android:id="@+id/MyButton2"
      android:layout_width="wrap_content"
      android:layout_margin="10dp"
      android:layout_height="wrap_content"
      android:text="Button 2"
      android:background="@android:color/holo_green_dark" />
   <Button
      android:id="@+id/MyButton3"
      android:layout_width="wrap_content"
      android:layout_margin="10dp"
      android:layout_height="wrap_content"
      android:text="Button 3"
      android:background="@android:color/holo_green_dark" />
</LinearLayout>

结果输出如下所示 -

linear layout horizontal

Linear Layout ─ Vertical

这种类型的布局将子视图垂直放置。

<?xml version = "1.0" encoding = "utf-8"?>
<LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"
   android:orientation = "vertical"
   android:layout_width = "fill_parent"
   android:layout_height = "fill_parent"
   android:background = "#d3d3d3"
   android:minWidth = "25px"
   android:minHeight = "25px">
   <Button
      android:id = "@+id/MyButton1"
      android:layout_width = "fill_parent"
      android:layout_margin = "10dp"
      android:layout_height = "wrap_content"
      android:text = "Button 1"
      android:background = "@android:color/holo_green_dark" />
   <Button
      android:id = "@+id/MyButton2"
      android:layout_width = "fill_parent"
      android:layout_margin = "10dp"
      android:layout_height = "wrap_content"
      android:text = "Button 2"
      android:background = "@android:color/holo_green_dark" />
   <Button
      android:id = "@+id/MyButton3"
      android:layout_width = "fill_parent"
      android:layout_margin = "10dp"
      android:layout_height = "wrap_content"
      android:text="Button 3"
      android:background = "@android:color/holo_green_dark" />
</LinearLayout>

其结果输出如下 -

linear layout vertical

Relative Layout

在此视图中，子视图的位置相对于其父视图或其兄弟视图。在以下示例中，我们将创建 3 个 EditText 视图和一个按钮，然后相对排列它们。

创建一个新项目并将其命名为 relative layout app 。打开 main.axml 并添加以下代码。

<?xml version = "1.0" encoding = "utf-8"?>
<RelativeLayout xmlns:android = "http://schemas.android.com/apk/res/android"
   android:layout_width = "match_parent"
   android:layout_height = "match_parent"
   android:paddingLeft = "16dp"
   android:background = "#d3d3d3"
   android:paddingRight = "16dp">
   <EditText
      android:id = "@+id/name"
      android:layout_width = "match_parent"
      android:layout_height = "wrap_content"
      android:hint = "First Name"
      android:textColorHint = "@android:color/background_dark"
      android:textColor = "@android:color/background_dark" />
   <EditText
      android:id = "@+id/lastName"
      android:layout_width = "0dp"
      android:layout_height = "wrap_content"
      android:hint = "Last Name"
      android:layout_below = "@id/name"
      android:textColorHint = "@android:color/background_dark"
      android:textColor = "@android:color/background_dark"
      android:layout_alignParentLeft = "true"
      android:layout_toLeftOf = "@+id/age" />
   <EditText
      android:id = "@id/age"
      android:layout_width = "80dp"
      android:layout_height = "wrap_content"
      android:layout_below = "@id/name"
      android:hint = "Age"
      android:textColorHint = "@android:color/background_dark"
      android:textColor = "@android:color/background_dark"
      android:layout_alignParentRight = "true" />
   <Button
      android:layout_width = "85dp"
      android:layout_height = "wrap_content"
      android:layout_below = "@id/age"
      android:layout_alignParentRight = "true"
      android:text = "Submit"
      android:background = "@android:color/holo_green_dark" />
</RelativeLayout>

此代码中我们使用的重要参数为 -

  1. android:layout_below - 它将子视图元素对其父视图下方。

  2. android:layout_alignParentLeft - 它将父元素左对齐。

  3. android:layout_toLeftOf - 此属性将一个元素左对齐另一个元素。

  4. android:layout_alignParentRight - 它将父元素右对齐。

当您现在构建并运行该应用程序时，它将生成以下输出屏幕 -

relative layout

Frame Layout

框架布局用于仅显示一个项目。在此布局中排列多个项目而不会让它们相互重叠是很困难的。

启动一个新项目并将其命名为 frameLayoutApp 。创建新的框架布局，如下所示。

<?xml version = "1.0" encoding = "utf-8"?>
<FrameLayout xmlns:android = "http://schemas.android.com/apk/res/android"
   android:layout_width = "fill_parent"
   android:layout_height = "fill_parent">
  <ImageView
      android:id = "@+id/ImageView1"
      android:scaleType = "matrix"
      android:layout_height = "fill_parent"
      android:layout_width = "fill_parent"
      android:src = "@drawable/img1" />
   <TextView
      android:layout_width = "fill_parent"
      android:layout_height = "wrap_content"
      android:textSize = "50dp"
      android:textColor = "#000"
      android:text = "This is a Lake" />
   <TextView
      android:gravity = "right"
      android:layout_width = "fill_parent"
      android:layout_height = "wrap_content"
      android:textSize = "50dp"
      android:text = "A very Deep Lake"
      android:layout_gravity = "bottom"
      android:textColor = "#fff" />
</FrameLayout>

以上代码创建了一个 imageView ，它填满了整个屏幕。然后两个文本视图悬浮在 imageView 以上。

现在，构建并运行您的应用程序。它将显示以下输出 -

frame layout

Table Layout

在此布局中，视图排列在 rows 和 columns 中。让我们看看其工作方式。

<?xml version = "1.0" encoding = "utf-8"?>
<TableLayout xmlns:android = "http://schemas.android.com/apk/res/android"
   android:layout_width = "fill_parent"
   android:background = "#d3d3d3"
   android:layout_height = "fill_parent"
   android:stretchColumns = "1">

   <TableRow>
      <TextView
         android:text = "First Name:"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content"
         android:textColor = "@android:color/black" />
      <EditText
         android:width = "100px"
         android:layout_width = "fill_parent"
         android:layout_height = "30dp"
         android:textColor = "@android:color/black" />
   </TableRow>

   <TableRow>
      <TextView
         android:text = "Last Name:"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content"
         android:textColor = "@android:color/black" />
      <EditText
         android:width = "50px"
         android:layout_width = "fill_parent"
         android:layout_height = "30dp"
         android:textColor = "@android:color/black" />
   </TableRow>

   <TableRow>
      <TextView
         android:text = "Residence:"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content"
         android:textColor = "@android:color/black" />
      <EditText
         android:width = "100px"
         android:layout_width = "fill_parent"
         android:layout_height = "30dp"
         android:textColor = "@android:color/black" />
   </TableRow>

   <TableRow>
      <TextView
         android:text = "Occupation:"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content"
         android:textColor = "@android:color/black" />
      <EditText
         android:width = "100px"
         android:layout_width = "fill_parent"
         android:layout_height = "30dp"
         android:textColor = "@android:color/black" />
   </TableRow>

   <TableRow>
      <Button
         android:text = "Cancel"
         android:layout_width = "wrap_content"
         android:layout_margin = "10dp"
         android:layout_height = "wrap_content"
         android:background = "@android:color/holo_green_dark" />
      <Button
         android:text = "Submit"
         android:width = "100px"
         android:layout_margin = "10dp"
         android:layout_width = "wrap_content"
         android:layout_height = "wrap_content"
         android:background = "@android:color/holo_green_dark" />
   </TableRow>
</TableLayout>

以上代码创建了一个使用 tables 和 rows 布置的简单数据输入表单。

table layout