Xamarin - 多屏應用程式

在本節中，我們將建立一個登入系統，允許使用者註冊。然後，在成功登入後，我們將註冊使用者帶到應用程式的主螢幕。

首先，建立一個新專案並將其命名為登入系統。在新專案中，轉到main.axml並新增兩個按鈕和一個進度條，如下所示。

<?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 = "@android:color/background_light" 
   android:weightSum = "100" 
   android:minWidth = "25px" 
   android:minHeight = "25px"> 
   <TextView 
      android:text = "Login App" 
      android:textAppearance = "?android:attr/textAppearanceMedium" 
      android:layout_width = "match_parent" 
      android:layout_weight = "20" 
      android:layout_height = "0dp" 
      android:textColor = "#368DEB" 
      android:id = "@+id/txtCreatAccount" 
      android:gravity = "center" 
      android:textStyle = "bold" 
      android:textSize = "25sp" /> 
   <Button 
      android:text = "Sign In" 
      android:layout_width = "match_parent" 
      android:layout_weight = "15" 
      android:layout_height = "0dp" 
      android:background = "@drawable/btnSignInStyle" 
      android:id = "@+id/btnSignIn" 
      android:layout_marginLeft = "20dp" 
      android:layout_marginRight = "20dp" 
      android:textSize = "15sp" /> 
   <Button 
      android:text = "Sign Up" 
      android:layout_width = "match_parent" 
      android:layout_weight = "15" 
      android:layout_height = "0dp" 
      android:background = "@drawable/btnSignUpStyle" 
      android:id = "@+id/btnSignUp" 
      android:layout_marginLeft = "20dp" 
      android:layout_marginRight = "20dp" 
      android:textSize = "15sp" /> 
   <RelativeLayout 
      android:layout_width = "match_parent" 
      android:layout_height = "0dp" 
      android:layout_weight = "50" 
      android:minWidth = "25px" 
      android:minHeight = "25px"> 
      <ProgressBar 
         android:layout_width = "wrap_content" 
         android:layout_height = "wrap_content" 
         android:id = "@+id/progressBar1" 
         android:background = "@drawable/progressBarStyle" 
         android:layout_centerInParent="true" 
         android:indeterminate = "true" 
         xmlns:tools = "
            http://schemas.android.com/tools" 
         tools:visibility = "invisible" /> 
   </RelativeLayout> 
</LinearLayout>

建立使用者介面後，重要的是要設定按鈕的樣式以使其看起來更具吸引力。為此，在drawable 資料夾下建立一個新的 XML 檔案，並將檔案命名為btnSignInStyle.xml。

在 XML 檔案中，新增以下程式碼行：

<selector xmlns:android = "http://schemas.android.com/apk/res/android"> 
   <item android:state_pressed = "false"> 
      <layer-list> 
         <item android:right = "5dp" android:top = "5dp"> 
            <shape> 
               <corners android:radius = "2dp"/> 
               <solid android:color = "#D6D6D6"/> 
            </shape> 
         </item>  
         <item android:left = "2dp" android:bottom = "2dp"> 
            <shape> 
               <corners android:radius = "4dp"/> 
               <gradient android:angle = "270" 
                  android:endColor = "#486EA9" android:startColor = "#486EA9"/> 
               <stroke android:width = "1dp" android:color = "#BABABA"/> 
               <padding android:bottom = "10dp" 
                  android:right = "10dp" android:left = "10dp" android:top = "10dp"/> 
            </shape>  
         </item> 
      </layer-list> 
   </item> 
   <item android:state_pressed = "true"> 
      <layer-list> 
         <item android:right = "5dp" android:top = "5dp"> 
            <shape> 
               <corners android:radius = "2dp"/> 
               <solid android:color = "#D6D6D6"/> 
            </shape> 
         </item>  
         <item android:left = "2dp" android:bottom = "2dp"> 
            <shape> 
               <corners android:radius = "4dp"/> 
               <gradient android:angle = "270" 
                  android:endColor = "#79C791" android:startColor = "#486EA9"/> 
               <stroke android:radius = "4dp" android:color = "#BABABA"/>
               <padding android:bottom = "10dp" 
                  android:right = "10dp" android:left = "10dp" android:top = "10dp"/> 
            </shape> 
         </item> 
      </layer-list> 
  </item> 
</selector>

以上程式碼設定按鈕載入時的顏色和點選時的顏色，還設定按鈕的圓角。

接下來，我們為註冊按鈕建立一個類似於上面的樣式 XML。為此，在drawable資料夾下建立另一個 XML，並將其命名為btnSignUpStyle.xml。它將繼承btnSignInStyle.xml中的所有內容。唯一的區別是按鈕的漸變開始和結束顏色。

將btnSignUpStyle.xml中的startColor和endColor更改為

<gradient android:angle="270" 
   android:endColor="#008000" android:startColor="#008000"/>

轉到layout 資料夾並建立一個新的 AXML 檔案，並將其命名為 registerDailog.axml。此檔案將包含應用程式中新使用者的註冊詳細資訊。此頁面將包含三個EditTexts和一個提交資料的按鈕。將以下程式碼新增到您的線性佈局程式碼中。

<EditText 
   android:layout_width = "match_parent" 
   android:layout_marginBottom = "10dp" 
   android:layout_marginTop = "25dp" 
   android:layout_marginRight = "25dp" 
   android:layout_marginLeft = "25dp" 
   android:layout_height = "35dp" 
   android:paddingLeft = "10dp" 
   android:id = "@+id/txtUsername" 
   android:hint = "Username" 
   android:textColor = "#000" /> 
<EditText 
   android:layout_width = "match_parent" 
   android:layout_height = "35dp" 
   android:id = "@+id/txtEmail" 
   android:layout_marginBottom = "10dp" 
   android:layout_marginTop = "25dp" 
   android:layout_marginRight = "25dp" 
   android:layout_marginLeft = "25dp" 
   android:paddingLeft = "10dp"
   android:textColor = "#000" 
   android:hint = "Email" /> 
<EditText 
   android:layout_width = "match_parent" 
   android:layout_height = "35dp" 
   android:layout_marginBottom = "10dp" 
   android:layout_marginTop = "25dp" 
   android:layout_marginRight = "25dp" 
   android:layout_marginLeft = "25dp" 
   android:paddingLeft = "10dp" 
   android:textColor = "#000" 
   android:id = "@+id/txtPassword" 
   android:hint = "Password" />
<Button 
   android:text = "Sign Up" 
   android:layout_width = "match_parent" 
   android:layout_height = "wrap_content" 
   android:id = "@+id/btnSave" 
   android:textSize = "20dp" 
   android:textColor = "#fff" 
   android:textStyle = "bold" 
   android:height = "70dp" 
   android:background = "@drawable/btnSignUpStyle" 
   android:paddingLeft = "5dp" 
   android:paddingRight = "5dp" 
   android:paddingTop = "5dp" 
   android:paddingBottom = "5dp" 
   android:layout_marginLeft = "25dp" 
   android:layout_marginRight = "25dp" 
   android:layout_centerHorizontal = "true" />

接下來，新增一個名為signUpDialog.cs的新類。此類將包含建立對話方塊所需的程式碼。以下示例顯示了程式碼。

public class OnSignUpEvent:EventArgs { 
   private string myUserName; 
   private string myEmail; 
   private string myPassword; 
   public string UserName { 
      get { 
         return myUserName; 
      } 
      set{ 
         myUserName = value;
      } 
   } 
      
   public string Email { 
      get { 
         return myEmail; 
      } 
      set { 
         myEmail = value; 
      } 
   } 
      
   public string Password { 
      get { 
         return myPassword; 
      } 
      set { 
         myPassword = value; 
      } 
   }  
   public OnSignUpEvent(string username, string 
      email, string password):base() { 
      UserName = username; 
      Email = email; 
      Password = password; 
   } 
     
   class SignUpDialog:DialogFragment { 
      private EditText txtUsername; 
      private EditText txtEmail; 
      private EditText txtPassword; 
      private Button btnSaveSignUp; 
      public event EventHandler<OnSignUpEvent> onSignUpComplete; 
      public override View OnCreateView(LayoutInflater inflater, 
         ViewGroup container, Bundle savedInstanceState) { 
         base.OnCreateView(inflater, container, savedInstanceState);       
         var view = inflater.Inflate(Resource.Layout.registerDialog, container, false); 
         txtUsername = view.FindViewById<EditText>(Resource.Id.txtUsername); 
         txtEmail = view.FindViewById<EditText>(Resource.Id.txtEmail); 
         txtPassword = view.FindViewById<EditText>(Resource.Id.txtPassword);
         btnSaveSignUp = view.FindViewById<Button>(Resource.Id.btnSave); 
         btnSaveSignUp.Click += btnSaveSignUp_Click;   
         return view; 
      }  
      void btnSaveSignUp_Click(object sender, EventArgs e) { 
         onSignUpComplete.Invoke(this, new OnSignUpEvent(txtUsername.Text, 
         
            txtEmail.Text, txtPassword.Text)); 
         this.Dismiss(); 
      } 
   }
}

在上面的程式碼中，我們使用了get和set屬性。get方法返回一個變數，而set方法為返回的變數賦值。這是一個示例：

public string Color { 
   get { 
      return color;  
   } 
   set { 
      color = value;  
   } 
}

在我們之前的示例中，我們建立了一個重寫檢視的方法。在該方法內部，我們建立了一個名為view的var，它引用了 layout 資料夾中包含的registerDialog.axml。

接下來，轉到mainActivity.cs以建立對話方塊片段。

private Button signUp; 
private Button submitNewUser; 
private EditText txtUsername; 
private EditText txtEmail; 
private EditText txtPassword; 

protected override void OnCreate(Bundle bundle) { 
   base.OnCreate(bundle);  
   SetContentView(Resource.Layout.Main);
   signUp = FindViewById<Button>(Resource.Id.btnSignUp); 
   submitNewUser = FindViewById<Button>(Resource.Id.btnSave); 
   txtUsername = FindViewById<EditText>(Resource.Id.txtUsername); 
   txtEmail = FindViewById<EditText>(Resource.Id.txtEmail); 
   txtPassword = FindViewById<EditText>(Resource.Id.txtPassword); 
            
   signUp.Click += (object sender, EventArgs args) => { 
      FragmentTransaction transFrag = FragmentManager.BeginTransaction(); 
      SignUpDialog diagSignUp = new SignUpDialog(); 
      diagSignUp.Show(transFrag, "Fragment Dialog"); 
      diagSignUp.onSignUpComplete += diagSignUp_onSignUpComplete; 
   }; 
}  
void diagSignUp_onSignUpComplete(object sender, OnSignUpEvent e) { 
   StartActivity(typeof(Activity2)); 
}

上面的程式碼包含一個按鈕點選事件，當點選時載入 signUp 對話方塊。在按鈕點選事件內部，我們建立了一個SignUpDialog類，它載入registerDialog.axml檔案。

然後我們使用FragmentTransaction transFrag = FragmentManager.BeginTransaction();將我們的registerDialog頁面顯示為 Android 對話方塊片段。

我們將新增另一個.axml檔案，名為home.axml。此佈局將是使用者成功登入系統後的登入螢幕。在此佈局中，我們將新增一個文字檢視，如下面的程式碼所示。

<TextView 
   android:text = "You have been succesfully registered. Welcome!" 
   android:textAppearance = "?android:attr/textAppearanceLarge" 
   android:layout_width = "match_parent" 
   android:layout_height = "wrap_content" 
   android:id = "@+id/textView1" />

接下來，我們建立一個名為Activity2.cs的最終活動。在此活動中，我們將使用findViewById查詢home.axml。

最後，構建並執行您的應用程式。它將顯示以下螢幕作為輸出。

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