Xamarin形成"更改并启用图像"按钮

Question

示例UI设计

有人知道如何更改Imagebutton的来源吗？参考图片链接，当用户点击步骤1(主页(时，它会将用户重定向到另一个页面(SecondPage(。一旦用户点击SecondPage中的"完成"按钮，我想更改我的图像按钮源，同时启用点击事件。我不确定是否要从一页调用该函数到另一页。

(附言：我的btnclickcount有时似乎不起作用……我只想在第一次点击按钮时记录开始日期时间(

public partial class MainPage : ContentPage
{
public string mainpagevalue;
int offlinecount = 0;
int onlinecount = 0;
public MainPage()
{
InitializeComponent();
}
private void btnOffline_Clicked(object sender, EventArgs e)
{
offlinecount++;
txtOfflineStatus.Text = "IN PROGRESS";
Navigation.PushAsync(new SecondPage(this, lblEndDT, txtOfflineStatus, btnOnline, btnMH));

if (offlinecount == 1)
{
string currentDT = DateTime.Now.ToString();
lblStartDT.Text = currentDT;
}

}
private void btnOnline_Clicked(object sender, EventArgs e)
{
onlinecount++;
txtOnlineStatus.Text = "IN PROGRESS";
Navigation.PushAsync(new ThirdPage(this, lblOnlineEndDT, btnTS, txtOnlineStatus));
if (onlinecount == 1)
{
string onlinestartDT = DateTime.Now.ToString();
lblOnlineStartDT.Text = onlinestartDT;
}
}

第三页

public partial class ThirdPage : ContentPage
{
Label wopLblOnlineEndDT;
MainPage mainpage;
ImageButton btntroubleshoot;
Label wolblOnlineStatus;
public ThirdPage()
{
InitializeComponent();
}
public ThirdPage(MainPage woPage, Label lblOnlineEndDT, ImageButton btnTS, Label lblOnlineStatus)
{
InitializeComponent();
mainpage = woPage;
wopLblOnlineEndDT = lblOnlineEndDT;
btntroubleshoot = btnTS;
wolblOnlineStatus = lblOnlineStatus;
}
private void BtnDone_Clicked(object sender, EventArgs e)
{
string edt = DateTime.Now.ToString();
wopLblOnlineEndDT.Text = edt;
mainpage.mainpagevalue = wopLblOnlineEndDT.Text;
btntroubleshoot.Source = "troubleshooting";
btntroubleshoot.IsEnabled = true;
wolblOnlineStatus.Text = "COMPLETED";
wolblOnlineStatus.TextColor = Color.FromRgb(0, 214, 54);
Navigation.PopAsync();
}
}

XAML

<ImageButton x:Name="btnOffline" IsEnabled="True" Source="@drawable/offlinetool.png" Grid.Row="1" Grid.Column="1" BackgroundColor="Transparent" Clicked="btnOffline_Clicked"/>
<Label Text="Offline Tool" Grid.Row="2" Grid.Column="1" Margin="15,0,0,0"/>
<ImageButton Source="@drawable/material.png" Grid.Row="4" Grid.Column="1" BackgroundColor="Transparent"/>
<Label Text="Material Handler" Grid.Row="5" Grid.Column="1" />
<Image Source="@drawable/Picture1.png" Grid.Row="6" Grid.ColumnSpan="6" BackgroundColor="Transparent"/>
<Label Text="Start Date Time:" Grid.Row="1" Grid.Column="3"/>
<Label Text="End Date Time:" Grid.Row="1" Grid.Column="3" Margin="7,40,0,0"/>
<Label Text="Status:" Grid.Row="2" Grid.Column="3" Margin="58,0,0,0" />
<Label x:Name="txtOfflineStatus" Text="NOT STARTED" TextColor="Red" Grid.Column="4" Grid.Row="2"/>
<Label x:Name="lblStartDT" Text="" Grid.Column="4" Grid.Row="1"/>
<Label x:Name="lblEndDT" Text="-" Grid.Column="4" Grid.Row="1" Margin="0,40,0,0"/>
<Label Text="Start Date Time:" Grid.Row="4" Grid.Column="3"  />
<Label Text="End Date Time:" Grid.Row="4" Grid.Column="3" Margin="7,40,0,0"/>
<Label Text="Status:" Grid.Row="5" Grid.Column="3" Margin="58,0,0,0" />
<Label Text="NOT STARTED" TextColor="Red" Grid.Column="4" Grid.Row="5"/>

<!--#Online Tool-->
<ImageButton x:Name="btnOnline" Source="@drawable/ot.png" Grid.Row="8" Grid.Column="1" BackgroundColor="Transparent" Clicked="btnOnline_Clicked" IsEnabled="False"/>
<Label Text="Online Tool" Grid.Row="9" Grid.Column="1" Margin="19,0,0,0"/>
<ImageButton x:Name="btnMH" Source="@drawable/mh.png" Grid.Row="11" Grid.Column="1" BackgroundColor="Transparent" Clicked="imgbtnMH_Clicked" IsEnabled="False"/>
<Label Text="Material Handler" Grid.Row="12" Grid.Column="1"/>
<Image Source="@drawable/Picture1.png" Grid.Row="13" Grid.ColumnSpan="6" BackgroundColor="Transparent"/>
<Label Text="Start Date Time:" Grid.Row="8" Grid.Column="3" />
<Label Text="End Date Time:" Grid.Row="8" Grid.Column="3" Margin="7,40,0,0"/>
<Label Text="Status:" Grid.Row="9" Grid.Column="3" Margin="58,0,0,0" />
<Label Text="NOT STARTED" TextColor="Red" Grid.Column="4" Grid.Row="9"/>
<Label x:Name="lblOnlineStartDT" Text="00:00:00" Grid.Column="4" Grid.Row="8"/>
<Label x:Name="lblOnlineEndDT" Text="" Grid.Column="4" Grid.Row="8" Margin="0,40,0,0"/>
<Label x:Name="txtOnlineStatus" Text="NOT STARTED" TextColor="Red" Grid.Column="4" Grid.Row="9"/>

Answer 1

您也可以将imageButton的引用传递给SecondPage，并在done方法中更改Source。让我来教你怎么做：

在MainPagexaml中，创建一个名为MyImageButton:的ImageButton

<StackLayout>
<!-- Place new controls here -->
<Label x:Name="lblStartDT" Text="startTest" 
HorizontalOptions="Center"
VerticalOptions="CenterAndExpand"/>
<Button Text="go to secondPage" Clicked="btnOffline_Clicked"  HorizontalOptions="Center"
VerticalOptions="CenterAndExpand"/>
<Label x:Name="lblEndDT" Text="endTest" 
HorizontalOptions="Center"
VerticalOptions="CenterAndExpand" />
<ImageButton x:Name="MyImageButton" Source="Images.png" IsEnabled="False" 
HorizontalOptions="Center"
VerticalOptions="CenterAndExpand" />
</StackLayout>

在代码隐藏中，将MyImageButton传递到SecondPage:

private void btnOffline_Clicked(object sender, EventArgs e)
{
//Pass the parametere you need when you go to SecondPage 
//Navigation.PushAsync(new SecondPage(this, lblEndDT));
Navigation.PushAsync(new SecondPage(this, lblEndDT, MyImageButton));
string currentDT = DateTime.Now.ToString();
lblStartDT.Text = currentDT;
}

在SecondPage中，获取myImageBtn的引用，并在done方法中进行修改：

public partial class SecondPage : ContentPage
{
Label MainPagelblEndDT;
MainPage mainPage;
ImageButton myImageBtn;
public SecondPage()
{
InitializeComponent();
}
public SecondPage(MainPage mainP,Label lblEndDT)
{
InitializeComponent();
//Get the lblEndDT reference here
MainPagelblEndDT = lblEndDT;
//Get the MainPage reference here
mainPage = mainP;
}
public SecondPage(MainPage mainP, Label lblEndDT, ImageButton imageBtn)
{
InitializeComponent();
//Get the lblEndDT reference here
MainPagelblEndDT = lblEndDT;
//Get the MainPage reference here
mainPage = mainP;
//Get the ImageButton reference here
myImageBtn = imageBtn;
}
private void Button_Clicked(object sender, EventArgs e)
{           
string edt = DateTime.Now.ToString();
//Use it
MainPagelblEndDT.Text = edt;      
mainPage.previouspagevalue = MainPagelblEndDT.Text;
//change the source of imageBtn
myImageBtn.Source = "Images1";
myImageBtn.IsEnabled = true;
Navigation.PopAsync();
}
}

这里提供了一个示例项目。

Answer 2

将按钮"不透明度"绑定到类似0.5的值，并禁用该按钮。

<ImageButton Command="{Binding EditActivityCommand}"
BackgroundColor="Transparent"
Opacity="{Binding Opacity}"
IsEnabled="{Binding IsAdmin}">