如何在 C++ Visual Studio 中从 Xaml 中动态删除按钮？

Question

这就是我在 C++ (Visual Studio C++ 2017) 中动态创建按钮的方式：

    Button^ myButton = ref new Button();
myButton->Content = "Button";
myButton->Height = 80;
myButton->Width = 150;
ContentPanel->Children->Append(myButton);

如何从 ContentPanel 中动态删除此按钮？

ContentPanel->Children-> RemoveAt(myButton); 

不起作用并产生错误。我在这里做错了什么？

完整示例：

    <Page
x:Class="App3.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:App3"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">

<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <StackPanel x:Name="ContentPanel">
        <TextBlock HorizontalAlignment="Left" Text="Hello!" />
    </StackPanel>
    <Button x:Name="InputButton" Content="Click" Click="InputButton_Click"/>

</Grid>

// MainPage.xaml.cpp
// Implementation of the MainPage class.
//

#include "pch.h"
#include "MainPage.xaml.h"

using namespace App3;

using namespace Platform;
using namespace Windows::Foundation;
using namespace Windows::Foundation::Collections;
using namespace Windows::UI::Xaml;
using namespace Windows::UI::Xaml::Controls;
using namespace Windows::UI::Xaml::Controls::Primitives;
using namespace Windows::UI::Xaml::Data;
using namespace Windows::UI::Xaml::Input;
using namespace Windows::UI::Xaml::Media;
using namespace Windows::UI::Xaml::Navigation;

MainPage::MainPage()
{
InitializeComponent();
}


void App3::MainPage::InputButton_Click(Platform::Object^ sender,     Windows::UI::Xaml::RoutedEventArgs^ e)
{
Button^ myButton = ref new Button();
if (myButton != nullptr)
{

    myButton->Margin = Thickness(10);
    myButton->Content = "myButton";
    myButton->Height = 80;
    myButton->Width = 150;
    myButton->Foreground = ref new SolidColorBrush (Windows::UI::Colors::Lavender);
    myButton->Background = ref new SolidColorBrush(Windows::UI::Colors::Olive);
    ContentPanel->Children->Append(myButton);
}
else
    ContentPanel->Children->RemoveAt(myButton);

}

此外，我猜 (myButton != nullptr) 不是测试“myButton”是否已经动态创建的正确方法（在之前调用“InputButton_Click”时）

Answer 1

RemoveAt 获取要删除的项目的索引。您应该在添加新项目时将其保存在某处，并在以后使用以将其删除。

    m_button_index = ContentPanel->Children->Size;
    ContentPanel->Children->Append(myButton);
}
else
    ContentPanel->Children->RemoveAt(m_button_index);

还请注意，检查 myButton != nullptr 是没有意义的，因为分配的按钮不是 null 或抛出异常，因此您的代码将始终添加按钮。