Xamarin 自定义控制命令不起作用
Xamarin Custom Control Command doesn't work
我希望我的自定义控件在单击按钮时触发命令。
public partial class TestControl : ContentView
{
public TestControl()
{
InitializeComponent();
Test = new Command(async () =>
{
await Application.Current.MainPage.DisplayAlert("asd", "asd", "asd");
});
}
public ICommand Test { get; }
}
<ContentView xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:controls="clr-namespace:eTApp.Controls"
x:DataType="controls:TestControl"
x:Class="eTApp.Controls.TestControl">
<ContentView.Content>
<StackLayout>
<Button
Text="press"
Command="{Binding Test}" />
</StackLayout>
</ContentView.Content>
</ContentView>
但是按下按钮没有任何反应。我尝试添加
<ContentView.BindingContext>
<controls:TestControl />
</ContentView.BindingContext>
但是应用程序会在启动时崩溃。我认为那是因为它创建了新的实例并耗尽了内存。
我做错了什么？
编辑：
单击按钮时没有日志错误。在代码隐藏中添加 BindingContext = this; 不会改变任何东西。但是当我在 XAML 文件中添加 BindingContext 时，此日志会在启动时出现并且应用程序冻结：
[Mono] Warning: Degraded allocation. Consider increasing nursery-size if the warning persists.
[Mono] GC_TAR_BRIDGE bridges 0 objects 0 opaque 0 colors 0 colors-bridged 0 colors-visible 52 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.03ms tarjan 0.03ms scc-setup 0.02ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.01ms
[Mono] GC_BRIDGE: Complete, was running for 0.14ms
[Mono] GC_MINOR: (Concurrent start) time 22.50ms, stw 56.42ms promoted 900K major size: 16448K in use: 15445K los size: 1024K in use: 871K
[Mono] GC_MAJOR_CONCURRENT_START: (Degraded mode overflow)
[mpanyname.eTAp] Explicit concurrent copying GC freed 406(29KB) AllocSpace objects, 0(0B) LOS objects, 50% free, 1601KB/3MB, paused 499us total 7.510ms
[Mono] GC_TAR_BRIDGE bridges 42 objects 43 opaque 1 colors 42 colors-bridged 42 colors-visible 42 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.04ms tarjan 0.02ms scc-setup 0.03ms gather-xref 0.07ms xref-setup 0.01ms cleanup 0.02ms
[Mono] GC_BRIDGE: Complete, was running for 8.62ms
[Mono] GC_MAJOR_CONCURRENT_FINISH: (finishing) time 734.57ms, stw 22.44ms los size: 1024K in use: 231K
[Mono] GC_MAJOR_SWEEP: major size: 16960K in use: 15533K
[Mono] GC_TAR_BRIDGE bridges 0 objects 0 opaque 0 colors 0 colors-bridged 0 colors-visible 42 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.04ms tarjan 0.02ms scc-setup 0.03ms gather-xref 0.07ms xref-setup 0.01ms cleanup 0.02ms
[Mono] GC_BRIDGE: Complete, was running for 0.24ms
[Mono] GC_MINOR: (Concurrent start) time 19.60ms, stw 38.71ms promoted 300K major size: 32640K in use: 31136K los size: 1024K in use: 504K
[Mono] GC_MAJOR_CONCURRENT_START: (Degraded mode overflow)
[mpanyname.eTAp] Explicit concurrent copying GC freed 3(16KB) AllocSpace objects, 0(0B) LOS objects, 50% free, 1601KB/3MB, paused 402us total 7.396ms
[Mono] GC_TAR_BRIDGE bridges 40 objects 41 opaque 1 colors 40 colors-bridged 40 colors-visible 40 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.05ms tarjan 0.02ms scc-setup 0.01ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.19ms
[Mono] GC_BRIDGE: Complete, was running for 9.27ms
[Mono] GC_MAJOR_CONCURRENT_FINISH: (finishing) time 520.80ms, stw 26.07ms los size: 1024K in use: 373K
[Mono] GC_MAJOR_SWEEP: major size: 32640K in use: 30767K
[Mono] Warning: Degraded allocation. Consider increasing nursery-size if the warning persists.
[Mono] GC_TAR_BRIDGE bridges 0 objects 0 opaque 0 colors 0 colors-bridged 0 colors-visible 40 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.05ms tarjan 0.02ms scc-setup 0.01ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.01ms
[Mono] GC_BRIDGE: Complete, was running for 0.16ms
[Mono] GC_MINOR: (Concurrent start) time 17.46ms, stw 43.08ms promoted 100K major size: 48336K in use: 46517K los size: 2048K in use: 941K
[Mono] GC_MAJOR_CONCURRENT_START: (Degraded mode overflow)
[mpanyname.eTAp] Explicit concurrent copying GC freed 3(16KB) AllocSpace objects, 0(0B) LOS objects, 50% free, 1601KB/3MB, paused 398us total 7.155ms
[Mono] GC_TAR_BRIDGE bridges 40 objects 41 opaque 1 colors 40 colors-bridged 40 colors-visible 40 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.05ms tarjan 0.02ms scc-setup 0.02ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.11ms
[Mono] GC_BRIDGE: Complete, was running for 8.62ms
[Mono] GC_MAJOR_CONCURRENT_FINISH: (finishing) time 291.47ms, stw 30.74ms los size: 2048K in use: 667K
[Mono] GC_MAJOR_SWEEP: major size: 48208K in use: 46018K
[Mono] GC_TAR_BRIDGE bridges 0 objects 0 opaque 0 colors 0 colors-bridged 0 colors-visible 40 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.05ms tarjan 0.02ms scc-setup 0.02ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.01ms
[Mono] GC_BRIDGE: Complete, was running for 0.12ms
[Mono] GC_MINOR: (Concurrent start) time 19.62ms, stw 47.45ms promoted 34K major size: 64576K in use: 62420K los size: 2048K in use: 667K
[Mono] GC_MAJOR_CONCURRENT_START: (Degraded mode overflow)
[mpanyname.eTAp] Explicit concurrent copying GC freed 3(16KB) AllocSpace objects, 0(0B) LOS objects, 50% free, 1601KB/3MB, paused 403us total 5.366ms
[Mono] GC_TAR_BRIDGE bridges 40 objects 41 opaque 1 colors 40 colors-bridged 40 colors-visible 40 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.20ms tarjan 0.02ms scc-setup 0.01ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.12ms
[Mono] GC_BRIDGE: Complete, was running for 7.67ms
[Mono] GC_MAJOR_CONCURRENT_FINISH: (finishing) time 198.38ms, stw 31.63ms los size: 2048K in use: 667K
[Mono] GC_MAJOR_SWEEP: major size: 64400K in use: 61857K
[libc] Fatal signal 11 (SIGSEGV), code 2 (SEGV_ACCERR), fault addr 0xff4f2fbc in tid 21571 (mpanyname.eTApp), pid 21571 (mpanyname.eTApp)
根据你的描述和代码，你想在自定义控件中创建Icommand，
我做了一个例子，你可以看看，首先创建Icommand BindableProperty。
测试控制：
<ContentView.Content>
<StackLayout>
<Button x:Name="btn1" Text="press" />
</StackLayout>
</ContentView.Content>
public partial class TestControl : ContentView
{
public ICommand CommandInButton
{
get { return (ICommand)GetValue(CommandInButtonProperty); }
set { SetValue(CommandInButtonProperty, value); }
}
public static readonly BindableProperty CommandInButtonProperty = BindableProperty.Create(
propertyName: "CommandInButton",
returnType: typeof(ICommand),
declaringType: typeof(TestControl),
defaultValue: null,
propertyChanged: CommandInButtonPropertyChanged);
private static void CommandInButtonPropertyChanged(BindableObject bindable, object oldValue, object newValue)
{
var control = (TestControl)bindable;
control.btn1.Command= (ICommand)newValue;
}
public TestControl()
{
InitializeComponent();
}
}
您的内容页数：
<local:TestControl CommandInButton="{Binding Test}" />
public ICommand Test { get; }
public Page3()
{
InitializeComponent();
Test = new Command(async () =>
{
await Application.Current.MainPage.DisplayAlert("asd", "asd", "asd");
});
this.BindingContext = this;
}
我希望我的自定义控件在单击按钮时触发命令。
public partial class TestControl : ContentView
{
public TestControl()
{
InitializeComponent();
Test = new Command(async () =>
{
await Application.Current.MainPage.DisplayAlert("asd", "asd", "asd");
});
}
public ICommand Test { get; }
}
<ContentView xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:controls="clr-namespace:eTApp.Controls"
x:DataType="controls:TestControl"
x:Class="eTApp.Controls.TestControl">
<ContentView.Content>
<StackLayout>
<Button
Text="press"
Command="{Binding Test}" />
</StackLayout>
</ContentView.Content>
</ContentView>
但是按下按钮没有任何反应。我尝试添加
<ContentView.BindingContext>
<controls:TestControl />
</ContentView.BindingContext>
但是应用程序会在启动时崩溃。我认为那是因为它创建了新的实例并耗尽了内存。
我做错了什么？
编辑：
单击按钮时没有日志错误。在代码隐藏中添加 BindingContext = this; 不会改变任何东西。但是当我在 XAML 文件中添加 BindingContext 时，此日志会在启动时出现并且应用程序冻结：
[Mono] Warning: Degraded allocation. Consider increasing nursery-size if the warning persists.
[Mono] GC_TAR_BRIDGE bridges 0 objects 0 opaque 0 colors 0 colors-bridged 0 colors-visible 52 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.03ms tarjan 0.03ms scc-setup 0.02ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.01ms
[Mono] GC_BRIDGE: Complete, was running for 0.14ms
[Mono] GC_MINOR: (Concurrent start) time 22.50ms, stw 56.42ms promoted 900K major size: 16448K in use: 15445K los size: 1024K in use: 871K
[Mono] GC_MAJOR_CONCURRENT_START: (Degraded mode overflow)
[mpanyname.eTAp] Explicit concurrent copying GC freed 406(29KB) AllocSpace objects, 0(0B) LOS objects, 50% free, 1601KB/3MB, paused 499us total 7.510ms
[Mono] GC_TAR_BRIDGE bridges 42 objects 43 opaque 1 colors 42 colors-bridged 42 colors-visible 42 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.04ms tarjan 0.02ms scc-setup 0.03ms gather-xref 0.07ms xref-setup 0.01ms cleanup 0.02ms
[Mono] GC_BRIDGE: Complete, was running for 8.62ms
[Mono] GC_MAJOR_CONCURRENT_FINISH: (finishing) time 734.57ms, stw 22.44ms los size: 1024K in use: 231K
[Mono] GC_MAJOR_SWEEP: major size: 16960K in use: 15533K
[Mono] GC_TAR_BRIDGE bridges 0 objects 0 opaque 0 colors 0 colors-bridged 0 colors-visible 42 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.04ms tarjan 0.02ms scc-setup 0.03ms gather-xref 0.07ms xref-setup 0.01ms cleanup 0.02ms
[Mono] GC_BRIDGE: Complete, was running for 0.24ms
[Mono] GC_MINOR: (Concurrent start) time 19.60ms, stw 38.71ms promoted 300K major size: 32640K in use: 31136K los size: 1024K in use: 504K
[Mono] GC_MAJOR_CONCURRENT_START: (Degraded mode overflow)
[mpanyname.eTAp] Explicit concurrent copying GC freed 3(16KB) AllocSpace objects, 0(0B) LOS objects, 50% free, 1601KB/3MB, paused 402us total 7.396ms
[Mono] GC_TAR_BRIDGE bridges 40 objects 41 opaque 1 colors 40 colors-bridged 40 colors-visible 40 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.05ms tarjan 0.02ms scc-setup 0.01ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.19ms
[Mono] GC_BRIDGE: Complete, was running for 9.27ms
[Mono] GC_MAJOR_CONCURRENT_FINISH: (finishing) time 520.80ms, stw 26.07ms los size: 1024K in use: 373K
[Mono] GC_MAJOR_SWEEP: major size: 32640K in use: 30767K
[Mono] Warning: Degraded allocation. Consider increasing nursery-size if the warning persists.
[Mono] GC_TAR_BRIDGE bridges 0 objects 0 opaque 0 colors 0 colors-bridged 0 colors-visible 40 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.05ms tarjan 0.02ms scc-setup 0.01ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.01ms
[Mono] GC_BRIDGE: Complete, was running for 0.16ms
[Mono] GC_MINOR: (Concurrent start) time 17.46ms, stw 43.08ms promoted 100K major size: 48336K in use: 46517K los size: 2048K in use: 941K
[Mono] GC_MAJOR_CONCURRENT_START: (Degraded mode overflow)
[mpanyname.eTAp] Explicit concurrent copying GC freed 3(16KB) AllocSpace objects, 0(0B) LOS objects, 50% free, 1601KB/3MB, paused 398us total 7.155ms
[Mono] GC_TAR_BRIDGE bridges 40 objects 41 opaque 1 colors 40 colors-bridged 40 colors-visible 40 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.05ms tarjan 0.02ms scc-setup 0.02ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.11ms
[Mono] GC_BRIDGE: Complete, was running for 8.62ms
[Mono] GC_MAJOR_CONCURRENT_FINISH: (finishing) time 291.47ms, stw 30.74ms los size: 2048K in use: 667K
[Mono] GC_MAJOR_SWEEP: major size: 48208K in use: 46018K
[Mono] GC_TAR_BRIDGE bridges 0 objects 0 opaque 0 colors 0 colors-bridged 0 colors-visible 40 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.05ms tarjan 0.02ms scc-setup 0.02ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.01ms
[Mono] GC_BRIDGE: Complete, was running for 0.12ms
[Mono] GC_MINOR: (Concurrent start) time 19.62ms, stw 47.45ms promoted 34K major size: 64576K in use: 62420K los size: 2048K in use: 667K
[Mono] GC_MAJOR_CONCURRENT_START: (Degraded mode overflow)
[mpanyname.eTAp] Explicit concurrent copying GC freed 3(16KB) AllocSpace objects, 0(0B) LOS objects, 50% free, 1601KB/3MB, paused 403us total 5.366ms
[Mono] GC_TAR_BRIDGE bridges 40 objects 41 opaque 1 colors 40 colors-bridged 40 colors-visible 40 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.20ms tarjan 0.02ms scc-setup 0.01ms gather-xref 0.01ms xref-setup 0.01ms cleanup 0.12ms
[Mono] GC_BRIDGE: Complete, was running for 7.67ms
[Mono] GC_MAJOR_CONCURRENT_FINISH: (finishing) time 198.38ms, stw 31.63ms los size: 2048K in use: 667K
[Mono] GC_MAJOR_SWEEP: major size: 64400K in use: 61857K
[libc] Fatal signal 11 (SIGSEGV), code 2 (SEGV_ACCERR), fault addr 0xff4f2fbc in tid 21571 (mpanyname.eTApp), pid 21571 (mpanyname.eTApp)
根据你的描述和代码，你想在自定义控件中创建Icommand，
我做了一个例子，你可以看看，首先创建Icommand BindableProperty。
测试控制：
<ContentView.Content>
<StackLayout>
<Button x:Name="btn1" Text="press" />
</StackLayout>
</ContentView.Content>
public partial class TestControl : ContentView
{
public ICommand CommandInButton
{
get { return (ICommand)GetValue(CommandInButtonProperty); }
set { SetValue(CommandInButtonProperty, value); }
}
public static readonly BindableProperty CommandInButtonProperty = BindableProperty.Create(
propertyName: "CommandInButton",
returnType: typeof(ICommand),
declaringType: typeof(TestControl),
defaultValue: null,
propertyChanged: CommandInButtonPropertyChanged);
private static void CommandInButtonPropertyChanged(BindableObject bindable, object oldValue, object newValue)
{
var control = (TestControl)bindable;
control.btn1.Command= (ICommand)newValue;
}
public TestControl()
{
InitializeComponent();
}
}
您的内容页数：
<local:TestControl CommandInButton="{Binding Test}" />
public ICommand Test { get; }
public Page3()
{
InitializeComponent();
Test = new Command(async () =>
{
await Application.Current.MainPage.DisplayAlert("asd", "asd", "asd");
});
this.BindingContext = this;
}