内存泄漏处理Xamarin.Forms [英] Memory leak handling Xamarin.Forms
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问题描述
我使用Xamarin.Forms创建的应用程序中存在内存泄漏问题.我的应用程序包含一个带图片的ListView.如果单击某个项目并返回到ListPage，则可以在输出"窗口中看到内存消耗.我尝试在ContentPage的OnDisappearing()中调用GC.Collect().
I have a memory leak issue in my application which I have created with Xamarin.Forms. My app consists of A ListView with Images. If I click on an item and come back to the ListPage I can see a memory hog in my Output window. I have tried calling GC.Collect() in OnDisappearing() of my ContentPage.
我在Android项目中看到了base.Dispose().但是我不知道如何使用它.
I have seen a base.Dispose() in my Android project. But I don't know how to use it.
ArticleListPage.xaml
ArticleListPage.xaml
<?xml version="1.0" encoding="utf-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:converters="clr-namespace:NewsArticles.Mobile.Converters;assembly=Something.NewsArticles.Mobile"
xmlns:themes="clr-namespace:NewsArticles.Mobile.Themes;assembly=Something.NewsArticles.Mobile"
x:Class="NewsArticles.Mobile.Pages.ArticlesListPage"
Title="{Binding PageTitle, Mode=OneWay}"
BackgroundColor="{x:Static themes:ColorResources.ArticleListPageBackgroundColor}">
<RelativeLayout>
<ContentPage.Resources>
<ResourceDictionary>
<converters:BooleanNegationConverter x:Key="booleanNegationConverter" />
<converters:StringToImageSourceConverter x:Key="stringToImageSourceConverter" />
</ResourceDictionary>
</ContentPage.Resources>
<ListView x:Name="ArticlesList"
StyleId="ArticlesList"
Grid.Row="1"
IsVisible="{Binding IsProcessing, Mode=OneWay, Converter={StaticResource booleanNegationConverter}}">
<ListView.BackgroundColor>
<OnPlatform x:TypeArguments="Color" iOS="Transparent" />
</ListView.BackgroundColor>
<ListView.RowHeight>
<OnPlatform x:TypeArguments="x:Int32" iOS="150" Android="180" WinPhone="170" />
</ListView.RowHeight>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ContentView BackgroundColor="{x:Static themes:ColorResources.ArticleListViewBackgroundColor}">
<ContentView.Padding>
<OnPlatform x:TypeArguments="Thickness"
iOS="10,5"
Android="10,10"
WinPhone="10,10" />
</ContentView.Padding>
<Grid BackgroundColor="White" Padding="10">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="120"/>
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Image Grid.Column="0"
Source="{Binding ImageUrl, Mode=OneWay, Converter={StaticResource stringToImageSourceConverter}}"
HorizontalOptions="FillAndExpand"
Aspect="AspectFill" />
<Grid Grid.Column="1" RowSpacing="0">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="20" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Label Grid.Row="0" Text="{Binding Title, Mode=OneWay}"
VerticalOptions="Start"
LineBreakMode="WordWrap"
TextColor="{x:Static themes:ColorResources.MainArticleTitleColor}"
Font="{x:Static themes:FontResources.ListArticleTitle}" />
<ContentView Grid.Row="1" Padding="0,2">
<Label Text="{Binding Author, Mode=OneWay }"
TextColor="Silver"
Font="{x:Static themes:FontResources.VerySmall}" />
</ContentView>
<Label Grid.Row="2" Text="{Binding Body, Mode=OneWay}"
LineBreakMode="TailTruncation"
TextColor="Gray"
Font="{x:Static themes:FontResources.VerySmall}" />
</Grid>
</Grid>
</ContentView>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</ContentPage>
推荐答案
I had this problem a while back and this article solved it for me. Basically you need to make a custom Renderer and place that in your droid project:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Views.InputMethods;
using Android.Widget;
using Android.Util;
using Application.Droid.CustomControls;
using ApplicationClient.CustomControls;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
[assembly: ExportRenderer(typeof(ApplicationClient.CustomControls.LSImage), typeof(LSImageRenderer))]
namespace Application.Droid.CustomControls
{
public class LSImageRenderer : ImageRenderer
{
Page page;
NavigationPage navigPage;
protected override void OnElementChanged(ElementChangedEventArgs<Image> e)
{
base.OnElementChanged(e);
if (e.OldElement == null)
{
if (GetContainingViewCell(e.NewElement) != null)
{
page = GetContainingPage(e.NewElement);
if (page.Parent is TabbedPage)
{
page.Disappearing += PageContainedInTabbedPageDisapearing;
return;
}
navigPage = GetContainingNavigationPage(page);
if (navigPage != null)
navigPage.Popped += OnPagePopped;
}
else if ((page = GetContainingTabbedPage(e.NewElement)) != null)
{
page.Disappearing += PageContainedInTabbedPageDisapearing;
}
}
}
void PageContainedInTabbedPageDisapearing (object sender, EventArgs e)
{
this.Dispose(true);
page.Disappearing -= PageContainedInTabbedPageDisapearing;
}
protected override void Dispose(bool disposing)
{
Log.Info("**** LSImageRenderer *****", "Image got disposed");
base.Dispose(disposing);
}
private void OnPagePopped(object s, NavigationEventArgs e)
{
if (e.Page == page)
{
this.Dispose(true);
navigPage.Popped -= OnPagePopped;
}
}
private Page GetContainingPage(Xamarin.Forms.Element element)
{
Element parentElement = element.ParentView;
if (typeof(Page).IsAssignableFrom(parentElement.GetType()))
return (Page)parentElement;
else
return GetContainingPage(parentElement);
}
private ViewCell GetContainingViewCell(Xamarin.Forms.Element element)
{
Element parentElement = element.Parent;
if (parentElement == null)
return null;
if (typeof(ViewCell).IsAssignableFrom(parentElement.GetType()))
return (ViewCell)parentElement;
else
return GetContainingViewCell(parentElement);
}
private TabbedPage GetContainingTabbedPage(Element element)
{
Element parentElement = element.Parent;
if (parentElement == null)
return null;
if (typeof(TabbedPage).IsAssignableFrom(parentElement.GetType()))
return (TabbedPage)parentElement;
else
return GetContainingTabbedPage(parentElement);
}
private NavigationPage GetContainingNavigationPage(Element element)
{
Element parentElement = element.Parent;
if (parentElement == null)
return null;
if (typeof(NavigationPage).IsAssignableFrom(parentElement.GetType()))
return (NavigationPage)parentElement;
else
return GetContainingNavigationPage(parentElement);
}
}
}
然后扩展Image类并将其放在PCL中或您的页面所在的任何位置.
Then Extend the Image class and place that in the PCL, or wherever your pages reside.
namespace ApplicationClient.CustomControls
{
public class LSImage : Image
{
}
}
然后，您必须修改XAML才能与此一起使用.
Then you have to modify the XAML to work with this as well.
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:ctrls="clr-namespace:ApplicationClient.CustomControls;assembly=ApplicationClient"
... >
<ctrls:LSImage ... />
</ContentPage>
这篇关于内存泄漏处理Xamarin.Forms的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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