使用字体时 WPF TextBlock 内存泄漏 [英] WPF TextBlock memory leak when using Font

问题描述

我在 Windows 7 上使用 .NET 4.5，可能会发现内存泄漏.
我有一个 TextBlock(不是 TextBox - 这不是撤消问题)，它每秒都会改变其值(CPU 使用率、时间等...).
使用 .NET Memory Profiler(并通过简单地观察任务管理器)我注意到内存不断增长.更准确地说，我看到了越来越多的 UnmanagedMemoryStream 实时实例(我尝试了 GC.Collect() ，但显然什么也没做).

I'm using .NET 4.5 on Windows 7, and might find a memory leak.
I have a TextBlock (not TextBox - it's not the Undo problem), which changes its value every second (CPU usage, time, etc...).
Using .NET Memory Profiler (and by simply watching task manager) I noticed the memory keeps on growing. To be more accurate, I see more and more live instances of UnmanagedMemoryStream (I tried GC.Collect() which obviously didn't do anything).

经过一些测试，我发现只有当我将TextBlock字体设置为资源字体时才会出现此问题，如下所示:

After some tests, I've found out that this problem appears only when I'm setting the TextBlock font to a resource font as follows:

<Style TargetType="{x:Type TextBlock}">
    <Setter Property="Control.Foreground" Value="#CCCCCC"/>
    <Setter Property="FontFamily" Value="pack://application:,,,/MyUIControls;component/./Fonts/#Noto Sans"/>
</Style>

我尝试直接从代码或通过绑定更新 Text 属性，两种方式的行为都相同.

I tried updating the Text property directly from code or via Binding, it behaves the same for both ways.

底线:
设置 FontFamily 后，每次更新文本时 UnmanagedMemoryStream 的实例都会(永远)出现.当我不这样做时(设置 FontFamily 属性)，内存是稳定的.
(顺便说一句，当我使用 Label 而不是 TextBlock 时也会发生这种情况)

Bottom line:
When the FontFamily is set, instances of UnmanagedMemoryStream keep on coming (forever) each time I'm updating the text. When I don't (set the FontFamily property), memory is stable.
(BTW, it happens when I use Label instead of TextBlock as well)

看起来像是内存泄漏，但我找不到任何有关它的参考.
有关如何解决的任何建议?

It looks like a memory leak but I couldn't find any reference about it.
Any suggestions of how can it be solved?

推荐答案

FontFamily 在使用时泄漏 UnmanagedMemoryStreams 如果它来自嵌入式资源或相关资源小路.当 FontFamily 来自系统字体或绝对路径时，它不会泄漏.

A FontFamily leaks UnmanagedMemoryStreams when it is used if it was sourced from an embedded resource or a relative path. When the FontFamily is sourced from a system font or absolute path, it does not leak.

您可以查看这里 并下载重现问题的项目.

You can look here and download the project that reproduces the problem.

解决方法:对于资源字体:将字体保存到临时文件夹并使用存储字体的绝对路径.对于相对路径字体:解析并使用绝对路径.

Workaround: For Resource fonts: save fonts into a temporary folder and use the absolute path to the stored font. For relative path fonts: resolve and use the absolute path instead.

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