blocks|key|339956|text|有人会猜想(我的WPF现在有点生疏了)，边距是一个对象，不能直接改变。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|339957|e.g|339958|MyControl.Margin+=+new+Margin(10,0,0,0);|code-block|syntax|javascript|339959|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

One would guess that (and my WPF is a little rusty right now) that Margin takes an object and cannot be directly changed.

e.g 

<pre><code>MyControl.Margin = new Margin(10,0,0,0);
</code></pre>

blocks|key|342291|text|Margin返回一个结构，这意味着您正在编辑一个copy。您将需要类似以下内容：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|BOLD|entityRanges|data|342292|var+margin+=+MyControl.Margin;
margin.Left+=+10;
MyControl.Margin+=+margin;|code-block|syntax|javascript|342293|entityMap^0|0|6|O|4|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|D]]|E|@]|F|$]]|$1|G|3|H|5|I|7|S|8|@]|E|@]|F|$J|K]]|$1|L|3|-4|5|6|7|T|8|@]|E|@]|F|$]]]|M|$]]

<code>Margin</code> is returning a struct, which means that you are editing a copy. You will need something like:

<pre><code>var margin = MyControl.Margin;
margin.Left = 10;
MyControl.Margin = margin;
</code></pre>

blocks|key|3320407|text|Margin属性返回Thickness结构，Left是该结构的一个属性。该语句执行的操作是从Margin属性复制结构值，并在副本上设置Left属性值。您会得到一个错误，因为您设置的值不会存储回Margin属性中。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3320408|(早期版本的C#会让你毫无抱怨地这么做，在新闻组和论坛上引发了很多问题，为什么这样的声明根本没有效果……)|3320409|要设置该属性，您需要从Margin属性获取Thickness结构，设置该值并将其存储回去：|3320410|Thickness+m+=+MyControl.Margin;
m.Left+=+10;
MyControl.Margin+=+m;|code-block|syntax|javascript|3320411|如果您要设置所有页边距，只需创建一个Thickness结构并一次性设置它们：|3320412|MyControl.Margin+=+new+Thickness(10,+10,+10,+10);|3320413|entityMap^0|0|6|A|9|M|4|1A|6|1V|4|2O|6|0|0|B|6|L|9|0|0|I|9|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]|$9|13|A|14|B|C]|$9|15|A|16|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|17|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|1D|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1E|8|@$9|1F|A|1G|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1H|8|@]|D|@]|E|$M|N]]|$1|S|3|-4|5|6|7|1I|8|@]|D|@]|E|$]]]|T|$]]

The <code>Margin</code> property returns a <code>Thickness</code> structure, of which <code>Left</code> is a property. What the statement does is copying the structure value from the <code>Margin</code> property and setting the <code>Left</code> property value on the copy. You get an error because the value that you set will not be stored back into the <code>Margin</code> property.

(Earlier versions of C# would just let you do it without complaining, causing a lot of questions in newsgroups and forums on why a statement like that had no effect at all...)

To set the property you would need to get the <code>Thickness</code> structure from the <code>Margin</code> property, set the value and store it back:

<pre><code>Thickness m = MyControl.Margin;
m.Left = 10;
MyControl.Margin = m;
</code></pre>

If you are going to set all the margins, just create a <code>Thickness</code> structure and set them all at once:

<pre><code>MyControl.Margin = new Thickness(10, 10, 10, 10);
</code></pre>

blocks|key|338840|text|问题是Margin是一个属性，它的类型(Thickness)是一个值类型。这意味着当你访问这个属性时，你会得到一个值的副本。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|338841|即使您可以为特定值更改Thickness.Left属性的值(gr...可变的值类型不应该存在)，它不会改变边距。|338842|相反，您需要将Margin属性设置为新值。例如(巧合的是，与Marc编写的代码相同)：|338843|Thickness+margin+=+MyControl.Margin;
margin.Left+=+10;
MyControl.Margin+=+margin;|code-block|syntax|javascript|338844|作为对库设计的说明，如果Thickness是不可变的，但是方法返回一个新的值，这个值是原始的副本，但替换了一个部分，那么我会非常喜欢它。然后你可以这样写：|338845|MyControl.Margin+=+MyControl.Margin.WithLeft(10);|338846|不用担心可变值类型的奇怪行为，很好，可读，都是一个表达式……|338847|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.windows.frameworkelement.margin.aspx|1|http://msdn.microsoft.com/en-us/library/system.windows.thickness.aspx|2|http://msdn.microsoft.com/en-us/library/system.windows.thickness.left.aspx^0|3|6|K|9|3|6|0|K|9|1|0|B|E|B|E|2|0|7|6|0|0|C|9|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]|$9|19|A|1A|B|C]]|D|@$9|1B|A|1C|1|1D]|$9|1E|A|1F|1|1G]]|E|$]]|$1|F|3|G|5|6|7|1H|8|@$9|1I|A|1J|B|C]]|D|@$9|1K|A|1L|1|1M]]|E|$]]|$1|H|3|I|5|6|7|1N|8|@$9|1O|A|1P|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|1Q|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1R|8|@$9|1S|A|1T|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1U|8|@]|D|@]|E|$M|N]]|$1|S|3|T|5|6|7|1V|8|@]|D|@]|E|$]]|$1|U|3|-4|5|6|7|1W|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]|12|$5|X|Y|Z|E|$10|13]]|14|$5|X|Y|Z|E|$10|15]]]]

The problem is that <a href="http://msdn.microsoft.com/en-us/library/system.windows.frameworkelement.margin.aspx" rel="noreferrer"><code>Margin</code></a> is a property, and its type (<a href="http://msdn.microsoft.com/en-us/library/system.windows.thickness.aspx" rel="noreferrer"><code>Thickness</code></a>) is a value type. That means when you access the property you're getting a copy of the value back.

Even though you can change the value of the <a href="http://msdn.microsoft.com/en-us/library/system.windows.thickness.left.aspx" rel="noreferrer"><code>Thickness.Left</code></a> property for a particular value (grr... mutable value types shouldn't exist), it wouldn't change the margin.

Instead, you'll need to set the <code>Margin</code> property to a new value. For instance (coincidentally the same code as Marc wrote):

<pre><code>Thickness margin = MyControl.Margin;
margin.Left = 10;
MyControl.Margin = margin;
</code></pre>

As a note for library design, I would have vastly preferred it if <code>Thickness</code> were immutable, but with methods that returned a new value which was a copy of the original, but with one part replaced. Then you could write:

<pre><code>MyControl.Margin = MyControl.Margin.WithLeft(10);
</code></pre>

No worrying about odd behaviour of mutable value types, nice and readable, all one expression...

blocks|key|337503|text|要使用Thickness，您需要创建项目.NET+framework+platform版本/将其更改为4.5。因为此方法仅在4.5版中可用。(您也可以直接下载PresentationFramework.dll并引用此dll，而无需创建.NET+framework版本/将其更改为4.5。)|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|337504|但是，如果您想简单地完成此操作，则可以使用以下代码：|337505|MyControl.Margin+=+new+Padding(int+left,+int+top,+int+right,+int+bottom);|code-block|syntax|javascript|337506|也是|337507|MyControl.Margin+=+new+Padding(int+all);|337508|这很简单，不需要对您的项目进行任何更改|337509|entityMap^0|3|9|K|E|39|E|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|12|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|13|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|14|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|15|8|@]|D|@]|E|$]]|$1|S|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|T|$]]

To use <code>Thickness</code> you need to create/change your project <code>.NET framework</code> platform version to 4.5. becaus this method available only in version 4.5. (Also you can just download PresentationFramework.dll and give referense to this dll, without create/change your <code>.NET framework</code> version to 4.5.) 

But if you want to do this simple, You can use this code:

<pre><code>MyControl.Margin = new Padding(int left, int top, int right, int bottom);
</code></pre>

also 

<pre><code>MyControl.Margin = new Padding(int all);
</code></pre>

This is simple and no needs any changes to your project

blocks|key|342401|text|这有点不清楚你在问什么，但为了让事情变得舒适，你可以继承你自己的控件，并用Marc建议的代码添加一个属性：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|342402|class+MyImage+:+Image+{
++++private+Thickness+thickness;
++++public+double+MarginLeft+{
++++++++get+{+return+Margin.Left;+}
++++++++set+{+thickness+=+Margin;+thickness.Left+=+value;+Margin+=+thickness;+}
++++}
}|code-block|syntax|javascript|342403|然后，在客户端代码中，您可以只编写|342404|MyImage+img+=+new+MyImage();
img.MarginLeft+=+10;
MessageBox.Show(img.Margin.Left.ToString());+//+or+img.MarginLeft|342405|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

It's a bit unclear what are you asking, but to make things comfortable, you can inherit your own Control and add a property with the code that Marc suggests:

<pre><code>class MyImage : Image {
 private Thickness thickness;
 public double MarginLeft {
 get { return Margin.Left; }
 set { thickness = Margin; thickness.Left = value; Margin = thickness; }
 }
}
</code></pre>

Then in the client code you can write just

<pre><code>MyImage img = new MyImage();
img.MarginLeft = 10;
MessageBox.Show(img.Margin.Left.ToString()); // or img.MarginLeft
</code></pre>

blocks|key|3320625|text|一个人可以简单地使用这个|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3320626|MyControl.Margin+=+new+System.Windows.Thickness(10,+0,+5,+0);|code-block|syntax|javascript|3320627|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

One could simply use this

<pre><code>MyControl.Margin = new System.Windows.Thickness(10, 0, 5, 0);
</code></pre>

blocks|key|337533|text|视情况而定，您也可以尝试在此处使用property+...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|337534|MyControl.Margin=new+Padding(0,0,0,0);|code-block|syntax|javascript|337535|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Depends on the situation, you can also try using padding property here...

<pre><code>MyControl.Margin=new Padding(0,0,0,0);
</code></pre>

blocks|key|3320678|text|边距=新厚度(+0，0，0，0)；|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3320679|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Margin = new Thickness(0, 0, 0, 0);

<pre><code>MyControl.Margin.Left = 10;
</code></pre>

Error:

<blockquote>
 Cannot modify the return value of 'System.Windows.FrameworkElement.Margin' because it is not a variable
</blockquote>

Setting Margin Properties in code

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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MyControl.Margin.Left = 10;错误：无法修改“System.Windows.FrameworkElement.Margin”的返回值，因为它不是变量

问在代码中设置边距属性
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