blocks|key|167961|text|我不确定你的信息是从哪里来的。MSDN+documentation说：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|167962|0到WM_USER+-1|style|BOLD|167963|保留供系统使用的消息。|167964|WM_USER至0x7FFF|167965|供私有窗口类使用的整型消息。|167966|WM_APP+(0x8000)至0xBFFF|167967|可供应用程序使用的消息。|167968|0xC000至0xFFFF|167969|供应用程序使用的字符串消息。|167970|大于0xFFFF|167971|由系统保留。|167972|167973|现在，WM_USER范围和WM_APP范围之间的区别是什么？这在很多地方都有报道。例如，here+is+what+Raymond+Chen+has+to+say。|CODE|167974|167975|+0x400..0x7FFF+(WM_USER+..WM_APP-1)：类定义的消息。|blockquote|167976|167977|这些消息的含义由window类的实现者决定。(非正式地:由为该窗口类调用RegisterClass的人执行。)例如，如果窗口是工具栏控件，则WM_USER%2B1消息表示TB_ENABLEBUTTON；如果是工具提示控件，则表示TTM_ACTIVATE；如果是对话框，则表示DM_SETDEFID。如果你创建了自己的控件，那就意味着完全不同的东西。由于任何人都可以在此范围内创建消息，因此操作系统不知道参数的含义，也无法执行自动编组。|167978|0x8000+..0xBFFF+(WM_APP+...messages+1)：应用程序定义的消息。|167979|这些消息的含义由创建窗口的应用程序确定。(非正式地:由调用CreateWindow的人执行。)此消息区域是在Windows+95中创建的，以确保对窗口进行子类化并生成自定义消息的应用程序不会干扰将来版本中由window类创建的新消息。同样，由于任何人都可以在此范围内创建消息，因此操作系统不知道参数的含义，也无法执行自动编组。|167980|167981|其中最重要的一点是，如果您在WM_USER范围内定义消息，那么请准备好让应用程序中的其他控件使用这些相同的消息。例如，您不能广播WM_USER范围内的消息。|167982|另一方面，WM_APP范围内的消息对于应用程序中的所有不同窗口类都具有相同的含义。|167983|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/windows/desktop/ms644931.aspx|1|http://blogs.msdn.com/b/oldnewthing/archive/2003/12/02/55914.aspx^0|K|D|0|0|0|C|0|0|0|E|0|0|0|M|0|0|0|D|0|0|0|8|0|0|0|3|7|D|6|18|10|1|0|0|1|16|0|0|0|0|1D|0|0|0|E|7|1S|7|0|5|6|0^^$0|@$1|2|3|4|5|6|7|1T|8|@]|9|@$A|1U|B|1V|1|1W]]|C|$]]|$1|D|3|E|5|6|7|1X|8|@$A|1Y|B|1Z|F|G]]|9|@]|C|$]]|$1|H|3|I|5|6|7|20|8|@]|9|@]|C|$]]|$1|J|3|K|5|6|7|21|8|@$A|22|B|23|F|G]]|9|@]|C|$]]|$1|L|3|M|5|6|7|24|8|@]|9|@]|C|$]]|$1|N|3|O|5|6|7|25|8|@$A|26|B|27|F|G]]|9|@]|C|$]]|$1|P|3|Q|5|6|7|28|8|@]|9|@]|C|$]]|$1|R|3|S|5|6|7|29|8|@$A|2A|B|2B|F|G]]|9|@]|C|$]]|$1|T|3|U|5|6|7|2C|8|@]|9|@]|C|$]]|$1|V|3|W|5|6|7|2D|8|@$A|2E|B|2F|F|G]]|9|@]|C|$]]|$1|X|3|Y|5|6|7|2G|8|@]|9|@]|C|$]]|$1|Z|3|-4|5|6|7|2H|8|@]|9|@]|C|$]]|$1|10|3|11|5|6|7|2I|8|@$A|2J|B|2K|F|12]|$A|2L|B|2M|F|12]]|9|@$A|2N|B|2O|1|2P]]|C|$]]|$1|13|3|-4|5|6|7|2Q|8|@]|9|@]|C|$]]|$1|14|3|15|5|16|7|2R|8|@$A|2S|B|2T|F|G]]|9|@]|C|$]]|$1|17|3|-4|5|6|7|2U|8|@]|9|@]|C|$]]|$1|18|3|19|5|6|7|2V|8|@]|9|@]|C|$]]|$1|1A|3|1B|5|6|7|2W|8|@$A|2X|B|2Y|F|G]]|9|@]|C|$]]|$1|1C|3|1D|5|6|7|2Z|8|@]|9|@]|C|$]]|$1|1E|3|-4|5|6|7|30|8|@]|9|@]|C|$]]|$1|1F|3|1G|5|6|7|31|8|@$A|32|B|33|F|12]|$A|34|B|35|F|12]]|9|@]|C|$]]|$1|1H|3|1I|5|6|7|36|8|@$A|37|B|38|F|12]]|9|@]|C|$]]|$1|1J|3|-4|5|6|7|39|8|@]|9|@]|C|$]]]|1K|$1L|$5|1M|1N|1O|C|$1P|1Q]]|1R|$5|1M|1N|1O|C|$1P|1S]]]]

I'm not sure where your information comes from. The MSDN <a href="http://msdn.microsoft.com/en-us/library/windows/desktop/ms644931.aspx" rel="noreferrer">documentation</a> says:

0 through WM_USER –1 Messages reserved for use by the system.

WM_USER through 0x7FFF Integer messages for use by private window classes.

WM_APP (0x8000) through 0xBFFF Messages available for use by applications.

0xC000 through 0xFFFF String messages for use by applications.

Greater than 0xFFFF Reserved by the system.

<hr>

Now, what is the difference between the <code>WM_USER</code> range, and the <code>WM_APP</code> range? This has been covered in many places. For instance, <a href="http://blogs.msdn.com/b/oldnewthing/archive/2003/12/02/55914.aspx" rel="noreferrer">here is what Raymond Chen has to say</a>.

<blockquote>
 0x400 .. 0x7FFF (WM_USER .. WM_APP-1): Class-defined messages.
 
 The meanings of these messages is determined by the implementor of the
 window class. (Informally: By the person who calls RegisterClass for
 that window class.) For example, the WM_USER+1 message means
 TB_ENABLEBUTTON if the window is a toolbar control, but it means
 TTM_ACTIVATE if it is a tooltip control, and it means DM_SETDEFID if
 it is a dialog box. If you created your own control, it would mean
 something else completely different. Since anybody can create a
 message in this range, the operating system does not know what the
 parameters mean and cannot perform automatic marshalling.
 
 0x8000 .. 0xBFFF (WM_APP ... MAXINTATOM-1): Application-defined messages.
 
 The meanings of these messages is determined by the application that
 created the window. (Informally: By the person who calls
 CreateWindow.) This message region was created in Windows 95 to ensure
 that applications which subclass a window and generate custom messages
 will not interfere with new messages created by the window class in
 future versions. Again, since anybody can create a message in this
 range, the operating system does not know what the parameters mean and
 cannot perform automatic marshalling.
</blockquote>

The main thing to take from all this is that if you define messages in the <code>WM_USER</code> range, then be prepared for other controls in your application to have their own use for those same messages. For instance, you must not broadcast messages in the <code>WM_USER</code> range.

On the other hand, messages in the <code>WM_APP</code> range are intended to have the same meaning for all different window classes in an application.

I'm was using private messages in my application for year like this:

<pre><code>UM_APP_BASE = WM_APP; // WM_APP is declared as WM_APP = $8000; in "Controls" unit.
</code></pre>

and then defined my private messages:

<pre><code>UM_EXPLORER_MSG = UM_APP_BASE + 1;
UM_LICENSE_CHANGE_MSG = UM_APP_BASE + 2;
etc...
</code></pre>

And use them like this in my class:

<pre><code>procedure UMLicenseChanged(var Message: TMessage); message UM_LICENSE_CHANGE_MSG;
</code></pre>

(I also use <code>RegisterWindowMessage</code> to "talk" to my other applications but that is a different story)

I don't remember what made me decide to use <code>WM_APP</code> rather than <code>WM_USER</code> as base in the first place. 
The docs says:

<blockquote>
 The WM_USER constant is used to distinguish between message values
 that are reserved for use by Windows and values that can be used by an
 application to send messages within a private window class. There are
 five ranges of message numbers:
</blockquote>

<pre><code>Range Meaning
0 through WM_USER - 1 Messages reserved for use by Windows.
WM_USER through 0x7FFF Integer messages for use by private window classes.
0x8000 through 0xBFFF Messages reserved for future use by Windows.
0xC000 through 0xFFFF String messages for use by applications.
Greater than 0xFFFF Reserved by Windows for future use.
</code></pre>

Which means that <code>WM_APP</code> is "reserved for future use by Windows".
On the other hand Delphi uses <code>CM_BASE = $B000;</code> which is in that range. and also <code>CN_BASE = $BC00;</code>

How do I define the base message so it wont collide with other messages used both by Windows/Delphi/Other controls?
Which base message is preferred as private for my application? and why? 
Should I use <code>WM_USER</code> instead of <code>WM_APP</code>? Note that <code>WM_USER</code> base is used in CommCtrl by Windows also e.g. <code>TB_ENABLEBUTTON = WM_USER + 1</code>. etc... 

I need some insights on this issue.

<hr>

I read this on my Delphi help API (D5). which is obviously obsolete! 
This is probably why I have decided to use <code>WM_APP</code>. 
Still, an explanation about the difference between the two would be nice :)

How to define private base Application messages?

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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我在我的应用程序中使用私人消息有一年了，就像这样：UM_APP_BASE = WM_APP; // WM_APP is declared as WM_APP = $8000; in "Controls" unit.然后定义了我的私人消息：UM_EXPLORER_MSG = UM_APP_BASE + 1;UM_LICE...

如何定义私有基础应用程序消息？-腾讯云开发者社区-腾讯云

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