blocks|key|214243|text|不幸的是，你所要求的在一般情况下是不可能的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|214244|Windows不知道实际的屏幕大小。Windows可能知道您的屏幕有1024x768像素，但它不知道屏幕实际有多大。您可以将电缆从旧的13英寸屏幕中拔出，并将其连接到19英寸显示器，而不更改分辨率。DPI会有所不同，但Windows不会注意到您更换了监视器。|214245|您可以获得打印机的真实物理尺寸和DPI+(假设驱动程序没有说谎)，但不能获得屏幕的真实尺寸和DPI。至少不是可靠的。|214246|已更新|offset|length|style|BOLD|214247|正如其他人所指出的，在新的监视器和操作系统(EDID)之间有双向通信的标准，这可能会使这些信息对某些设备可用。但我还没有找到提供此信息的监视器。|214248|即使EDID普遍可用，但在一般情况下仍然无法解决，因为显示器可以是视频投影仪，其中DPI将取决于缩放、焦点、镜头类型和投掷距离。投影仪极不可能知道投掷距离，因此它无法报告实际的DPI。|214249|entityMap^0|0|0|0|0|3|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|S|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|U|8|@$H|V|I|W|J|K]]|9|@]|A|$]]|$1|L|3|M|5|6|7|X|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|Y|8|@]|9|@]|A|$]]|$1|P|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|Q|$]]

What you're asking for is, unfortunately, not possible in the general case.

Windows doesn't know the physical screen size. Windows might know that your screen has 1024x768 pixels, but it doesn't know how big the screen actually is. You might pull the cable out of your old 13" screen and connect it to a 19" monitor without changing the resolution. The DPI would be different, but Windows won't notice that you changed monitors.

You can get the true physical dimensions and DPI for a printer (assuming the driver isn't lying), but not for a screen. At least not reliably.

UPDATED

As others have pointed out, there are standards for two-way communication between newer monitors and the OS (EDID), that might make this information available for some devices. But I haven't yet found a monitor that provides this information.

Even if EDID were universally available, it's still not solvable in the general case, as the display could be a video projector, where the DPI would depend on the zoom, the focus, the lens type, and the throw distance. A projector is extremely unlikely to know the throw distance, so there's no way for it to report the actual DPI.

blocks|key|214256|text|使用下面的方法可以发现获取DPI信息会产生精确值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|214257|ID2D1Factory*+m_pDirect2dFactory;
D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED,+&m_pDirect2dFactory);
FLOAT+dpiX,+dpiY;
m_pDirect2dFactory->GetDesktopDpi(+&dpiX,+&dpiY+);|code-block|syntax|javascript|214258|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|$]]

Getting DPI information is found to produce exact value using the below method.

<pre><code>ID2D1Factory* m_pDirect2dFactory;
D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &amp;m_pDirect2dFactory);
FLOAT dpiX, dpiY;
m_pDirect2dFactory-&gt;GetDesktopDpi( &amp;dpiX, &amp;dpiY );
</code></pre>

blocks|key|212381|text|我想你想要的是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|212382|GetDeviceCaps(hdcScreen,+LOGPIXELSX);+GetDeviceCaps(hdcScreen,+LOGPIXELSY);|offset|length|style|CODE|212383|entityMap^0|0|0|23|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

I think what you're after is:

<code>GetDeviceCaps(hdcScreen, LOGPIXELSX);
GetDeviceCaps(hdcScreen, LOGPIXELSY);</code>

blocks|key|3067928|text|我真的被这里的答案搞糊涂了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3067929|微软有一个GetDpiForMonitor方法：|3067930|https://msdn.microsoft.com/en-us/library/windows/desktop/dn280510(v=vs.85).aspx|offset|length|3067931|而监视器确实会将它们的物理尺寸暴露给工具。您可以使用HWiNFO64工具以厘米为单位读取显示器的宽度和高度。因此，如果他们正在获取它(DDI?)，那么理所当然地您可以自己访问该信息。|3067932|甚至一个不同的Stack+Overflow帖子也提到使用WmiMonitorBasicDisplayParams来获取数据。|3067933|How+to+get+monitor+size|3067934|所以顶部的帖子是完全错误的，100%25。|3067935|entityMap|0|LINK|mutability|MUTABLE|url|1|https://stackoverflow.com/questions/32617615/how-to-get-monitor-size^0|0|0|0|27|0|0|0|0|0|N|1|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|10|8|@]|9|@$F|11|G|12|1|13]]|A|$]]|$1|H|3|I|5|6|7|14|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|15|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|16|8|@]|9|@$F|17|G|18|1|19]]|A|$]]|$1|N|3|O|5|6|7|1A|8|@]|9|@]|A|$]]|$1|P|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|Q|$R|$5|S|T|U|A|$V|E]]|W|$5|S|T|U|A|$V|X]]]]

I'm honestly confused by the answers here.

Microsoft has a GetDpiForMonitor method:

<a href="https://msdn.microsoft.com/en-us/library/windows/desktop/dn280510(v=vs.85).aspx" rel="noreferrer">https://msdn.microsoft.com/en-us/library/windows/desktop/dn280510(v=vs.85).aspx</a>

And monitors DO expose their physical dimensions to tools. You can read your monitors width and height, in centimeters, using the HWiNFO64 tool. So if they're getting it (DDI?), it stands to reason that you can access that information yourself.

Even a different Stack Overflow post mentions using WmiMonitorBasicDisplayParams to get the data.

<a href="https://stackoverflow.com/questions/32617615/how-to-get-monitor-size">How to get monitor size</a>

So the top post is flat-out, 100%, wrong.

I would like to get the actual screen dpi/ppi, not the dpi setting used for font in C++.

I tried with the following codes:

Version 1, reports 72 dpi, which is wrong.

<pre><code>SetProcessDPIAware(); //true
HDC screen = GetDC(NULL);
double hSize = GetDeviceCaps(screen, HORZSIZE);
double vSize = GetDeviceCaps(screen, VERTSIZE);
double hRes = GetDeviceCaps(screen, HORZRES);
double vRes = GetDeviceCaps(screen, VERTRES);
double hPixelsPerInch = hRes / hSize * 25.4;
double vPixelsPerInch = vRes / vSize * 25.4;
ReleaseDC(NULL, screen);
return (hPixelsPerInch + vPixelsPerInch) * 0.5;
</code></pre>

Version 2, reports 96 dpi, which is the Windows dpi setting for font, but not the actual screen dpi.

<pre><code>SetProcessDPIAware(); //true
HDC screen = GetDC(NULL);
double hPixelsPerInch = GetDeviceCaps(screen,LOGPIXELSX);
double vPixelsPerInch = GetDeviceCaps(screen,LOGPIXELSY);
ReleaseDC(NULL, screen);
return (hPixelsPerInch + vPixelsPerInch) * 0.5;
</code></pre>

Getting actual screen dpi/ppi under windows

Windows

我想得到实际的屏幕dpi/ppi，而不是C++中用于字体的dpi设置。我尝试使用以下代码：版本1报告72 dpi，这是错误的。SetProcessDPIAware(); //trueHDC screen = GetDC(NULL);double hSize = GetDeviceCaps(screen, HORZSIZ...

问获取windows下的实际屏幕dpi/ppi
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