Win32api Clipboard Open failed

MY J 20

I copy different content，and openClipboard。I found that it open failed with the content copy from some app，like windows text editor；

Jeanine Zhang-MSFT 10,041 Reputation points Microsoft Vendor

2024-11-21T02:31:47.04+00:00

According to your description, is it "OpenClipboard" fails when copying data from some app? Whether have you referred to the official sample:Copying Information to the Clipboard

Could you please provide a minimum sample to help us reproduce the issue?
MY J 20 Reputation points

2024-11-21T14:59:38.0066667+00:00
the document say that I can use EnumClipboardFormats to iterator all the formats, and read the content , but some app doesn't follow this rules, the may set a format but not write the data, the lpvoid may be nullptr, like windows text editor, and onedrive. is it funny? the ms document say that "Enumerates the data formats currently available on the clipboard", but their'app and system don't follow it.

OpenClipboard(nullptr); UINT format = EnumClipboardFormats(0); while (format) { HGLOBAL hglobal = GetClipboardData(format); LPVOID lpvoid = GlobalLock(hglobal); if(lpvoid == nullptr) { cout << format << std::endl; } GlobalUnlock(hglobal); format = EnumClipboardFormats(format); }
Jeanine Zhang-MSFT 10,041 Reputation points Microsoft Vendor

2024-11-22T07:27:39.49+00:00

According to the Doc:EnumClipboardFormats function

Enumerates the data formats currently available on the clipboard.

You seem misunderstand the function, the function only returns the data formats rather than the content.

And according to the return value of the function: If the function succeeds, the return value is the clipboard format that follows the specified format, namely the next available clipboard format. We can also know that this function can only enumerate data formats.
MY J 20 Reputation points

2024-11-22T09:01:16.3533333+00:00

the "available " meaning that the data is available, if the format is available, then the data must be exist. if the data not exist, the clipboard shouldn't return a format.
MY J 20 Reputation points

2024-11-23T12:56:51.07+00:00

thanks， this may be good to explain that
Jeanine Zhang-MSFT 10,041 Reputation points Microsoft Vendor

2024-12-03T02:06:01.8966667+00:00

If your case has been solved, please help to mark the answer.

Accepted answer

RLWA32 46,111 Reputation points

2024-11-23T12:40:32.33+00:00

if the format is available, then the data must be exist.

One possibility is that an application has not properly implemented Delayed Rendering of clipboard data. If the application uses delayed rendering but fails to provide the data upon receiving the WM_RENDERFORMAT message or the WM_RENDERALLFORMATS message then the GetClipboardData function will not return a valid HGLOBAL even though a clipboard format has been enumerated.
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RLWA32 46,111 Reputation points

2024-11-22T10:15:42.85+00:00

I copy different content，and openClipboard。I found that it open failed...

The Remarks section of the documentation for OpenClipboard states "OpenClipboard fails if another window has the clipboard open." If the function fails you can call the GetOpenClipboardWindow function to identify the window holding the clipboard open or the GetClipboardOwner function if you want to identify the window/process that is the clipboard owner.
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