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How the clipboard works

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Re: How the clipboard works

#91

Post by johannes1234321 »

alkonaut wrote: post #78
wongarsu wrote: post #74

Earlier quoted context omitted.

I assume it's meant as a simplification? For comparison, when you copy something in Windows, for each offered format the software can decide to either immediately give the data to the OS for safe-keeping, or to just announce the availability of data in that format, and generate it on request. The intention obviously being that for example Excel might immediately put the text representation in the OS buffer, but only…

I’m a windows desktop dev since the last millennium and tbh never knew that there was an announce api. It seems really difficult to use as a tiered solution where you only return the more complex data when asked. After all, you must then still snapshot that data from the moment the copy occurred to be able to provide a snapshot from the time of the copy later?

You snapshot the data in your application's native data format, then you can convert it later to the best match for the consumer.

Taking the Excel example form above: You got to store the cell layout and values. If it's pasted into a different excel sheet you pass that structure over. If it is pasted in a richt text editor it is converted to some richt text table format. If it is pasted to a plain text editor it is made tab separated or something and if pasted into an image editor it is renders into a bmp (well, Excel doesn't do that, but imagine ...) Doing all those conversions beforehand, just due to pressing Ctrl-C, is expensive as most of the time none is needed.

Re: How the clipboard works

#92

Post by manwe150 »

alkonaut wrote: post #78
wongarsu wrote: post #74

Earlier quoted context omitted.

I assume it's meant as a simplification? For comparison, when you copy something in Windows, for each offered format the software can decide to either immediately give the data to the OS for safe-keeping, or to just announce the availability of data in that format, and generate it on request. The intention obviously being that for example Excel might immediately put the text representation in the OS buffer, but only…

I’m a windows desktop dev since the last millennium and tbh never knew that there was an announce api. It seems really difficult to use as a tiered solution where you only return the more complex data when asked. After all, you must then still snapshot that data from the moment the copy occurred to be able to provide a snapshot from the time of the copy later?

Usually applications just delete the clipboard data announcement once it first changes in the application

Re: How the clipboard works

#93

Post by mzs »

jeroenhd wrote: post #17

For those wondering about how Windows does this, there is, as you'd expect, a Raymond Chen article about it: https://devblogs.microsoft.com/oldnewthing/20210526-00/?p=10... (and some more, like https://devblogs.microsoft.com/oldnewthing/20220608-00/?p=10... ) Elsewhere in these comments there is also a link to an explainer for the macOS equivalent. Here's also an explainer for X11: https://www.uninformativ.de/blog/po…

For X11 there are also the CUT_BUFFER0-CUT_BUFFER7 properties and XDND.

Re: How the clipboard works

#94

Post by mzs »

the_mitsuhiko wrote: post #14

This design has the really annoying situation that applications closing down can't leave stuff in the clipboard. This results in a quite a frustrating behavior for users and also makes command line tools tricky. wl-clipboard lets you pipe text into the command to copy. The way it works is that it daemonizes in the background to fulfill the copy request. It either cancels on the first paste (command) or until some oth…

lots results when I google 'wayland clipboard manager' - here's the first

https://github.com/yory8/clipman

Re: How the clipboard works

#95

Post by tinalumfoil »

mzs wrote: post #94
the_mitsuhiko wrote: post #14

This design has the really annoying situation that applications closing down can't leave stuff in the clipboard. This results in a quite a frustrating behavior for users and also makes command line tools tricky. wl-clipboard lets you pipe text into the command to copy. The way it works is that it daemonizes in the background to fulfill the copy request. It either cancels on the first paste (command) or until some oth…

lots results when I google 'wayland clipboard manager' - here's the first https://github.com/yory8/clipman

That's an unfortunate list of known issues.

Re: How the clipboard works

#96

Post by wheybags »

the_mitsuhiko wrote: post #71
ygra wrote: post #54

Earlier quoted context omitted.

Annoyingy, in Excel's case that question "Do you really want to quit? You have copied large amounts of data to the clipboard." even occurs when you have a single cell's worth in the clipboard. But that's also a confirmation question that no one really understands unless they understand how the clipboard works (or can work).

> in Excel's case that question "Do you really want to quit? You have copied large amounts of data to the clipboard." even occurs when you have a single cell's worth in the clipboard That's not correct. You need to have quite a few cells in the clipboard for this to happen. > But that's also a confirmation question that no one really understands The dialog tells you exactly what it is asking for. It gives you three o…

Most users know about copy paste, but have no idea what "the clipboard" is.

Re: How the clipboard works

#97

Post by tantalor »

If the copy-side app is supposed to serve the selection whenever requested, then what happens if the user interaction causes the selection to change or be removed? e.g., editing text or navigating to another page

Does the copy-side app have to keep that selection around in memory forever? That seems like a big downside.

> A big upside of this design is that no data is copied around unnecessarily.

That's only true as long as the copy-side app still needs the data, otherwise it needs to save a local copy it doesn't need.

Re: How the clipboard works

#99

Post by lupire »

SeanLuke wrote: post #85
jeroenhd wrote: post #17

For those wondering about how Windows does this, there is, as you'd expect, a Raymond Chen article about it: https://devblogs.microsoft.com/oldnewthing/20210526-00/?p=10... (and some more, like https://devblogs.microsoft.com/oldnewthing/20220608-00/?p=10... ) Elsewhere in these comments there is also a link to an explainer for the macOS equivalent. Here's also an explainer for X11: https://www.uninformativ.de/blog/po…

> Elsewhere in these comments there is also a link to an explainer for the macOS equivalent. I know you didn't mean anything by this, but given that the entire concept of a clipboard was invented by the Mac/Lisa team (the Xerox Alto didn't have one), it seems wrong to describe it as an "equivalent" to Windows.

Coming first doesn't make it less equivalent.

Re: How the clipboard works

#100

Post by lupire »

Beltalowda wrote: post #48
the_mitsuhiko wrote: post #14

This design has the really annoying situation that applications closing down can't leave stuff in the clipboard. This results in a quite a frustrating behavior for users and also makes command line tools tricky. wl-clipboard lets you pipe text into the command to copy. The way it works is that it daemonizes in the background to fulfill the copy request. It either cancels on the first paste (command) or until some oth…

It's disappointing to see Wayland copied X11's annoying clipboard semantics. I've been using X11 for so long I'm used to it now, kind of, but it still regularly bugs me or leads me to accidentally "lose" some things. Some time ago I tried to copy something to the X11 clipboard with a Go app, and this is basically impossible as Go can't fork into the background like xclip etc. do, so you need to either depend on a bit…

Why can't a Go program fork into the background?
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