The clipboard and drag and drop

Ctrl+C puts the picture on the clipboard, Ctrl+V shows whatever picture is on it, and Ctrl+Shift+C copies the file’s path — quoted, so a path with a space in it survives being pasted into a terminal.

What is copied is the file’s own pixels, unconverted, which is the same decision the histogram and the eyedropper follow: the numbers on the clipboard are the numbers those tools report. A CF_DIB has nowhere to say what its numbers mean, so a wide-gamut picture will look flatter in an application that assumes sRGB. That is a true thing about the Windows clipboard rather than something a viewer should paper over by quietly rewriting the pixels on the way out. Transparency is composited onto white, because CF_DIB carries no dependable alpha and a cut-out is nearly always going onto a white page.

Ctrl+Alt+C copies it as something sendable. Two things go on the clipboard at once, the way a drag offers two: a JPEG file, and the pixels. A chat window or a mail client takes the file; an editor that paints takes the pixels, exactly as it does today.

The file is made to a budget in kilobytes, not to a quality number. Nobody knows what quality 74 weighs — it depends entirely on the picture — and everybody knows what an attachment limit is, so the viewer searches for the best-looking JPEG that fits and says which quality it settled on. The picture is shrunk to a maximum width first, and its colour is baked into sRGB, because what is travelling is a file going to a program that will very likely ignore a profile. Both numbers are in the settings, at 500 KB and 2048 pixels to start with. A budget nothing can meet is said so rather than quietly broken.

This is the one place the viewer writes a file without being asked for a file, and it is asked for this one: the JPEG goes to a folder of its own inside the temporary directory, named after the picture so what lands in a chat carries a name that means something. Nothing appears in the folder you are looking at.

A pasted picture is shown, not saved. It has no file behind it: the title says clipboard, the arrow keys have nowhere to go, and nothing is written to disk. A viewer that quietly saved a temporary file on every paste would be writing without being asked and leaving the results behind. See ADR 0020.

Drag and drop

Files dropped on the window open. A selection of several arrives as the several it was, and the arrow keys then walk those files rather than the hundreds sitting beside them in the folder — the same thing multi-select does from the shell. While files are held over the window it says so, because a drag with no answer looks like a window that will not take it.

Ctrl and a drag hands the picture the other way, into a chat, a mail, an editor. What travels is the file where there is one and the picture where there is not, offered together so the receiving application takes whichever it understands: a mail client gets the original file, with its format and its metadata intact, and an editor that paints gets the pixels. Only a copy is ever offered — a drag that could move the file would delete the photograph you are looking at. See ADR 0021.

The bare drag stays panning. A picture pasted from the clipboard has no file to hand over, so it travels as pixels only; nothing is written to disk to make it look otherwise.