# Browser Clipboard
Platform-neutral clipboard abstractions, to access platform-specific clipboards
(copy/paste) without platform-specific code.
## Clipboard Model
The clipboard can be thought of as an ordered dictionary keyed on format, with
the value as the payload. This dictionary is implemented and accessed
differently on different operating systems (OS’s).
## Interfaces
Interfaces include:
* `Clipboard`: reading/pasting from the clipboard.
* `ScopedClipboardWriter`: writing/copying to the clipboard.
* `ClipboardObserver`: notifications of clipboard events.
* `ClipboardFormatType`: specifying clipboard formats.
## Platform-specific behavior
While most platform-specific behavior should be abstracted away, some may
still be exposed. For some notable platform-specific behavior exposed by these
interfaces:
* `ClipboardAndroid` has a more limited set of supported formats.
* `ClipboardObserver` is only supported on some platforms, as other platforms
may require (inefficient) polling to implement.
* Every platform may have different combinations of clipboard formats written,
or metadata written, for each clipboard format. For example, text in Windows
is written with a carriage return accompanying newlines, and in Linux requires
multiple MIME types to represent.
* `ClipboardX11` supports both the usual clipboard buffer (CLIPBOARD selection),
as well as the middle-click paste buffer (PRIMARY selection). X11 selections
are documented in more detail in
[X11 documentation](https://tronche.com/gui/x/icccm/sec-2.html#s-2.6.1).
* `DataTransferPolicyController` is only currently exercised in ChromeOS.
* `ClipboardWin` and `ClipboardX11` have limits to the amount of registered
clipboard formats. Windows has the smallest limit on the number of formats, at
[16384](https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-registerclipboardformata#remarks),
and explored in
[this article](https://devblogs.microsoft.com/oldnewthing/20150319-00/?p=44433).
After these system resources are exhausted, the underlying OS may be rendered
unusable.
Codebase Browser
chromium