Dear all,
find attached (as header file) an enhancement to the SDL 1.3 Clipboard
API, which extends it to support arbitrary content types and implicit
conversion mappings to allow applications easier access to external
content.
Background----------
The current implementation only supports text content in a quite limited
fashion. Furthermore, on X11 various aspects of exchanging data are not
realised, such as request timestamp awareness, compound text handling or
a distinction between the clipboard and selection buffer.
Also, most applications nowadays make their content available in
multiple formats, which gives applications accessing that content more
freedom to choose the format which they can handle best.
Internals
From an internal perspective I would recommend to implement a singleton
data structure
struct _SDLClipboard {
SDL_ClipboardMode mode;
void _ownedcontent[]; / pointers to content in the clipboard */
/* next are only for X11 */
Time _timestamp[];
Atom _clipatoms[];
};
which keeps track of the set mode, registered clipboard types (relevant
for X11), timstamps and the content placed into the clipboard by the SDL
application (so it can access the most recent content without the need
to use the OS-specific clipboard APIs).
Would the structure need to use the Atomic API for thread safety? I did
not look into that too much, so how is done for other internals of SDL
1.3?
Discussion
BMP format for exchanging SDL surface data might be reasonable to
implement. On Win32 we can utilise the DIB clipboard type without too
much effort. Something similar can be used for X11-based systems.
From what I know, MacOS X uses TIFF as standard format, so maybe there
are native API calls to create TIFF buffers without the need to link
against libTIFF. If not, the BMP format could be used, too.
Since I do not know much about the MacOS X APIs, I would like to hear
some feedback on that matter from a more knowledgable person :-).
X11 supports selection buffers and a “standard” clipboard for retrieving
or placing content. It is - given the 3 majors, MacOS X, Win32, X11 -
the only one that supports those buffers.
Is support for the selection buffer wanted? If so, the methods clipboard
mode functions from the API proposal could be introduced. Since the
mouse selection is commonly used in X11 environments, I would like to
support this, though it will make the API a bit more complex.
Automatic type mapping
Different platforms support a variety of built-in formats, such as
XA_STRING and XA_COMPOUND_TEXT on X11, CF_TEXT and CF_UNICODETEXT on
Win32, own format type definition, etc.pp.
My proposal is to have a defined mapping set on each platform to ensure
a solid interoperability with different programs.
Plain Text content would be mapped from “text/plain” to:
X11:
XA_STRING
"TEXT"
“UTF8_STRING”
“text/plain”
“text/plain;charset=ascii"
Win32:
CF_UNICODETEXT
CF_TEXT
"text/plain”
"text/plain;charset=ascii"
MacOS X:
/* I would love to have some insights about the Mac APIs here */
Surface content would be mapped to:
X11:
XA_BITMAP (PBM)
XA_PIXMAP (PPM)
“image/pbm”
“image/ppm”
"image/bmp"
Win32:
CF_DIB
"image/bmp"
MacOS X:
/* I would love to have some insights about the Mac APIs here */
Other implicit mappings:
X11:
“text/plain;charset=utf-8” -> “UTF8_STRING"
Win32:
“audio/wav” -> CF_WAVE
"text/plain;charset=utf-8” -> CF_UNICODETEXT
MacOS X:
/* I would love to have some insights about the Mac APIs here */
Feedback is highly appreciated.
Best regards
Marcus
-------------- next part --------------
A non-text attachment was scrubbed…
Name: SDL_clipboard.h
Type: text/x-chdr
Size: 5640 bytes
Desc: not available
URL: http://lists.libsdl.org/pipermail/sdl-libsdl.org/attachments/20111116/ef946c27/attachment.h
-------------- next part --------------
A non-text attachment was scrubbed…
Name: not available
Type: application/pgp-signature
Size: 196 bytes
Desc: not available
URL: http://lists.libsdl.org/pipermail/sdl-libsdl.org/attachments/20111116/ef946c27/attachment.pgp