Graeme Geldenhuys schrieb:
On 23 January 2011 03:16, Hans-Peter Diettrich <DrDiettrich1@a*****> wrote:
Clipboard formats (CF_...) may be usable on all platforms with a
comparable/compatible clipboard functionality. But what about all the other
platforms?
As I mentioned, fpGUI uses mime-types. More and more platforms are
starting to use mime-types too - a natural evolution (considering the
success in emails).
That's okay for data files, but not necessarily sufficient for draggable
objects in general.
fpGUI will register the mime-types, and if a
similar platform specific type exists, fpGUI will automatically
register that format too (eg: mime-type 'text/plain' under Windows
will automatically also have the CF_TEXT type registered). For each
platform fpGUI supports, I simply need to override and implement
platform specific DND/Clipboard types too (not replacing the
mime-types though).
Such a *definition* of types doesn't make any sense to me, in DND or
clipboard context. Either different applications have to agree about
exchangable data formats, or a single application needs only private
types, for strictly private use.
Your current implementation is restricted to purely textual information,
Simply because I was in a rush to implement the basic workings of DND
for a new project of ours. Textual information was good enough to get
that app's DND going. The DND does does lend itself to other data
types too. Any binary data will simple be transfered via bytes, and
internal component-to-component DND could possible also support
TStream data.
This is one of the optimizations that can be implemented for internal app DND.
This is not a matter of optimization, it's a matter of specialization.
Every data type must be associated with a class (or component), that
*interprets* the data in the intended way. All you need is a
*registration* system for such classes.
I'm not sure whether your implementation of rich (html...) text will match
the platform standards - with possibly different standards on every single
platform :-(
Once I'm done with the complete DND implementation in fpGUI, the
developer can register for example HTML data via 'text/html', but can
retrieve 'text/plain' data (all HTML tags stripped) without any extra
effort. fpGUI will automatically do translations between various
popular formats.
This is a matter of extensions as well. Nice to have, but IMO subject to
according libraries. Windows leaves it to the clipboard owner, to
provide its data in any supported format, and only when requested by a
clipboard viewer. Only very basic conversions (text encoding) are
supplied by the OS, or may be supplied by e.g. fpGUI. Further filters or
converters can be taken from e.g. syntax highlighters or other
components, which can register themselves (see above).
Question remains: which mime type should be associated with e.g. dragging
files, or forms?
If it's between your own applications, you can use whatever mime-type
makes sense to you. But between applications, the most common mine
type would be 'text/uri-list'. URI lists are even good enough for DND
between computers (Gnome took shortcuts here and doesn't support
this). An example of the latter, is executing a X11 app or a remote
server, while the display of that app is on your system. So dragging
from that remote app to your local apps, the URI should contain the
system name (or IP) too.
Did you realize that URI lists are meaningful only to applications, that
can handle the referenced resources - in their specific data format,
that is not part of the URI. Otherwise the only use of such information
is textual display of the URIs themselves, that does not require any
special conversion.
How comes that I cannot drop anything from outside the demo app
I can drag text from a web page displayed in Firefox (data type is
'text/html' and a few others). I can also drag the URL of the website
to the demo app, without problems.
Okay, Firefox works - but why then do you not simply show the CF_TEXT or
CF_UNICODETEXT format?
Now that I have a source application, I can play a bit with the missing
display features of the demo app...
, and no other app accepts the "Drag Me!"?
The demo registers 'text/plain' and 'text/html' mime-types, so only
apps that accept that (or under Windows, the CF_TEXT format too) will
receive data. I can drag the "Drag Me!" green label for example into
gEdit and indeed I see the text data "My name is Earl" appear in
gEdit. What system are you using to run that demo?
I'm using Win7, and none of the standard applications (notepad...) seems
to even take notice of an drag from the demo app, while it reacts and
accepts drops from other sources.
DoDi
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