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digitalmars.D.dwt - Curse you, DWT Cursors!

reply Bill Baxter <dnewsgroup billbaxter.com> writes:
As far as I can tell SWT (and therefore DWT) Cursors do not support 
alpha masks (only 1-bit masks).  They also don't have any official way 
to do an end run around the API and use native calls if desired.

Fortunately the bits of state needed to work around it are public (the 
default constructor and access to the .handle property), though 
unintentionally so, it seems.

--bb
Apr 09 2008
parent reply Frank Benoit <keinfarbton googlemail.com> writes:
Bill Baxter schrieb:

 As far as I can tell SWT (and therefore DWT) Cursors do not support 
 alpha masks (only 1-bit masks).  They also don't have any official way 
 to do an end run around the API and use native calls if desired.
 
 Fortunately the bits of state needed to work around it are public (the 
 default constructor and access to the .handle property), though 
 unintentionally so, it seems.
 
 --bb


The JavaDoc of Cursor.handle:
the handle to the OS cursor resource (Warning: This field is platform 
dependent)
IMPORTANT: This field is not part of the SWT public API.

http://help.eclipse.org/help33/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/swt/graphics/Cursor.html#handle

There are several fields/methods that are accessible but not part of the 
public SWT API. This is, because they need to access those from other 
SWT packages. Not nice, but at least in the JavaDoc its documented.
Apr 13 2008
parent Bill Baxter <dnewsgroup billbaxter.com> writes:
Frank Benoit wrote:

 Bill Baxter schrieb:

 As far as I can tell SWT (and therefore DWT) Cursors do not support 
 alpha masks (only 1-bit masks).  They also don't have any official way 
 to do an end run around the API and use native calls if desired.

 Fortunately the bits of state needed to work around it are public (the 
 default constructor and access to the .handle property), though 
 unintentionally so, it seems.

 --bb


 
 The JavaDoc of Cursor.handle:
 the handle to the OS cursor resource (Warning: This field is platform 
 dependent)
 IMPORTANT: This field is not part of the SWT public API.
 
 http://help.eclipse.org/help33/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/swt/graphic
/Cursor.html#handle 
 
 
 There are several fields/methods that are accessible but not part of the 
 public SWT API. This is, because they need to access those from other 
 SWT packages. Not nice, but at least in the JavaDoc its documented.


Ok, I saw the comment and took it to mean that it may become 'private' 
at some point.  Anyway, the fact that it is accessible makes it possible 
to feed it a cursor loaded from the native API, so I see that as a good 
thing.

My guess is that that SWT designers have not really given much thought 
to allowing raw access to underlying platform resources because in java 
it would just be too much of a pain for anyone to want to try to 
customize their app's behavior with native code beyond what's provided 
in SWT.   However, in D the situation is different.  It's not at all 
difficult to access native APIs, and you have a handy version() 
statement that lets you conditionally compile the code that uses those APIs.

Qt's Cursor API, for instance, has an offical (Windows-only) API that 
takes an HCURSOR:
   http://doc.trolltech.com/4.3/qcursor.html#QCursor-6

So what I'm saying is that it might not be such a bad idea to provide 
official ways to do some platform-specific things in DWT, since DWT is 
not constrained by the same forces that constrain SWT.

--bb
Apr 13 2008