[haiku-bugs] [Haiku] #9457: API for Obtaining Cursor Shape Bitmap and Change Notification
- From: "AGMS" <trac@xxxxxxxxxxxx>
- Date: Wed, 13 Feb 2013 21:03:27 -0000
#9457: API for Obtaining Cursor Shape Bitmap and Change Notification
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Reporter: AGMS | Owner: axeld
Type: enhancement | Status: new
Priority: normal | Milestone: R1
Component: Servers/app_server | Version: R1/Development
Keywords: cursor, vnc | Blocked By:
Blocking: | Has a Patch: 0
Platform: All |
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While updating the BeOS VNC server for Haiku, it occurs to me that it
would be nice to have the Haiku specific cursor (hand shape, pointer
arrow, insertion marker, etc) displayed at the VNC client side of things.
VNC has an API for transmitting the cursor, and the client software does
change the system cursor there to match the new bitmap. All we need to
have is the bitmap from Haiku and some sort of notification of when it has
changed.
Since we're using a BDirectWindow to do the screen scraping, perhaps the
API could be added there (that also avoids the problem of deciding which
workspace it is on, etc). Though I think someone with more knowledge
should decide where it should go. The API could be something like this:
* GetCursorBitmap - reads the current cursor bitmap, includes alpha
transparency. Need the pixel format too, if it's not a simple RGBA 32 bit
pixel, and maybe worry about endianness too.
* GetCursorSerialNumber - gets the count of the number of times the cursor
has been changed. The idea is that the VNC server will periodically call
this and if the number has changed, get the new cursor bitmap and transmit
it over the network to the client.
* IsCursorDrawn - returns TRUE if the cursor is being drawn into the
screen video memory. FALSE if it is a separate video hardware cursor.
If the hardware cursor is off or not implemented, then it does seem to
work, since Haiku writes the cursor shape into the screen's bitmap and VNC
picks that up. If the hardware cursor is operational, then the user
doesn't see anything and the VNC client currently substitutes a black dot
or some other fixed graphic to show where the mouse is.
By the way, one other obvious but actually not useful VNC optimisation
would be to have the app_server report all the dirty areas of the screen,
so VNC can know which parts need updating over the network. It currently
scans the whole screen to find the changed parts, which can be slow. On
the other hand, the current method is more responsive since it scans in
slices so each update will be small enough to keep feedback (mouse
movement) fast. So using the dirty areas would actually make things feel
slower for the user!
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Ticket URL: <http://dev.haiku-os.org/ticket/9457>
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