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Class: GraphicsDevice


Inheritance:

   Object
   |
   +--GraphicsDevice
      |
      +--HostGraphicsDevice

Package:
stx:libview
Category:
Interface-Graphics
Version:
rev: 1.19 date: 2017/04/12 07:57:56
user: cg
file: GraphicsDevice.st directory: libview
module: stx stc-classLibrary: libview
Author:
Claus Gittinger

Description:


this abstract class was inserted to provide a home for ST-80 classes
(previously, DeviceWorkstation was directly under Object).

In ST/X, this is mostly dummy.

[instance variables:]
  displayId       <Handle>            the device handle
  screen          any                 another some device specific id
  eventListeners  <Collection> | nil  bunch of objects interested in events.
  deviceType      <Symbol>             some arbitrary symbol, used to choose windowSpecs.


Related information:

    DeviceWorkstation
    XWorkstation

Instance protocol:

accessing & queries
o  addEventListener: aListener
add a local eventListener (with new protocol - #processEvent:)
This one gets a chance to intercept all events for this device

o  bePDA

o  deviceType

o  deviceType: aSymbol

o  isPDA

o  isWebServiceDevice
I am not a WebService pseude-device

o  removeEventListener: aListener
remove a local eventListener (with new protocol - #processEvent:)

o  supportsAlphaChannel
return true, if this device supports alpha information.
Currently none does

creating graphics contexts
o  newGraphicsContextFor: aGraphicsMedium
create a new graphics context.
The defaults is to use the inherited graphics context.
Subclasses may redefine this to use their own graphics context

event processing
o  notifyEventListenersAbout: anEvent
notify all eventHandlers about an incoming event.
If any returns true, it is assumed to be eaten by the handler and not
enqueued (i.e. not passed to the windowGroup process)

misc
o  roundTripTime
answer the round trip time in milliseconds.
May be used to detect slow device connections.
Subclasses redefine this. Assume a fast Diplay connection
and answer 0 here
usage example(s):
     Screen current roundTripTime


Private classes:

    GraphicResourceAllocationFailure


ST/X 7.1.0.0; WebServer 1.663 at exept.de:8081; Mon, 12 Nov 2018 21:57:13 GMT