Class: GraphicsDevice

• Inheritance
• Description
• Instance protocol
  • accessing
  • accessing & queries
  • creating graphics contexts
  • event processing
  • misc
• Private classes

Inheritance:

   Object
   |
   +--GraphicsDevice
      |
      +--HostGraphicsDevice

Package:

stx:libview

Category:

Interface-Graphics

Version:

rev: 1.40 date: 2022/10/11 14:39:57

user: cg

file: GraphicsDevice.st directory: libview

module: stx stc-classLibrary: libview

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 (block or responds to #processEvent:).
  deviceType      <Symbol>             some arbitrary symbol, used to choose windowSpecs.

copyright
COPYRIGHT (c) 1997 by eXept Software AG / Claus Gittinger
	      All Rights Reserved

 This software is furnished under a license and may be used
 only in accordance with the terms of that license and with the
 inclusion of the above copyright notice.   This software may not
 be provided or otherwise made available to, or used by, any
 other person.  No title to or ownership of the software is
 hereby transferred.

Instance protocol:

 displayId

 screen

 bePDA

 deviceType

 deviceType: aSymbol

 isPDA

 isWebServiceDevice

I am not a WebService pseudo-device

 literalArrayEncoding

(comment from inherited method)
generate a literalArrayEncoding array for myself.
This uses #literalArrayEncodingSlotOrder which defines the slots and
order and #skippedInLiteralEncoding which defines slots to skip.
In addition, an object may define virtualSlotsInLiteralEncoding for slots
which are not really instvars, but should be fetched via getters.
For most subclasses, there is no need to redefine those.

 supportsAlphaChannel

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

 supportsJPGImages

return true, if this device directly supports jpg images.
Currently none does (except browser windows)

Usage example(s):

Display supportsJPGImages

 supportsNativeImages

return true, if this device directly supports images (png, jpg, tiff, etc.).
If true is returned, the concrete image format to use must be negotiated further.
Currently none does (except browser windows and electron)

 supportsPNGImages

return true, if this device directly supports png images.
Currently none does (except browser windows)

Usage example(s):

Display supportsPNGImages

 supportsTIFFImages

return true, if this device directly supports tiff images.
Currently none does (except browser windows)

Usage example(s):

Display supportsTIFFImages

 newGraphicsContextFor: aGraphicsMedium

create a new graphics context.
The default is to use the inherited graphics context.
Subclasses may redefine this to use their own graphics context

 addEventListener: aListenerOrBlock

add a local eventListener (either a block or someone with protocol - #processEvent:)
This one gets a chance to intercept all events for this device.
Warning: the listener gets invoked synchronously, directly from the
display event dispatcher. It shall not terminate or block the system for long.

 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)

 removeEventListener: aListener

remove a local eventListener
(which is a block or something understanding #processEvent:)

 flush

send all buffered drawing to the display.
This used to be called #synchronizeOutput, but has been renamed
for ST-80 compatibility.

 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