SET DISPLAY UPDATE STATE(3P) — Kubota Pacfic Computer Inc. (26 March 1991)

NAME

SET DISPLAY UPDATE STATE − set Workstation Deferral and Modification Modes

SYNOPSIS

C Syntax

void
pset_disp_upd_st ( ws, def_mode, mod_mode )
Pintws;workstation identifier
Pdefer_modedef_mode;deferral mode
Pmod_modemod_mode;modification mode

Required PHIGS Operating States

(PHOP, WSOP, ∗, ∗)

DESCRIPTION

Purpose

SET DISPLAY UPDATE STATE sets the deferral and modification modes in the specified workstation’s state list. These modes provide control over when and how changes to the structure store and workstation tables actually appear in the display. These values have a great effect on both visual results and performance.

The deferral mode controls when the display is updated (in other words, made entirely correct). This allows you to delay time-consuming or visually-distracting regeneration until a set of related changes are completed or until a correct display is absolutely necessary, as before an operator input interaction can proceed.

The modification mode controls the visual effects that take place while the workstation is postponing display updates. This allows you to selectively change the display, but to avoid regenerating the entire picture.

C Input Parameters

wsIdentifier of the workstation whose update state to set.

def_mode
An enumerated value specifying the deferral mode to be set for this workstation. Valid values are defined in phigs.h:

PDEFER_ASAP Make the display visually correct As Soon As Possible
PDEFER_BNIG Make the display visually correct Before the Next Interaction Globally
PDEFER_BNILMake the display visually correct Before the Next Interaction Locally
PDEFER_ASTIMake the display visually correct At Some Time
PDEFER_WAIT Make the display visually correct When the Application Requests It

mod_mode
An enumerated value specifying the modification mode to be set for this workstation. Valid values are defined in phigs.h:

PMODE_NIVENo Immediate Visual Effects
PMODE_UWOR Update Without Regeneration
PMODE_UQUM Use Quick Update Methods

Execution

The SET DISPLAY UPDATE STATE sets the deferral mode and modification mode entries in the specified workstation’s state list. These modes control the degree to which the display must reflect the state of the central structure store and the workstation tables.

Deferral Modes

The deferral mode PDEFER_ASAP (As Soon As Possible) demands that the display be consistent with the structure store and the workstation state list at all times. This typically causes a regeneration (in other words, clearing of the display and traversal of all posted structure networks) for every change to a structure appearing on the workstation, and for every change to the workstation’s state list. The modification mode is unused when the deferral mode is ASAP.

The deferral mode PDEFER_BNIG (Before the Next Interaction Globally) behaves just like PDEFER_ASAP when any input device is active on any workstation. The deferral mode PDEFER_BNIL (Before the Next Interaction Locally) behaves just like PDEFER_ASAP when any input device is active on this workstation. Otherwise, they behave exactly like At Some Time, as described below. An input device is considered active the entire time it is in EVENT or SAMPLE mode, or while a REQUEST is pending for the device (although nothing but window redisplay can occur while a REQUEST is pending, because it necessarily blocks).

The deferral mode PDEFER_ASTI (At Some Time) updates the display only at certain times, which are at the discretion of the PEX implementation and are workstation dependent.

The deferral mode PDEFER_WAIT (When the Application Requests It) does not implicitly update the display. Explicit updates are requested by using REDRAW ALL STRUCTURES or UPDATE WORKSTATION with PERFORM.

Modification Modes

During modification mode PDEFER_NIVE (No Immediate Visual Effects), the only changes to the display are those that would be done in accordance with the deferral mode.

Note: When the Application Requests It and No Immediate Visual Effects used together prohibit any change to the display in response to changes in the central structure store or the workstation state lists.

The modification mode PDEFER_UWOR (Update Without Regeneration) performs all updates that can be realized immediately without regenerating the entire display. This includes the actions whose dynamic modification accepted entries in the workstation description table are set to Immediately.

The modification mode PDEFER_UQUM (Use Quick Update Methods) allows use of workstation dependent simulations of changes that cannot be performed immediately unless the display is regenerated. These simulations are described in the section Available Quick Update Methods. Actions for which a quick update method is available have dynamic modification accepted entries in the workstation description table set to Can Be Simulated. As in Update Without Regeneration mode, actions whose dynamic modification accepted entries in the workstation description table are set to Immediately are performed immediately. Unless an action can be simulated or the update performed immediately, the update is deferred, as if the modification mode were No Immediate Visual Effects.

State of Visual Representation

The workstation’s state of visual representation indicates whether the display is Correct, Simulated (but no updates have been deferred), or Deferred. This state list value may be obtained using INQUIRE DISPLAY UPDATE STATE(3P).

Changing the deferral mode causes a regeneration, if the display is not correct and the new deferral mode requires it. Changing the modification mode has no retroactive effect on previous changes that have been simulated or deferred.

Available Quick Update Methods

Quick update methods are dependent on the server implementation. The PEX-SI API does not provide any quick updates.

Interactions between Deferral and Modification Modes and X Window System

PEX-SI regenerates the image from the CSS when the window is damaged by window system events. This can occur even if the deferral mode is When the Application Requests It (WAIT) and the modification mode is No Immediate Visual Effects, which used together prohibit implicit changes to the display. However, only the damaged portion of the PEX-SI canvas is repainted. Hence, the regeneration may use newer information than that which generated the older, out-of-date, but not damaged portion, which is also visible and may not match the newly drawn portion. To remove any visible mismatch, the entire window can be updated by selecting Refresh from the canvas’s Frame menu (assuming that the user is using XView).

ERRORS

003Ignoring function, function requires state (PHOP, WSOP, ∗, ∗)

054Ignoring function, the specified workstation is not open

059Ignoring function, the specified workstation does not have output capability (in other words, the workstation category is neither OUTPUT, OUTIN, nor MO)

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