Window Objects: 3.2 Using Multiple Displays: GenDisplayControl

The GenDisplayGroup object does half the job of managing display objects: it creates a space for the displays and manages them as its children. However, the display group does very little interaction with the user. Instead, the user works mainly with the GenDisplayControl object.

The GenDisplayControl is usually a child of a "Window" GenInteraction, which is itself a child of the primary. GenDisplayControlClass is a subclass of GenControlClass , and it has all the functionality of that class. For more information, see the GenControlClass chapter.

GenDisplayControlClass is based very closely on GenControlClass . The differences between it and GenControlClass are shown below in Instance Data of GenDisplayControlClass .

Code Display 4-4 Instance Data of GenDisplayControlClass

/* GDCII_attrs is a byte-length flag field. There is currently only one flag,
 * namely GDCA_MAXIMIZED_NAME_ON_PRIMARY; this specifies that if the active
 * display is maximized, its name should be shown as the primary's long-term 
 * moniker. */
    @instance 		GenDisplayControlAttributes				GDCII_attrs =
						(GDCA_MAXIMIZED_NAME_ON_PRIMARY);

@default		GI_states = @default | GS_ENABLED;
@default 		GCI_output = {TO_APP_TARGET};

  typedef WordFlags GDCFeatures;
#define GDCF_OVERLAPPING_MAXIMIZED					0x0004
#define GDCF_TILE					0x0002
#define GDCF_DISPLAY_LIST					0x0001

  typedef WordFlags GDCToolboxFeatures;
#define GDCTF_OVERLAPPING_MAXIMIZED					0x0004
#define GDCTF_TILE					0x0002
#define GDCTF_DISPLAY_LIST					0x0001

#define GDC_DEFAULT_FEATURES 				(GDCF_OVERLAPPING_MAXIMIZED | GDCF_TILE 
				| GDCF_DISPLAY_LIST)

#define GDC_DEFAULT_TOOLBOX_FEATURES (GDCF_DISPLAY_LIST)

/* A GenDisplayControl also features a single hint which affects the display of 
 * the features list. */
    @vardata void  HINT_DISPLAY_CONTROL_NO_FEATURES_IF_TRANSPARENT_DOC_CTRL_MODE;

The GDCII_attrs field contains a set of GenDisplayControlAttributes . There is currently only one flag defined among these attributes:

GDCA_MAXIMIZED_NAME_ON_PRIMARY: If this attribute is set and the active display is maximized, the name of the selected display will be shown in the long term moniker of the GenPrimary.

HINT_DISPLAY_CONTROL_NO_FEATURES_IF_TRANSPARENT_DOC_CTRL_MODE suppresses display of the features list if the application is running in "transparent document control" mode, as selected by the user level of the application.

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3.3 Using GenDisplayClass Objects