1.50 class elevation

General description of an elevated area. Elevations are mainly used to describe the edges of dialog_item objects. Elevations are reusable named objects. In its most simple form, an elevation object is simply created from its elevation<-height:

new(X, elevation(1))

describes a elevation<-kind: 3d elevation suitable for a colour environment.

Elevations come in two flavours: elevation<-kind: 3d will paint a hilited edge on the top and left sides of the object and a reduced edge on the bottom and right sides. By default these colours are computed from the context background colour using colour<-hilite and colour<-reduce.

A elevation<-kind: shadow elevation is designed for monochrome displays. It will paint a shadow at the bottom and right side of the objects to simulate the object elevated above the surface.

1.50.1 Instance variables

elevation <- colour: [{hilited,reduced}|colour|pixmap]

Colour or pixmap object used to fill the top of the elevated area. When @default, only the edges will be painted.

elevation <- height: int

Height above the surface. Actually this is the with of the edges painted with elevation<-relief and elevation<-shadow.

elevation <- kind: {3d,shadow}

How the elevation is realised. The default is 3d, which implies the top- and left-edges are painted using the elevation<-relief colour and the bottom- and right sides using the elevation<-shadow colour. elevation<-kind shadow will paint a shadow image at the bottom-right side of the object.

elevation <- name: name|int*

Identifier for reuse. All elevation objects created with a non @nil elevation<-name are stored in the table @elevations. elevation<-convert will convert elevation identifiers to elevation objects.

elevation <- relief: [colour|pixmap]

Colour/pixmap used at light side. When @default, the elevation object will invoke colour<-hilite using the current background. See also elevation<-shadow.

elevation <- shadow: [colour|pixmap]

Colour used to paint the right and bottom edges of the object. When @default, the elevation object will invoke‘colour elevation<-reduce’on the current background colour.

1.50.2 Send methods

elevation ->initialise: name=[name|int]*, height=[int], colour=[{hilited,reduced}|colour|pixmap], relief=[colour|pixmap], shadow=[colour|pixmap], kind=[{3d,shadow}], background=[{reduced}|colour|pixmap]

Create from elevation<-name and description parameters. In most cases the user will create an elevation object simply from its elevation<-height:

?- new(X, elevation(1)).

This will create a default elevation object. See the various attributes for the interpretation of the default values.

elevation ->unlink:

If the elevation<-name is not @nil, delete this elevation from the reuse table @elevations.

1.50.3 Get methods

elevation <-lookup: name=[name|int]*, height=[int], colour=[{hilited,reduced}|colour|pixmap], relief=[colour|pixmap], shadow=[colour|pixmap], kind=[{3d,shadow}], background=[{reduced}|colour|pixmap] -> elevation

elevation <-convert: name|int -> elevation

The elevation<-convert and elevation<-lookup methods realise reuse of elevation objects from the @elevations table.

elevation <-modify: attribute={height,colour,relief,shadow,kind,background}, value=any -> elevation

As elevation objects are reusable if they are named (see elevation->initialise), attributes of named elevation objects cannot be modified. This method returns a new elevation object with the requested attribute modified if the elevation<-name is not @nil and just modifies the attribute otherwise.