PlaceableTwopass [Layout Library (Eve)]

Detailed Description

A model of the PlaceableTwopass concept is an item that can be measured and placed within a visual space.

Refinement Of:

Associated Types:

Extents Type	typename placeable_extents_type<PlaceableTwopass>::type	Models adobe::extents_t. Used by the PlaceableTwopass to relate the minimum visual extents it requires in order to be placed correctly.
Placement Data Type	typename placement_data_type<PlaceableTwopass>::type	Models adobe::place_data_t. Contains the derived information necessary for the PlaceableTwopass to position itself within the visual space

Todo:

Need concepts for extents and placement data

Notation:

T	A type that is a model of PlaceableTwopass
t	Object of type T
e	Object of type typename placeable_extents_type<PlaceableTwopass>::type
p	Object of type typename placement_data_type<PlaceableTwopass>::type

Definitions:

Valid Expressions:

Name	Expression	Type requirements	Return type
Measure Horizontal	measure_horizontal(t, e);	e is a reference parameter that on return must contain the calculated horizontal extents of t within the visual space	void
Measure Vertical	measure_vertical(t, e, p);	p contains the calculated place_data_t of t within the visual space. e is a ouput only reference parameter that on return must contain the minimum visual vertical properties required by this visual element	void
Place	place(t, p);	p contains the calculated horizontal and vertical extents of t within the visual space	void

Expression Semantics:

Name	Expression	Precondition	Semantics	Postcondition
Place	place(t, p);	p must not be less than the minimum extents specified by measure_horizontal and measure_vertical	Places t within the visual space according to p	t is properly placed within the visual space

Complexity Guarantees:

Invariants:

Type(s) Modeling this Concept:

• Most text-based user interface elements are PlaceableTwopass, in that they need to be measured before they can be placed appropriately within the dialog to which they belong.

Notes:

See Also:

concept_placeable_twopass, measure_horizontal, measure_vertical, place

Example:

    PlaceableTwopass_t             p;

    using adobe::measure_horizontal;
    using adobe::measure_vertical;
    using adobe::place;

    adobe::extents_t h;
    measure_horizontal(p, h);

    adobe::extents_t v;
    adobe::place_data_t(/*initialized with h and actual placement location*/);

    measure_vertical(p, v, d);

    /* update place data, d, with vertical info returned in v, then call: */
    place(p, d);