Limits

Overview

Each element provides information on how it wants to be sized by means of min and max limits: a hint that determine its actual extent and how it will be placed in the view depending on available window space.

view_limits

view_limits is a struct that gives us the min and max information:

Declaration

struct view_limits
{
   point    min = {0.0, 0.0};
   point    max = {full_extent, full_extent};
};

Notation

full_extent: An implementation-defined huge number that signifies an unbounded extent.
point: A data structure representing a coordinate in a 2D space used to specify positions or dimensions within the graphical context.

full_limits

By default, an element has full limits, meaning there is no constraints on its size. It is infinitely resizable:

constexpr view_limits full_limits = {
   {0.0, 0.0}
 , {full_extent, full_extent}
};

An element with full_limits can be resized from an empty point (zero x and y size) up to the full extent of the screen, and beyond (if possible).

An element has a fixed horizontal size if this expression is true: limits.min.x == limits.max.x.
An element has a fixed vertical size if this expression is true: limits.min.y == limits.max.y.

Examples

{{100, 100}, {100, 100}}; // Fixed size

{{100, 100}, {100, full_extent}}; // Fixed width, flexible height

{{100, 100}, {100, 200}}; // Fixed width, semi-flexible height (100 to 200)

Terms and Expressions

For the purpose of this document, we will use these terms and expressions:

limits: The limits of an element
limits.min: The minimum limits of an element
limits.min.x: The minimum horizontal limit of an element
limits.min.y: The minimum vertical limit of an element
limits.max: The maximum limits of an element
limits.max.x: The maximum horizontal limit of an element
limits.max.y: The maximum vertical limit of an element
horizontal limits: (limits.min.x, limits.max.x)
vertical limits: (limits.min.y, limits.max.y)
minimum limits: (limits.min.x, limits.min.y)
maximum limits: (limits.max.x, limits.max.y)
minimum horizontal limit: limits.min.x
maximum horizontal limit: limits.max.x
minimum vertical limit: limits.min.y
maximum vertical limit: limits.max.y