The AUI Box Model is layout structure for all types of AViews, which combines margin, padding, border, and background elements to create a visual container, defining the outer appearance of each AView as a rectangular block on-screen.

Box key components#

View's content box: the area are whose size is defined by AView::getContentMinimumSize() and AView::getContentSize(). The content area is the innermost area, wrapping view's specific contents only (i.e, label's text); control it by implementing AView::getContentMinimumWidth() and AView::getContentMinimumHeight().
View's box: the area whose size is defined by AView::size(). Use ass::FixedSize, ass::MinSize and ass::MaxSize to control it.

Views are responsible to handle its padding properly. As an AUI user, you wouldn't need to bother about that unless you are implementing custom AView::render().

BackgroundSolid and similar Aui Style Sheets properties are fit into this box.

Border property outlines this box from the inner side, and never affects the layout; it's just a visual trait.
View's margin: the margin is the outermost layer, wrapping the content, padding, and border as whitespace between this box and other elements; control it using ass::Margin.

Layout manager of view's parent is responsible to handling margin properly. All layout managers tend to honor children margins; with an exception to AWindow (it's margin has no effect) and AAbsoluteLayout (positioning and sizing is defined manually). As an AUI user, you wouldn't need to bother about that unless you are implementing custom layout manager.

Comparison to CSS#

AUI shares principles with web technologies with some exceptions. In AUI:

border never affects layout
element's size includes padding, thus it differs from "content area"

AUI's box model is equal to CSS's "alternate box model", with an exception to border.

Contents

Box key components

Comparison to CSS

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