Design of an immediate graphical user interface api with managed layouts
Terms:
1. Canvas - a drawing area
User stories
1. I would like to call UI-rendering functions without specifying dimensions and locations
2. I would like to call custom UI-rendering functions while specifying dimensions and locations
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Story 2 needs a way to get a proper starting location or a bounding box If 1 is in place.
Consider the single method Layout interface:
type Layout interface {
// Advances the layout and returns a starting point
// for an element based on the last ending point.
Next(last Point) Point
}
Story 1 necessitates that library-aware UI-rendering functions acquire their starting locations
on their own. This allows for the following two approaches (more are possible of course)
* Store the ending point of the last element. New calls can get it and pass it to the layout
+ does not advance the layout unless required, saving cpu
+ does not imply a dependency on the layout, the UI drawing needs just a starting point
* Store the next starting point by calling Next() at the end of the element drawing routine.
The next drawing can continue from it.
- advancing the layout costs cpu
- the user might want an out of layer render
- puts a dependency on the layout
The first strategy is definatelly more sound and neatly allows for a layout-aware tracker
to handle the locations.
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3. I would like to enhance drawing functions with additional behavior (e.g. layout trackers, styling, etc)