An abstract widget is a category defined purely by what it does, not by how it looks.
A widget (sometimes called a concrete or specific widget) is one actual control you can place in a UI.
Button
The function gc.measureText(text) is a method provided by the Canvas 2D rendering context (gc is short for graphics context). It is used to measure how much space a specific string of text will occupy when rendered on the canvas with the current font settings.
Canvas Buffer: The utility renders text onto an off-screen canvas buffer to measure it accurately (like getting pixel-perfect metrics).
Caching: To improve performance, it caches the result of text measurements so that the same text string doesn’t need to be measured again unless the font changes.
Height = Ascent + Descent:
Ascent: Distance from the baseline to the top of the tallest character (like “Gˇ”).
Descent: Distance from the baseline to the bottom of the lowest character (like the tail of “g”).
The total font height is the sum of these two.
SKContainer to hold “child” widgets (i.e. SKElements)
