some convenience c++ functions

reset the state to default

API click: on mouse down, move the cursor to the clicked location, and reset the selection

API cut: delete selection

discard the oldest entry in the redo list--it's bad if this ever happens, but because undo & redo have to store the actual characters in different cas

API drag: on mouse drag, move the cursor and selection endpoint to the clicked location

API initialize

API key: process a keyboard input

API paste: replace existing selection with passed-in text

stb_textedit internally allows for a single undo record to do addition and deletion, but somehow, calling the stb_textedit_paste() function creates tw

returns number of contours

rects array must be big enough to accommodate all characters in the given ranges

note: this routine clips fills that extend off the edges... ideally this wouldn't happen, but it could happen if the truetype glyph bounding boxes are

x^3 + c*x^2 + b*x + a = 0

tessellate until threshold p is happy... @TODO warped to compensate for non-linear stretching

Convert ABGR To AR30.

Same as NV12 but U and V swapped.