_HEIGHT - mkilgore/QB64pe GitHub Wiki

The _HEIGHT function returns the height of an image handle or of the current write page.

Syntax

columns& = _HEIGHT[(imageHandle&)]

If imageHandle& is omitted, it's assumed to be the handle of the current SCREEN or write page.
To get the height of the current program screen window use zero for the handle value or nothing: lines& = _HEIGHT(0) or lines& = _HEIGHT
If the image specified by imageHandle& is in text only(SCREEN 0) mode, the number of characters per row is returned.
If the image specified by imageHandle& is in graphics mode, the number of pixels per row is returned.
If imageHandle& is an invalid handle, then an invalid handle error is returned.
The last visible pixel coordinate of a program screen is _HEIGHT - 1.