Calculate rectangular text metrics

Reviewed and updated November 2018

Updated axcall MIAMEX, MX_GDICALC, MXGDI_CALCRECT, handle, status, lft, top, rght, btm, memo, height, overflow {,flags}

This operation calculates how much text will fit in a specified rectangle, based on the current printer context and font.

Parameter	Type	I/O	Description
handle	B,4	in	Device context handle (from MXGDI_OPEN)
status	F,6	out	MX_GDICALC Status Codes.
lft,top, rght,btm	Num	in/out	Coordinates of the rectangle, in the units specified by mapmode when the printer device context was established. Coordinates rght and btm are are updated only when flags parameter contains TRF_CALCRECT option. lft and top are never updated.
memo	String	in/out	On input, specifies the text we want to output within the rectangle. On return, it contains the amount of the original text that actually fits in the rectangle.
height	Num	out	If memo fits entirely within the rectangle, height returns the rectangle height actually required (which may be less than the full rectangle height). Otherwise, it will return the input height of the rectangle.
overflow	String	out	Returns the trailing portion of memo which does not fit within the rectangle. If it all fits, then a null string is returned here. Note that this operation supports a dynamic string (S,0).
Flags	Num	in	Optional flags used when calculating the optimum rectangle based on various formatting options.

Comments

The vertical spacing used for the calculation is the natural vertical spacing for the current font and printer device context. To make sure you get the same spacing when actually printing, use the GDI printing directive //RESETLPP after the //SETFONT and before the //TEXTRECTANGLE. The vertical spacing is not automatically reset by //SETFONT.

If memo must be wrapped to multiple lines to fit within the rectangle, standard word-wrapping logic will be used to avoid breaking lines mid-word. Embedded CRLFs are also respected.

You can use this operation iteratively (changing the font size incrementally each time) to determine the optimum font size for the specified memo text to fit within the rectangle.

The test program GDICALC in EXLIB:[908,37] is to illustrate this kind of logic.

Note that MXGDI_CALCRECT assumes vertical spacing optimum for the font, i.e. as if a //RESETLPP command had been executed after the //SETFONT. If you don't do this in the actual GDI print file, the spacing for the print operation may not match that used for the calculations.