Scaled (and rotated?) text drawing

[stevesims]

It would be nice to support scaled text drawing. Applying a factor to scale width and/or height of text when output would be good.

Unfortunately this functionality is not currently supported by vdp-gl.

A possible solution to this would be to support applying a transformation matrix to text drawing operations. This could allow for both scaling, and also rotation when drawing text. Transformation matrixes are being considered for bitmap plotting - this could potentially use a very similar approach.

NB rotation when drawing a complete string of text may require support within the VDP to understand drawing strings - currently text is drawn strictly one character at a time. Issues around rotating text are complex, and affect cursor position as well as just printing individual characters.

[stevesims]

we now have transformed bitmap plotting. the basic mechanism for this could be replicated for glyph plotting

inside agon-vdp the main complexity is really cursor movement - ensuring that the cursor moves as appropriate/expected from character to character. as there is no underlying support for printing strings of glyphs as a singular block of text, this may result in slightly idiosyncratic cursor movement

[stevesims]

The command VDU 23,0,&96,flags,bufferId; set a transform to be used by the graphics system.

The obvious thing to do here is to add a flag for "text" to this call. However as noted above there are complications here when it comes to cursor movement. One possibility could be to add a second flag to apply the transform to cursor movement too.

The VDP however now supports VDU 23, 0, &9B, bufferId; to print a buffer to the screen as a single string. We could have the transform apply only to this command.