84PCSE:RAM:Page3:8941

Synopsis

Unofficial Name: pixelShadow

Memory Address: (Page 3) 8941h

Length: 8400 bytes

Stores a monochrome image of the current screen contents (excluding the status bar area.)

Comments

Under normal circumstances, the system text drawing routines will draw character bitmaps to this buffer (in addition to displaying the character on screen.) This area is then used by ScrollUp and ScrollDown to redraw the screen contents somewhat more quickly than PutMap would. (The downside, of course, is that maintaining the pixelShadow buffer makes PutMap itself somewhat slower.)

Several flags affect the use of this buffer:

• When either appTextSave is cleared or textDisplayOnly is set, nothing is drawn to the pixel shadow. For example, appTextSave is normally cleared by the OS when a menu is displayed.
• If putmapUsePixShad2 is set, pixelShadow2 is used instead.
• For variable-width text routines, if write_on_graph is set, the characters are drawn to the graph buffer instead.

See also

• pixelShadow2
• cmdPixelShadow