Row operations

Scrolling and stamping whole framebuffer rows at word speed. More...

Functions
void	gfx_scroll (int y, int h, int dx, int dy, int fill=-1)
	Moves a band of rows by (dx, dy) pixels inside the band.
void	gfx_copyRow (int y, const uint8_t *src, int x0, int x1)
	Copies pixels [x0, x1) of a full-width row buffer into framebuffer row y, clipped.

Detailed Description

Scrolling and stamping whole framebuffer rows at word speed.

Word copies in SRAM. newlib-nano's memmove/memcpy are byte loops in flash here: a screen shake built on memmove cost ~10 ms a frame.

Function Documentation

gfx_scroll()

void gfx_scroll	(	int	y,
		int	h,
		int	dx,
		int	dy,
		int	fill = -1
	)

Moves a band of rows by (dx, dy) pixels inside the band.

Moves the band of rows y..y+h-1 by dx pixels right and dy rows down (negative = left/up). Odd dx is fine (nibble shifts). It works on whole rows and ignores the clip rectangle - it is a post-process: shake, scrolling backgrounds.

Parameters

y	First row of the band.
h	Rows in the band (clipped to the screen).
dx	Pixels to move right; negative moves left.
dy	Rows to move down; negative moves up.
fill	Palette index for the pixels uncovered by the move, or -1 (the default) to leave them as they were.

gfx_copyRow()

void gfx_copyRow	(	int	y,
		const uint8_t *	src,
		int	x0,
		int	x1
	)

Copies pixels [x0, x1) of a full-width row buffer into framebuffer row y, clipped.

Build a pattern row once, stamp it into many rows at word speed: tiled floors, checkerboards, gradients.

Parameters

y	Framebuffer row.
src	A row of GFX_FB_STRIDE bytes, packed like the framebuffer.
x0	First pixel copied.
x1	One past the last pixel copied.