Compose 1-bpp images of arbitrary size with the canvas primitives. More...

Macros
#define	HOST_SURFACE_MAX_PER_PLUGIN 2
	Maximum surfaces a plugin may hold at once.
#define	HOST_SURFACE_MAX_BYTES 65536
	Maximum packed pixel bytes per surface (stride * height).

Functions
int	host_surface_create (uint16_t w, uint16_t h)
	Create a w x h surface, cleared to white.
int	host_surface_destroy (uint32_t surface)
	Destroy a surface and free its memory.
int	host_surface_clear (uint32_t surface)
	Clear a surface to white.
int	host_surface_set_font (uint32_t surface, uint8_t font_id)
	Select the font for subsequent text calls (HOST_FONT_* id).
int	host_surface_set_text_size (uint32_t surface, uint8_t size)
	Set the integer text scale (1..4) for subsequent text calls.
int	host_surface_set_text_color (uint32_t surface, uint8_t inverted)
	Draw text white-on-black (inverted != 0) or black-on-white.
int	host_surface_set_shade (uint32_t surface, uint8_t shade)
	Set the fill shade for filled shapes: 0 white .. 255 solid black.
int	host_surface_draw_text (uint32_t surface, int16_t x, int16_t y, const char *text)
	Draw UTF-8 text with the current font/size at (x, y) baseline-top.
int	host_surface_draw_text_aligned (uint32_t surface, int16_t x, int16_t y, int16_t w, const char *text, uint8_t align)
	Draw UTF-8 text aligned within a w-wide box starting at x.
int	host_surface_measure_text (uint32_t surface, const char text, uint16_t out_w, uint16_t *out_h)
	Measure UTF-8 text with the surface's current font/size.
int	host_surface_draw_pixel (uint32_t surface, int16_t x, int16_t y)
	Draw a pixel (current shade decides ink: shade > 0 draws black).
int	host_surface_draw_line (uint32_t surface, int16_t x0, int16_t y0, int16_t x1, int16_t y1)
	Draw a line.
int	host_surface_draw_rect (uint32_t surface, int16_t x, int16_t y, int16_t w, int16_t h, uint8_t filled)
	Draw a rectangle; filled ones use the current shade.
int	host_surface_draw_circle (uint32_t surface, int16_t x, int16_t y, int16_t r, uint8_t filled)
	Draw a circle centered at (x, y); filled ones use the current shade.
int	host_surface_draw_triangle (uint32_t surface, int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2, uint8_t filled)
	Draw a triangle; filled ones use the current shade.
int	host_surface_draw_round_rect (uint32_t surface, int16_t x, int16_t y, int16_t w, int16_t h, int16_t r, uint8_t filled)
	Draw a rounded rectangle with corner radius r.
int	host_surface_hline (uint32_t surface, int16_t x, int16_t y, int16_t w)
	Draw a horizontal line of width w.
int	host_surface_vline (uint32_t surface, int16_t x, int16_t y, int16_t h)
	Draw a vertical line of height h.
int	host_surface_draw_bitmap (uint32_t surface, int16_t x, int16_t y, int16_t w, int16_t h, const uint8_t *data, uint32_t len)
	Blit a packed 1-bpp bitmap (MSB-first, set bit = black) at (x, y).
int	host_surface_export (uint32_t surface, uint8_t out, size_t out_size, uint16_t out_stride_bytes)
	Copy the surface's packed pixel rows into out.
int	host_surface_export_jpg (uint32_t surface, uint8_t quality, uint8_t out, size_t out_size, uint32_t out_len)
	Encode the surface as a grayscale JPEG.
int	host_surface_draw_sprite (uint32_t surface, int16_t x, int16_t y, uint32_t sprite)
	Stamp a sprite's current frame onto a surface at (x, y).

Detailed Description

Compose 1-bpp images of arbitrary size with the canvas primitives.

A surface is an offscreen render target independent of the view stack - e.g. 384 px wide for a thermal print band while the display is only 296x128. The draw API mirrors the canvas view (same fonts, shades and primitives); coordinates are raw surface pixels with no header offset. Export yields packed rows (MSB-first, set bit = black - the same layout as the QR and image APIs) or an encoded grayscale JPEG.

No capability required: pure compute with a hard memory cap. A plugin can hold at most 2 surfaces of up to 64 KiB pixel data each; all surfaces are freed when the plugin unloads.