sbuf

Scanline buffering for generic rendering engines on serial displays

Highlights

• Scanline based buffering
• No dynamic memory allocation
• Minimal RAM needed
• Double buffering to support DMA
• Overlappig segments supported
• Interlacing

Configuration

name	default	note
SBF_SW	240	width
SBF_SH	240	height
SBF_MAX_SECTIONS	8	max number of sections in a scanline, depends on the complexity of the object

RAM

• two scanlines -- SBF_SW * 2
• scanline buffer -- SBF_SH * SBF_MAX_SECTIONS * 4 bytes
• work array -- SBF_SH / 2 bytes

Usage

1. define SBUF_IMPLEMENTATION
2. include sbuf.h
3. implement the callback function

   void fill_scanline_type(uint8_t *buf, int y, int x0, int x1)
   {
     if( NULL == buf ) {
       // clear this scanline 'y' between x0 and x1 including x0 and x1
       // or render the background image to this area
     } else {
       // render the provided 'buf' to line 'y' from x0 to x1
     }
   }

4. call sbf_init() once
5. render your scene calling sbf_add_segment() as many times as needed NOTE: No more than SBF_MAX_SECTIONS calls per scanline!
6. call sbf_render_frame() to render the result
7. if interlacing is used, negate the flip marker

Demo

st7789-driver-demo.mp4

also using the ninety3d library