RFC modframebuf.c scrolling behaviour
Currently framebuf_scroll does not clear the region of the display which is exposed by scrolling. While I appreciate that this behaviour is by design, I'd submit that it's seldom what is actually required.
An option would be good, perhaps via a colour arg:
- Behave as at present leaving exposed region unchanged.
- Fill with a colour.
Any thoughts, or reasons why the current behaviour has been chosen?
extmod/modframebuf.c framebuf1_text() does not clear pixels
This section of the code looks wrong:
if (vline_data & 1) { // only draw if pixel set
if (0 <= y && y < self->height) { // clip y
uint byte_pos = x0 + self->stride * ((uint)y >> 3);
if (col == 0) {
// clear pixel
self->buf[byte_pos] &= ~(1 << (y & 7));
} else {
// set pixel
self->buf[byte_pos] |= 1 << (y & 7);
}
}
If the pixel is not set, it should surely clear down the pixel in the framebuf as we don't know its prior contents. Further, if we happen to be drawing with col==0 to a part of the framebuf which is already zero, then nothing will be drawn, because in that circumstance the code never sets a pixel.
I hope I'm right on this observation from reviewing the code: I haven't had the opportunity to try it since my SSD1306 was DOA.