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JPEGDEC: Use 4-bit dither.

This commit is contained in:
Phil Howard 2022-06-09 20:32:18 +01:00
parent 62818a5f49
commit d2b065d2da
3 changed files with 16 additions and 5 deletions
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5
libraries/jpegdec/JPEGDEC.cpp
View File

@ -188,11 +188,14 @@ int JPEGDEC::decode(int x, int y, int iOptions)
_jpeg.iXOffset = x;
_jpeg.iYOffset = y;
_jpeg.iOptions = iOptions;
_jpeg.pDitherBuffer = nullptr;
return DecodeJPEG(&_jpeg);
} /* decode() */
int JPEGDEC::decodeDither(uint8_t *pDither, int iOptions)
int JPEGDEC::decodeDither(int x, int y, uint8_t *pDither, int iOptions)
{
_jpeg.iXOffset = x;
_jpeg.iYOffset = y;
_jpeg.iOptions = iOptions;
_jpeg.pDitherBuffer = pDither;
return DecodeJPEG(&_jpeg);

2
libraries/jpegdec/JPEGDEC.h
View File

@ -213,7 +213,7 @@ class JPEGDEC
#endif
void close();
int decode(int x, int y, int iOptions);
int decodeDither(uint8_t *pDither, int iOptions);
int decodeDither(int x, int y, uint8_t *pDither, int iOptions);
int getOrientation();
int getWidth();
int getHeight();

14
micropython/modules/jpegdec/jpegdec.cpp
View File

@ -38,7 +38,7 @@ int JPEGDraw(JPEGDRAW *pDraw) {
for(int x = 0; x < pDraw->iWidth; x++) {
int i = y * pDraw->iWidth + x;
uint8_t p = pixels[i / 2];
p >>= (i & 0b1) * 4;
p >>= (i & 0b1) ? 0 : 4;
p &= 0xf;
current_graphics->set_pen(p);
current_graphics->pixel({pDraw->x + x, pDraw->y + y});
@ -108,7 +108,7 @@ static int _open(_JPEG_obj_t *self, void *buf, size_t len) {
break;
// TODO currently uses EIGHT_BIT_GREYSCALE and shifts down should this use a 4-bit dither?
case PicoGraphics::PEN_P4:
self->jpeg->setPixelType(EIGHT_BIT_GRAYSCALE);
self->jpeg->setPixelType(FOUR_BIT_DITHERED);
break;
// TODO 2-bit is currently unsupported
case PicoGraphics::PEN_P2:
@ -174,7 +174,15 @@ mp_obj_t _JPEG_decode(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args
// We need to store a pointer to the PicoGraphics surface
// since the JPEGDRAW struct has no userdata
current_graphics = self->graphics->graphics;
int result = self->jpeg->decode(x, y, f);
int result = -1;
if(self->graphics->graphics->pen_type == PicoGraphics::PEN_P4) {
uint8_t *buf = new uint8_t[1024];
result = self->jpeg->decodeDither(x, y, buf, f);
delete[] buf;
} else {
result = self->jpeg->decode(x, y, f);
}
current_graphics = nullptr;
return result == 1 ? mp_const_true : mp_const_false;
}