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PNGdec: Add support for palette offsets and greyscale copy mode #919

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merged 4 commits into from
Apr 11, 2024
Merged

PNGdec: Add support for palette offsets and greyscale copy mode #919

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c7b788c
PNGdec: Add palette offset arg.
Gadgetoid Mar 28, 2024
27b9131
PNGdec: Add copy support and offset to greyscale.
Gadgetoid Mar 28, 2024
d34e692
PNGdec: Don't add palette_offset twice.
Gadgetoid Mar 28, 2024
a537672
PNGdec: Don't convert greys if mode=COPY.
Gadgetoid Mar 28, 2024
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55 changes: 38 additions & 17 deletions micropython/modules/pngdec/pngdec.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ typedef struct _PNG_decode_target {
Rect source = {0, 0, 0, 0};
Point scale = {1, 1};
int rotation = 0;
uint8_t palette_offset = 0;
} _PNG_decode_target;

typedef struct _PNG_obj_t {
Expand Down Expand Up @@ -126,6 +127,7 @@ mp_event_handle_nowait();
PicoGraphics *current_graphics = (PicoGraphics *)target->target;
Point current_position = target->position;
uint8_t current_mode = target->mode;
uint8_t current_palette_offset = target->palette_offset;
Point scale = target->scale;
int rotation = target->rotation;
Point step = {0, 0};
Expand Down Expand Up @@ -161,22 +163,15 @@ mp_event_handle_nowait();

//mp_printf(&mp_plat_print, "Drawing scanline at %d, %dbpp, type: %d, width: %d pitch: %d alpha: %d\n", pDraw->y , pDraw->iBpp, pDraw->iPixelType, pDraw->iWidth, pDraw->iPitch, pDraw->iHasAlpha);
uint8_t *pixel = (uint8_t *)pDraw->pPixels;
if(pDraw->iPixelType == PNG_PIXEL_TRUECOLOR ) {
if(pDraw->iPixelType == PNG_PIXEL_TRUECOLOR || pDraw->iPixelType == PNG_PIXEL_TRUECOLOR_ALPHA) {
for(int x = 0; x < pDraw->iWidth; x++) {
uint8_t r = *pixel++;
uint8_t g = *pixel++;
uint8_t b = *pixel++;
if(x < target->source.x || x >= target->source.x + target->source.w) continue;
current_graphics->set_pen(r, g, b);
current_graphics->rectangle({current_position.x, current_position.y, scale.x, scale.y});
current_position += step;
}
} else if (pDraw->iPixelType == PNG_PIXEL_TRUECOLOR_ALPHA) {
for(int x = 0; x < pDraw->iWidth; x++) {
uint8_t r = *pixel++;
uint8_t g = *pixel++;
uint8_t b = *pixel++;
uint8_t a = *pixel++;
uint8_t a = 1;
if (pDraw->iHasAlpha) {
a = *pixel++;
}
if(x < target->source.x || x >= target->source.x + target->source.w) continue;
if (a) {
current_graphics->set_pen(r, g, b);
Expand All @@ -194,26 +189,46 @@ mp_event_handle_nowait();
i >>= (x & 0b1) ? 0 : 4;
i &= 0xf;
if (x & 1) pixel++;
i = (i << 4) | i;
// Just copy the colour into the upper and lower nibble
if(current_mode != MODE_COPY) {
i = (i << 4) | i;
}
} else if (pDraw->iBpp == 2) { // 2bpp
i = *pixel;
i >>= 6 - ((x & 0b11) << 1);
i &= 0x3;
if ((x & 0b11) == 0b11) pixel++;
// Evenly spaced 4-colour palette
i = (0xFFB86800 >> (i * 8)) & 0xFF;
if(current_mode != MODE_COPY) {
i = (0xFFB86800 >> (i * 8)) & 0xFF;
}
} else { // 1bpp
i = *pixel;
i >>= 7 - (x & 0b111);
i &= 0b1;
if ((x & 0b111) == 0b111) pixel++;
i = i ? 255 : 0;
if(current_mode != MODE_COPY) {
i = i ? 255 : 0;
}
}
if(x < target->source.x || x >= target->source.x + target->source.w) continue;

//mp_printf(&mp_plat_print, "Drawing pixel at %dx%d, %dbpp, value %d\n", current_position.x, current_position.y, pDraw->iBpp, i);
if (current_mode != MODE_PEN) {
current_graphics->set_pen(i, i, i);
// Allow greyscale PNGs to be copied just like an indexed PNG
// since we might want to offset and recolour them.
if(current_mode == MODE_COPY
&& (current_graphics->pen_type == PicoGraphics::PEN_P8
|| current_graphics->pen_type == PicoGraphics::PEN_P4
|| current_graphics->pen_type == PicoGraphics::PEN_3BIT
|| current_graphics->pen_type == PicoGraphics::PEN_INKY7)) {
if(current_palette_offset > 0) {
i = ((int16_t)(i) + current_palette_offset) & 0xff;
}
current_graphics->set_pen(i);
} else {
current_graphics->set_pen(i, i, i);
}
}
if (current_mode != MODE_PEN || i == 0) {
current_graphics->rectangle({current_position.x, current_position.y, scale.x, scale.y});
Expand Down Expand Up @@ -269,6 +284,9 @@ mp_event_handle_nowait();

// Copy raw palette indexes over
if(current_mode == MODE_COPY) {
if(current_palette_offset > 0) {
i = ((int16_t)(i) + current_palette_offset) & 0xff;
}
current_graphics->set_pen(i);
current_graphics->rectangle({current_position.x, current_position.y, scale.x, scale.y});
// Posterized output to the available palete
Expand Down Expand Up @@ -364,7 +382,7 @@ mp_obj_t _PNG_openRAM(mp_obj_t self_in, mp_obj_t buffer) {

// decode
mp_obj_t _PNG_decode(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
enum { ARG_self, ARG_x, ARG_y, ARG_scale, ARG_mode, ARG_source, ARG_rotate };
enum { ARG_self, ARG_x, ARG_y, ARG_scale, ARG_mode, ARG_source, ARG_rotate, ARG_palette_offset };
static const mp_arg_t allowed_args[] = {
{ MP_QSTR_, MP_ARG_REQUIRED | MP_ARG_OBJ },
{ MP_QSTR_x, MP_ARG_INT, {.u_int = 0} },
Expand All @@ -373,6 +391,7 @@ mp_obj_t _PNG_decode(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args)
{ MP_QSTR_mode, MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_source, MP_ARG_OBJ, {.u_obj = nullptr} },
{ MP_QSTR_rotate, MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_palette_offset, MP_ARG_INT, {.u_int = 0} },
};

mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
Expand Down Expand Up @@ -432,6 +451,8 @@ mp_obj_t _PNG_decode(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args)

self->decode_target->position = {args[ARG_x].u_int, args[ARG_y].u_int};

self->decode_target->palette_offset = args[ARG_palette_offset].u_int;

// Just-in-time open of the filename/buffer we stored in self->file via open_RAM or open_file

// Source is a filename
Expand Down
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