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Align the data format with new spec #37

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This commit is contained in:
Dominic Szablewski
2021-11-27 17:23:52 +01:00
parent a902b57ede
commit 697abf6696
1 changed files with 65 additions and 69 deletions
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134
qoi.h
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@@ -75,10 +75,14 @@ you can define QOI_MALLOC and QOI_FREE before including this library.
A QOI file has a 12 byte header, followed by any number of data "chunks".
struct qoi_header_t {
char [4]; // magic bytes "qoif"
unsigned short width; // image width in pixels (BE)
unsigned short height; // image height in pixels (BE)
unsigned int size; // number of data bytes following this header (BE)
char magic[4]; // magic bytes "qoif"
uint32_t width; // image width in pixels (BE)
uint32_t height; // image height in pixels (BE)
uint8_t channels; // must be 3 (RGB) or 4 (RGBA)
uint8_t colorspace; // a bitmap 0000rgba where
// - a zero bit indicates sRGBA,
// - a one bit indicates linear (user interpreted)
// colorspace for each channel
};
The decoder and encoder start with {r: 0, g: 0, b: 0, a: 255} as the previous
@@ -113,24 +117,24 @@ QOI_RUN_16 {
QOI_DIFF_8 {
u8 tag : 2; // b10
u8 dr : 2; // 2-bit red channel difference: -1..2
u8 dg : 2; // 2-bit green channel difference: -1..2
u8 db : 2; // 2-bit blue channel difference: -1..2
u8 dr : 2; // 2-bit red channel difference: -2..1
u8 dg : 2; // 2-bit green channel difference: -2..1
u8 db : 2; // 2-bit blue channel difference: -2..1
}
QOI_DIFF_16 {
u8 tag : 3; // b110
u8 dr : 5; // 5-bit red channel difference: -15..16
u8 dg : 4; // 4-bit green channel difference: -7.. 8
u8 db : 4; // 4-bit blue channel difference: -7.. 8
u8 dr : 5; // 5-bit red channel difference: -16..15
u8 dg : 4; // 4-bit green channel difference: -8.. 7
u8 db : 4; // 4-bit blue channel difference: -8.. 7
}
QOI_DIFF_24 {
u8 tag : 4; // b1110
u8 dr : 5; // 5-bit red channel difference: -15..16
u8 dg : 5; // 5-bit green channel difference: -15..16
u8 db : 5; // 5-bit blue channel difference: -15..16
u8 da : 5; // 5-bit alpha channel difference: -15..16
u8 dr : 5; // 5-bit red channel difference: -16..15
u8 dg : 5; // 5-bit green channel difference: -16..15
u8 db : 5; // 5-bit blue channel difference: -16..15
u8 da : 5; // 5-bit alpha channel difference: -16..15
}
QOI_COLOR {
@@ -246,26 +250,19 @@ typedef union {
unsigned int v;
} qoi_rgba_t;
void qoi_write_16(unsigned char *bytes, int *p, unsigned short v) {
bytes[(*p)++] = (0xff00 & v) >> 8;
bytes[(*p)++] = (0xff & v);
}
void qoi_write_32(unsigned char *bytes, int *p, unsigned int v) {
qoi_write_16(bytes, p, (v & 0xffff0000) >> 16);
qoi_write_16(bytes, p, (v & 0xffff));
}
unsigned int qoi_read_16(const unsigned char *bytes, int *p) {
unsigned int a = bytes[(*p)++];
unsigned int b = bytes[(*p)++];
return (a << 8) | b;
bytes[(*p)++] = (0xff000000 & v) >> 24;
bytes[(*p)++] = (0x00ff0000 & v) >> 16;
bytes[(*p)++] = (0x0000ff00 & v) >> 8;
bytes[(*p)++] = (0x000000ff & v);
}
unsigned int qoi_read_32(const unsigned char *bytes, int *p) {
unsigned int a = qoi_read_16(bytes, p);
unsigned int b = qoi_read_16(bytes, p);
return (a << 16) | b;
unsigned int a = bytes[(*p)++];
unsigned int b = bytes[(*p)++];
unsigned int c = bytes[(*p)++];
unsigned int d = bytes[(*p)++];
return (a << 24) | (b << 16) | (c << 8) | d;
}
void *qoi_encode(const void *data, int w, int h, int channels, int *out_len) {
@@ -286,9 +283,10 @@ void *qoi_encode(const void *data, int w, int h, int channels, int *out_len) {
}
qoi_write_32(bytes, &p, QOI_MAGIC);
qoi_write_16(bytes, &p, w);
qoi_write_16(bytes, &p, h);
qoi_write_32(bytes, &p, 0); // size, will be set later
qoi_write_32(bytes, &p, w);
qoi_write_32(bytes, &p, h);
bytes[p++] = channels;
bytes[p++] = 0; // TODO: accept a colorspace as a parameter to this function
const unsigned char *pixels = (const unsigned char *)data;
@@ -342,26 +340,26 @@ void *qoi_encode(const void *data, int w, int h, int channels, int *out_len) {
int va = px.rgba.a - px_prev.rgba.a;
if (
vr > -16 && vr < 17 && vg > -16 && vg < 17 &&
vb > -16 && vb < 17 && va > -16 && va < 17
vr > -17 && vr < 16 && vg > -17 && vg < 16 &&
vb > -17 && vb < 16 && va > -17 && va < 16
) {
if (
va == 0 && vr > -2 && vr < 3 &&
vg > -2 && vg < 3 && vb > -2 && vb < 3
va == 0 && vr > -3 && vr < 2 &&
vg > -3 && vg < 2 && vb > -3 && vb < 2
) {
bytes[p++] = QOI_DIFF_8 | ((vr + 1) << 4) | (vg + 1) << 2 | (vb + 1);
bytes[p++] = QOI_DIFF_8 | ((vr + 2) << 4) | (vg + 2) << 2 | (vb + 2);
}
else if (
va == 0 && vr > -16 && vr < 17 &&
vg > -8 && vg < 9 && vb > -8 && vb < 9
va == 0 && vr > -17 && vr < 16 &&
vg > -9 && vg < 8 && vb > -9 && vb < 8
) {
bytes[p++] = QOI_DIFF_16 | (vr + 15);
bytes[p++] = ((vg + 7) << 4) | (vb + 7);
bytes[p++] = QOI_DIFF_16 | (vr + 16);
bytes[p++] = ((vg + 8) << 4) | (vb + 8);
}
else {
bytes[p++] = QOI_DIFF_24 | ((vr + 15) >> 1);
bytes[p++] = ((vr + 15) << 7) | ((vg + 15) << 2) | ((vb + 15) >> 3);
bytes[p++] = ((vb + 15) << 5) | (va + 15);
bytes[p++] = QOI_DIFF_24 | ((vr + 16) >> 1);
bytes[p++] = ((vr + 16) << 7) | ((vg + 16) << 2) | ((vb + 16) >> 3);
bytes[p++] = ((vb + 16) << 5) | (va + 16);
}
}
else {
@@ -380,35 +378,33 @@ void *qoi_encode(const void *data, int w, int h, int channels, int *out_len) {
bytes[p++] = 0;
}
int data_len = p - QOI_HEADER_SIZE;
*out_len = p;
p = 8;
qoi_write_32(bytes, &p, data_len);
return bytes;
}
void *qoi_decode(const void *data, int size, int *out_w, int *out_h, int channels) {
if (channels < 3 || channels > 4 || size < QOI_HEADER_SIZE) {
if (channels < 3 || channels > 4 || size < QOI_HEADER_SIZE + QOI_PADDING) {
return NULL;
}
const unsigned char *bytes = (const unsigned char *)data;
int p = 0;
int magic = qoi_read_32(bytes, &p);
int w = qoi_read_16(bytes, &p);
int h = qoi_read_16(bytes, &p);
int data_len = qoi_read_32(bytes, &p);
unsigned int header_magic = qoi_read_32(bytes, &p);
unsigned int header_w = qoi_read_32(bytes, &p);
unsigned int header_h = qoi_read_32(bytes, &p);
unsigned int header_channels = bytes[p++];
unsigned int header_colorspace = bytes[p++];
if (
w == 0 || h == 0 || magic != QOI_MAGIC ||
size != data_len + QOI_HEADER_SIZE
header_w == 0 || header_h == 0 ||
header_channels < 3 || header_channels > 4 ||
header_magic != QOI_MAGIC
) {
return NULL;
}
int px_len = w * h * channels;
int px_len = header_w * header_h * channels;
unsigned char *pixels = QOI_MALLOC(px_len);
if (!pixels) {
return NULL;
@@ -437,23 +433,23 @@ void *qoi_decode(const void *data, int size, int *out_w, int *out_h, int channel
run = (((b1 & 0x1f) << 8) | (b2)) + 32;
}
else if ((b1 & QOI_MASK_2) == QOI_DIFF_8) {
px.rgba.r += ((b1 >> 4) & 0x03) - 1;
px.rgba.g += ((b1 >> 2) & 0x03) - 1;
px.rgba.b += ( b1 & 0x03) - 1;
px.rgba.r += ((b1 >> 4) & 0x03) - 2;
px.rgba.g += ((b1 >> 2) & 0x03) - 2;
px.rgba.b += ( b1 & 0x03) - 2;
}
else if ((b1 & QOI_MASK_3) == QOI_DIFF_16) {
int b2 = bytes[p++];
px.rgba.r += (b1 & 0x1f) - 15;
px.rgba.g += (b2 >> 4) - 7;
px.rgba.b += (b2 & 0x0f) - 7;
px.rgba.r += (b1 & 0x1f) - 16;
px.rgba.g += (b2 >> 4) - 8;
px.rgba.b += (b2 & 0x0f) - 8;
}
else if ((b1 & QOI_MASK_4) == QOI_DIFF_24) {
int b2 = bytes[p++];
int b3 = bytes[p++];
px.rgba.r += (((b1 & 0x0f) << 1) | (b2 >> 7)) - 15;
px.rgba.g += ((b2 & 0x7c) >> 2) - 15;
px.rgba.b += (((b2 & 0x03) << 3) | ((b3 & 0xe0) >> 5)) - 15;
px.rgba.a += (b3 & 0x1f) - 15;
px.rgba.r += (((b1 & 0x0f) << 1) | (b2 >> 7)) - 16;
px.rgba.g += ((b2 & 0x7c) >> 2) - 16;
px.rgba.b += (((b2 & 0x03) << 3) | ((b3 & 0xe0) >> 5)) - 16;
px.rgba.a += (b3 & 0x1f) - 16;
}
else if ((b1 & QOI_MASK_4) == QOI_COLOR) {
if (b1 & 8) { px.rgba.r = bytes[p++]; }
@@ -475,8 +471,8 @@ void *qoi_decode(const void *data, int size, int *out_w, int *out_h, int channel
}
}
*out_w = w;
*out_h = h;
*out_w = header_w;
*out_h = header_h;
return pixels;
}