From 697abf669640472892a0911487f8b8d35f469aa3 Mon Sep 17 00:00:00 2001 From: Dominic Szablewski <dominic@phoboslab.org> Date: Sat, 27 Nov 2021 17:23:52 +0100 Subject: [PATCH] Align the data format with new spec #37 --- qoi.h | 134 ++++++++++++++++++++++++++++------------------------------ 1 file changed, 65 insertions(+), 69 deletions(-) diff --git a/qoi.h b/qoi.h index e5f4d45..6dd232d 100644 --- a/qoi.h +++ b/qoi.h @@ -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; }