Add support for QOI file format

Allows to decode QOI images.
See https://qoiformat.org for format description.

Resolves #195, #196.

Co-authored-by: sepi <[email protected]>
Co-authored-by: Sashko <[email protected]>
Signed-off-by: Artem Senichev <[email protected]>

README.md

@@ -15,7 +15,8 @@ Fully customizable and lightweight image viewer for Wayland based display server
   - EXR (via [OpenEXR](https://openexr.com));
   - BMP (built-in);
   - PNM (built-in);
-  - TGA (built-in).
+  - TGA (built-in);
+  - QOI (built-in).
 - Fully customizable keyboard bindings, colors, and [many other](https://github.com/artemsen/swayimg/blob/master/extra/swayimgrc) parameters;
 - Loading images from files and pipes;
 - Gallery and viewer modes with slideshow and animation support;

meson.build

@@ -190,6 +190,7 @@ sources = [
   'src/viewer.c',
   'src/formats/bmp.c',
   'src/formats/pnm.c',
+  'src/formats/qoi.c',
   'src/formats/tga.c',
   xdg_shell_h,
   xdg_shell_c,

src/formats/qoi.c

@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: MIT
+// QOI format decoder.
+// Copyright (C) 2024 Artem Senichev <[email protected]>
+
+#include "../loader.h"
+
+#include <arpa/inet.h>
+#include <string.h>
+
+// Chunk tags
+#define QOI_OP_INDEX 0x00
+#define QOI_OP_DIFF  0x40
+#define QOI_OP_LUMA  0x80
+#define QOI_OP_RUN   0xc0
+#define QOI_OP_RGB   0xfe
+#define QOI_OP_RGBA  0xff
+
+// Mask of second byte in steram
+#define QOI_MASK_2 0xc0
+
+// Size of color map
+#define QOI_CLRMAP_SIZE 64
+// Calc color index in map
+#define QOI_CLRMAP_INDEX(r, g, b, a) \
+    ((r * 3 + g * 5 + b * 7 + a * 11) % QOI_CLRMAP_SIZE)
+
+// QOI signature
+static const uint8_t signature[] = { 'q', 'o', 'i', 'f' };
+
+// QOI file header
+struct __attribute__((__packed__)) qoi_header {
+    uint8_t magic[4];   // Magic bytes "qoif"
+    uint32_t width;     // Image width in pixels
+    uint32_t height;    // Image height in pixels
+    uint8_t channels;   // Number of color channels: 3 = RGB, 4 = RGBA
+    uint8_t colorspace; // 0 = sRGB with linear alpha, 1 = all channels linear
+};
+
+// QOI loader implementation
+enum loader_status decode_qoi(struct image* ctx, const uint8_t* data,
+                              size_t size)
+{
+    const struct qoi_header* qoi = (const struct qoi_header*)data;
+    argb_t color_map[QOI_CLRMAP_SIZE];
+    struct pixmap* pm;
+    uint8_t a, r, g, b;
+    size_t total_pixels;
+    size_t rlen;
+    size_t pos;
+
+    // check signature
+    if (size < sizeof(*qoi) ||
+        memcmp(qoi->magic, signature, sizeof(signature))) {
+        return ldr_unsupported;
+    }
+    // check format
+    if (qoi->width == 0 || qoi->height == 0 || qoi->channels < 3 ||
+        qoi->channels > 4) {
+        return ldr_fmterror;
+    }
+
+    // allocate image buffer
+    pm = image_allocate_frame(ctx, htonl(qoi->width), htonl(qoi->height));
+    if (!pm) {
+        return ldr_fmterror;
+    }
+
+    // initialize decoder state
+    r = 0;
+    g = 0;
+    b = 0;
+    a = 0xff;
+    rlen = 0;
+    pos = sizeof(struct qoi_header);
+    total_pixels = pm->width * pm->height;
+    memset(color_map, 0, sizeof(color_map));
+
+    // decode image
+    for (size_t i = 0; i < total_pixels; ++i) {
+        if (rlen > 0) {
+            --rlen;
+        } else {
+            uint8_t tag;
+            if (pos >= size) {
+                break;
+            }
+            tag = data[pos++];
+
+            if (tag == QOI_OP_RGB) {
+                if (pos + 3 >= size) {
+                    goto fail;
+                }
+                r = data[pos++];
+                g = data[pos++];
+                b = data[pos++];
+            } else if (tag == QOI_OP_RGBA) {
+                if (pos + 4 >= size) {
+                    goto fail;
+                }
+                r = data[pos++];
+                g = data[pos++];
+                b = data[pos++];
+                a = data[pos++];
+            } else if ((tag & QOI_MASK_2) == QOI_OP_INDEX) {
+                const argb_t clr = color_map[tag & 0x3f];
+                a = ARGB_GET_A(clr);
+                r = ARGB_GET_R(clr);
+                g = ARGB_GET_G(clr);
+                b = ARGB_GET_B(clr);
+            } else if ((tag & QOI_MASK_2) == QOI_OP_DIFF) {
+                r += (int8_t)((tag >> 4) & 3) - 2;
+                g += (int8_t)((tag >> 2) & 3) - 2;
+                b += (int8_t)(tag & 3) - 2;
+            } else if ((tag & QOI_MASK_2) == QOI_OP_LUMA) {
+                uint8_t diff;
+                int8_t diff_green;
+                if (pos + 1 >= size) {
+                    goto fail;
+                }
+                diff = data[pos++];
+                diff_green = (int8_t)(tag & 0x3f) - 32;
+                r += diff_green - 8 + ((diff >> 4) & 0x0f);
+                g += diff_green;
+                b += diff_green - 8 + (diff & 0x0f);
+            } else if ((tag & QOI_MASK_2) == QOI_OP_RUN) {
+                rlen = (tag & 0x3f);
+            }
+            color_map[QOI_CLRMAP_INDEX(r, g, b, a)] = ARGB(a, r, g, b);
+        }
+        pm->data[i] = ARGB(a, r, g, b);
+    }
+
+    image_set_format(ctx, "QOI %dbpp", qoi->channels * 8);
+    ctx->alpha = (qoi->channels == 4);
+    return ldr_success;
+
+fail:
+    image_free_frames(ctx);
+    return ldr_fmterror;
+}

src/loader.c

@@ -68,6 +68,7 @@ const char* supported_formats = "bmp, pnm, tga"
 // declaration of loaders
 LOADER_DECLARE(bmp);
 LOADER_DECLARE(pnm);
+LOADER_DECLARE(qoi);
 LOADER_DECLARE(tga);
 #ifdef HAVE_LIBEXR
 LOADER_DECLARE(exr);
@@ -133,7 +134,7 @@ static const image_decoder decoders[] = {
 #ifdef HAVE_LIBTIFF
     &LOADER_FUNCTION(tiff),
 #endif
-    &LOADER_FUNCTION(tga),
+    &LOADER_FUNCTION(qoi),  &LOADER_FUNCTION(tga),
 };
 
 /** Background thread loader queue. */

test/loader_test.cpp

@@ -58,6 +58,7 @@ TEST_F(Loader, External)
 
 TEST_LOADER(bmp);
 TEST_LOADER(pnm);
+TEST_LOADER(qoi);
 TEST_LOADER(tga);
 #ifdef HAVE_LIBEXR
 // TEST_LOADER(exr);

test/meson.build

@@ -19,6 +19,7 @@ sources = [
   '../src/pixmap.c',
   '../src/formats/bmp.c',
   '../src/formats/pnm.c',
+  '../src/formats/qoi.c',
   '../src/formats/tga.c',
 ]
 if exif.found()