Get rid of our spng dependency

Thumbnails can be properly loaded using Wuffs now.

6 files changed, 189 insertions, 140 deletions

diff --git a/README.adoc b/README.adoc
index 143c0c8..d245a0f 100644
--- a/README.adoc
+++ b/README.adoc
@@ -38,7 +38,7 @@ Building and Running
 --------------------
 Build dependencies: Meson, pkg-config +
 Runtime dependencies: gtk+-3.0, glib>=2.64, pixman-1, shared-mime-info,
-libturbojpeg, libwebp, spng>=0.7.0 +
+libturbojpeg, libwebp +
 Optional dependencies: lcms2, LibRaw, librsvg-2.0, xcursor, libheif, libtiff,
 ExifTool, resvg (unstable API, needs to be requested explicitly)
 
diff --git a/fiv-io.c b/fiv-io.c
index dcec86a..ddb8526 100644
--- a/fiv-io.c
+++ b/fiv-io.c
@@ -582,6 +582,9 @@ load_wuffs_frame(struct load_wuffs_frame_context *ctx, GError **error)
 		return false;
 	}
 
+	// TODO(p): Maybe pre-clear with
+	// wuffs_base__frame_config__background_color(&fc).
+
 	// Wuffs' test/data/animated-red-blue.gif, e.g., needs this handling.
 	cairo_format_t decode_format = ctx->cairo_format;
 	if (wuffs_base__frame_config__index(&fc) > 0 &&
@@ -785,7 +788,7 @@ open_wuffs(wuffs_base__image_decoder *dec, wuffs_base__io_buffer src,
 	struct load_wuffs_frame_context ctx = {
 		.dec = dec, .src = &src, .target = ioctx->screen_profile};
 
-	// TODO(p): PNG text chunks (Wuffs #58).
+	// TODO(p): PNG text chunks, like we do with PNG thumbnails.
 	// TODO(p): See if something could and should be done about
 	// https://www.w3.org/TR/png-hdr-pq/
 	wuffs_base__image_decoder__set_report_metadata(
@@ -969,6 +972,166 @@ open_wuffs_using(wuffs_base__image_decoder *(*allocate)(),
 	return surface;
 }
 
+// --- Wuffs for PNG thumbnails ------------------------------------------------
+
+static bool
+pull_metadata_kvp(wuffs_png__decoder *dec, wuffs_base__io_buffer *src,
+	GHashTable *texts, gchar **key, GError **error)
+{
+	wuffs_base__more_information minfo = {};
+	GBytes *bytes = NULL;
+	if (!(bytes = pull_metadata(
+			wuffs_png__decoder__upcast_as__wuffs_base__image_decoder(dec),
+			src, &minfo, error)))
+		return false;
+
+	switch (wuffs_base__more_information__metadata__fourcc(&minfo)) {
+	case WUFFS_BASE__FOURCC__KVPK:
+		g_assert(*key == NULL);
+		*key = g_strndup(
+			g_bytes_get_data(bytes, NULL), g_bytes_get_size(bytes));
+		break;
+	case WUFFS_BASE__FOURCC__KVPV:
+		g_assert(*key != NULL);
+		g_hash_table_insert(texts, *key, g_strndup(
+			g_bytes_get_data(bytes, NULL), g_bytes_get_size(bytes)));
+		*key = NULL;
+	}
+
+	g_bytes_unref(bytes);
+	return true;
+}
+
+// An uncomplicated variant of fiv_io_open(), might be up for refactoring.
+cairo_surface_t *
+fiv_io_open_png_thumbnail(const char *path, GError **error)
+{
+	wuffs_png__decoder dec = {};
+	wuffs_base__status status = wuffs_png__decoder__initialize(
+		&dec, sizeof dec, WUFFS_VERSION, WUFFS_INITIALIZE__ALREADY_ZEROED);
+	if (!wuffs_base__status__is_ok(&status)) {
+		set_error(error, wuffs_base__status__message(&status));
+		return NULL;
+	}
+
+	gchar *data = NULL;
+	gsize len = 0;
+	if (!g_file_get_contents(path, &data, &len, error))
+		return NULL;
+
+	wuffs_base__io_buffer src =
+		wuffs_base__ptr_u8__reader((uint8_t *) data, len, TRUE);
+	wuffs_png__decoder__set_report_metadata(
+		&dec, WUFFS_BASE__FOURCC__KVP, true);
+
+	wuffs_base__image_config cfg = {};
+	wuffs_base__slice_u8 workbuf = {};
+	cairo_surface_t *surface = NULL;
+	bool success = false;
+
+	GHashTable *texts =
+		g_hash_table_new_full(g_str_hash, g_str_equal, g_free, g_free);
+	gchar *key = NULL;
+	while (true) {
+		status = wuffs_png__decoder__decode_image_config(&dec, &cfg, &src);
+		if (wuffs_base__status__is_ok(&status))
+			break;
+
+		if (status.repr != wuffs_base__note__metadata_reported) {
+			set_error(error, wuffs_base__status__message(&status));
+			goto fail;
+		}
+		if (!pull_metadata_kvp(&dec, &src, texts, &key, error))
+			goto fail;
+	}
+
+	g_assert(key == NULL);
+
+	uint32_t width = wuffs_base__pixel_config__width(&cfg.pixcfg);
+	uint32_t height = wuffs_base__pixel_config__height(&cfg.pixcfg);
+	if (width > INT16_MAX || height > INT16_MAX) {
+		set_error(error, "image dimensions overflow");
+		goto fail;
+	}
+
+	wuffs_base__pixel_config__set(&cfg.pixcfg,
+		WUFFS_BASE__PIXEL_FORMAT__BGRA_PREMUL,
+		WUFFS_BASE__PIXEL_SUBSAMPLING__NONE, width, height);
+
+	uint64_t workbuf_len_max_incl =
+		wuffs_png__decoder__workbuf_len(&dec).max_incl;
+	if (workbuf_len_max_incl) {
+		workbuf = wuffs_base__malloc_slice_u8(malloc, workbuf_len_max_incl);
+		if (!workbuf.ptr) {
+			set_error(error, "failed to allocate a work buffer");
+			goto fail;
+		}
+	}
+
+	surface = cairo_image_surface_create(
+		wuffs_base__image_config__first_frame_is_opaque(&cfg)
+			? CAIRO_FORMAT_RGB24
+			: CAIRO_FORMAT_ARGB32,
+		width, height);
+
+	cairo_status_t surface_status = cairo_surface_status(surface);
+	if (surface_status != CAIRO_STATUS_SUCCESS) {
+		set_error(error, cairo_status_to_string(surface_status));
+		goto fail;
+	}
+
+	wuffs_base__pixel_buffer pb = {};
+	status = wuffs_base__pixel_buffer__set_from_slice(&pb, &cfg.pixcfg,
+		wuffs_base__make_slice_u8(cairo_image_surface_get_data(surface),
+			cairo_image_surface_get_stride(surface) *
+				cairo_image_surface_get_height(surface)));
+	if (!wuffs_base__status__is_ok(&status)) {
+		set_error(error, wuffs_base__status__message(&status));
+		goto fail;
+	}
+
+	status = wuffs_png__decoder__decode_frame(&dec, &pb, &src,
+		WUFFS_BASE__PIXEL_BLEND__SRC, workbuf, NULL);
+	if (!wuffs_base__status__is_ok(&status)) {
+		set_error(error, wuffs_base__status__message(&status));
+		goto fail;
+	}
+
+	// The specification does not say where the required metadata should be,
+	// it could very well be broken up into two parts.
+	wuffs_base__frame_config fc = {};
+	while (true) {
+		// Not interested in APNG, might even throw an error in that case.
+		status = wuffs_png__decoder__decode_frame_config(&dec, &fc, &src);
+		if (status.repr == wuffs_base__note__end_of_data ||
+			wuffs_base__status__is_ok(&status))
+			break;
+
+		if (status.repr != wuffs_base__note__metadata_reported) {
+			set_error(error, wuffs_base__status__message(&status));
+			goto fail;
+		}
+		if (!pull_metadata_kvp(&dec, &src, texts, &key, error))
+			goto fail;
+	}
+
+	g_assert(key == NULL);
+
+	cairo_surface_mark_dirty(surface);
+	cairo_surface_set_user_data(surface, &fiv_io_key_text,
+		g_hash_table_ref(texts), (cairo_destroy_func_t) g_hash_table_unref);
+	success = true;
+
+fail:
+	if (!success)
+		g_clear_pointer(&surface, cairo_surface_destroy);
+
+	free(workbuf.ptr);
+	g_free(data);
+	g_hash_table_unref(texts);
+	return surface;
+}
+
 // --- JPEG --------------------------------------------------------------------
 
 static GBytes *
@@ -2555,6 +2718,7 @@ cairo_user_data_key_t fiv_io_key_orientation;
 cairo_user_data_key_t fiv_io_key_icc;
 cairo_user_data_key_t fiv_io_key_xmp;
 cairo_user_data_key_t fiv_io_key_thum;
+cairo_user_data_key_t fiv_io_key_text;
 
 cairo_user_data_key_t fiv_io_key_frame_next;
 cairo_user_data_key_t fiv_io_key_frame_previous;
diff --git a/fiv-io.h b/fiv-io.h
index 5a3ba27..3d5aca6 100644
--- a/fiv-io.h
+++ b/fiv-io.h
@@ -53,6 +53,9 @@ extern cairo_user_data_key_t fiv_io_key_icc;
 extern cairo_user_data_key_t fiv_io_key_xmp;
 /// GBytes with a WebP's THUM chunk, used for our thumbnails.
 extern cairo_user_data_key_t fiv_io_key_thum;
+/// GHashTable with key-value pairs from PNG's tEXt, zTXt, iTXt chunks.
+/// Currently only read by fiv_io_open_png_thumbnail().
+extern cairo_user_data_key_t fiv_io_key_text;
 
 /// The next frame in a sequence, as a surface, in a chain, pre-composited.
 /// There is no wrap-around.
@@ -95,6 +98,7 @@ typedef struct {
 cairo_surface_t *fiv_io_open(const FivIoOpenContext *ctx, GError **error);
 cairo_surface_t *fiv_io_open_from_data(
 	const char *data, size_t len, const FivIoOpenContext *ctx, GError **error);
+cairo_surface_t *fiv_io_open_png_thumbnail(const char *path, GError **error);
 
 // --- Thumbnail passing utilities ---------------------------------------------
 
diff --git a/fiv-thumbnail.c b/fiv-thumbnail.c
index 44f2735..c6e1896 100644
--- a/fiv-thumbnail.c
+++ b/fiv-thumbnail.c
@@ -18,7 +18,6 @@
 #include "config.h"
 
 #include <glib/gstdio.h>
-#include <spng.h>
 #include <webp/demux.h>
 #include <webp/encode.h>
 #include <webp/mux.h>
@@ -446,138 +445,33 @@ read_wide_thumbnail(
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
-static int  // tri-state
-check_spng_thumbnail_texts(struct spng_text *texts, uint32_t texts_len,
-	const gchar *target, time_t mtime)
-{
-	// May contain Thumb::Image::Width Thumb::Image::Height,
-	// but those aren't interesting currently (would be for fast previews).
-	bool need_uri = true, need_mtime = true;
-	for (uint32_t i = 0; i < texts_len; i++) {
-		struct spng_text *text = texts + i;
-		if (!strcmp(text->keyword, THUMB_URI)) {
-			need_uri = false;
-			if (strcmp(target, text->text))
-				return false;
-		}
-		if (!strcmp(text->keyword, THUMB_MTIME)) {
-			need_mtime = false;
-			if (atol(text->text) != mtime)
-				return false;
-		}
-	}
-	return need_uri || need_mtime ? -1 : true;
-}
-
-static int  // tri-state
-check_spng_thumbnail(spng_ctx *ctx, const gchar *target, time_t mtime, int *err)
-{
-	uint32_t texts_len = 0;
-	if ((*err = spng_get_text(ctx, NULL, &texts_len)))
-		return false;
-
-	int result = false;
-	struct spng_text *texts = g_malloc0_n(texts_len, sizeof *texts);
-	if (!(*err = spng_get_text(ctx, texts, &texts_len)))
-		result = check_spng_thumbnail_texts(texts, texts_len, target, mtime);
-	g_free(texts);
-	return result;
-}
-
 static cairo_surface_t *
-read_spng_thumbnail(
+read_png_thumbnail(
 	const gchar *path, const gchar *uri, time_t mtime, GError **error)
 {
-	FILE *fp;
-	cairo_surface_t *result = NULL;
-	if (!(fp = fopen(path, "rb"))) {
-		set_error(error, g_strerror(errno));
+	cairo_surface_t *surface = fiv_io_open_png_thumbnail(path, error);
+	if (!surface)
 		return NULL;
-	}
-
-	errno = 0;
-	spng_ctx *ctx = spng_ctx_new(0);
-	if (!ctx) {
-		set_error(error, g_strerror(errno));
-		goto fail_init;
-	}
-
-	int err;
-	size_t size = 0;
-	if ((err = spng_set_png_file(ctx, fp)) ||
-		(err = spng_set_image_limits(ctx, INT16_MAX, INT16_MAX)) ||
-		(err = spng_decoded_image_size(ctx, SPNG_FMT_RGBA8, &size))) {
-		set_error(error, spng_strerror(err));
-		goto fail;
-	}
-	if (check_spng_thumbnail(ctx, uri, mtime, &err) == false) {
-		set_error(error, err ? spng_strerror(err) : "mismatch");
-		goto fail;
-	}
-
-	struct spng_ihdr ihdr = {};
-	struct spng_trns trns = {};
-	spng_get_ihdr(ctx, &ihdr);
-	bool may_be_translucent = !spng_get_trns(ctx, &trns) ||
-		ihdr.color_type == SPNG_COLOR_TYPE_GRAYSCALE_ALPHA ||
-		ihdr.color_type == SPNG_COLOR_TYPE_TRUECOLOR_ALPHA;
-
-	cairo_surface_t *surface = cairo_image_surface_create(
-		may_be_translucent ? CAIRO_FORMAT_ARGB32 : CAIRO_FORMAT_RGB24,
-		ihdr.width, ihdr.height);
-
-	cairo_status_t surface_status = cairo_surface_status(surface);
-	if (surface_status != CAIRO_STATUS_SUCCESS) {
-		set_error(error, cairo_status_to_string(surface_status));
-		goto fail_data;
-	}
-
-	uint32_t *data = (uint32_t *) cairo_image_surface_get_data(surface);
-	g_assert((size_t) cairo_image_surface_get_stride(surface) *
-		cairo_image_surface_get_height(surface) == size);
 
-	cairo_surface_flush(surface);
-	if ((err = spng_decode_image(ctx, data, size, SPNG_FMT_RGBA8,
-		SPNG_DECODE_TRNS | SPNG_DECODE_GAMMA))) {
-		set_error(error, spng_strerror(err));
-		goto fail_data;
-	}
-
-	// The specification does not say where the required metadata should be,
-	// it could very well be broken up into two parts.
-	if (check_spng_thumbnail(ctx, uri, mtime, &err) != true) {
-		set_error(
-			error, err ? spng_strerror(err) : "mismatch or not a thumbnail");
-		goto fail_data;
+	GHashTable *texts = cairo_surface_get_user_data(surface, &fiv_io_key_text);
+	if (!texts) {
+		set_error(error, "not a thumbnail");
+		cairo_surface_destroy(surface);
+		return NULL;
 	}
 
-	// pixman can be mildly abused to do this operation, but it won't be faster.
-	if (may_be_translucent) {
-		for (size_t i = size / sizeof *data; i--; ) {
-			const uint8_t *unit = (const uint8_t *) &data[i];
-			uint32_t a = unit[3],
-				b = PREMULTIPLY8(a, unit[2]),
-				g = PREMULTIPLY8(a, unit[1]),
-				r = PREMULTIPLY8(a, unit[0]);
-			data[i] = a << 24 | r << 16 | g << 8 | b;
-		}
-	} else {
-		for (size_t i = size / sizeof *data; i--; ) {
-			uint32_t rgba = g_ntohl(data[i]);
-			data[i] = rgba << 24 | rgba >> 8;
-		}
+	// May contain Thumb::Image::Width Thumb::Image::Height,
+	// but those aren't interesting currently (would be for fast previews).
+	const char *text_uri = g_hash_table_lookup(texts, THUMB_URI);
+	const char *text_mtime = g_hash_table_lookup(texts, THUMB_MTIME);
+	if (!text_uri || strcmp(text_uri, uri) ||
+		!text_mtime || atol(text_mtime) != mtime) {
+		set_error(error, "mismatch or not a thumbnail");
+		cairo_surface_destroy(surface);
+		return NULL;
 	}
 
-	cairo_surface_mark_dirty((result = surface));
-
-fail_data:
-	if (!result)
-		cairo_surface_destroy(surface);
-fail:
-	spng_ctx_free(ctx);
-fail_init:
-	fclose(fp);
-	return result;
+	return surface;
 }
 
 cairo_surface_t *
@@ -616,7 +510,7 @@ fiv_thumbnail_lookup(char *uri, gint64 mtime_msec, FivThumbnailSize size)
 
 		gchar *path =
 			g_strdup_printf("%s/%s/%s.png", thumbnails_dir, name, sum);
-		result = read_spng_thumbnail(path, uri, mtime_msec / 1000, &error);
+		result = read_png_thumbnail(path, uri, mtime_msec / 1000, &error);
 		if (error) {
 			g_debug("%s: %s", path, error->message);
 			g_clear_error(&error);
diff --git a/meson.build b/meson.build
index 38afe47..b885e2e 100644
--- a/meson.build
+++ b/meson.build
@@ -39,11 +39,6 @@ dependencies = [
 	dependency('libwebpdemux'),
 	dependency('libwebpdecoder', required : false),
 	dependency('libwebpmux'),
-	# https://github.com/google/wuffs/issues/58
-	dependency('spng', version : '>=0.7.0',
-		default_options: 'default_library=static',
-		# fallback : ['spng', 'spng_dep'],
-	),
 
 	lcms2,
 	libjpegqs,
diff --git a/subprojects/spng.wrap b/subprojects/spng.wrap
deleted file mode 100644
index 93904f2..0000000
--- a/subprojects/spng.wrap
+++ /dev/null
@@ -1,8 +0,0 @@
-[wrap-file]
-directory = libspng-0.7.2
-source_url = https://github.com/randy408/libspng/archive/refs/tags/v0.7.2.tar.gz
-source_filename = libspng-0.7.2.tar.gz
-source_hash = 4acf25571d31f540d0b7ee004f5461d68158e0a13182505376805da99f4ccc4e
-
-[provide]
-spng = spng_dep