Move thumbnails into their own source file

And clean up identifiers.

1 files changed, 494 insertions, 0 deletions

diff --git a/fiv-thumbnail.c b/fiv-thumbnail.c
new file mode 100644
index 0000000..1384213
--- /dev/null
+++ b/fiv-thumbnail.c
@@ -0,0 +1,494 @@
+//
+// fiv-thumbnail.c: thumbnail management
+//
+// Copyright (c) 2021, Přemysl Eric Janouch <p@janouch.name>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+//
+
+#include <spng.h>
+#include <webp/encode.h>
+#include <webp/mux.h>
+#include <glib/gstdio.h>
+
+#include <math.h>
+#include <stdbool.h>
+
+#include "fiv-io.h"
+#include "fiv-thumbnail.h"
+#include "xdg.h"
+
+#ifndef __linux__
+#define st_mtim st_mtimespec
+#endif  // ! __linux__
+
+// TODO(p): Consider merging back with fiv-io.
+#define FIV_THUMBNAIL_ERROR fiv_thumbnail_error_quark()
+
+G_DEFINE_QUARK(fiv-thumbnail-error-quark, fiv_thumbnail_error)
+
+enum FivThumbnailError {
+	FIV_THUMBNAIL_ERROR_IO
+};
+
+static void
+set_error(GError **error, const char *message)
+{
+	g_set_error_literal(
+		error, FIV_THUMBNAIL_ERROR, FIV_THUMBNAIL_ERROR_IO, message);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+GType
+fiv_thumbnail_size_get_type(void)
+{
+	static gsize guard;
+	if (g_once_init_enter(&guard)) {
+#define XX(name, value, dir) {FIV_THUMBNAIL_SIZE_ ## name, \
+	"FIV_THUMBNAIL_SIZE_" #name, #name},
+		static const GEnumValue values[] = {FIV_THUMBNAIL_SIZES(XX) {}};
+#undef XX
+		GType type = g_enum_register_static(
+			g_intern_static_string("FivThumbnailSize"), values);
+		g_once_init_leave(&guard, type);
+	}
+	return guard;
+}
+
+#define XX(name, value, dir) {value, dir},
+FivThumbnailSizeInfo
+	fiv_thumbnail_sizes[FIV_THUMBNAIL_SIZE_COUNT] = {
+		FIV_THUMBNAIL_SIZES(XX)};
+#undef XX
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+cairo_user_data_key_t fiv_thumbnail_key_lq;
+
+static void
+mark_thumbnail_lq(cairo_surface_t *surface)
+{
+	cairo_surface_set_user_data(
+		surface, &fiv_thumbnail_key_lq, (void *) (intptr_t) 1, NULL);
+}
+
+gchar *
+fiv_thumbnail_get_root(void)
+{
+	gchar *cache_dir = get_xdg_home_dir("XDG_CACHE_HOME", ".cache");
+	gchar *thumbnails_dir = g_build_filename(cache_dir, "thumbnails", NULL);
+	g_free(cache_dir);
+	return thumbnails_dir;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+// In principle similar to rescale_thumbnail() from fiv-browser.c.
+static cairo_surface_t *
+rescale_thumbnail(cairo_surface_t *thumbnail, double row_height)
+{
+	cairo_format_t format = cairo_image_surface_get_format(thumbnail);
+	int width = cairo_image_surface_get_width(thumbnail);
+	int height = cairo_image_surface_get_height(thumbnail);
+
+	double scale_x = 1;
+	double scale_y = 1;
+	if (width > FIV_THUMBNAIL_WIDE_COEFFICIENT * height) {
+		scale_x = FIV_THUMBNAIL_WIDE_COEFFICIENT * row_height / width;
+		scale_y = round(scale_x * height) / height;
+	} else {
+		scale_y = row_height / height;
+		scale_x = round(scale_y * width) / width;
+	}
+	if (scale_x == 1 && scale_y == 1)
+		return cairo_surface_reference(thumbnail);
+
+	int projected_width = round(scale_x * width);
+	int projected_height = round(scale_y * height);
+	cairo_surface_t *scaled = cairo_image_surface_create(
+		(format == CAIRO_FORMAT_RGB24 || format == CAIRO_FORMAT_RGB30)
+			? CAIRO_FORMAT_RGB24
+			: CAIRO_FORMAT_ARGB32,
+		projected_width, projected_height);
+
+	cairo_t *cr = cairo_create(scaled);
+	cairo_scale(cr, scale_x, scale_y);
+
+	cairo_set_source_surface(cr, thumbnail, 0, 0);
+	cairo_pattern_t *pattern = cairo_get_source(cr);
+	cairo_pattern_set_filter(pattern, CAIRO_FILTER_BEST);
+	cairo_pattern_set_extend(pattern, CAIRO_EXTEND_PAD);
+
+	cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+	cairo_paint(cr);
+	cairo_destroy(cr);
+	mark_thumbnail_lq(scaled);
+	return scaled;
+}
+
+static WebPData
+encode_thumbnail(cairo_surface_t *surface)
+{
+	WebPData bitstream = {};
+	WebPConfig config = {};
+	if (!WebPConfigInit(&config) || !WebPConfigLosslessPreset(&config, 6))
+		return bitstream;
+
+	config.near_lossless = 95;
+	config.thread_level = true;
+	if (!WebPValidateConfig(&config))
+		return bitstream;
+
+	bitstream.bytes = fiv_io_encode_webp(surface, &config, &bitstream.size);
+	return bitstream;
+}
+
+static void
+save_thumbnail(cairo_surface_t *thumbnail, const char *path, GString *thum)
+{
+	WebPMux *mux = WebPMuxNew();
+	WebPData bitstream = encode_thumbnail(thumbnail);
+	gboolean ok = WebPMuxSetImage(mux, &bitstream, true) == WEBP_MUX_OK;
+	WebPDataClear(&bitstream);
+
+	WebPData data = {.bytes = (const uint8_t *) thum->str, .size = thum->len};
+	ok = ok && WebPMuxSetChunk(mux, "THUM", &data, false) == WEBP_MUX_OK;
+
+	WebPData assembled = {};
+	WebPDataInit(&assembled);
+	ok = ok && WebPMuxAssemble(mux, &assembled) == WEBP_MUX_OK;
+	WebPMuxDelete(mux);
+	if (!ok) {
+		g_warning("thumbnail encoding failed");
+		return;
+	}
+
+	GError *e = NULL;
+	while (!g_file_set_contents(
+		path, (const gchar *) assembled.bytes, assembled.size, &e)) {
+		bool missing_parents =
+			e->domain == G_FILE_ERROR && e->code == G_FILE_ERROR_NOENT;
+		g_debug("%s: %s", path, e->message);
+		g_clear_error(&e);
+		if (!missing_parents)
+			break;
+
+		gchar *dirname = g_path_get_dirname(path);
+		int err = g_mkdir_with_parents(dirname, 0755);
+		if (err)
+			g_debug("%s: %s", dirname, g_strerror(errno));
+
+		g_free(dirname);
+		if (err)
+			break;
+	}
+
+	// It would be possible to create square thumbnails as well,
+	// but it seems like wasted effort.
+	WebPDataClear(&assembled);
+}
+
+gboolean
+fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size, GError **error)
+{
+	g_return_val_if_fail(max_size >= FIV_THUMBNAIL_SIZE_MIN &&
+		max_size <= FIV_THUMBNAIL_SIZE_MAX, FALSE);
+
+	// Local files only, at least for now.
+	gchar *path = g_file_get_path(target);
+	if (!path)
+		return FALSE;
+
+	GMappedFile *mf = g_mapped_file_new(path, FALSE, error);
+	if (!mf) {
+		g_free(path);
+		return FALSE;
+	}
+
+	GStatBuf st = {};
+	if (g_stat(path, &st)) {
+		set_error(error, g_strerror(errno));
+		g_free(path);
+		return FALSE;
+	}
+
+	// TODO(p): Add a flag to avoid loading all pages and frames.
+	FivIoProfile sRGB = fiv_io_profile_new_sRGB();
+	gsize filesize = g_mapped_file_get_length(mf);
+	cairo_surface_t *surface = fiv_io_open_from_data(
+		g_mapped_file_get_contents(mf), filesize, path, sRGB, FALSE, error);
+
+	g_free(path);
+	g_mapped_file_unref(mf);
+	if (sRGB)
+		fiv_io_profile_free(sRGB);
+	if (!surface)
+		return FALSE;
+
+	// Boilerplate copied from fiv_thumbnail_lookup().
+	gchar *uri = g_file_get_uri(target);
+	gchar *sum = g_compute_checksum_for_string(G_CHECKSUM_MD5, uri, -1);
+	gchar *thumbnails_dir = fiv_thumbnail_get_root();
+
+	GString *thum = g_string_new("");
+	g_string_append_printf(
+		thum, "%s%c%s%c", "Thumb::URI", 0, uri, 0);
+	g_string_append_printf(
+		thum, "%s%c%ld%c", "Thumb::Mtime", 0, (long) st.st_mtim.tv_sec, 0);
+	g_string_append_printf(
+		thum, "%s%c%ld%c", "Thumb::Size", 0, (long) filesize, 0);
+	g_string_append_printf(thum, "%s%c%d%c", "Thumb::Image::Width", 0,
+		cairo_image_surface_get_width(surface), 0);
+	g_string_append_printf(thum, "%s%c%d%c", "Thumb::Image::Height", 0,
+		cairo_image_surface_get_height(surface), 0);
+
+	// Without a CMM, no conversion is attempted.
+	if (sRGB) {
+		g_string_append_printf(
+			thum, "%s%c%s%c", "Thumb::ColorSpace", 0, "sRGB", 0);
+	}
+
+	for (int use = max_size; use >= FIV_THUMBNAIL_SIZE_MIN; use--) {
+		cairo_surface_t *scaled =
+			rescale_thumbnail(surface, fiv_thumbnail_sizes[use].size);
+		gchar *path = g_strdup_printf("%s/wide-%s/%s.webp", thumbnails_dir,
+			fiv_thumbnail_sizes[use].thumbnail_spec_name, sum);
+		save_thumbnail(scaled, path, thum);
+		cairo_surface_destroy(scaled);
+		g_free(path);
+	}
+
+	g_string_free(thum, TRUE);
+
+	g_free(thumbnails_dir);
+	g_free(sum);
+	g_free(uri);
+	cairo_surface_destroy(surface);
+	return TRUE;
+}
+
+static cairo_surface_t *
+read_wide_thumbnail(
+	const gchar *path, const gchar *uri, time_t mtime, GError **error)
+{
+	// TODO(p): Validate fiv_io_key_thum.
+	(void) uri;
+	(void) mtime;
+	return fiv_io_open(path, NULL, FALSE, error);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+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(
+	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));
+		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;
+	}
+
+	// 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;
+		}
+	}
+
+	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;
+}
+
+cairo_surface_t *
+fiv_thumbnail_lookup(GFile *target, FivThumbnailSize size)
+{
+	g_return_val_if_fail(size >= FIV_THUMBNAIL_SIZE_MIN &&
+		size <= FIV_THUMBNAIL_SIZE_MAX, NULL);
+
+	// Local files only, at least for now.
+	gchar *path = g_file_get_path(target);
+	if (!path)
+		return NULL;
+
+	GStatBuf st = {};
+	int err = g_stat(path, &st);
+	g_free(path);
+	if (err)
+		return NULL;
+
+	gchar *uri = g_file_get_uri(target);
+	gchar *sum = g_compute_checksum_for_string(G_CHECKSUM_MD5, uri, -1);
+	gchar *thumbnails_dir = fiv_thumbnail_get_root();
+
+	// The lookup sequence is: nominal..max, then mirroring back to ..min.
+	cairo_surface_t *result = NULL;
+	GError *error = NULL;
+	for (int i = 0; i < FIV_THUMBNAIL_SIZE_COUNT; i++) {
+		FivThumbnailSize use = size + i;
+		if (use > FIV_THUMBNAIL_SIZE_MAX)
+			use = FIV_THUMBNAIL_SIZE_MAX - i;
+
+		const char *name = fiv_thumbnail_sizes[use].thumbnail_spec_name;
+		gchar *wide =
+			g_strdup_printf("%s/wide-%s/%s.webp", thumbnails_dir, name, sum);
+		result = read_wide_thumbnail(wide, uri, st.st_mtim.tv_sec, &error);
+		if (error) {
+			g_debug("%s: %s", wide, error->message);
+			g_clear_error(&error);
+		}
+		g_free(wide);
+		if (result) {
+			// Higher up we can't distinguish images smaller than the thumbnail.
+			// Also, try not to rescale the already rescaled.
+			if (use != size)
+				mark_thumbnail_lq(result);
+			break;
+		}
+
+		gchar *path =
+			g_strdup_printf("%s/%s/%s.png", thumbnails_dir, name, sum);
+		result = read_spng_thumbnail(path, uri, st.st_mtim.tv_sec, &error);
+		if (error) {
+			g_debug("%s: %s", path, error->message);
+			g_clear_error(&error);
+		}
+		g_free(path);
+		if (result) {
+			// Whatever produced it, we may be able to outclass it.
+			mark_thumbnail_lq(result);
+			break;
+		}
+	}
+
+	// TODO(p): We can definitely extract embedded thumbnails, but it should be
+	// done as a separate stage--the file may be stored on a slow device.
+
+	g_free(thumbnails_dir);
+	g_free(sum);
+	g_free(uri);
+	return result;
+}