Update README

.clang-format

@@ -0,0 +1,12 @@
+BasedOnStyle: LLVM
+ColumnLimit: 80
+IndentWidth: 4
+TabWidth: 4
+UseTab: ForContinuationAndIndentation
+AlwaysBreakAfterReturnType: AllDefinitions
+BreakBeforeBraces: Linux
+SpaceAfterCStyleCast: true
+AlignAfterOpenBracket: DontAlign
+AlignOperands: DontAlign
+SpacesBeforeTrailingComments: 2
+WhitespaceSensitiveMacros: ['G_DEFINE_QUARK']

README.adoc

@@ -2,41 +2,13 @@ fastiv
 ======
 
 'fastiv' is a fast image viewer, supporting BMP, PNG, GIF, JPEG, and optionally
-RAW pictures.
+RAW pictures.  Currently, it's not particularly usable.
 
-It is meant to be a viable replacement for Eye of GNOME, which is slow, likes
-to break on huge pictures, and its underlying gdk-pixbuf can only be made to use
-the broken libopenraw
-https://mail.gnome.org/archives/eog-list/2016-January/msg00004.html[as of now].
-
-Further development
--------------------
-Urgent blockers for the first stable version:
-
- - directory browsing
- - implement zoom and scrolling
-
-High priority:
-
- - some level of asynchronous loading and preloading,
-   which becomes a difficult problem with network mounts,
-   confusingly acting as fast devices
- - write a replacement for GNOME's Nautilus in grid mode:
-   read-only, with focus on staggered previews and minimising wasted space
-
-Low priority:
-
- - display 16-bit pictures smoothly, using the 30-bit depth under X.org
- - make RAW as fast as it can possibly be
- - load everything that resembles a picture, potentially even play video
- - port to something less hostile than the current GNOME stack, such as SDL,
-   although it may involve a lot of reimplemented code,
-   or result in reduced functionality
-
-Non-goals:
-
- - fancy UI, focus solely on speed of use
+Non-goals
+---------
+ - fancy UI--the focus is on speed of use first, colour accuracy second
  - memory efficiency, though preloading can cause some pressure
+ - portability to non-UNIXy systems
 
 Packages
 --------
@@ -46,8 +18,8 @@ a package with the latest development version from Archlinux's AUR.
 Building and Running
 --------------------
 Build dependencies: Meson, pkg-config +
-Runtime dependencies: gtk+-3.0, libpng > 1.5.4, libturbojpeg, LibRaw (optional),
-shared-mime-info
+Runtime dependencies: gtk+-3.0, shared-mime-info, libpng>=1.5.4, libturbojpeg,
+LibRaw (optional)
 
  $ git clone --recursive https://git.janouch.name/p/fastiv.git
  $ meson builddir

fastiv-browser.c

@@ -18,6 +18,7 @@
 #include <math.h>
 
 #include "fastiv-browser.h"
+#include "fastiv-io.h"
 #include "fastiv-view.h"
 
 typedef struct entry Entry;
@@ -73,8 +74,8 @@ fastiv_browser_get_request_mode(G_GNUC_UNUSED GtkWidget *widget)
 }
 
 static void
-fastiv_browser_get_preferred_width(GtkWidget *widget,
-	gint *minimum, gint *natural)
+fastiv_browser_get_preferred_width(
+	GtkWidget *widget, gint *minimum, gint *natural)
 {
 	G_GNUC_UNUSED FastivBrowser *self = FASTIV_BROWSER(widget);
 	// TODO(p): Set it to the width of the widget with one wide item within.
@@ -82,8 +83,8 @@ fastiv_browser_get_preferred_width(GtkWidget *widget,
 }
 
 static void
-fastiv_browser_get_preferred_height_for_width(GtkWidget *widget,
-	G_GNUC_UNUSED gint width, gint *minimum, gint *natural)
+fastiv_browser_get_preferred_height_for_width(
+	GtkWidget *widget, G_GNUC_UNUSED gint width, gint *minimum, gint *natural)
 {
 	G_GNUC_UNUSED FastivBrowser *self = FASTIV_BROWSER(widget);
 	// TODO(p): Re-layout, figure it out.
@@ -108,8 +109,8 @@ fastiv_browser_realize(GtkWidget *widget)
 		.wclass = GDK_INPUT_OUTPUT,
 
 		.visual = gtk_widget_get_visual(widget),
-		.event_mask  = gtk_widget_get_events(widget)
-			| GDK_KEY_PRESS_MASK | GDK_BUTTON_PRESS_MASK,
+		.event_mask = gtk_widget_get_events(widget) | GDK_KEY_PRESS_MASK |
+			GDK_BUTTON_PRESS_MASK,
 	};
 
 	// We need this window to receive input events at all.
@@ -130,8 +131,8 @@ fastiv_browser_draw(GtkWidget *widget, cairo_t *cr)
 
 	GtkAllocation allocation;
 	gtk_widget_get_allocation(widget, &allocation);
-	gtk_render_background(gtk_widget_get_style_context(widget), cr,
-		0, 0, allocation.width, allocation.height);
+	gtk_render_background(gtk_widget_get_style_context(widget), cr, 0, 0,
+		allocation.width, allocation.height);
 
 	const double row_height = 256;
 
@@ -151,8 +152,8 @@ fastiv_browser_draw(GtkWidget *widget, cairo_t *cr)
 		int projected_width = round(scale * width);
 		int projected_height = round(scale * height);
 
-		if (occupied_width != 0
-		 && occupied_width + projected_width > allocation.width) {
+		if (occupied_width != 0 &&
+			occupied_width + projected_width > allocation.width) {
 			occupied_width = 0;
 			y += row_height;
 		}
@@ -177,17 +178,15 @@ fastiv_browser_class_init(FastivBrowserClass *klass)
 
 	GtkWidgetClass *widget_class = GTK_WIDGET_CLASS(klass);
 	widget_class->get_request_mode = fastiv_browser_get_request_mode;
-	widget_class->get_preferred_width =
-		fastiv_browser_get_preferred_width;
+	widget_class->get_preferred_width = fastiv_browser_get_preferred_width;
 	widget_class->get_preferred_height_for_width =
 		fastiv_browser_get_preferred_height_for_width;
 	widget_class->realize = fastiv_browser_realize;
 	widget_class->draw = fastiv_browser_draw;
 
 	// TODO(p): Connect to this and emit it.
-	browser_signals[ITEM_ACTIVATED] =
-		g_signal_new("item-activated", G_TYPE_FROM_CLASS(klass),
-			0, 0, NULL, NULL, NULL, G_TYPE_NONE, 0);
+	browser_signals[ITEM_ACTIVATED] = g_signal_new("item-activated",
+		G_TYPE_FROM_CLASS(klass), 0, 0, NULL, NULL, NULL, G_TYPE_NONE, 0);
 
 	// TODO(p): Later override "screen_changed", recreate Pango layouts there,
 	// if we get to have any, or otherwise reflect DPI changes.
@@ -216,12 +215,12 @@ fastiv_browser_load(FastivBrowser *self, const char *path)
 
 	const char *filename;
 	while ((filename = g_dir_read_name(dir))) {
-		if (!strcmp(filename, ".")
-		 || !strcmp(filename, ".."))
+		if (!strcmp(filename, ".") || !strcmp(filename, ".."))
 			continue;
 
 		gchar *subpath = g_build_filename(path, filename, NULL);
-		g_array_append_val(self->entries, ((Entry) {
+		g_array_append_val(self->entries,
+			((Entry){
 				.thumbnail = fastiv_io_lookup_thumbnail(subpath),
 				.filename = subpath,
 			}));

fastiv-io-benchmark.c

@@ -15,8 +15,8 @@
 // CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 //
 
-#include <time.h>
 #include <gdk-pixbuf/gdk-pixbuf.h>
+#include <time.h>
 
 #include "fastiv-view.h"
 

fastiv-io.c

@@ -17,8 +17,8 @@
 
 #include "config.h"
 
-#include <glib.h>
 #include <cairo.h>
+#include <glib.h>
 #include <turbojpeg.h>
 #ifdef HAVE_LIBRAW
 #include <libraw.h>
@@ -37,6 +37,22 @@
 #define WUFFS_CONFIG__MODULE__ZLIB
 #include "wuffs-mirror-release-c/release/c/wuffs-v0.3.c"
 
+#include "xdg.h"
+
+// A subset of shared-mime-info that produces an appropriate list of
+// file extensions. Chiefly motivated by the suckiness of RAW images:
+// someone else will maintain the list of file extensions for us.
+const char *fastiv_io_supported_media_types[] = {
+	"image/bmp",
+	"image/gif",
+	"image/png",
+	"image/jpeg",
+#ifdef HAVE_LIBRAW
+	"image/x-dcraw",
+#endif  // HAVE_LIBRAW
+	NULL
+};
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 #define FASTIV_IO_ERROR fastiv_io_error_quark()
@@ -50,8 +66,7 @@ enum FastivIoError {
 static void
 set_error(GError **error, const char *message)
 {
-	g_set_error_literal(error,
-		FASTIV_IO_ERROR, FASTIV_IO_ERROR_OPEN, message);
+	g_set_error_literal(error, FASTIV_IO_ERROR, FASTIV_IO_ERROR_OPEN, message);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -60,8 +75,8 @@ set_error(GError **error, const char *message)
 // is pure C, and a good reference. I can't use the auxiliary libraries,
 // since they depend on C++, which is undesirable.
 static cairo_surface_t *
-open_wuffs(wuffs_base__image_decoder *dec,
-	wuffs_base__io_buffer src, GError **error)
+open_wuffs(
+	wuffs_base__image_decoder *dec, wuffs_base__io_buffer src, GError **error)
 {
 	wuffs_base__image_config cfg;
 	wuffs_base__status status =
@@ -156,8 +171,8 @@ open_wuffs(wuffs_base__image_decoder *dec,
 	// Starting to modify pixel data directly. Probably an unnecessary call.
 	cairo_surface_flush(surface);
 
-	status = wuffs_base__image_decoder__decode_frame(dec, &pb, &src,
-		WUFFS_BASE__PIXEL_BLEND__SRC, workbuf, NULL);
+	status = wuffs_base__image_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));
 		cairo_surface_destroy(surface);
@@ -182,8 +197,8 @@ open_wuffs_using(wuffs_base__image_decoder *(*allocate)(),
 		return NULL;
 	}
 
-	cairo_surface_t *surface = open_wuffs(dec,
-		wuffs_base__ptr_u8__reader((uint8_t *) data, len, TRUE), error);
+	cairo_surface_t *surface = open_wuffs(
+		dec, wuffs_base__ptr_u8__reader((uint8_t *) data, len, TRUE), error);
 	free(dec);
 	return surface;
 }
@@ -241,8 +256,8 @@ open_libjpeg_turbo(const gchar *data, gsize len, GError **error)
 
 	int stride = cairo_image_surface_get_stride(surface);
 	if (tjDecompress2(dec, (const unsigned char *) data, len,
-			cairo_image_surface_get_data(surface), width, stride,
-			height, pixel_format, TJFLAG_ACCURATEDCT)) {
+			cairo_image_surface_get_data(surface), width, stride, height,
+			pixel_format, TJFLAG_ACCURATEDCT)) {
 		set_error(error, tjGetErrorStr2(dec));
 		cairo_surface_destroy(surface);
 		tjDestroy(dec);
@@ -253,8 +268,8 @@ open_libjpeg_turbo(const gchar *data, gsize len, GError **error)
 	if (pixel_format == TJPF_CMYK) {
 		// CAIRO_STRIDE_ALIGNMENT is 4 bytes, so there will be no padding with
 		// ARGB/BGR/XRGB/BGRX.
-		trivial_cmyk_to_bgra(cairo_image_surface_get_data(surface),
-			width * height);
+		trivial_cmyk_to_bgra(
+			cairo_image_surface_get_data(surface), width * height);
 	}
 
 	// Pixel data has been written, need to let Cairo know.
@@ -270,8 +285,8 @@ static cairo_surface_t *
 open_libraw(const gchar *data, gsize len, GError **error)
 {
 	// https://github.com/LibRaw/LibRaw/issues/418
-	libraw_data_t *iprc = libraw_init(LIBRAW_OPIONS_NO_MEMERR_CALLBACK
-		| LIBRAW_OPIONS_NO_DATAERR_CALLBACK);
+	libraw_data_t *iprc = libraw_init(
+		LIBRAW_OPIONS_NO_MEMERR_CALLBACK | LIBRAW_OPIONS_NO_DATAERR_CALLBACK);
 	if (!iprc) {
 		set_error(error, "failed to obtain a LibRaw handle");
 		return NULL;
@@ -354,8 +369,8 @@ open_libraw(const gchar *data, gsize len, GError **error)
 	unsigned char *p = image->data;
 	for (ushort y = 0; y < image->height; y++) {
 		for (ushort x = 0; x < image->width; x++) {
-			*pixels++ = 0xff000000 | (uint32_t) p[0] << 16
-				| (uint32_t) p[1] << 8 | (uint32_t) p[2];
+			*pixels++ = 0xff000000 | (uint32_t) p[0] << 16 |
+				(uint32_t) p[1] << 8 | (uint32_t) p[2];
 			p += 3;
 		}
 	}
@@ -393,18 +408,18 @@ fastiv_io_open(const gchar *path, GError **error)
 		// Note that BMP can redirect into another format,
 		// which is so far unsupported here.
 		surface = open_wuffs_using(
-			wuffs_bmp__decoder__alloc_as__wuffs_base__image_decoder,
-			data, len, error);
+			wuffs_bmp__decoder__alloc_as__wuffs_base__image_decoder, data, len,
+			error);
 		break;
 	case WUFFS_BASE__FOURCC__GIF:
 		surface = open_wuffs_using(
-			wuffs_gif__decoder__alloc_as__wuffs_base__image_decoder,
-			data, len, error);
+			wuffs_gif__decoder__alloc_as__wuffs_base__image_decoder, data, len,
+			error);
 		break;
 	case WUFFS_BASE__FOURCC__PNG:
 		surface = open_wuffs_using(
-			wuffs_png__decoder__alloc_as__wuffs_base__image_decoder,
-			data, len, error);
+			wuffs_png__decoder__alloc_as__wuffs_base__image_decoder, data, len,
+			error);
 		break;
 	case WUFFS_BASE__FOURCC__JPEG:
 		surface = open_libjpeg_turbo(data, len, error);
@@ -432,11 +447,8 @@ fastiv_io_open(const gchar *path, GError **error)
 // scaled, linear encoded, pre-multiplied component values must be used!"
 //
 // We can use the pixman library to scale, PIXMAN_a8r8g8b8_sRGB.
-#include <png.h>
 #include <glib/gstdio.h>
-
-// TODO(p): Reorganize the sources.
-gchar *get_xdg_home_dir(const char *var, const char *default_);
+#include <png.h>
 
 static void
 redirect_png_error(png_structp pngp, const char *error)
@@ -453,8 +465,8 @@ discard_png_warning(png_structp pngp, const char *warning)
 }
 
 static int
-check_png_thumbnail(png_structp pngp, png_infop infop, const gchar *target,
-	time_t mtime)
+check_png_thumbnail(
+	png_structp pngp, png_infop infop, 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).
@@ -482,8 +494,8 @@ check_png_thumbnail(png_structp pngp, png_infop infop, const gchar *target,
 // TODO(p): Support spng as well (it can't premultiply alpha by itself,
 // but at least it won't gamma-adjust it for us).
 static cairo_surface_t *
-read_png_thumbnail(const gchar *path, const gchar *uri, time_t mtime,
-	GError **error)
+read_png_thumbnail(
+	const gchar *path, const gchar *uri, time_t mtime, GError **error)
 {
 	FILE *fp;
 	if (!(fp = fopen(path, "rb"))) {
@@ -492,8 +504,8 @@ read_png_thumbnail(const gchar *path, const gchar *uri, time_t mtime,
 	}
 
 	cairo_surface_t *volatile surface = NULL;
-	png_structp pngp = png_create_read_struct(PNG_LIBPNG_VER_STRING,
-		error, redirect_png_error, discard_png_warning);
+	png_structp pngp = png_create_read_struct(
+		PNG_LIBPNG_VER_STRING, error, redirect_png_error, discard_png_warning);
 	png_infop infop = png_create_info_struct(pngp);
 	if (!infop) {
 		set_error(error, g_strerror(errno));
@@ -603,8 +615,8 @@ fastiv_io_lookup_thumbnail(const gchar *target)
 	const gchar *sizes[] = {"large", "x-large", "xx-large", "normal"};
 	GError *error = NULL;
 	for (gsize i = 0; !result && i < G_N_ELEMENTS(sizes); i++) {
-		gchar *path = g_strdup_printf("%s/thumbnails/%s/%s.png",
-			cache_dir, sizes[i], sum);
+		gchar *path = g_strdup_printf(
+			"%s/thumbnails/%s/%s.png", cache_dir, sizes[i], sum);
 		result = read_png_thumbnail(path, uri, st.st_mtim.tv_sec, &error);
 		if (error) {
 			g_debug("%s: %s", path, error->message);

fastiv-io.h

@@ -0,0 +1,26 @@
+//
+// fastiv-io.h: image loaders
+//
+// 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.
+//
+
+#pragma once
+
+#include <cairo.h>
+#include <glib.h>
+
+extern const char *fastiv_io_supported_media_types[];
+
+cairo_surface_t *fastiv_io_open(const gchar *path, GError **error);
+cairo_surface_t *fastiv_io_lookup_thumbnail(const gchar *target);

fastiv-view.c

@@ -17,6 +17,7 @@
 
 #include <math.h>
 
+#include "fastiv-io.h"
 #include "fastiv-view.h"
 
 struct _FastivView {
@@ -56,8 +57,8 @@ fastiv_view_finalize(GObject *gobject)
 }
 
 static void
-fastiv_view_get_preferred_height(GtkWidget *widget,
-	gint *minimum, gint *natural)
+fastiv_view_get_preferred_height(
+	GtkWidget *widget, gint *minimum, gint *natural)
 {
 	*minimum = 0;
 	*natural = 0;
@@ -67,8 +68,7 @@ fastiv_view_get_preferred_height(GtkWidget *widget,
 }
 
 static void
-fastiv_view_get_preferred_width(GtkWidget *widget,
-	gint *minimum, gint *natural)
+fastiv_view_get_preferred_width(GtkWidget *widget, gint *minimum, gint *natural)
 {
 	*minimum = 0;
 	*natural = 0;
@@ -112,14 +112,14 @@ static gboolean
 fastiv_view_draw(GtkWidget *widget, cairo_t *cr)
 {
 	FastivView *self = FASTIV_VIEW(widget);
-	if (!self->surface
-	 || !gtk_cairo_should_draw_window(cr, gtk_widget_get_window(widget)))
+	if (!self->surface ||
+		!gtk_cairo_should_draw_window(cr, gtk_widget_get_window(widget)))
 		return TRUE;
 
 	GtkAllocation allocation;
 	gtk_widget_get_allocation(widget, &allocation);
-	gtk_render_background(gtk_widget_get_style_context(widget), cr,
-		0, 0, allocation.width, allocation.height);
+	gtk_render_background(gtk_widget_get_style_context(widget), cr, 0, 0,
+		allocation.width, allocation.height);
 
 	int w = get_display_width(self);
 	int h = get_display_height(self);
@@ -132,8 +132,8 @@ fastiv_view_draw(GtkWidget *widget, cairo_t *cr)
 		y = round((allocation.height - h) / 2.);
 
 	cairo_scale(cr, self->scale, self->scale);
-	cairo_set_source_surface(cr, self->surface,
-		x / self->scale, y / self->scale);
+	cairo_set_source_surface(
+		cr, self->surface, x / self->scale, y / self->scale);
 
 	// TODO(p): Prescale it ourselves to an off-screen bitmap, gamma-correctly.
 	cairo_pattern_set_filter(cairo_get_source(cr), CAIRO_FILTER_GOOD);

fastiv-view.h

@@ -24,7 +24,3 @@ G_DECLARE_FINAL_TYPE(FastivView, fastiv_view, FASTIV, VIEW, GtkWidget)
 
 /// Try to open the given file, synchronously, to be displayed by the widget.
 gboolean fastiv_view_open(FastivView *self, const gchar *path, GError **error);
-
-// Private, fastiv-io.c
-cairo_surface_t *fastiv_io_open(const gchar *path, GError **error);
-cairo_surface_t *fastiv_io_lookup_thumbnail(const gchar *target);

fastiv.c

@@ -15,25 +15,26 @@
 // CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 //
 
-#include <gtk/gtk.h>
 #include <glib.h>
 #include <glib/gstdio.h>
+#include <gtk/gtk.h>
 
-#include <stdio.h>
-#include <stdarg.h>
-#include <stdlib.h>
 #include <locale.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
 
 #include <fnmatch.h>
 
 #include "config.h"
-#include "fastiv-view.h"
 #include "fastiv-browser.h"
+#include "fastiv-io.h"
+#include "fastiv-view.h"
+#include "xdg.h"
 
 // --- Utilities ---------------------------------------------------------------
 
-static void
-exit_fatal(const gchar *format, ...) G_GNUC_PRINTF(1, 2);
+static void exit_fatal(const gchar *format, ...) G_GNUC_PRINTF(1, 2);
 
 static void
 exit_fatal(const gchar *format, ...)
@@ -49,191 +50,6 @@ exit_fatal(const gchar *format, ...)
 	exit(EXIT_FAILURE);
 }
 
-/// Add `element` to the `output` set. `relation` is a map of sets of strings
-/// defining is-a relations, and is traversed recursively.
-static void
-add_applying_transitive_closure(const gchar *element, GHashTable *relation,
-	GHashTable *output)
-{
-	// Stop condition.
-	if (!g_hash_table_add(output, g_strdup(element)))
-		return;
-
-	// TODO(p): Iterate over all aliases of `element` in addition to
-	// any direct match (and rename this no-longer-generic function).
-	GHashTable *targets = g_hash_table_lookup(relation, element);
-	if (!targets)
-		return;
-
-	GHashTableIter iter;
-	g_hash_table_iter_init(&iter, targets);
-
-	gpointer key = NULL, value = NULL;
-	while (g_hash_table_iter_next(&iter, &key, &value))
-		add_applying_transitive_closure(key, relation, output);
-}
-
-// --- XDG ---------------------------------------------------------------------
-
-gchar *
-get_xdg_home_dir(const char *var, const char *default_)
-{
-	const char *env = getenv(var);
-	if (env && *env == '/')
-		return g_strdup(env);
-
-	// The specification doesn't handle a missing HOME variable explicitly.
-	// Implicitly, assuming Bourne shell semantics, it simply resolves empty.
-	const char *home = getenv("HOME");
-	return g_build_filename(home ? home : "", default_, NULL);
-}
-
-static gchar **
-get_xdg_data_dirs(void)
-{
-	// GStrvBuilder is too new, it would help a little bit.
-	GPtrArray *output = g_ptr_array_new_with_free_func(g_free);
-	g_ptr_array_add(output, get_xdg_home_dir("XDG_DATA_HOME", ".local/share"));
-
-	const gchar *xdg_data_dirs;
-	if (!(xdg_data_dirs = getenv("XDG_DATA_DIRS")) || !*xdg_data_dirs)
-		xdg_data_dirs = "/usr/local/share/:/usr/share/";
-
-	gchar **candidates = g_strsplit(xdg_data_dirs, ":", 0);
-	for (gchar **p = candidates; *p; p++) {
-		if (**p == '/')
-			g_ptr_array_add(output, *p);
-		else
-			g_free(*p);
-	}
-	g_free(candidates);
-	g_ptr_array_add(output, NULL);
-	return (gchar **) g_ptr_array_free(output, FALSE);
-}
-
-// --- Filtering ---------------------------------------------------------------
-
-// Derived from shared-mime-info-spec 0.21.
-
-// TODO(p): Move to fastiv-io.c, expose the prototype in a header file
-// (perhaps finally start a new one for it).
-// A subset of shared-mime-info that produces an appropriate list of
-// file extensions. Chiefly motivated by the suckiness of RAW images:
-// someone else will maintain the list of file extensions for us.
-static const char *supported_media_types[] = {
-	"image/bmp",
-	"image/gif",
-	"image/png",
-	"image/jpeg",
-#ifdef HAVE_LIBRAW
-	"image/x-dcraw",
-#endif  // HAVE_LIBRAW
-};
-
-static void
-read_mime_subclasses(const gchar *path, GHashTable *subclass_sets)
-{
-	gchar *data = NULL;
-	if (!g_file_get_contents(path, &data, NULL /* length */, NULL /* error */))
-		return;
-
-	// The format of this file is unspecified,
-	// but in practice it's a list of space-separated media types.
-	gchar *datasave = NULL;
-	for (gchar *line = strtok_r(data, "\r\n", &datasave); line;
-			line = strtok_r(NULL, "\r\n", &datasave)) {
-		gchar *linesave = NULL,
-			*subclass = strtok_r(line, " ", &linesave),
-			*superclass = strtok_r(NULL, " ", &linesave);
-
-		// Nothing about comments is specified, we're being nice.
-		if (!subclass || *subclass == '#' || !superclass)
-			continue;
-
-		GHashTable *set = NULL;
-		if (!(set = g_hash_table_lookup(subclass_sets, superclass))) {
-			set = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
-			g_hash_table_insert(subclass_sets, g_strdup(superclass), set);
-		}
-		g_hash_table_add(set, g_strdup(subclass));
-	}
-	g_free(data);
-}
-
-static gboolean
-filter_mime_globs(const gchar *path, guint is_globs2, GHashTable *supported_set,
-	GHashTable *output_set)
-{
-	gchar *data = NULL;
-	if (!g_file_get_contents(path, &data, NULL /* length */, NULL /* error */))
-		return FALSE;
-
-	gchar *datasave = NULL;
-	for (const gchar *line = strtok_r(data, "\r\n", &datasave); line;
-			line = strtok_r(NULL, "\r\n", &datasave)) {
-		if (*line == '#')
-			continue;
-
-		// We do not support __NOGLOBS__, nor even parse out the "cs" flag.
-		// The weight is irrelevant.
-		gchar **f = g_strsplit(line, ":", 0);
-		if (g_strv_length(f) >= is_globs2 + 2) {
-			const gchar *type = f[is_globs2 + 0], *glob = f[is_globs2 + 1];
-			if (g_hash_table_contains(supported_set, type))
-				g_hash_table_add(output_set, g_utf8_strdown(glob, -1));
-		}
-		g_strfreev(f);
-	}
-	g_free(data);
-	return TRUE;
-}
-
-static gchar **
-get_supported_globs (void)
-{
-	gchar **data_dirs = get_xdg_data_dirs();
-
-	// The mime.cache format is inconvenient to parse,
-	// we'll do it from the text files manually, and once only.
-	GHashTable *subclass_sets = g_hash_table_new_full(g_str_hash, g_str_equal,
-		g_free, (GDestroyNotify) g_hash_table_destroy);
-	for (gsize i = 0; data_dirs[i]; i++) {
-		gchar *path =
-			g_build_filename(data_dirs[i], "mime", "subclasses", NULL);
-		read_mime_subclasses(path, subclass_sets);
-		g_free(path);
-	}
-
-	// A hash set of all supported media types, including subclasses,
-	// but not aliases.
-	GHashTable *supported =
-		g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
-	for (gsize i = 0; i < G_N_ELEMENTS(supported_media_types); i++) {
-		add_applying_transitive_closure(supported_media_types[i],
-			subclass_sets, supported);
-	}
-	g_hash_table_destroy(subclass_sets);
-
-	// We do not support the distinction of case-sensitive globs (:cs).
-	GHashTable *globs =
-		g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
-	for (gsize i = 0; data_dirs[i]; i++) {
-		gchar *path2 = g_build_filename(data_dirs[i], "mime", "globs2", NULL);
-		gchar *path1 = g_build_filename(data_dirs[i], "mime", "globs", NULL);
-		if (!filter_mime_globs(path2, TRUE, supported, globs))
-			filter_mime_globs(path1, FALSE, supported, globs);
-		g_free(path2);
-		g_free(path1);
-	}
-	g_strfreev(data_dirs);
-	g_hash_table_destroy(supported);
-
-	gchar **result = (gchar **) g_hash_table_get_keys_as_array(globs, NULL);
-	g_hash_table_steal_all(globs);
-	g_hash_table_destroy(globs);
-	return result;
-}
-
 // --- Main --------------------------------------------------------------------
 
 struct {
@@ -275,8 +91,8 @@ is_supported(const gchar *filename)
 static void
 show_error_dialog(GError *error)
 {
-	GtkWidget *dialog = gtk_message_dialog_new(GTK_WINDOW(g.window),
-		GTK_DIALOG_MODAL,
+	GtkWidget *dialog =
+		gtk_message_dialog_new(GTK_WINDOW(g.window), GTK_DIALOG_MODAL,
 			GTK_MESSAGE_ERROR, GTK_BUTTONS_CLOSE, "%s", error->message);
 	gtk_dialog_run(GTK_DIALOG(dialog));
 	gtk_widget_destroy(dialog);
@@ -350,7 +166,6 @@ open(const gchar *path)
 		}
 	}
 	g_free(dirname);
-
 }
 
 static void
@@ -363,8 +178,8 @@ on_open(void)
 
 	// NOTE: gdk-pixbuf has gtk_file_filter_add_pixbuf_formats().
 	GtkFileFilter *filter = gtk_file_filter_new();
-	for (gsize i = 0; i < G_N_ELEMENTS(supported_media_types); i++)
-		gtk_file_filter_add_mime_type(filter, supported_media_types[i]);
+	for (const char **p = fastiv_io_supported_media_types; *p; p++)
+		gtk_file_filter_add_mime_type(filter, *p);
 	gtk_file_filter_set_name(filter, "Supported images");
 	gtk_file_chooser_add_filter(GTK_FILE_CHOOSER(dialog), filter);
 
@@ -389,9 +204,8 @@ on_previous(void)
 	if (g.files_index >= 0) {
 		int previous =
 			(g.files->len - 1 + g.files_index - 1) % (g.files->len - 1);
-		char *absolute =
-			g_canonicalize_filename(g_ptr_array_index(g.files, previous),
-				g.directory);
+		char *absolute = g_canonicalize_filename(
+			g_ptr_array_index(g.files, previous), g.directory);
 		open(absolute);
 		g_free(absolute);
 	}
@@ -402,9 +216,8 @@ on_next(void)
 {
 	if (g.files_index >= 0) {
 		int next = (g.files_index + 1) % (g.files->len - 1);
-		char *absolute =
-			g_canonicalize_filename(g_ptr_array_index(g.files, next),
-				g.directory);
+		char *absolute = g_canonicalize_filename(
+			g_ptr_array_index(g.files, next), g.directory);
 		open(absolute);
 		g_free(absolute);
 	}
@@ -427,8 +240,8 @@ main(int argc, char *argv[])
 	};
 
 	GError *error = NULL;
-	if (!gtk_init_with_args(&argc, &argv, " - fast image viewer",
-		options, NULL, &error))
+	if (!gtk_init_with_args(
+			&argc, &argv, " - fast image viewer", options, NULL, &error))
 		exit_fatal("%s", error->message);
 	if (show_version) {
 		printf(PROJECT_NAME " " PROJECT_VERSION "\n");
@@ -496,7 +309,7 @@ main(int argc, char *argv[])
 		g_cclosure_new(G_CALLBACK(on_next), NULL, NULL));
 	gtk_window_add_accel_group(GTK_WINDOW(g.window), accel_group);
 
-	g.supported_globs = get_supported_globs();
+	g.supported_globs = extract_mime_globs(fastiv_io_supported_media_types);
 	g.files = g_ptr_array_new_full(16, g_free);
 	gchar *cwd = g_get_current_dir();
 
@@ -508,9 +321,9 @@ main(int argc, char *argv[])
 	if (!path_arg) {
 		load_directory(cwd);
 	} else if (g_stat(path_arg, &st)) {
-		show_error_dialog(g_error_new(G_FILE_ERROR,
-			g_file_error_from_errno(errno),
-			"%s: %s", path_arg, g_strerror(errno)));
+		show_error_dialog(
+			g_error_new(G_FILE_ERROR, g_file_error_from_errno(errno), "%s: %s",
+				path_arg, g_strerror(errno)));
 		load_directory(cwd);
 	} else {
 		gchar *path_arg_absolute = g_canonicalize_filename(path_arg, cwd);

meson.build

@@ -20,7 +20,7 @@ configure_file(
 )
 
 executable('fastiv', 'fastiv.c', 'fastiv-view.c', 'fastiv-io.c',
-	'fastiv-browser.c',
+	'fastiv-browser.c', 'xdg.c',
 	install : true,
 	dependencies : [dependencies])
 

tools/Makefile

@@ -1,7 +1,7 @@
 SHELL = /bin/sh
 # libjq 1.6 lacks a pkg-config file, and there is no release in sight.
 CFLAGS = -g -O2 -Wall -Wextra `pkg-config --cflags $(deps)`
-LDFLAGS = -ljq `pkg-config --libs $(deps)`
+LDLIBS = -ljq `pkg-config --libs $(deps)`
 
 deps = libpng
 targets = pnginfo

xdg.c

@@ -0,0 +1,186 @@
+//
+// xdg.c: various *nix desktop utilities
+//
+// 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 <glib.h>
+
+/// Add `element` to the `output` set. `relation` is a map of sets of strings
+/// defining is-a relations, and is traversed recursively.
+static void
+add_applying_transitive_closure(
+	const gchar *element, GHashTable *relation, GHashTable *output)
+{
+	// Stop condition.
+	if (!g_hash_table_add(output, g_strdup(element)))
+		return;
+
+	// TODO(p): Iterate over all aliases of `element` in addition to
+	// any direct match (and rename this no-longer-generic function).
+	GHashTable *targets = g_hash_table_lookup(relation, element);
+	if (!targets)
+		return;
+
+	GHashTableIter iter;
+	g_hash_table_iter_init(&iter, targets);
+
+	gpointer key = NULL, value = NULL;
+	while (g_hash_table_iter_next(&iter, &key, &value))
+		add_applying_transitive_closure(key, relation, output);
+}
+
+char *
+get_xdg_home_dir(const char *var, const char *default_)
+{
+	const char *env = getenv(var);
+	if (env && *env == '/')
+		return g_strdup(env);
+
+	// The specification doesn't handle a missing HOME variable explicitly.
+	// Implicitly, assuming Bourne shell semantics, it simply resolves empty.
+	const char *home = getenv("HOME");
+	return g_build_filename(home ? home : "", default_, NULL);
+}
+
+static gchar **
+get_xdg_data_dirs(void)
+{
+	// GStrvBuilder is too new, it would help a little bit.
+	GPtrArray *output = g_ptr_array_new_with_free_func(g_free);
+	g_ptr_array_add(output, get_xdg_home_dir("XDG_DATA_HOME", ".local/share"));
+
+	const gchar *xdg_data_dirs;
+	if (!(xdg_data_dirs = getenv("XDG_DATA_DIRS")) || !*xdg_data_dirs)
+		xdg_data_dirs = "/usr/local/share/:/usr/share/";
+
+	gchar **candidates = g_strsplit(xdg_data_dirs, ":", 0);
+	for (gchar **p = candidates; *p; p++) {
+		if (**p == '/')
+			g_ptr_array_add(output, *p);
+		else
+			g_free(*p);
+	}
+	g_free(candidates);
+	g_ptr_array_add(output, NULL);
+	return (gchar **) g_ptr_array_free(output, FALSE);
+}
+
+// --- Filtering ---------------------------------------------------------------
+
+// Derived from shared-mime-info-spec 0.21.
+
+static void
+read_mime_subclasses(const gchar *path, GHashTable *subclass_sets)
+{
+	gchar *data = NULL;
+	if (!g_file_get_contents(path, &data, NULL /* length */, NULL /* error */))
+		return;
+
+	// The format of this file is unspecified,
+	// but in practice it's a list of space-separated media types.
+	gchar *datasave = NULL;
+	for (gchar *line = strtok_r(data, "\r\n", &datasave); line;
+			line = strtok_r(NULL, "\r\n", &datasave)) {
+		gchar *linesave = NULL,
+			*subclass = strtok_r(line, " ", &linesave),
+			*superclass = strtok_r(NULL, " ", &linesave);
+
+		// Nothing about comments is specified, we're being nice.
+		if (!subclass || *subclass == '#' || !superclass)
+			continue;
+
+		GHashTable *set = NULL;
+		if (!(set = g_hash_table_lookup(subclass_sets, superclass))) {
+			set = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
+			g_hash_table_insert(subclass_sets, g_strdup(superclass), set);
+		}
+		g_hash_table_add(set, g_strdup(subclass));
+	}
+	g_free(data);
+}
+
+static gboolean
+filter_mime_globs(const gchar *path, guint is_globs2, GHashTable *supported_set,
+	GHashTable *output_set)
+{
+	gchar *data = NULL;
+	if (!g_file_get_contents(path, &data, NULL /* length */, NULL /* error */))
+		return FALSE;
+
+	gchar *datasave = NULL;
+	for (const gchar *line = strtok_r(data, "\r\n", &datasave); line;
+			line = strtok_r(NULL, "\r\n", &datasave)) {
+		if (*line == '#')
+			continue;
+
+		// We do not support __NOGLOBS__, nor even parse out the "cs" flag.
+		// The weight is irrelevant.
+		gchar **f = g_strsplit(line, ":", 0);
+		if (g_strv_length(f) >= is_globs2 + 2) {
+			const gchar *type = f[is_globs2 + 0], *glob = f[is_globs2 + 1];
+			if (g_hash_table_contains(supported_set, type))
+				g_hash_table_add(output_set, g_utf8_strdown(glob, -1));
+		}
+		g_strfreev(f);
+	}
+	g_free(data);
+	return TRUE;
+}
+
+char **
+extract_mime_globs(const char **media_types)
+{
+	gchar **data_dirs = get_xdg_data_dirs();
+
+	// The mime.cache format is inconvenient to parse,
+	// we'll do it from the text files manually, and once only.
+	GHashTable *subclass_sets = g_hash_table_new_full(
+		g_str_hash, g_str_equal, g_free, (GDestroyNotify) g_hash_table_destroy);
+	for (gsize i = 0; data_dirs[i]; i++) {
+		gchar *path =
+			g_build_filename(data_dirs[i], "mime", "subclasses", NULL);
+		read_mime_subclasses(path, subclass_sets);
+		g_free(path);
+	}
+
+	// A hash set of all supported media types, including subclasses,
+	// but not aliases.
+	GHashTable *supported =
+		g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
+	while (*media_types) {
+		add_applying_transitive_closure(
+			*media_types++, subclass_sets, supported);
+	}
+	g_hash_table_destroy(subclass_sets);
+
+	// We do not support the distinction of case-sensitive globs (:cs).
+	GHashTable *globs =
+		g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
+	for (gsize i = 0; data_dirs[i]; i++) {
+		gchar *path2 = g_build_filename(data_dirs[i], "mime", "globs2", NULL);
+		gchar *path1 = g_build_filename(data_dirs[i], "mime", "globs", NULL);
+		if (!filter_mime_globs(path2, TRUE, supported, globs))
+			filter_mime_globs(path1, FALSE, supported, globs);
+		g_free(path2);
+		g_free(path1);
+	}
+	g_strfreev(data_dirs);
+	g_hash_table_destroy(supported);
+
+	gchar **result = (gchar **) g_hash_table_get_keys_as_array(globs, NULL);
+	g_hash_table_steal_all(globs);
+	g_hash_table_destroy(globs);
+	return result;
+}

xdg.h

@@ -0,0 +1,19 @@
+//
+// xdg.h: various *nix desktop utilities
+//
+// 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.
+//
+
+char *get_xdg_home_dir(const char *var, const char *default_);
+char **extract_mime_globs(const char **media_types);