Add a lossless JPEG cropper

This is more of an MVP, as metadata probably need adjustments.

README.adoc

@@ -52,6 +52,8 @@ direct installations.  To test the program, help it find its custom thumbnailer:
 
  $ PATH=$(pwd):$PATH ./fiv
 
+The lossless JPEG cropper is intended to be invoked from a context menu.
+
 Documentation
 -------------
 For information concerning usage, refer to link:docs/fiv.html[the user guide],

fiv-io.c

@@ -3098,6 +3098,7 @@ fiv_io_encode_webp(
 		for (int i = h * picture.argb_stride; i-- > 0; argb++)
 			*argb |= 0xFF000000;
 
+	// TODO(p): Prevent or propagate VP8_ENC_ERROR_BAD_DIMENSION.
 	picture.writer = WebPMemoryWrite;
 	picture.custom_ptr = &writer;
 	if (!WebPEncode(config, &picture))

fiv-jpegcrop.c

@@ -0,0 +1,421 @@
+//
+// fiv-jpegcrop.c: lossless JPEG cropper
+//
+// Copyright (c) 2022, 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 <gtk/gtk.h>
+#include <turbojpeg.h>
+
+#include "config.h"
+
+// --- Utilities ---------------------------------------------------------------
+
+static void exit_fatal(const gchar *format, ...) G_GNUC_PRINTF(1, 2);
+
+static void
+exit_fatal(const gchar *format, ...)
+{
+	va_list ap;
+	va_start(ap, format);
+
+	gchar *format_nl = g_strdup_printf("%s\n", format);
+	vfprintf(stderr, format_nl, ap);
+	free(format_nl);
+
+	va_end(ap);
+	exit(EXIT_FAILURE);
+}
+
+// --- Main --------------------------------------------------------------------
+
+struct {
+	GFile *location;
+	gchar *data;
+	gsize len;
+	int width, height, subsampling, colorspace;
+	int mcu_width, mcu_height;
+	cairo_surface_t *surface;
+
+	int top, left, right, bottom;
+
+	GtkWidget *label;
+	GtkWidget *window;
+	GtkWidget *scrolled;
+	GtkWidget *view;
+} g;
+
+static void
+show_error_dialog(GError *error)
+{
+	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);
+	g_error_free(error);
+}
+
+static gboolean
+on_draw(G_GNUC_UNUSED GtkWidget *widget, cairo_t *cr,
+	G_GNUC_UNUSED gpointer user_data)
+{
+	cairo_set_source_surface(cr, g.surface, 1, 1);
+	cairo_paint(cr);
+
+	cairo_rectangle(cr,
+		1 + g.left - 0.5,
+		1 + g.top - 0.5,
+		g.right - g.left + 1,
+		g.bottom - g.top + 1);
+	cairo_set_source_rgb(cr, 1, 1, 1);
+	cairo_set_line_width(cr, 1);
+	cairo_set_operator(cr, CAIRO_OPERATOR_DIFFERENCE);
+	cairo_stroke(cr);
+
+	cairo_set_fill_rule(cr, CAIRO_FILL_RULE_EVEN_ODD);
+	cairo_rectangle(cr, 1, 1, g.width, g.height);
+	cairo_rectangle(
+		cr, g.left, g.top, g.right - g.left + 2, g.bottom - g.top + 2);
+	cairo_clip(cr);
+	cairo_set_source_rgba(cr, 0, 0, 0, 0.5);
+	cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
+	cairo_paint(cr);
+	return TRUE;
+}
+
+static GFile *
+choose_filename(void)
+{
+	GtkWidget *dialog = gtk_file_chooser_dialog_new("Saved cropped image as",
+		GTK_WINDOW(g.window), GTK_FILE_CHOOSER_ACTION_SAVE,
+		"_Cancel", GTK_RESPONSE_CANCEL,
+		"_Save", GTK_RESPONSE_ACCEPT, NULL);
+	GtkFileChooser *chooser = GTK_FILE_CHOOSER(dialog);
+	gtk_file_chooser_set_local_only(chooser, FALSE);
+	gtk_file_chooser_set_do_overwrite_confirmation(chooser, TRUE);
+	(void) gtk_file_chooser_set_file(chooser, g.location, NULL);
+
+	GtkFileFilter *jpeg = gtk_file_filter_new();
+	gtk_file_filter_add_mime_type(jpeg, "image/jpeg");
+	gtk_file_filter_add_pattern(jpeg, "*.jpg");
+	gtk_file_filter_add_pattern(jpeg, "*.jpeg");
+	gtk_file_filter_add_pattern(jpeg, "*.jpe");
+	gtk_file_filter_set_name(jpeg, "JPEG");
+	gtk_file_chooser_add_filter(chooser, jpeg);
+
+	GtkFileFilter *all = gtk_file_filter_new();
+	gtk_file_filter_add_pattern(all, "*");
+	gtk_file_filter_set_name(all, "All files");
+	gtk_file_chooser_add_filter(chooser, all);
+
+	GFile *file = NULL;
+	switch (gtk_dialog_run(GTK_DIALOG(dialog))) {
+	default:
+		gtk_widget_destroy(dialog);
+		// Fall-through.
+	case GTK_RESPONSE_NONE:
+		return file;
+	case GTK_RESPONSE_ACCEPT:
+		file = gtk_file_chooser_get_file(chooser);
+		gtk_widget_destroy(dialog);
+		return file;
+	}
+}
+
+static void
+on_save_as(G_GNUC_UNUSED GtkButton *button, G_GNUC_UNUSED gpointer user_data)
+{
+	tjhandle h = tjInitTransform();
+	if (!h) {
+		show_error_dialog(g_error_new_literal(
+			G_IO_ERROR, G_IO_ERROR_FAILED, tjGetErrorStr2(h)));
+		return;
+	}
+
+	// Convert up front, because the target is in memory.
+	tjtransform t = {
+		.r.x = g.left,
+		.r.y = g.top,
+		.r.w = g.right - g.left,
+		.r.h = g.bottom - g.top,
+		.op = TJXOP_NONE,
+		.options = TJXOPT_CROP | TJXOPT_PROGRESSIVE | TJXOPT_PERFECT,
+	};
+
+	guchar *data = NULL;
+	gulong len = 0;
+	if (tjTransform(h, (const guchar *) g.data, g.len, 1, &data, &len, &t, 0)) {
+		show_error_dialog(g_error_new_literal(
+			G_IO_ERROR, G_IO_ERROR_FAILED, tjGetErrorStr2(h)));
+		goto out;
+	}
+
+	GFile *file = choose_filename();
+	GError *error = NULL;
+	if (file &&
+		!g_file_replace_contents(file, (const char *) data, len, NULL, FALSE,
+			G_FILE_CREATE_NONE, NULL, NULL, &error)) {
+		show_error_dialog(error);
+		goto out;
+	}
+
+	g_clear_object(&file);
+	tjFree(data);
+out:
+	if (tjDestroy(h)) {
+		show_error_dialog(g_error_new_literal(
+			G_IO_ERROR, G_IO_ERROR_FAILED, tjGetErrorStr2(h)));
+	}
+}
+
+static void
+update_label(void)
+{
+	gchar *text = g_strdup_printf("(%d, %d) × (%d, %d)", g.left, g.top,
+		g.right - g.left, g.bottom - g.top);
+	gtk_label_set_label(GTK_LABEL(g.label), text);
+	g_free(text);
+}
+
+static void
+update(void)
+{
+	update_label();
+	gtk_widget_queue_draw(g.view);
+}
+
+static void
+on_reset(G_GNUC_UNUSED GtkButton *button, G_GNUC_UNUSED gpointer user_data)
+{
+	g.top = 0;
+	g.left = 0;
+	g.right = g.width;
+	g.bottom = g.height;
+	update();
+}
+
+static gboolean
+on_mouse(guint state, guint button, gdouble x, gdouble y)
+{
+	if (state != 0)
+		return FALSE;
+
+	switch (button) {
+	case GDK_BUTTON_PRIMARY:
+		g.left = MAX(0, (int) (x - 1)) / g.mcu_width * g.mcu_width;
+		g.top = MAX(0, (int) (y - 1)) / g.mcu_height * g.mcu_height;
+		update();
+		return TRUE;
+	case GDK_BUTTON_SECONDARY:
+		g.right = MIN(x, g.width);  // Inclusive of pointer position.
+		g.bottom = MIN(y, g.height);  // Inclusive of pointer position.
+		update();
+		return TRUE;
+	default:
+		return FALSE;
+	}
+}
+
+static gboolean
+on_press(G_GNUC_UNUSED GtkWidget *self, GdkEventButton *event,
+	G_GNUC_UNUSED gpointer user_data)
+{
+	return on_mouse(event->state, event->button, event->x, event->y);
+}
+
+static gboolean
+on_motion(G_GNUC_UNUSED GtkWidget *self, GdkEventMotion *event,
+	G_GNUC_UNUSED gpointer user_data)
+{
+	switch (event->state) {
+	case GDK_BUTTON1_MASK:
+		return on_mouse(0, GDK_BUTTON_PRIMARY, event->x, event->y);
+	case GDK_BUTTON3_MASK:
+		return on_mouse(0, GDK_BUTTON_SECONDARY, event->x, event->y);
+	}
+	return FALSE;
+}
+
+static gboolean
+open_jpeg(const gchar *data, gsize len, GError **error)
+{
+	tjhandle h = tjInitDecompress();
+	if (!h) {
+		g_set_error_literal(
+			error, G_IO_ERROR, G_IO_ERROR_FAILED, tjGetErrorStr2(h));
+		return FALSE;
+	}
+
+	if (tjDecompressHeader3(h, (const guint8 *) data, len, &g.width, &g.height,
+			&g.subsampling, &g.colorspace)) {
+		g_set_error_literal(
+			error, G_IO_ERROR, G_IO_ERROR_FAILED, tjGetErrorStr2(h));
+		tjDestroy(h);
+		return FALSE;
+	}
+
+	g.top = 0;
+	g.left = 0;
+	g.right = g.width;
+	g.bottom = g.height;
+
+	g.mcu_width = tjMCUWidth[g.subsampling];
+	g.mcu_height = tjMCUHeight[g.subsampling];
+
+	if (tjDestroy(h)) {
+		g_set_error_literal(
+			error, G_IO_ERROR, G_IO_ERROR_FAILED, tjGetErrorStr2(h));
+		return FALSE;
+	}
+
+	// TODO(p): Eventually, convert to using fiv-io.c directly,
+	// which will pull in most of fiv's dependencies,
+	// but also enable correct color management, even for CMYK.
+	// NOTE: It's possible to include this as a mode of the main binary.
+	GInputStream *is = g_memory_input_stream_new_from_data(data, len, NULL);
+	GdkPixbuf *pixbuf = gdk_pixbuf_new_from_stream(is, NULL, error);
+	g_object_unref(is);
+	if (!pixbuf)
+		return FALSE;
+
+	const char *orientation = gdk_pixbuf_get_option(pixbuf, "orientation");
+	if (orientation && strlen(orientation) == 1) {
+		int n = *orientation - '0';
+		if (n >= 1 && n <= 8) {
+			// TODO(p): Apply this to the view, somehow.
+		}
+	}
+
+	g.surface = gdk_cairo_surface_create_from_pixbuf(pixbuf, 1, NULL);
+	cairo_status_t surface_status = cairo_surface_status(g.surface);
+	if (surface_status != CAIRO_STATUS_SUCCESS) {
+		g_set_error_literal(error, G_IO_ERROR, G_IO_ERROR_FAILED,
+			cairo_status_to_string(surface_status));
+		g_clear_pointer(&g.surface, cairo_surface_destroy);
+		g_object_unref(pixbuf);
+		return FALSE;
+	}
+	return TRUE;
+}
+
+int
+main(int argc, char *argv[])
+{
+	gboolean show_version = FALSE;
+	gchar **path_args = NULL;
+
+	const GOptionEntry options[] = {
+		{G_OPTION_REMAINING, 0, 0, G_OPTION_ARG_FILENAME_ARRAY, &path_args,
+			NULL, "[FILE | URI]"},
+		{"version", 'V', G_OPTION_FLAG_IN_MAIN, G_OPTION_ARG_NONE,
+			&show_version, "Output version information and exit", NULL},
+		{},
+	};
+
+	GError *error = NULL;
+	gboolean initialized = gtk_init_with_args(
+		&argc, &argv, " - Lossless JPEG cropper", options, NULL, &error);
+	if (show_version) {
+		printf("fiv-jpegcrop " PROJECT_VERSION "\n");
+		return 0;
+	}
+	if (!initialized)
+		exit_fatal("%s", error->message);
+
+	// TODO(p): Rather use G_OPTION_ARG_CALLBACK with G_OPTION_FLAG_FILENAME.
+	// Alternatively, GOptionContext with gtk_get_option_group(TRUE).
+	// Then we can show the help string here instead (in fiv as well).
+	if (!path_args || !path_args[0] || path_args[1])
+		exit_fatal("invalid arguments");
+
+	gtk_window_set_default_icon_name(PROJECT_NAME);
+
+	g.location = g_file_new_for_commandline_arg(path_args[0]);
+	g.window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+	g_signal_connect(g.window, "destroy", G_CALLBACK(gtk_main_quit), NULL);
+
+	GFileInfo *info = g_file_query_info(g.location,
+		G_FILE_ATTRIBUTE_STANDARD_NAME
+		"," G_FILE_ATTRIBUTE_STANDARD_DISPLAY_NAME,
+		G_FILE_QUERY_INFO_NONE, NULL, &error);
+	if (!info ||
+		!g_file_load_contents(
+			g.location, NULL, &g.data, &g.len, NULL, &error) ||
+		!open_jpeg(g.data, g.len, &error)) {
+		show_error_dialog(error);
+		exit(EXIT_FAILURE);
+	}
+
+	GtkWidget *header = gtk_header_bar_new();
+	gtk_window_set_titlebar(GTK_WINDOW(g.window), header);
+	gtk_header_bar_set_title(
+		GTK_HEADER_BAR(header), g_file_info_get_display_name(info));
+	gtk_header_bar_set_subtitle(GTK_HEADER_BAR(header),
+		"Use L/R mouse buttons to adjust the crop region.");
+	gtk_header_bar_set_show_close_button(GTK_HEADER_BAR(header), TRUE);
+
+	g.label = gtk_label_new(NULL);
+	gtk_header_bar_pack_start(GTK_HEADER_BAR(header), g.label);
+	update_label();
+
+	GtkWidget *save = gtk_button_new_from_icon_name(
+		"document-save-as-symbolic", GTK_ICON_SIZE_BUTTON);
+	gtk_widget_set_tooltip_text(save, "Save as...");
+	g_signal_connect(save, "clicked", G_CALLBACK(on_save_as), NULL);
+	gtk_header_bar_pack_end(GTK_HEADER_BAR(header), save);
+
+	GtkWidget *reset = gtk_button_new_with_mnemonic("_Reset");
+	gtk_widget_set_tooltip_text(reset, "Reset the crop region");
+	g_signal_connect(reset, "clicked", G_CALLBACK(on_reset), NULL);
+	gtk_header_bar_pack_end(GTK_HEADER_BAR(header), reset);
+
+	g.view = gtk_drawing_area_new();
+	gtk_widget_set_size_request(g.view, g.width + 2, g.height + 2);
+	gtk_widget_add_events(
+		g.view, GDK_BUTTON_PRESS_MASK | GDK_POINTER_MOTION_MASK);
+	g_signal_connect(g.view, "draw", G_CALLBACK(on_draw), NULL);
+	g_signal_connect(g.view, "button-press-event",
+		G_CALLBACK(on_press), NULL);
+	g_signal_connect(g.view, "motion-notify-event",
+		G_CALLBACK(on_motion), NULL);
+
+	// TODO(p): Track middle mouse button drags, adjust the adjustments.
+	g.scrolled = gtk_scrolled_window_new(NULL, NULL);
+	gtk_scrolled_window_set_overlay_scrolling(
+		GTK_SCROLLED_WINDOW(g.scrolled), FALSE);
+	gtk_scrolled_window_set_propagate_natural_width(
+		GTK_SCROLLED_WINDOW(g.scrolled), TRUE);
+	gtk_scrolled_window_set_propagate_natural_height(
+		GTK_SCROLLED_WINDOW(g.scrolled), TRUE);
+
+	gtk_container_add(GTK_CONTAINER(g.scrolled), g.view);
+	gtk_container_add(GTK_CONTAINER(g.window), g.scrolled);
+	gtk_window_set_default_size(GTK_WINDOW(g.window), 800, 600);
+	gtk_widget_show_all(g.window);
+
+	// It probably needs to be realized.
+	GdkWindow *window = gtk_widget_get_window(g.view);
+	GdkCursor *cursor =
+		gdk_cursor_new_from_name(gdk_window_get_display(window), "crosshair");
+	gdk_window_set_cursor(window, cursor);
+	g_object_unref(cursor);
+
+	gtk_main();
+
+	g_free(g.data);
+	g_object_unref(g.location);
+	g_object_unref(info);
+	return 0;
+}

fiv-jpegcrop.desktop

@@ -0,0 +1,11 @@
+[Desktop Entry]
+Type=Application
+Name=fiv JPEG Cropper
+GenericName=Lossless JPEG Cropper
+Icon=fiv
+Exec=fiv-jpegcrop %u
+NoDisplay=true
+Terminal=false
+StartupNotify=true
+Categories=Graphics;2DGraphics;
+MimeType=image/jpeg;

meson.build

@@ -105,13 +105,21 @@ exe = executable('fiv', 'fiv.c', 'fiv-view.c', 'fiv-io.c',
 	'fiv-browser.c', 'fiv-sidebar.c', 'fiv-thumbnail.c', 'xdg.c', resources,
 	install : true,
 	dependencies : [dependencies])
-
 if gdkpixbuf.found()
 	executable('io-benchmark', 'fiv-io-benchmark.c', 'fiv-io.c', 'xdg.c',
 		build_by_default : false,
 		dependencies : [dependencies, gdkpixbuf])
 endif
 
+jpegcrop = executable('fiv-jpegcrop', 'fiv-jpegcrop.c',
+	install : true,
+	dependencies : [
+		dependency('gtk+-3.0'),
+		dependency('libturbojpeg'),
+	])
+install_data('fiv-jpegcrop.desktop',
+	install_dir : get_option('datadir') / 'applications')
+
 # XXX: With gdk-pixbuf, this even depends on currently installed modules.
 if meson.is_cross_build()
 	install_data('fiv.desktop',