static GtkWidget *
gth_file_tool_adjust_contrast_get_options (GthFileTool *base)
{
	GthFileToolAdjustContrast *self;
	GtkWidget                 *window;
	GtkWidget                 *viewer_page;
	GtkWidget                 *viewer;
	cairo_surface_t           *source;
	GtkWidget                 *options;
	int                        width, height;
	GtkAllocation              allocation;
	GtkWidget                 *filter_grid;

	self = (GthFileToolAdjustContrast *) base;

	window = gth_file_tool_get_window (base);
	viewer_page = gth_browser_get_viewer_page (GTH_BROWSER (window));
	if (! GTH_IS_IMAGE_VIEWER_PAGE (viewer_page))
		return NULL;

	_cairo_clear_surface (&self->priv->preview);
	_cairo_clear_surface (&self->priv->destination);

	viewer = gth_image_viewer_page_get_image_viewer (GTH_IMAGE_VIEWER_PAGE (viewer_page));
	source = gth_image_viewer_page_tool_get_source (GTH_IMAGE_VIEWER_PAGE_TOOL (self));
	if (source == NULL)
		return NULL;

	width = cairo_image_surface_get_width (source);
	height = cairo_image_surface_get_height (source);
	gtk_widget_get_allocation (GTK_WIDGET (viewer), &allocation);
	if (scale_keeping_ratio (&width, &height, PREVIEW_SIZE * allocation.width, PREVIEW_SIZE * allocation.height, FALSE))
		self->priv->preview = _cairo_image_surface_scale_fast (source, width, height);
	else
		self->priv->preview = cairo_surface_reference (source);

	self->priv->destination = cairo_surface_reference (self->priv->preview);
	self->priv->apply_to_original = FALSE;
	self->priv->closing = FALSE;

	self->priv->builder = _gtk_builder_new_from_file ("adjust-contrast-options.ui", "file_tools");
	options = _gtk_builder_get_widget (self->priv->builder, "options");
	gtk_widget_show (options);

	filter_grid = gth_filter_grid_new ();
	gth_filter_grid_add_filter (GTH_FILTER_GRID (filter_grid),
				    METHOD_STRETCH_0_5,
				    get_image_task_for_method (METHOD_STRETCH_0_5),
				    _("Stretch"),
				    _("Stretch the histogram trimming the 0.5%"));
	gth_filter_grid_add_filter (GTH_FILTER_GRID (filter_grid),
				    METHOD_EQUALIZE_SQUARE_ROOT,
				    get_image_task_for_method (METHOD_EQUALIZE_SQUARE_ROOT),
				    _("Equalize"),
				    _("Equalize the histogram using the square root function"));
	gth_filter_grid_add_filter (GTH_FILTER_GRID (filter_grid),
				    METHOD_EQUALIZE_LINEAR,
				    get_image_task_for_method (METHOD_EQUALIZE_LINEAR),
				    _("Uniform"),
				    _("Equalize the histogram using the linear function"));

	g_signal_connect (filter_grid,
			  "activated",
			  G_CALLBACK (filter_grid_activated_cb),
			  self);

	gtk_widget_show (filter_grid);
	gtk_box_pack_start (GTK_BOX (GET_WIDGET ("filter_grid_box")), filter_grid, TRUE, FALSE, 0);

	self->priv->preview_tool = gth_preview_tool_new ();
	gth_preview_tool_set_image (GTH_PREVIEW_TOOL (self->priv->preview_tool), self->priv->preview);
	gth_image_viewer_set_tool (GTH_IMAGE_VIEWER (viewer), self->priv->preview_tool);
	gth_filter_grid_activate (GTH_FILTER_GRID (filter_grid), METHOD_STRETCH_0_5);
	gth_filter_grid_generate_previews (GTH_FILTER_GRID (filter_grid), source);

	return options;
}
static GtkWidget *
gth_file_tool_grayscale_get_options (GthFileTool *base)
{
	GthFileToolGrayscale *self;
	GtkWidget            *window;
	GtkWidget            *viewer_page;
	GtkWidget            *viewer;
	cairo_surface_t      *source;
	GtkWidget            *options;
	int                   width, height;
	GtkAllocation         allocation;

	self = (GthFileToolGrayscale *) base;

	window = gth_file_tool_get_window (base);
	viewer_page = gth_browser_get_viewer_page (GTH_BROWSER (window));
	if (! GTH_IS_IMAGE_VIEWER_PAGE (viewer_page))
		return NULL;

	cairo_surface_destroy (self->priv->destination);
	cairo_surface_destroy (self->priv->preview);

	viewer = gth_image_viewer_page_get_image_viewer (GTH_IMAGE_VIEWER_PAGE (viewer_page));
	source = gth_image_viewer_page_tool_get_source (GTH_IMAGE_VIEWER_PAGE_TOOL (self));
	if (source == NULL)
		return NULL;

	width = cairo_image_surface_get_width (source);
	height = cairo_image_surface_get_height (source);
	gtk_widget_get_allocation (GTK_WIDGET (viewer), &allocation);
	if (scale_keeping_ratio (&width, &height, PREVIEW_SIZE * allocation.width, PREVIEW_SIZE * allocation.height, FALSE))
		self->priv->preview = _cairo_image_surface_scale_bilinear (source, width, height);
	else
		self->priv->preview = cairo_surface_reference (source);

	self->priv->destination = cairo_surface_reference (self->priv->preview);
	self->priv->apply_to_original = FALSE;
	self->priv->closing = FALSE;

	self->priv->builder = _gtk_builder_new_from_file ("grayscale-options.ui", "file_tools");
	options = _gtk_builder_get_widget (self->priv->builder, "options");
	gtk_widget_show (options);

	g_signal_connect (GET_WIDGET ("ok_button"),
			  "clicked",
			  G_CALLBACK (ok_button_clicked_cb),
			  self);
	g_signal_connect_swapped (GET_WIDGET ("cancel_button"),
				  "clicked",
				  G_CALLBACK (gth_file_tool_cancel),
				  self);
	g_signal_connect (GET_WIDGET ("brightness_radiobutton"),
			  "clicked",
			  G_CALLBACK (method_changed_cb),
			  self);
	g_signal_connect (GET_WIDGET ("saturation_radiobutton"),
			  "clicked",
			  G_CALLBACK (method_changed_cb),
			  self);
	g_signal_connect (GET_WIDGET ("average_radiobutton"),
			  "clicked",
			  G_CALLBACK (method_changed_cb),
			  self);
	g_signal_connect (GET_WIDGET ("preview_checkbutton"),
			  "toggled",
			  G_CALLBACK (preview_checkbutton_toggled_cb),
			  self);

	self->priv->preview_tool = gth_preview_tool_new ();
	gth_preview_tool_set_image (GTH_PREVIEW_TOOL (self->priv->preview_tool), self->priv->preview);
	gth_image_viewer_set_tool (GTH_IMAGE_VIEWER (viewer), self->priv->preview_tool);
	apply_changes (self);

	return options;
}