Update user guides

Now add text labels, and this project is functionally complete.

CMakeLists.txt

@@ -155,19 +155,10 @@ set (logdiag_HEADERS
 	${liblogdiag_HEADERS}
 	src/ld-window-main.h)
 
-# Resource compilation for MinGW
-if (MINGW)
-	set (CMAKE_RC_COMPILER_INIT windres)
-	enable_language (RC)
-	set (CMAKE_RC_FLAGS "-O coff")
-	set (CMAKE_RC_COMPILE_OBJECT
-		"<CMAKE_RC_COMPILER> <FLAGS> <DEFINES> -o <OBJECT> <SOURCE>")
-endif (MINGW)
-
+# Resource compilation for Windows
 if (WIN32)
-	set (logdiag_SOURCES
-		${logdiag_SOURCES}
-		share/logdiag.rc)
+	# The file isn't scanned for dependencies, but they will only rarely change
+	list (APPEND logdiag_SOURCES share/logdiag.rc)
 endif (WIN32)
 
 # Generate a configure file

docs/user-guide/user-guide-cs.html

@@ -16,8 +16,8 @@ q:lang(cs):after { content: "“"; }
 <p class="details">
 <span id="author">Přemysl Eric Janouch</span><br>
 <span id="email"><a href="mailto:p@janouch.name">p@janouch.name</a></span><br>
-<span id="revnumber">verze 0.2.0,</span>
-<span id="revdate">2018-06-27</span>
+<span id="revnumber">verze 0.2.2,</span>
+<span id="revdate">2021-10-28</span>
 
 <p class="figure"><img src="logdiag-cs.png" alt="Okno programu logdiag">
 
@@ -118,15 +118,11 @@ a přetáhněte kurzor myši na místo, kde chcete, aby spojení končilo.
 Pokud jste nějaký soubor již bez přípony uložili, napravíte to dodatečným
 přidáním přípony k jeho názvu.
 
-<h3>Jak můžu diagram vytisknout?</h3>
-<p>Současná verze aplikace není schopná přímo tisknout. Pro vytištění
-vytvořeného diagramu můžete klávesou PrintScreen sejmout snímek obrazovky,
-vložit jej například do aplikace Malování, oříznout požadovanou část
-a vytisknout ji z tohoto grafického editoru.
-
 <h3>Schází mi popisky</h3>
-<p>Obdobně jako v předchozím případě tato funkcionalita zatím neexistuje,
-ale je možné tento nedostatek obejít přes běžný grafický editor.
+<p>Tato funkcionalita zatím neexistuje, ale je možné tento nedostatek obejít
+buď sejmutím snímku obrazovky klávesou PrintScreen a jeho vložením například
+do aplikace Malování, nebo obdobně doplněním vašich textů do <q>vytištěného</q>
+PDF souboru.
 
 <script>
 var toc = '', all = document.querySelectorAll('h2')

docs/user-guide/user-guide-en.html

@@ -16,8 +16,8 @@ q:lang(en):after { content: "’"; }
 <p class="details">
 <span id="author">Přemysl Eric Janouch</span><br>
 <span id="email"><a href="mailto:p@janouch.name">p@janouch.name</a></span><br>
-<span id="revnumber">version 0.2.0,</span>
-<span id="revdate">2018-06-27</span>
+<span id="revnumber">version 0.2.2,</span>
+<span id="revdate">2021-10-28</span>
 
 <p class="figure"><img src="logdiag-en.png" alt="logdiag program window">
 
@@ -110,15 +110,11 @@ want the connection to end.
 In case you’ve already saved a file without an extension, you may fix this
 situation by adding the suffix to its name.
 
-<h3>How do I print a diagram?</h3>
-<p>The current version of application is not able to print directly. To print
-out a created diagram, you may use the PrintScreen key to capture a screenshot,
-then insert it to, for example, Paint, and print it from inside the graphics
-editor.
-
 <h3>I miss labels</h3>
-<p>Similarly to the previous case, this functionality doesn’t exist yet, but it
-is possible to get around this limitation using a graphics editor.
+<p>This functionality doesn't exist yet, but it is possible to get around this
+limitation either by using the PrintScreen key to capture a screenshot
+and inserting it to, for example, Paint, or similarly by adding your texts
+to a <q>printed</q> PDF file.
 
 <script>
 var toc = '', all = document.querySelectorAll('h2')

liblogdiag/ld-diagram-view.c

@@ -2,7 +2,7 @@
  * ld-diagram-view.c
  *
  * This file is a part of logdiag.
- * Copyright 2010, 2011, 2012, 2015 Přemysl Eric Janouch
+ * Copyright 2010 - 2021 Přemysl Eric Janouch
  *
  * See the file LICENSE for licensing information.
  *
@@ -335,7 +335,7 @@ static void oper_select_begin (LdDiagramView *self, const LdPoint *point);
 static void oper_select_end (LdDiagramView *self);
 static void oper_select_get_rectangle (LdDiagramView *self, LdRectangle *rect);
 static void oper_select_queue_draw (LdDiagramView *self);
-static void oper_select_draw (GtkWidget *widget, DrawData *data);
+static void oper_select_draw (DrawData *data);
 static void oper_select_motion (LdDiagramView *self, const LdPoint *point);
 
 static void oper_move_selection_begin (LdDiagramView *self,
@@ -374,13 +374,19 @@ static void on_drag_leave (GtkWidget *widget, GdkDragContext *drag_ctx,
 	guint time, gpointer user_data);
 
 static gboolean on_draw (GtkWidget *widget, cairo_t *cr, gpointer user_data);
-static void draw_grid (GtkWidget *widget, DrawData *data);
-static void draw_diagram (GtkWidget *widget, DrawData *data);
-static void draw_terminal (GtkWidget *widget, DrawData *data);
+static void draw_grid (DrawData *data);
+static void draw_diagram (DrawData *data);
+static void draw_terminal (DrawData *data);
 static void draw_object (LdDiagramObject *diagram_object, DrawData *data);
 static void draw_symbol (LdDiagramSymbol *diagram_symbol, DrawData *data);
 static void draw_connection (LdDiagramConnection *connection, DrawData *data);
 
+/* Export. */
+
+static void get_diagram_bounds (LdDiagramView *self, LdRectangle *rect);
+static gboolean get_object_bounds (LdDiagramView *self, LdDiagramObject *object,
+	LdRectangle *rect);
+
 
 G_DEFINE_TYPE_WITH_CODE (LdDiagramView, ld_diagram_view, GTK_TYPE_DRAWING_AREA,
 	G_IMPLEMENT_INTERFACE (GTK_TYPE_SCROLLABLE,
@@ -1045,6 +1051,27 @@ ld_diagram_view_diagram_to_widget_coords (LdDiagramView *self,
 	*wy = scale * (dy - self->priv->y) + 0.5 * allocation.height;
 }
 
+static void
+ld_diagram_view_diagram_to_widget_coords_rect (LdDiagramView *self,
+	const LdRectangle *area, LdRectangle *rect)
+{
+	gdouble x1, x2, y1, y2;
+
+	ld_diagram_view_diagram_to_widget_coords (self,
+		area->x,
+		area->y,
+		&x1, &y1);
+	ld_diagram_view_diagram_to_widget_coords (self,
+		area->x + area->width,
+		area->y + area->height,
+		&x2, &y2);
+
+	rect->x = floor (x1);
+	rect->y = floor (y1);
+	rect->width  = ceil (x2) - rect->x;
+	rect->height = ceil (y2) - rect->y;
+}
+
 /**
  * ld_diagram_view_get_x:
  * @self: an #LdDiagramView object.
@@ -1612,14 +1639,12 @@ get_symbol_clip_area (LdDiagramView *self,
 }
 
 static gboolean
-get_symbol_area (LdDiagramView *self, LdDiagramSymbol *symbol,
+get_symbol_area_in_diagram_units (LdDiagramView *self, LdDiagramSymbol *symbol,
 	LdRectangle *rect)
 {
 	gdouble object_x, object_y;
 	LdSymbol *library_symbol;
 	LdRectangle area;
-	gdouble x1, x2;
-	gdouble y1, y2;
 	gint rotation;
 
 	g_object_get (symbol, "x", &object_x, "y", &object_y,
@@ -1633,24 +1658,23 @@ get_symbol_area (LdDiagramView *self, LdDiagramSymbol *symbol,
 
 	rotate_symbol_area (&area, rotation);
 
-	ld_diagram_view_diagram_to_widget_coords (self,
-		object_x + area.x,
-		object_y + area.y,
-		&x1, &y1);
-	ld_diagram_view_diagram_to_widget_coords (self,
-		object_x + area.x + area.width,
-		object_y + area.y + area.height,
-		&x2, &y2);
+	rect->x = object_x + area.x;
+	rect->y = object_y + area.y;
+	rect->width  = (rect->x + area.width)  - rect->x;
+	rect->height = (rect->y + area.height) - rect->y;
+	return TRUE;
+}
 
-	x1 = floor (x1);
-	y1 = floor (y1);
-	x2 = ceil (x2);
-	y2 = ceil (y2);
+static gboolean
+get_symbol_area (LdDiagramView *self, LdDiagramSymbol *symbol,
+	LdRectangle *rect)
+{
+	LdRectangle intermediate;
 
-	rect->x = x1;
-	rect->y = y1;
-	rect->width  = x2 - x1;
-	rect->height = y2 - y1;
+	if (!get_symbol_area_in_diagram_units (self, symbol, &intermediate))
+		return FALSE;
+
+	ld_diagram_view_diagram_to_widget_coords_rect (self, &intermediate, rect);
 	return TRUE;
 }
 
@@ -1782,7 +1806,7 @@ get_connection_clip_area (LdDiagramView *self,
 }
 
 static gboolean
-get_connection_area (LdDiagramView *self,
+get_connection_area_in_diagram_units (LdDiagramView *self,
 	LdDiagramConnection *connection, LdRectangle *rect)
 {
 	gdouble x_origin, y_origin;
@@ -1799,20 +1823,13 @@ get_connection_area (LdDiagramView *self,
 
 	g_object_get (connection, "x", &x_origin, "y", &y_origin, NULL);
 
-	ld_diagram_view_diagram_to_widget_coords (self,
-		x_origin + points->points[0].x,
-		y_origin + points->points[0].y,
-		&x, &y);
-
-	x_max = x_min = x;
-	y_max = y_min = y;
+	x_max = x_min = x_origin + points->points[0].x;
+	y_max = y_min = y_origin + points->points[0].y;
 
 	for (i = 1; i < points->length; i++)
 	{
-		ld_diagram_view_diagram_to_widget_coords (self,
-			x_origin + points->points[i].x,
-			y_origin + points->points[i].y,
-			&x, &y);
+		x = x_origin + points->points[i].x;
+		y = y_origin + points->points[i].y;
 
 		if (x < x_min)
 			x_min = x;
@@ -1834,6 +1851,19 @@ get_connection_area (LdDiagramView *self,
 	return TRUE;
 }
 
+static gboolean
+get_connection_area (LdDiagramView *self,
+	LdDiagramConnection *connection, LdRectangle *rect)
+{
+	LdRectangle intermediate;
+
+	if (!get_connection_area_in_diagram_units (self, connection, &intermediate))
+		return FALSE;
+
+	ld_diagram_view_diagram_to_widget_coords_rect (self, &intermediate, rect);
+	return TRUE;
+}
+
 
 /* ===== Operations ======================================================== */
 
@@ -2101,7 +2131,7 @@ oper_select_queue_draw (LdDiagramView *self)
 }
 
 static void
-oper_select_draw (GtkWidget *widget, DrawData *data)
+oper_select_draw (DrawData *data)
 {
 	static const double dashes[] = {3, 5};
 	SelectData *select_data;
@@ -2664,19 +2694,19 @@ on_draw (GtkWidget *widget, cairo_t *cr, gpointer user_data)
 	cairo_paint (data.cr);
 
 	if (data.self->priv->show_grid)
-		draw_grid (widget, &data);
+		draw_grid (&data);
 
-	draw_diagram (widget, &data);
-	draw_terminal (widget, &data);
+	draw_diagram (&data);
+	draw_terminal (&data);
 
 	if (data.self->priv->operation == OPER_SELECT)
-		oper_select_draw (widget, &data);
+		oper_select_draw (&data);
 
 	return FALSE;
 }
 
 static void
-draw_grid (GtkWidget *widget, DrawData *data)
+draw_grid (DrawData *data)
 {
 	gdouble grid_step;
 	gint grid_factor;
@@ -2738,7 +2768,7 @@ draw_grid (GtkWidget *widget, DrawData *data)
 }
 
 static void
-draw_terminal (GtkWidget *widget, DrawData *data)
+draw_terminal (DrawData *data)
 {
 	LdDiagramViewPrivate *priv;
 	LdPoint widget_coords;
@@ -2760,7 +2790,7 @@ draw_terminal (GtkWidget *widget, DrawData *data)
 }
 
 static void
-draw_diagram (GtkWidget *widget, DrawData *data)
+draw_diagram (DrawData *data)
 {
 	GList *objects, *iter;
 
@@ -2905,5 +2935,98 @@ draw_connection (LdDiagramConnection *connection, DrawData *data)
 
 draw_connection_end:
 	ld_point_array_free (points);
-	return;
+}
+
+
+/* ===== Export ============================================================ */
+
+static void
+get_diagram_bounds (LdDiagramView *self, LdRectangle *rect)
+{
+	GList *objects;
+	gboolean initialized = FALSE;
+	LdRectangle partial;
+	gdouble x2, y2;
+
+	g_return_if_fail (LD_IS_DIAGRAM_VIEW (self));
+	g_return_if_fail (rect != NULL);
+
+	memset (rect, 0, sizeof *rect);
+	objects = (GList *) ld_diagram_get_objects (self->priv->diagram);
+	for (; objects != NULL; objects = objects->next)
+	{
+		if (!get_object_bounds (self, objects->data, &partial))
+			continue;
+
+		if (!initialized)
+		{
+			*rect = partial;
+			initialized = TRUE;
+			continue;
+		}
+
+		x2 = MAX (partial.x + partial.width,  rect->x + rect->width);
+		y2 = MAX (partial.y + partial.height, rect->y + rect->height);
+		rect->x = MIN (rect->x, partial.x);
+		rect->y = MIN (rect->y, partial.y);
+		rect->width  = x2 - rect->x;
+		rect->height = y2 - rect->y;
+	}
+}
+
+static gboolean
+get_object_bounds (LdDiagramView *self, LdDiagramObject *object,
+	LdRectangle *rect)
+{
+	if (LD_IS_DIAGRAM_SYMBOL (object))
+		return get_symbol_area_in_diagram_units (self,
+			LD_DIAGRAM_SYMBOL (object), rect);
+	if (LD_IS_DIAGRAM_CONNECTION (object))
+		return get_connection_area_in_diagram_units (self,
+			LD_DIAGRAM_CONNECTION (object), rect);
+	return FALSE;
+}
+
+/**
+ * ld_diagram_view_get_export_bounds:
+ * @self: an #LdDiagramView object.
+ * @rect: (out): diagram boundaries.
+ *
+ * Get the smallest rectangular area containing all objects in the diagram.
+ * The diagram object itself doesn't have any idea of how symbols are rendered.
+ *
+ * Return value: export units per diagram unit.
+ */
+gdouble
+ld_diagram_view_get_export_bounds (LdDiagramView *self, LdRectangle *rect)
+{
+	LdRectangle intermediate;
+
+	get_diagram_bounds (self, &intermediate);
+	ld_diagram_view_diagram_to_widget_coords_rect (self, &intermediate, rect);
+	return ld_diagram_view_get_scale_in_px (self);
+}
+
+/**
+ * ld_diagram_view_export:
+ * @self: an #LdDiagramView object.
+ * @cr: Cairo context to draw on.
+ * @clip: the clip area (the function itself does not clip).
+ *
+ * Get the smallest rectangular area containing all objects in the diagram.
+ * The diagram object itself doesn't have any idea of how symbols are rendered.
+ */
+void
+ld_diagram_view_export (LdDiagramView *self, cairo_t *cr,
+	const LdRectangle *clip)
+{
+	DrawData data;
+
+	data.cr = cr;
+	data.self = self;
+	/* FIXME: Various functions call this directly, this export is a hack. */
+	data.scale = ld_diagram_view_get_scale_in_px (data.self);
+	data.exposed_rect = *clip;
+
+	draw_diagram (&data);
 }

liblogdiag/ld-diagram-view.h

@@ -2,7 +2,7 @@
  * ld-diagram-view.h
  *
  * This file is a part of logdiag.
- * Copyright 2010, 2011 Přemysl Eric Janouch
+ * Copyright 2010 - 2021 Přemysl Eric Janouch
  *
  * See the file LICENSE for licensing information.
  *
@@ -96,6 +96,11 @@ void ld_diagram_view_set_show_grid (LdDiagramView *self, gboolean show_grid);
 void ld_diagram_view_add_object_begin (LdDiagramView *self,
 	LdDiagramObject *object);
 
+gdouble ld_diagram_view_get_export_bounds (LdDiagramView *self,
+	LdRectangle *rect);
+void ld_diagram_view_export (LdDiagramView *self,
+	cairo_t *cr, const LdRectangle *clip);
+
 
 G_END_DECLS
 

share/gui/window-main.ui

@@ -1,18 +1,16 @@
 <ui>
 	<menubar name="MenuBar">
-		<menu name="FileMenu" action="FileMenu">
+		<menu action="FileMenu">
 			<menuitem action="New" />
 			<menuitem action="Open" />
 			<menuitem action="Save" />
 			<menuitem action="SaveAs" />
 			<separator />
-<!--
-			<menuitem action="Export" />
+			<menuitem action="Print" />
 			<separator />
--->
 			<menuitem action="Quit" />
 		</menu>
-		<menu name="EditMenu" action="EditMenu">
+		<menu action="EditMenu">
 			<menuitem action="Undo" />
 			<menuitem action="Redo" />
 			<separator />
@@ -25,7 +23,7 @@
 			<separator />
 			<menuitem action="SelectAll" />
 		</menu>
-		<menu name="ViewMenu" action="ViewMenu">
+		<menu action="ViewMenu">
 			<menuitem action="MainToolbar" />
 			<menuitem action="LibraryPane" />
 			<separator />
@@ -35,7 +33,7 @@
 			<menuitem action="ZoomOut" />
 			<menuitem action="NormalSize" />
 		</menu>
-		<menu name="HelpMenu" action="HelpMenu">
+		<menu action="HelpMenu">
 			<menuitem action="UserGuide" />
 			<menuitem action="About" />
 		</menu>

share/logdiag.manifest

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
+<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
+	<assemblyIdentity name="logdiag" version="1.0.0.0" type="win32" />
+	<dependency>
+		<dependentAssembly>
+			<assemblyIdentity name="Microsoft.Windows.Common-Controls"
+				version="6.0.0.0" type="win32" processorArchitecture="*"
+				publicKeyToken="6595b64144ccf1df" language="*" />
+		</dependentAssembly>
+	</dependency>
+</assembly>

share/logdiag.rc

@@ -1 +1,3 @@
+#include <windows.h>
 LD_ICON ICON "logdiag.ico"
+CREATEPROCESS_MANIFEST_RESOURCE_ID RT_MANIFEST "logdiag.manifest"

src/ld-window-main.c

@@ -56,6 +56,8 @@ struct _LdWindowMainPrivate
 
 static void ld_window_main_finalize (GObject *gobject);
 static void load_library_directories (LdLibrary *library);
+static void display_and_free_error (LdWindowMain *self, const gchar *title,
+	GError *error);
 
 static void on_ui_proxy_connected (GtkUIManager *ui, GtkAction *action,
 	GtkWidget *proxy, LdWindowMain *window);
@@ -104,9 +106,14 @@ static void on_action_new (GtkAction *action, LdWindowMain *self);
 static void on_action_open (GtkAction *action, LdWindowMain *self);
 static void on_action_save (GtkAction *action, LdWindowMain *self);
 static void on_action_save_as (GtkAction *action, LdWindowMain *self);
+static void on_action_print (GtkAction *action, LdWindowMain *self);
+static void on_action_print_draw_page (GtkPrintOperation *operation,
+	GtkPrintContext *context, int page_nr, LdWindowMain *self);
 static void on_action_quit (GtkAction *action, LdWindowMain *self);
 static void on_action_user_guide (GtkAction *action, LdWindowMain *self);
 static void on_action_about (GtkAction *action, LdWindowMain *self);
+static gboolean on_action_about_activate_link (GtkAboutDialog *dialog,
+	gchar *uri, LdWindowMain *self);
 
 static void on_action_undo (GtkAction *action, LdWindowMain *self);
 static void on_action_redo (GtkAction *action, LdWindowMain *self);
@@ -142,11 +149,11 @@ static GtkActionEntry wm_action_entries[] =
 		{"SaveAs", GTK_STOCK_SAVE_AS, N_("Save _As..."), "<Shift><Ctrl>S",
 			N_("Save the current diagram with another name"),
 			G_CALLBACK (on_action_save_as)},
-/*
- *		{"Export", NULL, N_("_Export"), NULL,
- *			N_("Export the diagram"),
- *			NULL},
- */
+
+		{"Print", GTK_STOCK_PRINT, N_("_Print"), "<Ctrl>P",
+			N_("Print the diagram"),
+			G_CALLBACK (on_action_print)},
+
 		{"Quit", GTK_STOCK_QUIT, N_("_Quit"), "<Ctrl>Q",
 			N_("Quit the application"),
 			G_CALLBACK (on_action_quit)},
@@ -444,6 +451,21 @@ load_library_directories (LdLibrary *library)
 	g_free (user_dir);
 }
 
+static void
+display_and_free_error (LdWindowMain *self, const gchar *title, GError *error)
+{
+	GtkWidget *message_dialog;
+
+	message_dialog = gtk_message_dialog_new (GTK_WINDOW (self),
+		GTK_DIALOG_MODAL, GTK_MESSAGE_ERROR, GTK_BUTTONS_OK, "%s", title);
+	gtk_message_dialog_format_secondary_text
+		(GTK_MESSAGE_DIALOG (message_dialog), "%s", error->message);
+	g_error_free (error);
+
+	gtk_dialog_run (GTK_DIALOG (message_dialog));
+	gtk_widget_destroy (message_dialog);
+}
+
 /*
  * on_delete:
  *
@@ -975,6 +997,87 @@ on_action_save_as (GtkAction *action, LdWindowMain *self)
 	diagram_show_save_as_dialog (self);
 }
 
+static void
+on_action_print (GtkAction *action, LdWindowMain *self)
+{
+	static GtkPrintSettings *settings = NULL;
+	GError *error = NULL;
+	GtkPrintOperation *print;
+	GtkPrintOperationResult res;
+	gchar *name;
+
+	print = gtk_print_operation_new ();
+	gtk_print_operation_set_n_pages (print, 1);
+	gtk_print_operation_set_embed_page_setup (print, TRUE);
+	gtk_print_operation_set_unit (print, GTK_UNIT_MM);
+
+	name = diagram_get_name (self);
+	gtk_print_operation_set_job_name (print, name);
+	g_free (name);
+
+	if (settings != NULL)
+		gtk_print_operation_set_print_settings (print, settings);
+	g_signal_connect (print, "draw-page",
+		G_CALLBACK (on_action_print_draw_page), self);
+
+	/* On Windows, it is not possible to get a print preview from the system
+	 * print dialog.  But in Windows XP previews do not work at all--unreadable
+	 * EMFs come out.  Windows 10 errors out with "A sharing violation occurred
+	 * while accessing" the temporary EMF file on our first run of
+	 * GtkPrintOperation, and following that it opens the previews up in
+	 * fucking Paint, so there is no point in trying.  It lacks a stage
+	 * or controls for setting up page parameters anyway.
+	 */
+	res = gtk_print_operation_run (print,
+		GTK_PRINT_OPERATION_ACTION_PRINT_DIALOG,
+		GTK_WINDOW (self), &error);
+	if (res == GTK_PRINT_OPERATION_RESULT_APPLY)
+	{
+		if (settings != NULL)
+			g_object_unref (settings);
+		settings
+			= g_object_ref (gtk_print_operation_get_print_settings (print));
+	}
+	if (error)
+		display_and_free_error (self, _("Error"), error);
+
+	g_object_unref (print);
+}
+
+static void
+on_action_print_draw_page (GtkPrintOperation *operation,
+	GtkPrintContext *context, int page_nr, LdWindowMain *self)
+{
+	cairo_t *cr;
+	LdDiagramView *view;
+	gdouble area_width_mm, area_height_mm;
+	gdouble diagram_width_mm, diagram_height_mm;
+	gdouble diagram_to_export_units, scale;
+	LdRectangle bounds;
+
+	cr = gtk_print_context_get_cairo_context (context);
+	view = self->priv->view;
+
+	area_width_mm = gtk_print_context_get_width (context);
+	area_height_mm = gtk_print_context_get_height (context);
+	diagram_to_export_units = ld_diagram_view_get_export_bounds (view, &bounds);
+
+	/* Scale for the view's constant, measured in milimetres. */
+	scale = 1 / diagram_to_export_units * LD_DIAGRAM_VIEW_BASE_UNIT_LENGTH;
+	diagram_width_mm = bounds.width * scale;
+	diagram_height_mm = bounds.height * scale;
+
+	/* Scale to fit the paper. */
+	if (area_width_mm < diagram_width_mm)
+		scale *= area_width_mm / diagram_width_mm;
+	if (area_height_mm < diagram_height_mm)
+		scale *= area_height_mm / diagram_height_mm;
+
+	cairo_scale (cr, scale, scale);
+	cairo_translate (cr, -bounds.x, -bounds.y);
+	ld_diagram_view_export (view, cr, &bounds);
+}
+
 static void
 on_action_quit (GtkAction *action, LdWindowMain *self)
 {
@@ -1040,21 +1143,36 @@ on_action_user_guide (GtkAction *action, LdWindowMain *self)
 
 	if (!open_file (file, gtk_window_get_screen (GTK_WINDOW (self)), &error))
 	{
-		GtkWidget *message_dialog;
-
-		message_dialog = gtk_message_dialog_new (GTK_WINDOW (self),
-			GTK_DIALOG_MODAL, GTK_MESSAGE_ERROR, GTK_BUTTONS_OK,
-			_("Failed to open the user guide"));
-		gtk_message_dialog_format_secondary_text
-			(GTK_MESSAGE_DIALOG (message_dialog), "%s", error->message);
-		g_error_free (error);
-
-		gtk_dialog_run (GTK_DIALOG (message_dialog));
-		gtk_widget_destroy (message_dialog);
+		display_and_free_error (self,
+			_("Failed to open the user guide"), error);
 	}
 	g_object_unref (file);
 }
 
+static void
+on_action_about (GtkAction *action, LdWindowMain *self)
+{
+	GtkWidget *about_dialog;
+
+	about_dialog = g_object_new (GTK_TYPE_ABOUT_DIALOG,
+		"program-name", PROJECT_NAME,
+		"logo-icon-name", PROJECT_NAME,
+		"version", PROJECT_VERSION,
+		"translator-credits", _("translator-credits"),
+		"copyright", "Copyright 2010 - 2021 Přemysl Eric Janouch",
+		"website", PROJECT_URL,
+		NULL);
+
+	g_signal_connect (about_dialog, "activate-link",
+		G_CALLBACK (on_action_about_activate_link), self);
+
+	gtk_window_set_transient_for (GTK_WINDOW (about_dialog), GTK_WINDOW (self));
+	gtk_window_set_modal (GTK_WINDOW (about_dialog), TRUE);
+	gtk_window_set_destroy_with_parent (GTK_WINDOW (about_dialog), TRUE);
+	gtk_dialog_run (GTK_DIALOG (about_dialog));
+	gtk_widget_destroy (about_dialog);
+}
+
 static gboolean
 on_action_about_activate_link (GtkAboutDialog *dialog, gchar *uri,
 	LdWindowMain *self)
@@ -1080,30 +1198,6 @@ on_action_about_activate_link (GtkAboutDialog *dialog, gchar *uri,
 	return FALSE;
 }
 
-static void
-on_action_about (GtkAction *action, LdWindowMain *self)
-{
-	GtkWidget *about_dialog;
-
-	about_dialog = g_object_new (GTK_TYPE_ABOUT_DIALOG,
-		"program-name", PROJECT_NAME,
-		"logo-icon-name", PROJECT_NAME,
-		"version", PROJECT_VERSION,
-		"translator-credits", _("translator-credits"),
-		"copyright", "Copyright 2010 - 2021 Přemysl Eric Janouch",
-		"website", PROJECT_URL,
-		NULL);
-
-	g_signal_connect (about_dialog, "activate-link",
-		G_CALLBACK (on_action_about_activate_link), self);
-
-	gtk_window_set_transient_for (GTK_WINDOW (about_dialog), GTK_WINDOW (self));
-	gtk_window_set_modal (GTK_WINDOW (about_dialog), TRUE);
-	gtk_window_set_destroy_with_parent (GTK_WINDOW (about_dialog), TRUE);
-	gtk_dialog_run (GTK_DIALOG (about_dialog));
-	gtk_widget_destroy (about_dialog);
-}
-
 static void
 on_action_undo (GtkAction *action, LdWindowMain *self)
 {