MODULE drawing ;

(*
   m2-GTK4 example - drawing with GtkDrawingArea, Cairo and Pango.

   Draws a filled circle, a line and a Pango text layout.

   Build:  make examples
   Run:    ./build/examples/drawing
*)

FROM Gio IMPORT g_application_run;
FROM GtkApplication IMPORT gtk_application_new;
FROM GtkWindow IMPORT gtk_application_window_new, gtk_window_set_title,
   gtk_window_set_default_size, gtk_window_set_child, gtk_window_present;
FROM GtkDrawingArea IMPORT gtk_drawing_area_new,
   gtk_drawing_area_set_content_width,
   gtk_drawing_area_set_content_height, gtk_drawing_area_set_draw_func;
FROM Cairo IMPORT cairo_set_source_rgb, cairo_rectangle, cairo_fill,
   cairo_arc, cairo_set_line_width, cairo_stroke, cairo_move_to, cairo_line_to;
FROM Pango IMPORT pango_font_description_from_string,
   pango_font_description_free, pango_layout_set_text,
   pango_layout_set_font_description;
FROM PangoCairo IMPORT pango_cairo_create_layout, pango_cairo_show_layout;
FROM GObject IMPORT g_object_unref;
FROM GtkClosures IMPORT Connect2;
FROM SYSTEM IMPORT ADDRESS, ADR;
FROM libc IMPORT printf;

CONST
   AppId = "org.example.m2gtk4.Drawing";

PROCEDURE Draw (area: ADDRESS; cr: ADDRESS; width, height: INTEGER;
                data: ADDRESS);
VAR
   layout, desc: ADDRESS;
BEGIN
   cairo_set_source_rgb(cr, 0.95, 0.95, 0.97);
   cairo_rectangle(cr, 0.0, 0.0, VAL(REAL, width), VAL(REAL, height));
   cairo_fill(cr);

   cairo_set_source_rgb(cr, 0.20, 0.50, 0.90);
   cairo_arc(cr, 80.0, 80.0, 50.0, 0.0, 6.2831853);
   cairo_fill(cr);

   cairo_set_source_rgb(cr, 0.90, 0.20, 0.20);
   cairo_set_line_width(cr, 6.0);
   cairo_move_to(cr, 150.0, 40.0);
   cairo_line_to(cr, 330.0, 140.0);
   cairo_stroke(cr);

   layout := pango_cairo_create_layout(cr);
   desc := pango_font_description_from_string("Sans Bold 18");
   pango_layout_set_font_description(layout, desc);
   pango_font_description_free(desc);
   pango_layout_set_text(layout, "Cairo + Pango from Modula-2", -1);
   cairo_set_source_rgb(cr, 0.10, 0.10, 0.10);
   cairo_move_to(cr, 20.0, 160.0);
   pango_cairo_show_layout(cr, layout);
   g_object_unref(layout)
END Draw;

PROCEDURE OnActivate (application: ADDRESS; data: ADDRESS);
VAR
   window, area: ADDRESS;
BEGIN
   area := gtk_drawing_area_new();
   gtk_drawing_area_set_content_width(area, 360);
   gtk_drawing_area_set_content_height(area, 200);
   gtk_drawing_area_set_draw_func(area, ADR(Draw), NIL, NIL);

   window := gtk_application_window_new(application);
   gtk_window_set_title(window, "m2-GTK4 Drawing");
   gtk_window_set_default_size(window, 400, 240);
   gtk_window_set_child(window, area);
   gtk_window_present(window)
END OnActivate;

VAR
   app: ADDRESS;
BEGIN
   app := gtk_application_new(AppId, 0);
   IF app = NIL THEN
      printf("gtk_application_new failed\n");
      HALT(1)
   END;
   Connect2(app, "activate", OnActivate, NIL);
   g_application_run(app, 0, NIL)
END drawing.