MODULE gestures ;

(*
   m2-GTK4 example - gestures on a drawing area.

   A GtkGestureClick reports the click position and a GtkGestureDrag
   reports the drag offset, both in a label.  Demonstrates connecting
   signals with the exact C callback signatures.

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

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 GtkBox IMPORT gtk_box_new, gtk_box_append, gtk_box_set_spacing;
FROM GtkEnums IMPORT GtkVertical;
FROM GtkLabel IMPORT gtk_label_new, gtk_label_set_text;
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 GtkWidget IMPORT gtk_widget_add_controller;
FROM GtkGestures IMPORT gtk_gesture_click_new, gtk_gesture_drag_new;
FROM Cairo IMPORT cairo_set_source_rgb, cairo_rectangle, cairo_fill;
FROM GObject IMPORT g_signal_connect_data, GConnectDefault;
FROM GtkUtils IMPORT Connect, IntToStr, StrAppend;
FROM SYSTEM IMPORT ADDRESS, ADR;
FROM libc IMPORT printf;

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

VAR
   label: ADDRESS;

PROCEDURE Show (kind: ARRAY OF CHAR; a, b: REAL);
VAR
   num: ARRAY [0..15] OF CHAR;
   line: ARRAY [0..63] OF CHAR;
BEGIN
   line[0] := 0C;
   StrAppend(line, kind);
   IntToStr(TRUNC(a), num);
   StrAppend(line, num);
   StrAppend(line, ", ");
   IntToStr(TRUNC(b), num);
   StrAppend(line, num);
   gtk_label_set_text(label, line)
END Show;

(* void pressed(GtkGestureClick *g, int n, double x, double y, gpointer u) *)
PROCEDURE OnPressed (g: ADDRESS; n_press: INTEGER; x, y: REAL; user: ADDRESS);
BEGIN
   Show("click at ", x, y)
END OnPressed;

(* void drag-update(GtkGestureDrag *g, double ox, double oy, gpointer u) *)
PROCEDURE OnDragUpdate (g: ADDRESS; offset_x, offset_y: REAL; user: ADDRESS);
BEGIN
   Show("drag offset ", offset_x, offset_y)
END OnDragUpdate;

PROCEDURE Draw (area: ADDRESS; cr: ADDRESS; width, height: INTEGER;
                data: ADDRESS);
BEGIN
   cairo_set_source_rgb(cr, 0.90, 0.93, 0.98);
   cairo_rectangle(cr, 0.0, 0.0, VAL(REAL, width), VAL(REAL, height));
   cairo_fill(cr)
END Draw;

PROCEDURE OnActivate (application: ADDRESS; data: ADDRESS);
VAR
   window, box, area, click, drag: ADDRESS;
BEGIN
   area := gtk_drawing_area_new();
   gtk_drawing_area_set_content_width(area, 320);
   gtk_drawing_area_set_content_height(area, 200);
   gtk_drawing_area_set_draw_func(area, ADR(Draw), NIL, NIL);

   click := gtk_gesture_click_new();
   g_signal_connect_data(click, "pressed", ADR(OnPressed), NIL, NIL,
                         GConnectDefault);
   gtk_widget_add_controller(area, click);

   drag := gtk_gesture_drag_new();
   g_signal_connect_data(drag, "drag-update", ADR(OnDragUpdate), NIL, NIL,
                         GConnectDefault);
   gtk_widget_add_controller(area, drag);

   label := gtk_label_new("click or drag the area");

   box := gtk_box_new(GtkVertical, 10);
   gtk_box_set_spacing(box, 10);
   gtk_box_append(box, area);
   gtk_box_append(box, label);

   window := gtk_application_window_new(application);
   gtk_window_set_title(window, "m2-GTK4 Gestures");
   gtk_window_set_default_size(window, 360, 260);
   gtk_window_set_child(window, box);
   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;
   Connect(app, "activate", ADR(OnActivate), NIL);
   g_application_run(app, 0, NIL)
END gestures.