[Java-gnome-developer] Create a custom GTK RoundedFrame in Java Gnome

[bob <loi...@pa...>]

When I'm reading the banshee source (C# language), I found how to create
a custom component in C#. It's very simple, the developer had to extend
the Gtk.Bin Object.

I search to do the same thing in Java but I don't found any "simple"
solution, we couldn't extends the Bin object.

I think it is possible to create this component in C and create binding
like all object in java-gnome but it's not very simple (add C code and
add Java binding working with java-gnome).

There is a solution to create a custom widget in Java ? Could you update
the java-gnome library to do it ?

//
// The custom GTK widget RoundedFrame
//

namespace Hyena.Widgets
{
    public class RoundedFrame : Bin
    {
        private Theme theme;
        protected Theme Theme {
            get { return theme; }
        }

        private Widget child;
        private Gdk.Rectangle child_allocation;
        private bool fill_color_set;
        private Cairo.Color fill_color;
        private bool draw_border = true;
        private Pattern fill_pattern;
        private int frame_width;

        // Ugh, this is to avoid the GLib.MissingIntPtrCtorException
seen by some; BGO #552169
        protected RoundedFrame (IntPtr ptr) : base (ptr)
        {
        }

        public RoundedFrame ()
        {
        }

        public void SetFillColor (Cairo.Color color)
        {
            fill_color = color;
            fill_color_set = true;
            QueueDraw ();
        }

        public void UnsetFillColor ()
        {
            fill_color_set = false;
            QueueDraw ();
        }

        public Pattern FillPattern {
            get { return fill_pattern; }
            set {
                fill_pattern = value;
                QueueDraw ();
            }
        }

        public bool DrawBorder {
            get { return draw_border; }
            set { draw_border = value; QueueDraw (); }
        }

#region Gtk.Widget Overrides

        protected override void OnStyleSet (Style previous_style)
        {
            base.OnStyleSet (previous_style);
            theme = Hyena.Gui.Theming.ThemeEngine.CreateTheme (this);
            frame_width = (int)theme.Context.Radius + 1;
        }

        protected override void OnSizeRequested (ref Requisition
requisition)
        {
            if (child != null && child.Visible) {
                // Add the child's width/height
                Requisition child_requisition = child.SizeRequest ();
                requisition.Width = Math.Max (0,
child_requisition.Width);
                requisition.Height = child_requisition.Height;
            } else {
                requisition.Width = 0;
                requisition.Height = 0;
            }

            // Add the frame border
            requisition.Width += ((int)BorderWidth + frame_width) * 2;
            requisition.Height += ((int)BorderWidth + frame_width) * 2;
        }

        protected override void OnSizeAllocated (Gdk.Rectangle
allocation)
        {
            base.OnSizeAllocated (allocation);

            child_allocation = new Gdk.Rectangle ();

            if (child == null || !child.Visible) {
                return;
            }

            child_allocation.X = (int)BorderWidth + frame_width;
            child_allocation.Y = (int)BorderWidth + frame_width;
            child_allocation.Width = (int)Math.Max (1, Allocation.Width
- child_allocation.X * 2);
            child_allocation.Height = (int)Math.Max (1,
Allocation.Height - child_allocation.Y -
                (int)BorderWidth - frame_width);

            child_allocation.X += Allocation.X;
            child_allocation.Y += Allocation.Y;

            child.SizeAllocate (child_allocation);
        }

        protected override void OnSetScrollAdjustments (Adjustment hadj,
Adjustment vadj)
        {
            // This is to satisfy the gtk_widget_set_scroll_adjustments
            // inside of GtkScrolledWindow so it doesn't complain about
            // its child not being scrollable.
        }

        protected override bool OnExposeEvent (Gdk.EventExpose evnt)
        {
            if (!IsDrawable) {
                return false;
            }

            Cairo.Context cr = Gdk.CairoHelper.Create (evnt.Window);

            try {
                DrawFrame (cr, evnt.Area);
                if (child != null) {
                    PropagateExpose (child, evnt);
                }
                return false;
            } finally {
                CairoExtensions.DisposeContext (cr);
            }
        }

        private void DrawFrame (Cairo.Context cr, Gdk.Rectangle clip)
        {
            int x = child_allocation.X - frame_width;
            int y = child_allocation.Y - frame_width;
            int width = child_allocation.Width + 2 * frame_width;
            int height = child_allocation.Height + 2 * frame_width;

            Gdk.Rectangle rect = new Gdk.Rectangle (x, y, width,
height);

            theme.Context.ShowStroke = draw_border;

            if (fill_color_set) {
                theme.DrawFrameBackground (cr, rect, fill_color);
            } else if (fill_pattern != null) {
                theme.DrawFrameBackground (cr, rect, fill_pattern);
            } else {
                theme.DrawFrameBackground (cr, rect, true);
                theme.DrawFrameBorder (cr, rect);
            }
        }

#endregion

#region Gtk.Container Overrides

        protected override void OnAdded (Widget widget)
        {
            child = widget;
            base.OnAdded (widget);
        }

        protected override void OnRemoved (Widget widget)
        {
            if (child == widget) {
                child = null;
            }

            base.OnRemoved (widget);
        }

#endregion

    }
}