[examples/] add gtk-sierpinski.pl

examples/gtk-sierpinski.pl

@@ -0,0 +1,73 @@
+# Main documentation: http://docs.go-mono.com, particularly Gnome
+# (for Gdk and Gtk) and Mono (for Cairo) libraries.
+# See also: The X-Windows Disaster at http://www.art.net/~hopkins/Don/unix-haters/handbook.html
+
+constant $GTK = "gtk-sharp,Version=2.12.0.0,Culture=neutral,PublicKeyToken=35e10195dab3c99f";
+constant $GDK = "gdk-sharp, Version=2.12.0.0, Culture=neutral, PublicKeyToken=35e10195dab3c99f";
+constant $GLIB = "glib-sharp, Version=2.12.0.0, Culture=neutral, PublicKeyToken=35e10195dab3c99f";
+# use 'gacutil -l' to look up similar module details
+
+constant Application    = CLR::("Gtk.Application,$GTK");
+constant Window         = CLR::("Gtk.Window,$GTK");
+constant GdkCairoHelper = CLR::("Gdk.CairoHelper,$GDK");
+constant GtkDrawingArea = CLR::("Gtk.DrawingArea,$GTK");
+constant GLibTimeout    = CLR::("GLib.Timeout,$GLIB");
+
+Application.Init;
+my $window = Window.new("sierpinski");
+my $windowSizeX = 640; my $windowSizeY = 560;
+$window.Resize($windowSizeX, $windowSizeY);
+my $drawingarea = GtkDrawingArea.new;
+$drawingarea.add_ExposeEvent: sub ($obj, $args) {
+    $args;  # suppress 'declared but not used' warnings
+    my $cc = GdkCairoHelper.Create($obj.GdkWindow);  # Cairo Context
+    my $windowX; my $windowY; my $windowWidth; my $windowHeight; my $windowDepth;
+    # TODO: the following line seems to pass parameters by value, it needs to pass by reference to integers
+    # Tracked as https://github.com/sorear/niecza/issues/57
+    $obj.GdkWindow.GetGeometry($windowX, $windowY, $windowWidth, $windowHeight, $windowDepth);
+    # TODO: remove the following cheat that works around the above problem
+    $windowWidth = $windowSizeX; $windowHeight = $windowSizeY;
+    $cc.SetSourceRGB(0, 1, 0); $cc.Paint();  # Make a green background
+    # Start the recursive drawing process
+    my $x0=0; my $y0=0; my  $x1=$windowWidth-1; my $y1=$windowHeight/2;
+    my $x2=0; my $y2=$windowHeight-1;
+    my $depth = Sierpinski($cc, $x0, $y0, $x1, $y1, $x2, $y2, True, 1);
+    my $label = sprintf("%d x %d, %d levels", $windowWidth, $windowHeight, $depth);
+    say $label;
+    $cc.Target.Dispose;
+    # TODO: Currently the following error appears at exit:
+    # Cairo.Context: called from finalization thread, programmer is missing a call to Dispose
+    # The following line should fix the above, but gives this error: Unable to resolve method Dispose
+    # $cc.Dispose(); # Should do: ((IDisposable) cc).Dispose();
+    # Tracked as https://github.com/sorear/niecza/issues/56
+};
+$window.add_DeleteEvent: sub ($obj, $args) {
+    $obj; $args; # suppress "declared but not used" Potential difficulties
+    Application.Quit;
+};
+$window.Add($drawingarea);
+$window.ShowAll;
+Application.Run;
+
+sub Sierpinski($cc, $x0, $y0, $x1, $y1, $x2, $y2, $colorflag, $depth is copy)
+{
+    if $colorflag { $cc.SetSourceRGB(0, 0, 1); }
+    else { $cc.SetSourceRGB(1, 1, 0); }
+    $cc.MoveTo($x0.Int, $y0.Int); $cc.LineTo($x1.Int, $y1.Int);
+    $cc.LineTo($x2.Int, $y2.Int); $cc.LineTo($x0.Int, $y0.Int);
+    $cc.Fill;
+    $cc.Stroke;
+    if (($x1-$x0)>2) && (($y2-$y0)>2) {  # Prepare to recurse
+        ++$depth;
+        # Calculate the midpoints of the 3 edges of the triangle
+        my $x01=(($x0+$x1)/2).Int; my $y01=(($y0+$y1)/2).Int;
+        my $x12=(($x1+$x2)/2).Int; my $y12=(($y1+$y2)/2).Int;
+        my $x20=(($x2+$x0)/2).Int; my $y20=(($y2+$y0)/2).Int;
+        # Recursively draw three smaller triangles
+        Sierpinski($cc, $x0, $y0,  $x01,$y01, $x20,$y20, !$colorflag, $depth);
+        Sierpinski($cc, $x01,$y01, $x1, $y1,  $x12,$y12, !$colorflag, $depth);
+        $depth =
+        Sierpinski($cc, $x20,$y20, $x12,$y12, $x2, $y2,  !$colorflag, $depth);
+    }
+    $depth;
+}