GtkSharp/sample/GtkDemo/DemoDrawingArea.cs
John Luke db410e9497 implement some of the DemoApplicationWindow
fix some bugs in DemoEditableCells
use more consistent tabs and spaces
add a TODO of what is left
use the using () pattern to dispose Dialogs automatically
use args.RetVal when handling the DeleteEvent

svn path=/trunk/gtk-sharp/; revision=32017
2004-08-07 17:06:29 +00:00

244 lines
7.1 KiB
C#

//
// DemoDrawingArea.cs, port of drawingarea.c from gtk-demo
//
// Author: Daniel Kornhauser <dkor@alum.mit.edu>
// Rachel Hestilow <hestilow@ximian.com>
//
// Copyright (C) 2003, Ximian Inc.
//
/* Drawing Area
*
* GtkDrawingArea is a blank area where you can draw custom displays
* of various kinds.
*
* This demo has two drawing areas. The checkerboard area shows
* how you can just draw something; all you have to do is write
* a signal handler for ExposeEvent, as shown here.
*
* The "scribble" area is a bit more advanced, and shows how to handle
* events such as button presses and mouse motion. Click the mouse
* and drag in the scribble area to draw squiggles. Resize the window
* to clear the area.
*/
using System;
using Gtk;
using Gdk;
namespace GtkDemo
{
public class DemoDrawingArea : Gtk.Window
{
private static Pixmap pixmap = null;
private static DrawingArea drawingArea;
private static DrawingArea drawingArea1;
public DemoDrawingArea () : base ("Drawing Area")
{
this.DeleteEvent += new DeleteEventHandler (WindowDelete);
this.BorderWidth = 8;
VBox vbox = new VBox (false, 8);
vbox.BorderWidth = 8;
this.Add (vbox);
// Create the checkerboard area
Label label = new Label ();
label.Markup = "<u>Checkerboard pattern</u>";
vbox.PackStart (label, false, false, 0);
Frame frame = new Frame ();
frame.ShadowType = ShadowType.In;
vbox.PackStart (frame, true, true, 0);
drawingArea = new DrawingArea ();
// set a minimum size
drawingArea.SetSizeRequest (100,100);
frame.Add (drawingArea);
drawingArea.ExposeEvent += new ExposeEventHandler (CheckerboardExpose);
// Create the scribble area
Label label1 = new Label ("<u>Scribble area</u>");
label1.UseMarkup = true;
vbox.PackStart (label1, false, false, 0);
Frame frame1 = new Frame ();
frame1.ShadowType = ShadowType.In;
vbox.PackStart (frame1, true, true, 0);
drawingArea1 = new DrawingArea ();
// set a minimun size
drawingArea1.SetSizeRequest (100, 100);
frame1.Add (drawingArea1);
// Signals used to handle backing pixmap
drawingArea1.ExposeEvent += new ExposeEventHandler (ScribbleExpose);
drawingArea1.ConfigureEvent += new ConfigureEventHandler (ScribbleConfigure);
// Event signals
drawingArea1.MotionNotifyEvent += new MotionNotifyEventHandler (ScribbleMotionNotify);
drawingArea1.ButtonPressEvent += new ButtonPressEventHandler (ScribbleButtonPress);
// Ask to receive events the drawing area doesn't normally
// subscribe to
drawingArea1.Events = EventMask.LeaveNotifyMask | EventMask.ButtonPressMask |
EventMask.PointerMotionMask | EventMask.PointerMotionHintMask;
this.ShowAll ();
}
private void WindowDelete (object o, DeleteEventArgs args)
{
this.Hide ();
this.Destroy ();
args.RetVal = true;
}
private void CheckerboardExpose (object o, ExposeEventArgs args)
{
// Defining the size of the Checks
const int CheckSize = 10;
const int Spacing = 2;
// Defining the color of the Checks
int i, j, xcount, ycount;
Gdk.GC gc, gc1, gc2;
Gdk.Color color = new Gdk.Color ();
EventExpose eventExpose = args.Event;
Gdk.Window window = eventExpose.Window;
gc1 = new Gdk.GC (window);
color.Red = 30000;
color.Green = 0;
color.Blue = 30000;
gc1.RgbFgColor = color;
gc2 = new Gdk.GC (window);
color.Red = 65535;
color.Green = 65535;
color.Blue = 65535;
gc2.RgbFgColor = color;
// Start redrawing the Checkerboard
xcount = 0;
i = Spacing;
while (i < drawingArea.Allocation.Width){
j = Spacing;
ycount = xcount % 2; //start with even/odd depending on row
while (j < drawingArea.Allocation.Height){
gc = new Gdk.GC (window);
if (ycount % 2 != 0){
gc = gc1;}
else{
gc = gc2;}
window.DrawRectangle(gc, true, i, j, CheckSize, CheckSize);
j += CheckSize + Spacing;
++ycount;
}
i += CheckSize + Spacing;
++xcount;
}
// return true because we've handled this event, so no
// further processing is required.
args.RetVal = true;
}
private void ScribbleExpose (object o, ExposeEventArgs args)
{
// We use the "ForegroundGC" for the widget since it already exists,
// but honestly any GC would work. The only thing to worry about
// is whether the GC has an inappropriate clip region set.
EventExpose eventExpose = args.Event;
Gdk.Window window = eventExpose.Window;
Rectangle area = eventExpose.Area;
window.DrawDrawable (drawingArea1.Style.ForegroundGC(StateType.Normal),
pixmap,
area.X, area.Y,
area.X, area.Y,
area.Width, area.Height);
args.RetVal = false;
}
// Create a new pixmap of the appropriate size to store our scribbles
private void ScribbleConfigure (object o, ConfigureEventArgs args)
{
EventConfigure eventConfigure = args.Event;
Gdk.Window window = eventConfigure.Window;
Rectangle allocation = drawingArea1.Allocation;
pixmap = new Pixmap (window,
allocation.Width,
allocation.Height,
-1);
// Initialize the pixmap to white
pixmap.DrawRectangle (drawingArea1.Style.WhiteGC, true, 0, 0,
allocation.Width, allocation.Height);
// We've handled the configure event, no need for further processing.
args.RetVal = true;
}
private void ScribbleMotionNotify (object o, MotionNotifyEventArgs args)
{
// This call is very important; it requests the next motion event.
// If you don't call Window.GetPointer() you'll only get
// a single motion event. The reason is that we specified
// PointerMotionHintMask in drawingArea1.Events.
// If we hadn't specified that, we could just use ExposeEvent.x, ExposeEvent.y
// as the pointer location. But we'd also get deluged in events.
// By requesting the next event as we handle the current one,
// we avoid getting a huge number of events faster than we
// can cope.
int x, y;
ModifierType state;
EventMotion ev = args.Event;
Gdk.Window window = ev.Window;
if (ev.IsHint) {
ModifierType s;
window.GetPointer (out x, out y, out s);
state = s;
} else {
x = (int) ev.X;
y = (int) ev.Y;
state = (ModifierType) ev.State;
}
if ((state & ModifierType.Button1Mask) != 0 && pixmap != null)
DrawBrush (x, y);
/* We've handled it, stop processing */
args.RetVal = true;
}
// Draw a rectangle on the screen
static void DrawBrush (double x, double y)
{
Rectangle update_rect = new Rectangle ();
update_rect.X = (int) x - 3;
update_rect.Y = (int) y - 3;
update_rect.Width = 6;
update_rect.Height = 6;
//Paint to the pixmap, where we store our state
pixmap.DrawRectangle (drawingArea1.Style.BlackGC, true,
update_rect.X, update_rect.Y,
update_rect.Width, update_rect.Height);
drawingArea1.QueueDrawArea (update_rect.X, update_rect.Y,
update_rect.Width, update_rect.Height);
}
private void ScribbleButtonPress (object o, ButtonPressEventArgs args)
{
EventButton ev = args.Event;
if (ev.Button == 1 && pixmap != null)
DrawBrush (ev.X, ev.Y);
//We've handled the event, stop processing
args.RetVal = true;
}
}
}