227 lines
6.6 KiB
Ruby
227 lines
6.6 KiB
Ruby
|
# Copyright (c) 2003-2005 Ruby-GNOME2 Project Team
|
||
|
|
# This program is licenced under the same licence as Ruby-GNOME2.
|
||
|
|
#
|
||
|
|
# $Id: drawingarea.rb,v 1.5 2005/02/12 23:02:43 kzys Exp $
|
||
|
|
=begin
|
||
|
|
= Drawing Area
|
||
|
|
|
||
|
|
Gtk::DrawingArea 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 expose_event, 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.
|
||
|
|
=end
|
||
|
|
|
||
|
|
require 'common'
|
||
|
|
|
||
|
|
module Demo
|
||
|
|
class DrawingArea < BasicWindow
|
||
|
|
def initialize
|
||
|
|
# Pixmap for scribble area, to store current scribbles
|
||
|
|
@pixmap = nil
|
||
|
|
super('Drawing Area')
|
||
|
|
|
||
|
|
self.border_width = 8
|
||
|
|
|
||
|
|
vbox = Gtk::VBox.new(false, 8)
|
||
|
|
vbox.border_width = 8
|
||
|
|
add(vbox)
|
||
|
|
|
||
|
|
|
||
|
|
## Create the checkerboard area
|
||
|
|
label = Gtk::Label.new
|
||
|
|
label.set_markup('<u>Checkerboard pattern</u>')
|
||
|
|
vbox.pack_start(label, false, false, 0)
|
||
|
|
|
||
|
|
frame = Gtk::Frame.new
|
||
|
|
frame.shadow_type = Gtk::SHADOW_IN
|
||
|
|
vbox.pack_start(frame, true, true, 0)
|
||
|
|
|
||
|
|
da = Gtk::DrawingArea.new
|
||
|
|
# set a minimum size
|
||
|
|
da.set_size_request(100, 100)
|
||
|
|
|
||
|
|
frame.add(da)
|
||
|
|
|
||
|
|
da.signal_connect('expose_event') do |widget, event|
|
||
|
|
checkerboard_expose(widget)
|
||
|
|
end
|
||
|
|
|
||
|
|
## Create the scribble area
|
||
|
|
label = Gtk::Label.new
|
||
|
|
label.set_markup('<u>Scribble area</u>')
|
||
|
|
vbox.pack_start(label, false, false, 0)
|
||
|
|
|
||
|
|
frame = Gtk::Frame.new
|
||
|
|
frame.shadow_type = Gtk::SHADOW_IN
|
||
|
|
vbox.pack_start(frame, true, true, 0)
|
||
|
|
|
||
|
|
da = Gtk::DrawingArea.new
|
||
|
|
# set a minimum size
|
||
|
|
da.set_size_request(100, 100)
|
||
|
|
|
||
|
|
frame.add(da)
|
||
|
|
|
||
|
|
# Signals used to handle backing pixmap
|
||
|
|
da.signal_connect('expose_event') do |*args|
|
||
|
|
scribble_expose_event(*args)
|
||
|
|
end
|
||
|
|
da.signal_connect('configure_event') do |widget, event|
|
||
|
|
scribble_configure_event(widget)
|
||
|
|
end
|
||
|
|
|
||
|
|
# Event signals
|
||
|
|
da.signal_connect('motion_notify_event') do |*args|
|
||
|
|
scribble_motion_notify_event(*args)
|
||
|
|
end
|
||
|
|
da.signal_connect('button_press_event') do |*args|
|
||
|
|
scribble_button_press_event(*args)
|
||
|
|
end
|
||
|
|
|
||
|
|
# Ask to receive events the drawing area doesn't normally
|
||
|
|
# subscribe to
|
||
|
|
da.events |= (Gdk::Event::LEAVE_NOTIFY_MASK |
|
||
|
|
Gdk::Event::BUTTON_PRESS_MASK |
|
||
|
|
Gdk::Event::POINTER_MOTION_MASK |
|
||
|
|
Gdk::Event::POINTER_MOTION_HINT_MASK)
|
||
|
|
end
|
||
|
|
|
||
|
|
# Create a new pixmap of the appropriate size to store our scribbles
|
||
|
|
def scribble_configure_event(widget)
|
||
|
|
@pixmap = Gdk::Pixmap.new(self.window,
|
||
|
|
widget.allocation.width,
|
||
|
|
widget.allocation.height,
|
||
|
|
-1)
|
||
|
|
|
||
|
|
# Initialize the pixmap to white
|
||
|
|
@pixmap.draw_rectangle(widget.style.white_gc,
|
||
|
|
true,
|
||
|
|
0, 0,
|
||
|
|
widget.allocation.width,
|
||
|
|
widget.allocation.height)
|
||
|
|
|
||
|
|
# We've handled the configure event, no need for further processing.
|
||
|
|
return true
|
||
|
|
end
|
||
|
|
|
||
|
|
CHECK_SIZE = 10
|
||
|
|
SPACING = 2
|
||
|
|
def checkerboard_expose(da)
|
||
|
|
# At the start of an expose handler, a clip region of event.area
|
||
|
|
# is set on the window, and event.area has been cleared to the
|
||
|
|
# widget's background color. The docs for
|
||
|
|
# gdk_window_begin_paint_region give more details on how this
|
||
|
|
# works.
|
||
|
|
|
||
|
|
|
||
|
|
# It would be a bit more efficient to keep these
|
||
|
|
# GC's around instead of recreating on each expose, but
|
||
|
|
# this is the lazy/slow way.
|
||
|
|
gc1 = Gdk::GC.new(da.window)
|
||
|
|
gc1.rgb_fg_color = Gdk::Color.new(30000, 0, 30000)
|
||
|
|
|
||
|
|
gc2 = Gdk::GC.new(da.window)
|
||
|
|
gc2.rgb_fg_color = Gdk::Color.new(65535, 65535, 65535)
|
||
|
|
|
||
|
|
xcount = 0
|
||
|
|
SPACING.step(da.allocation.width, CHECK_SIZE + SPACING) do |i|
|
||
|
|
ycount = xcount % 2; # start with even/odd depending on row
|
||
|
|
SPACING.step(da.allocation.height, CHECK_SIZE + SPACING) do |j|
|
||
|
|
gc = if ycount % 2 == 1
|
||
|
|
gc1
|
||
|
|
else
|
||
|
|
gc2
|
||
|
|
end
|
||
|
|
|
||
|
|
# If we're outside event.area, this will do nothing.
|
||
|
|
# It might be mildly more efficient if we handled
|
||
|
|
# the clipping ourselves, but again we're feeling lazy.
|
||
|
|
|
||
|
|
da.window.draw_rectangle(gc, true, i, j, CHECK_SIZE, CHECK_SIZE)
|
||
|
|
ycount += 1
|
||
|
|
end
|
||
|
|
xcount += 1
|
||
|
|
end
|
||
|
|
# return true because we've handled this event, so no
|
||
|
|
# further processing is required.
|
||
|
|
#
|
||
|
|
return true
|
||
|
|
end
|
||
|
|
|
||
|
|
# Redraw the screen from the pixmap
|
||
|
|
def scribble_expose_event(widget, event)
|
||
|
|
# We use the 'foreground GC' 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.
|
||
|
|
widget.window.draw_drawable(widget.style.fg_gc(widget.state),
|
||
|
|
@pixmap,
|
||
|
|
# Only copy the area that was exposed.
|
||
|
|
event.area.x, event.area.y,
|
||
|
|
event.area.x, event.area.y,
|
||
|
|
event.area.width, event.area.height)
|
||
|
|
return false
|
||
|
|
end
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
def draw_brush(widget, x, y)
|
||
|
|
update_rect = Gdk::Rectangle.new(x - 3, y - 3, 6, 6)
|
||
|
|
|
||
|
|
# Paint to the pixmap, where we store our state
|
||
|
|
@pixmap.draw_rectangle(widget.style.black_gc,
|
||
|
|
true,
|
||
|
|
update_rect.x, update_rect.y,
|
||
|
|
update_rect.width, update_rect.height)
|
||
|
|
|
||
|
|
# Now invalidate the affected region of the drawing area.
|
||
|
|
widget.window.invalidate(update_rect, false)
|
||
|
|
end
|
||
|
|
|
||
|
|
def scribble_button_press_event(widget, event)
|
||
|
|
unless @pixmap
|
||
|
|
# paranoia check, in case we haven't gotten a configure event
|
||
|
|
return false
|
||
|
|
end
|
||
|
|
|
||
|
|
if event.button == 1
|
||
|
|
draw_brush(widget, event.x, event.y)
|
||
|
|
end
|
||
|
|
|
||
|
|
# We've handled the event, stop processing
|
||
|
|
return true
|
||
|
|
end
|
||
|
|
|
||
|
|
def scribble_motion_notify_event(widget, event)
|
||
|
|
unless @pixmap
|
||
|
|
# paranoia check, in case we haven't gotten a configure event
|
||
|
|
return false
|
||
|
|
end
|
||
|
|
|
||
|
|
# This call is very important; it requests the next motion event.
|
||
|
|
# If you don't call Gdk::Window#pointer you'll only get
|
||
|
|
# a single motion event. The reason is that we specified
|
||
|
|
# Gdk::POINTER_MOTION_HINT_MASK to Gtk::Widget#set_events.
|
||
|
|
# If we hadn't specified that, we could just use event.x, event.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.
|
||
|
|
|
||
|
|
win, x, y, state = event.window.pointer
|
||
|
|
|
||
|
|
if (state & Gdk::Window::BUTTON1_MASK) != 0
|
||
|
|
draw_brush(widget, x, y)
|
||
|
|
end
|
||
|
|
|
||
|
|
# We've handled it, stop processing
|
||
|
|
return true
|
||
|
|
end
|
||
|
|
end
|
||
|
|
end
|