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<html>
<head>
<meta name="description" content="Pmw - a toolkit for building high-level compound widgets in Python">
<meta name="content" content="python, megawidget, mega widget, compound widget, gui, tkinter">
<title>Pmw.ScrolledCanvas reference manual</title>
</head>
<body bgcolor="#ffffff" text="#000000" link="#0000ee"
vlink="551a8b" alink="ff0000">
<h1 ALIGN="CENTER">Pmw.ScrolledCanvas</h1>
<center><IMG SRC=ScrolledCanvas.gif ALT="" WIDTH=382 HEIGHT=240></center>
<dl>
<dt> <h3>Name</h3></dt><dd>
<p>Pmw.ScrolledCanvas() -
canvas with optional scrollbars
</p>
</dd>
<dt> <h3>Inherits</h3></dt><dd>
<a href="MegaWidget.html">Pmw.MegaWidget</a><br>
</dd>
<dt> <h3>Description</h3></dt><dd>
<p>
A scrolled canvas consists of a standard canvas widget with optional
scrollbars which can be used to scroll the canvas. The scrollbars
can be <em>dynamic</em>, which means that a scrollbar will only be
displayed if it is necessary, that is, if the scrollregion of the
canvas is larger than the canvas.</p>
<p></p>
</dd>
<dt> <h3>Options</h3></dt><dd>
Options for this megawidget and its base
classes are described below.<p></p>
<a name=option.borderframe></a>
<dl><dt> <strong>borderframe
</strong></dt><dd>
Initialisation option. If true, the <strong>borderframe</strong> component will be created. The default is <strong>0</strong>.</p>
</dd></dl>
<a name=option.canvasmargin></a>
<dl><dt> <strong>canvasmargin
</strong></dt><dd>
Initialisation option. The margin around the items in the canvas. Used by the
<strong>resizescrollregion()</strong> method. The default is <strong>0</strong>.</p>
</dd></dl>
<a name=option.hscrollmode></a>
<dl><dt> <strong>hscrollmode
</strong></dt><dd>
The horizontal scroll mode. If <strong>'none'</strong>, the horizontal scrollbar
will never be displayed. If <strong>'static'</strong>, the scrollbar will always
be displayed. If <strong>'dynamic'</strong>, the scrollbar will be displayed
only if necessary. The default is <strong>'dynamic'</strong>.</p>
</dd></dl>
<a name=option.labelmargin></a>
<dl><dt> <strong>labelmargin
</strong></dt><dd>
Initialisation option. If the <strong>labelpos</strong> option is not <strong>None</strong>, this specifies the
distance between the <strong>label</strong> component and the rest of the
megawidget. The default is <strong>0</strong>.</p>
</dd></dl>
<a name=option.labelpos></a>
<dl><dt> <strong>labelpos
</strong></dt><dd>
Initialisation option. Specifies where to place the <strong>label</strong> component. If not
<strong>None</strong>, it should be a concatenation of one or two of the
letters <strong>'n'</strong>, <strong>'s'</strong>, <strong>'e'</strong> and <strong>'w'</strong>. The first letter
specifies on which side of the megawidget to place the label.
If a second letter is specified, it indicates where on that
side to place the label. For example, if <strong>labelpos</strong> is <strong>'w'</strong>,
the label is placed in the center of the left hand side; if
it is <strong>'wn'</strong>, the label is placed at the top of the left
hand side; if it is <strong>'ws'</strong>, the label is placed at the
bottom of the left hand side.</p>
<p> If <strong>None</strong>, a label component is not created. The default is <strong>None</strong>.</p>
</dd></dl>
<a name=option.scrollmargin></a>
<dl><dt> <strong>scrollmargin
</strong></dt><dd>
Initialisation option. The distance between the scrollbars and the enclosing canvas
widget. The default is <strong>2</strong>.</p>
</dd></dl>
<a name=option.usehullsize></a>
<dl><dt> <strong>usehullsize
</strong></dt><dd>
Initialisation option. If true, the size of the megawidget is determined solely by the
width and height options of the <strong>hull</strong> component.</p>
<p> Otherwise, the size of the megawidget is determined by the width
and height of the <strong>canvas</strong> component, along with the size and/or
existence of the other components, such as the label, the
scrollbars and the scrollmargin option. All these affect the
overall size of the megawidget. The default is <strong>0</strong>.</p>
</dd></dl>
<a name=option.vscrollmode></a>
<dl><dt> <strong>vscrollmode
</strong></dt><dd>
The vertical scroll mode. If <strong>'none'</strong>, the vertical scrollbar
will never be displayed. If <strong>'static'</strong>, the scrollbar will always
be displayed. If <strong>'dynamic'</strong>, the scrollbar will be displayed
only if necessary. The default is <strong>'dynamic'</strong>.</p>
</dd></dl>
</dd>
<dt> <h3>Components</h3></dt><dd>
Components created by this megawidget and its base
classes are described below.<p></p>
<a name=component.borderframe></a>
<dl><dt> <strong>borderframe
</strong></dt><dd>
A frame widget which snuggly fits around the canvas, to give the
appearance of a canvas border. It is created with a border so
that the canvas, which is created without a border, looks like it
has a border. By default, this component is a Tkinter.Frame.</p>
</dd></dl>
<a name=component.canvas></a>
<dl><dt> <strong>canvas
</strong></dt><dd>
The canvas widget which is scrolled by the scrollbars. If the
<strong>borderframe</strong> option is true, this is created with a borderwidth
of <strong>0</strong> to overcome a known problem with canvas widgets: if a
widget inside a canvas extends across one of the edges of the
canvas, then the widget obscures the border of the canvas.
Therefore, if the canvas has no border, then this overlapping does
not occur. By default, this component is a Tkinter.Canvas.</p>
</dd></dl>
<a name=component.horizscrollbar></a>
<dl><dt> <strong>horizscrollbar
</strong></dt><dd>
The horizontal scrollbar. By default, this component is a Tkinter.Scrollbar. Its component group is <strong>Scrollbar</strong>.</p>
</dd></dl>
<a name=component.hull></a>
<dl><dt> <strong>hull
</strong></dt><dd>
This acts as the body for the entire megawidget. Other components
are created as children of the hull to further specialise this
class. By default, this component is a Tkinter.Frame.</p>
</dd></dl>
<a name=component.label></a>
<dl><dt> <strong>label
</strong></dt><dd>
If the <strong>labelpos</strong> option is not <strong>None</strong>, this component is
created as a text label for the megawidget. See the
<strong>labelpos</strong> option for details. Note that to set, for example,
the <strong>text</strong> option of the label, you need to use the <strong>label_text</strong>
component option. By default, this component is a Tkinter.Label.</p>
</dd></dl>
<a name=component.vertscrollbar></a>
<dl><dt> <strong>vertscrollbar
</strong></dt><dd>
The vertical scrollbar. By default, this component is a Tkinter.Scrollbar. Its component group is <strong>Scrollbar</strong>.</p>
</dd></dl>
</dd>
<a name=methods></a>
<dt> <h3>Methods</h3></dt><dd>
Only methods specific to this megawidget are described below.
For a description of its inherited methods, see the
manual for its base class
<strong><a href="MegaWidget.html#methods">Pmw.MegaWidget</a></strong>.
In addition, methods from the
<strong>Tkinter.Canvas</strong> class
are forwarded by this megawidget to the
<strong>canvas</strong> component.
<p></p>
<a name=method.bbox></a>
<dl><dt> <strong>bbox</strong>(*<em>args</em>)</dt><dd>
This method is explicitly forwarded to the <strong>canvas</strong> component's
<code>bbox()</code> method. Without this explicit forwarding, the <code>bbox()</code>
method (aliased to <code>grid_bbox()</code>) of the <strong>hull</strong> would be invoked,
which is probably not what the programmer intended.</p>
</dd></dl>
<a name=method.interior></a>
<dl><dt> <strong>interior</strong>()</dt><dd>
Return the canvas widget within which the programmer should create
graphical items and child widgets. This is the same as
<code>component('canvas')</code>.</p>
</dd></dl>
<a name=method.resizescrollregion></a>
<dl><dt> <strong>resizescrollregion</strong>()</dt><dd>
Resize the scrollregion of the <strong>canvas</strong> component to be the
bounding box covering all the items in the canvas plus a margin on
all sides, as specified by the <strong>canvasmargin</strong> option.</p>
</dd></dl>
</dd>
<dt> <h3>Example</h3></dt><dd>
The image at the top of this manual is a snapshot
of the window (or part of the window) produced
by the following code.<p></p>
<pre>
class Demo:
def __init__(self, parent):
# Create the ScrolledCanvas.
self.sc = Pmw.ScrolledCanvas(parent,
borderframe = 1,
labelpos = 'n',
label_text = 'ScrolledCanvas',
usehullsize = 1,
hull_width = 400,
hull_height = 300,
)
# Create a group widget to contain the scrollmode options.
w = Pmw.Group(parent, tag_text='Scroll mode')
w.pack(side = 'bottom', padx = 5, pady = 5)
hmode = Pmw.OptionMenu(w.interior(),
labelpos = 'w',
label_text = 'Horizontal:',
items = ['none', 'static', 'dynamic'],
command = self.sethscrollmode,
menubutton_width = 8,
)
hmode.pack(side = 'left', padx = 5, pady = 5)
hmode.invoke('dynamic')
vmode = Pmw.OptionMenu(w.interior(),
labelpos = 'w',
label_text = 'Vertical:',
items = ['none', 'static', 'dynamic'],
command = self.setvscrollmode,
menubutton_width = 8,
)
vmode.pack(side = 'left', padx = 5, pady = 5)
vmode.invoke('dynamic')
buttonBox = Pmw.ButtonBox(parent)
buttonBox.pack(side = 'bottom')
buttonBox.add('yview', text = 'Show\nyview', command = self.showYView)
buttonBox.add('scroll', text = 'Page\ndown', command = self.pageDown)
buttonBox.add('center', text = 'Center', command = self.centerPage)
# Pack this last so that the buttons do not get shrunk when
# the window is resized.
self.sc.pack(padx = 5, pady = 5, fill = 'both', expand = 1)
self.sc.component('canvas').bind('<1>', self.addcircle)
testEntry = Tkinter.Entry(parent)
self.sc.create_line(20, 20, 100, 100)
self.sc.create_oval(100, 100, 200, 200, fill = 'green')
self.sc.create_text(100, 20, anchor = 'nw',
text = 'Click in the canvas\nto draw ovals',
font = testEntry.cget('font'))
button = Tkinter.Button(self.sc.interior(),
text = 'Hello,\nWorld!\nThis\nis\na\nbutton.')
self.sc.create_window(200, 200,
anchor='nw',
window = button)
# Set the scroll region of the canvas to include all the items
# just created.
self.sc.resizescrollregion()
self.colours = ('red', 'green', 'blue', 'yellow', 'cyan', 'magenta',
'black', 'white')
self.oval_count = 0
self.rand = 12345
def sethscrollmode(self, tag):
self.sc.configure(hscrollmode = tag)
def setvscrollmode(self, tag):
self.sc.configure(vscrollmode = tag)
def addcircle(self, event):
x = self.sc.canvasx(event.x)
y = self.sc.canvasy(event.y)
width = 10 + self.random() % 100
height = 10 + self.random() % 100
self.sc.create_oval(
x - width, y - height, x + width, y + height,
fill = self.colours[self.oval_count])
self.oval_count = (self.oval_count + 1) % len(self.colours)
self.sc.resizescrollregion()
# Simple random number generator.
def random(self):
self.rand = (self.rand * 125) % 2796203
return self.rand
def showYView(self):
print self.sc.yview()
def pageDown(self):
self.sc.yview('scroll', 1, 'page')
def centerPage(self):
top, bottom = self.sc.yview()
size = bottom - top
middle = 0.5 - size / 2
self.sc.yview('moveto', middle)
</pre>
</dd>
</dl>
<center><P ALIGN="CENTER">
<IMG SRC = blue_line.gif ALT = "" WIDTH=320 HEIGHT=5>
</p></center>
<font size=-1>
<center><P ALIGN="CENTER">
Pmw 1.2 -
5 Aug 2003
- <a href="index.html">Home</a>
<br>Manual page last reviewed: 20 September 1998
</p></center>
</font>
</body>
</html>
|
