| 1 | |
| 2 | <html> |
| 3 | <head> |
| 4 | <meta name="description" content="Pmw - a toolkit for building high-level compound widgets in Python"> |
| 5 | <meta name="content" content="python, megawidget, mega widget, compound widget, gui, tkinter"> |
| 6 | <title>Pmw.ScrolledCanvas reference manual</title> |
| 7 | </head> |
| 8 | |
| 9 | <body bgcolor="#ffffff" text="#000000" link="#0000ee" |
| 10 | vlink="551a8b" alink="ff0000"> |
| 11 | |
| 12 | <h1 ALIGN="CENTER">Pmw.ScrolledCanvas</h1> |
| 13 | |
| 14 | <center><IMG SRC=ScrolledCanvas.gif ALT="" WIDTH=382 HEIGHT=240></center> |
| 15 | <dl> |
| 16 | <dt> <h3>Name</h3></dt><dd> |
| 17 | <p>Pmw.ScrolledCanvas() - |
| 18 | canvas with optional scrollbars |
| 19 | </p> |
| 20 | |
| 21 | |
| 22 | </dd> |
| 23 | <dt> <h3>Inherits</h3></dt><dd> |
| 24 | <a href="MegaWidget.html">Pmw.MegaWidget</a><br> |
| 25 | </dd> |
| 26 | <dt> <h3>Description</h3></dt><dd> |
| 27 | <p> |
| 28 | A scrolled canvas consists of a standard canvas widget with optional |
| 29 | scrollbars which can be used to scroll the canvas. The scrollbars |
| 30 | can be <em>dynamic</em>, which means that a scrollbar will only be |
| 31 | displayed if it is necessary, that is, if the scrollregion of the |
| 32 | canvas is larger than the canvas.</p> |
| 33 | |
| 34 | <p></p> |
| 35 | |
| 36 | |
| 37 | </dd> |
| 38 | <dt> <h3>Options</h3></dt><dd> |
| 39 | Options for this megawidget and its base |
| 40 | classes are described below.<p></p> |
| 41 | <a name=option.borderframe></a> |
| 42 | <dl><dt> <strong>borderframe |
| 43 | </strong></dt><dd> |
| 44 | Initialisation option. If true, the <strong>borderframe</strong> component will be created. The default is <strong>0</strong>.</p> |
| 45 | |
| 46 | |
| 47 | </dd></dl> |
| 48 | <a name=option.canvasmargin></a> |
| 49 | <dl><dt> <strong>canvasmargin |
| 50 | </strong></dt><dd> |
| 51 | Initialisation option. The margin around the items in the canvas. Used by the |
| 52 | <strong>resizescrollregion()</strong> method. The default is <strong>0</strong>.</p> |
| 53 | |
| 54 | |
| 55 | </dd></dl> |
| 56 | <a name=option.hscrollmode></a> |
| 57 | <dl><dt> <strong>hscrollmode |
| 58 | </strong></dt><dd> |
| 59 | The horizontal scroll mode. If <strong>'none'</strong>, the horizontal scrollbar |
| 60 | will never be displayed. If <strong>'static'</strong>, the scrollbar will always |
| 61 | be displayed. If <strong>'dynamic'</strong>, the scrollbar will be displayed |
| 62 | only if necessary. The default is <strong>'dynamic'</strong>.</p> |
| 63 | |
| 64 | |
| 65 | </dd></dl> |
| 66 | <a name=option.labelmargin></a> |
| 67 | <dl><dt> <strong>labelmargin |
| 68 | </strong></dt><dd> |
| 69 | Initialisation option. If the <strong>labelpos</strong> option is not <strong>None</strong>, this specifies the |
| 70 | distance between the <strong>label</strong> component and the rest of the |
| 71 | megawidget. The default is <strong>0</strong>.</p> |
| 72 | |
| 73 | |
| 74 | </dd></dl> |
| 75 | <a name=option.labelpos></a> |
| 76 | <dl><dt> <strong>labelpos |
| 77 | </strong></dt><dd> |
| 78 | Initialisation option. Specifies where to place the <strong>label</strong> component. If not |
| 79 | <strong>None</strong>, it should be a concatenation of one or two of the |
| 80 | letters <strong>'n'</strong>, <strong>'s'</strong>, <strong>'e'</strong> and <strong>'w'</strong>. The first letter |
| 81 | specifies on which side of the megawidget to place the label. |
| 82 | If a second letter is specified, it indicates where on that |
| 83 | side to place the label. For example, if <strong>labelpos</strong> is <strong>'w'</strong>, |
| 84 | the label is placed in the center of the left hand side; if |
| 85 | it is <strong>'wn'</strong>, the label is placed at the top of the left |
| 86 | hand side; if it is <strong>'ws'</strong>, the label is placed at the |
| 87 | bottom of the left hand side.</p> |
| 88 | <p> If <strong>None</strong>, a label component is not created. The default is <strong>None</strong>.</p> |
| 89 | |
| 90 | |
| 91 | |
| 92 | </dd></dl> |
| 93 | <a name=option.scrollmargin></a> |
| 94 | <dl><dt> <strong>scrollmargin |
| 95 | </strong></dt><dd> |
| 96 | Initialisation option. The distance between the scrollbars and the enclosing canvas |
| 97 | widget. The default is <strong>2</strong>.</p> |
| 98 | |
| 99 | |
| 100 | </dd></dl> |
| 101 | <a name=option.usehullsize></a> |
| 102 | <dl><dt> <strong>usehullsize |
| 103 | </strong></dt><dd> |
| 104 | Initialisation option. If true, the size of the megawidget is determined solely by the |
| 105 | width and height options of the <strong>hull</strong> component.</p> |
| 106 | <p> Otherwise, the size of the megawidget is determined by the width |
| 107 | and height of the <strong>canvas</strong> component, along with the size and/or |
| 108 | existence of the other components, such as the label, the |
| 109 | scrollbars and the scrollmargin option. All these affect the |
| 110 | overall size of the megawidget. The default is <strong>0</strong>.</p> |
| 111 | |
| 112 | |
| 113 | |
| 114 | </dd></dl> |
| 115 | <a name=option.vscrollmode></a> |
| 116 | <dl><dt> <strong>vscrollmode |
| 117 | </strong></dt><dd> |
| 118 | The vertical scroll mode. If <strong>'none'</strong>, the vertical scrollbar |
| 119 | will never be displayed. If <strong>'static'</strong>, the scrollbar will always |
| 120 | be displayed. If <strong>'dynamic'</strong>, the scrollbar will be displayed |
| 121 | only if necessary. The default is <strong>'dynamic'</strong>.</p> |
| 122 | |
| 123 | |
| 124 | </dd></dl> |
| 125 | </dd> |
| 126 | <dt> <h3>Components</h3></dt><dd> |
| 127 | Components created by this megawidget and its base |
| 128 | classes are described below.<p></p> |
| 129 | <a name=component.borderframe></a> |
| 130 | <dl><dt> <strong>borderframe |
| 131 | </strong></dt><dd> |
| 132 | A frame widget which snuggly fits around the canvas, to give the |
| 133 | appearance of a canvas border. It is created with a border so |
| 134 | that the canvas, which is created without a border, looks like it |
| 135 | has a border. By default, this component is a Tkinter.Frame.</p> |
| 136 | |
| 137 | |
| 138 | </dd></dl> |
| 139 | <a name=component.canvas></a> |
| 140 | <dl><dt> <strong>canvas |
| 141 | </strong></dt><dd> |
| 142 | The canvas widget which is scrolled by the scrollbars. If the |
| 143 | <strong>borderframe</strong> option is true, this is created with a borderwidth |
| 144 | of <strong>0</strong> to overcome a known problem with canvas widgets: if a |
| 145 | widget inside a canvas extends across one of the edges of the |
| 146 | canvas, then the widget obscures the border of the canvas. |
| 147 | Therefore, if the canvas has no border, then this overlapping does |
| 148 | not occur. By default, this component is a Tkinter.Canvas.</p> |
| 149 | |
| 150 | |
| 151 | </dd></dl> |
| 152 | <a name=component.horizscrollbar></a> |
| 153 | <dl><dt> <strong>horizscrollbar |
| 154 | </strong></dt><dd> |
| 155 | The horizontal scrollbar. By default, this component is a Tkinter.Scrollbar. Its component group is <strong>Scrollbar</strong>.</p> |
| 156 | |
| 157 | |
| 158 | </dd></dl> |
| 159 | <a name=component.hull></a> |
| 160 | <dl><dt> <strong>hull |
| 161 | </strong></dt><dd> |
| 162 | This acts as the body for the entire megawidget. Other components |
| 163 | are created as children of the hull to further specialise this |
| 164 | class. By default, this component is a Tkinter.Frame.</p> |
| 165 | |
| 166 | |
| 167 | </dd></dl> |
| 168 | <a name=component.label></a> |
| 169 | <dl><dt> <strong>label |
| 170 | </strong></dt><dd> |
| 171 | If the <strong>labelpos</strong> option is not <strong>None</strong>, this component is |
| 172 | created as a text label for the megawidget. See the |
| 173 | <strong>labelpos</strong> option for details. Note that to set, for example, |
| 174 | the <strong>text</strong> option of the label, you need to use the <strong>label_text</strong> |
| 175 | component option. By default, this component is a Tkinter.Label.</p> |
| 176 | |
| 177 | |
| 178 | </dd></dl> |
| 179 | <a name=component.vertscrollbar></a> |
| 180 | <dl><dt> <strong>vertscrollbar |
| 181 | </strong></dt><dd> |
| 182 | The vertical scrollbar. By default, this component is a Tkinter.Scrollbar. Its component group is <strong>Scrollbar</strong>.</p> |
| 183 | |
| 184 | |
| 185 | </dd></dl> |
| 186 | </dd> |
| 187 | <a name=methods></a> |
| 188 | <dt> <h3>Methods</h3></dt><dd> |
| 189 | Only methods specific to this megawidget are described below. |
| 190 | For a description of its inherited methods, see the |
| 191 | manual for its base class |
| 192 | <strong><a href="MegaWidget.html#methods">Pmw.MegaWidget</a></strong>. |
| 193 | In addition, methods from the |
| 194 | <strong>Tkinter.Canvas</strong> class |
| 195 | are forwarded by this megawidget to the |
| 196 | <strong>canvas</strong> component. |
| 197 | <p></p> |
| 198 | <a name=method.bbox></a> |
| 199 | <dl><dt> <strong>bbox</strong>(*<em>args</em>)</dt><dd> |
| 200 | This method is explicitly forwarded to the <strong>canvas</strong> component's |
| 201 | <code>bbox()</code> method. Without this explicit forwarding, the <code>bbox()</code> |
| 202 | method (aliased to <code>grid_bbox()</code>) of the <strong>hull</strong> would be invoked, |
| 203 | which is probably not what the programmer intended.</p> |
| 204 | |
| 205 | |
| 206 | </dd></dl> |
| 207 | <a name=method.interior></a> |
| 208 | <dl><dt> <strong>interior</strong>()</dt><dd> |
| 209 | Return the canvas widget within which the programmer should create |
| 210 | graphical items and child widgets. This is the same as |
| 211 | <code>component('canvas')</code>.</p> |
| 212 | |
| 213 | |
| 214 | </dd></dl> |
| 215 | <a name=method.resizescrollregion></a> |
| 216 | <dl><dt> <strong>resizescrollregion</strong>()</dt><dd> |
| 217 | Resize the scrollregion of the <strong>canvas</strong> component to be the |
| 218 | bounding box covering all the items in the canvas plus a margin on |
| 219 | all sides, as specified by the <strong>canvasmargin</strong> option.</p> |
| 220 | |
| 221 | |
| 222 | </dd></dl> |
| 223 | </dd> |
| 224 | <dt> <h3>Example</h3></dt><dd> |
| 225 | The image at the top of this manual is a snapshot |
| 226 | of the window (or part of the window) produced |
| 227 | by the following code.<p></p> |
| 228 | <pre> |
| 229 | class Demo: |
| 230 | def __init__(self, parent): |
| 231 | # Create the ScrolledCanvas. |
| 232 | self.sc = Pmw.ScrolledCanvas(parent, |
| 233 | borderframe = 1, |
| 234 | labelpos = 'n', |
| 235 | label_text = 'ScrolledCanvas', |
| 236 | usehullsize = 1, |
| 237 | hull_width = 400, |
| 238 | hull_height = 300, |
| 239 | ) |
| 240 | |
| 241 | # Create a group widget to contain the scrollmode options. |
| 242 | w = Pmw.Group(parent, tag_text='Scroll mode') |
| 243 | w.pack(side = 'bottom', padx = 5, pady = 5) |
| 244 | |
| 245 | hmode = Pmw.OptionMenu(w.interior(), |
| 246 | labelpos = 'w', |
| 247 | label_text = 'Horizontal:', |
| 248 | items = ['none', 'static', 'dynamic'], |
| 249 | command = self.sethscrollmode, |
| 250 | menubutton_width = 8, |
| 251 | ) |
| 252 | hmode.pack(side = 'left', padx = 5, pady = 5) |
| 253 | hmode.invoke('dynamic') |
| 254 | |
| 255 | vmode = Pmw.OptionMenu(w.interior(), |
| 256 | labelpos = 'w', |
| 257 | label_text = 'Vertical:', |
| 258 | items = ['none', 'static', 'dynamic'], |
| 259 | command = self.setvscrollmode, |
| 260 | menubutton_width = 8, |
| 261 | ) |
| 262 | vmode.pack(side = 'left', padx = 5, pady = 5) |
| 263 | vmode.invoke('dynamic') |
| 264 | |
| 265 | buttonBox = Pmw.ButtonBox(parent) |
| 266 | buttonBox.pack(side = 'bottom') |
| 267 | buttonBox.add('yview', text = 'Show\nyview', command = self.showYView) |
| 268 | buttonBox.add('scroll', text = 'Page\ndown', command = self.pageDown) |
| 269 | buttonBox.add('center', text = 'Center', command = self.centerPage) |
| 270 | |
| 271 | # Pack this last so that the buttons do not get shrunk when |
| 272 | # the window is resized. |
| 273 | self.sc.pack(padx = 5, pady = 5, fill = 'both', expand = 1) |
| 274 | |
| 275 | self.sc.component('canvas').bind('<1>', self.addcircle) |
| 276 | |
| 277 | testEntry = Tkinter.Entry(parent) |
| 278 | self.sc.create_line(20, 20, 100, 100) |
| 279 | self.sc.create_oval(100, 100, 200, 200, fill = 'green') |
| 280 | self.sc.create_text(100, 20, anchor = 'nw', |
| 281 | text = 'Click in the canvas\nto draw ovals', |
| 282 | font = testEntry.cget('font')) |
| 283 | button = Tkinter.Button(self.sc.interior(), |
| 284 | text = 'Hello,\nWorld!\nThis\nis\na\nbutton.') |
| 285 | self.sc.create_window(200, 200, |
| 286 | anchor='nw', |
| 287 | window = button) |
| 288 | |
| 289 | # Set the scroll region of the canvas to include all the items |
| 290 | # just created. |
| 291 | self.sc.resizescrollregion() |
| 292 | |
| 293 | self.colours = ('red', 'green', 'blue', 'yellow', 'cyan', 'magenta', |
| 294 | 'black', 'white') |
| 295 | self.oval_count = 0 |
| 296 | self.rand = 12345 |
| 297 | |
| 298 | def sethscrollmode(self, tag): |
| 299 | self.sc.configure(hscrollmode = tag) |
| 300 | |
| 301 | def setvscrollmode(self, tag): |
| 302 | self.sc.configure(vscrollmode = tag) |
| 303 | |
| 304 | def addcircle(self, event): |
| 305 | x = self.sc.canvasx(event.x) |
| 306 | y = self.sc.canvasy(event.y) |
| 307 | width = 10 + self.random() % 100 |
| 308 | height = 10 + self.random() % 100 |
| 309 | self.sc.create_oval( |
| 310 | x - width, y - height, x + width, y + height, |
| 311 | fill = self.colours[self.oval_count]) |
| 312 | self.oval_count = (self.oval_count + 1) % len(self.colours) |
| 313 | self.sc.resizescrollregion() |
| 314 | |
| 315 | # Simple random number generator. |
| 316 | def random(self): |
| 317 | self.rand = (self.rand * 125) % 2796203 |
| 318 | return self.rand |
| 319 | |
| 320 | def showYView(self): |
| 321 | print self.sc.yview() |
| 322 | |
| 323 | def pageDown(self): |
| 324 | self.sc.yview('scroll', 1, 'page') |
| 325 | |
| 326 | def centerPage(self): |
| 327 | top, bottom = self.sc.yview() |
| 328 | size = bottom - top |
| 329 | middle = 0.5 - size / 2 |
| 330 | self.sc.yview('moveto', middle) |
| 331 | |
| 332 | </pre> |
| 333 | </dd> |
| 334 | </dl> |
| 335 | |
| 336 | <center><P ALIGN="CENTER"> |
| 337 | <IMG SRC = blue_line.gif ALT = "" WIDTH=320 HEIGHT=5> |
| 338 | </p></center> |
| 339 | |
| 340 | |
| 341 | <font size=-1> |
| 342 | <center><P ALIGN="CENTER"> |
| 343 | Pmw 1.2 - |
| 344 | 5 Aug 2003 |
| 345 | - <a href="index.html">Home</a> |
| 346 | <br>Manual page last reviewed: 20 September 1998 |
| 347 | </p></center> |
| 348 | </font> |
| 349 | |
| 350 | </body> |
| 351 | </html> |
| 352 | |