wxPython/docs/MigrationGuide.html

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  11 <div class="document" id="wxpython-2-5-migration-guide">
  12 <h1 class="title">wxPython 2.5 Migration Guide</h1>
  13 <p>This document will help explain some of the major changes in wxPython
  14 2.5 and let you know what you need to do to adapt your programs to
  15 those changes.  Be sure to also check in the CHANGES.txt file like
  16 usual to see info about the not so major changes and other things that
  17 have been added to wxPython.</p>
  18 <div class="section" id="wxname-change">
  19 <h1><a name="wxname-change">wxName Change</a></h1>
  20 <p>The <strong>wxWindows</strong> project and library is now known as
  21 <strong>wxWidgets</strong>.  Please see <a class="reference" href="http://www.wxwindows.org/name.htm">here</a> for more details.</p>
  22 <p>This won't really affect wxPython all that much, other than the fact
  23 that the wxwindows.org domain name will be changing to wxwidgets.org,
  24 so mail list, CVS, and etc. addresses will be changing.  We're going
  25 to try and smooth the transition as much as possible, but I wanted you
  26 all to be aware of this change if you run into any issues.</p>
  27 </div>
  28 <div class="section" id="module-initialization">
  29 <h1><a name="module-initialization">Module Initialization</a></h1>
  30 <p>The import-startup-bootstrap process employed by wxPython was changed
  31 such that wxWidgets and the underlying gui toolkit are <strong>not</strong>
  32 initialized until the wx.App object is created (but before wx.App.OnInit
  33 is called.)  This was required because of some changes that were made
  34 to the C++ wxApp class.</p>
  35 <p>There are both benefits and potential problems with this change.  The
  36 benefits are that you can import wxPython without requiring access to
  37 a GUI (for checking version numbers, etc.) and that in a
  38 multi-threaded environment the thread that creates the app object will
  39 now be the GUI thread instead of the one that imports wxPython.  Some
  40 potential problems are that the C++ side of the &quot;stock-objects&quot;
  41 (wx.BLUE_PEN, wx.TheColourDatabase, etc.) are not initialized until
  42 the wx.App object is created, so you should not use them until after
  43 you have created your wx.App object.  If you do then an exception will
  44 be raised telling you that the C++ object has not been initialized
  45 yet.</p>
  46 <p>Also, you will probably not be able to do any kind of GUI or bitmap
  47 operation unless you first have created an app object, (even on
  48 Windows where most anything was possible before.)</p>
  49 </div>
  50 <div class="section" id="swig-1-3">
  51 <h1><a name="swig-1-3">SWIG 1.3</a></h1>
  52 <p>wxPython is now using SWIG 1.3.x from CVS (with several of my own
  53 customizations added that I hope to get folded back into the main SWIG
  54 distribution.)  This has some far reaching ramifications:</p>
  55 <blockquote>
  56 <p>All classes derive from object and so all are now &quot;new-style
  57 classes&quot;</p>
  58 <p>Public data members of the C++ classes are wrapped as Python
  59 properties using property() instead of using __getattr__/__setattr__
  60 like before.  Normally you shouldn't notice any difference, but if
  61 you were previously doing something with __getattr__/__setattr__
  62 in derived classes then you may have to adjust things.</p>
  63 <p>Static C++ methods are wrapped using the staticmethod()
  64 feature of Python and so are accessible as ClassName.MethodName
  65 as expected.  They are still available as top level functions
  66 ClassName_MethodName as before.</p>
  67 <p>The relationship between the wxFoo and wxFooPtr classes have
  68 changed for the better.  Specifically, all instances that you see
  69 will be wxFoo even if they are created internally using wxFooPtr,
  70 because wxFooPtr.__init__ will change the instance's __class__ as
  71 part of the initialization.  If you have any code that checks
  72 class type using something like isinstance(obj, wxFooPtr) you will
  73 need to change it to isinstance(obj, wxFoo).</p>
  74 </blockquote>
  75 </div>
  76 <div class="section" id="binding-events">
  77 <h1><a name="binding-events">Binding Events</a></h1>
  78 <p>All of the EVT_* functions are now instances of the wx.PyEventBinder
  79 class.  They have a __call__ method so they can still be used as
  80 functions like before, but making them instances adds some
  81 flexibility.</p>
  82 <p>wx.EvtHandler (the base class for wx.Window) now has a Bind method that
  83 makes binding events to windows a little easier.  Here is its
  84 definition and docstring:</p>
  85 <pre class="literal-block">
  86 def Bind(self, event, handler, source=None, id=wxID_ANY, id2=wxID_ANY):
  87     &quot;&quot;&quot;
  88     Bind an event to an event handler.
  89
  90       event     One of the EVT_* objects that specifies the
  91                 type of event to bind.
  92
  93       handler   A callable object to be invoked when the event
  94                 is delivered to self.  Pass None to disconnect an
  95                 event handler.
  96
  97       source    Sometimes the event originates from a different window
  98                 than self, but you still want to catch it in self.  (For
  99                 example, a button event delivered to a frame.)  By
 100                 passing the source of the event, the event handling
 101                 system is able to differentiate between the same event
 102                 type from different controls.
 103
 104       id,id2    Used for menu IDs or for event types that require a
 105                 range of IDs
 106
 107     &quot;&quot;&quot;
 108 </pre>
 109 <p>Some examples of its use:</p>
 110 <pre class="literal-block">
 111 self.Bind(wx.EVT_SIZE,   self.OnSize)
 112 self.Bind(wx.EVT_BUTTON, self.OnButtonClick, theButton)
 113 self.Bind(wx.EVT_MENU,   self.OnExit, id=wx.ID_EXIT)
 114 </pre>
 115 <p>The wx.Menu methods that add items to a wx.Menu have been modified
 116 such that they return a reference to the wx.MenuItem that was created.
 117 Additionally menu items and toolbar items have been modified to
 118 automatically generate a new ID if -1 is given, similar to using -1
 119 with window classess.  This means that you can create menu or toolbar
 120 items and event bindings without having to predefine a unique menu ID,
 121 although you still can use IDs just like before if you want.  For
 122 example, these are all equivallent other than their specific ID
 123 values:</p>
 124 <pre class="literal-block">
 125 1.
 126   item = menu.Append(-1, &quot;E&amp;xit&quot;, &quot;Terminate the App&quot;)
 127   self.Bind(wx.EVT_MENU, self.OnExit, item)
 128
 129 2.
 130   item = menu.Append(wx.ID_EXIT, &quot;E&amp;xit&quot;, &quot;Terminate the App&quot;)
 131   self.Bind(wx.EVT_MENU, self.OnExit, item)
 132
 133 3.
 134   menu.Append(wx.ID_EXIT, &quot;E&amp;xit&quot;, &quot;Terminate the App&quot;)
 135   self.Bind(wx.EVT_MENU, self.OnExit, id=wx.ID_EXIT)
 136 </pre>
 137 <p>If you create your own custom event types and EVT_* functions, and you
 138 want to be able to use them with the Bind method above then you should
 139 change your EVT_* to be an instance of wxPyEventBinder instead of a
 140 function.  If you used to have something like this:</p>
 141 <pre class="literal-block">
 142 myCustomEventType = wxNewEventType()
 143 def EVT_MY_CUSTOM_EVENT(win, id, func):
 144     win.Connect(id, -1, myCustomEventType, func)
 145 </pre>
 146 <p>Change it like so:</p>
 147 <pre class="literal-block">
 148 myCustomEventType = wx.NewEventType()
 149 EVT_MY_CUSTOM_EVENT = wx.PyEventBinder(myCustomEventType, 1)
 150 </pre>
 151 <p>The second parameter is an integer in [0, 1, 2] that specifies the
 152 number of IDs that are needed to be passed to Connect.</p>
 153 </div>
 154 <div class="section" id="the-wx-namespace">
 155 <h1><a name="the-wx-namespace">The wx Namespace</a></h1>
 156 <p>The second phase of the wx Namespace Transition has begun.  That means
 157 that the real names of the classes and other symbols do not have the
 158 'wx' prefix and the modules are located in a Python package named
 159 wx.  There is still a Python package named wxPython with modules
 160 that have the names with the wx prefix for backwards compatibility.
 161 Instead of dynamically changing the names at module load time like in
 162 2.4, the compatibility modules are generated at build time and contain
 163 assignment statements like this:</p>
 164 <pre class="literal-block">
 165 wxWindow = wx.core.Window
 166 </pre>
 167 <p>Don't let the &quot;core&quot; in the name bother you.  That and some other
 168 modules are implementation details, and everything that was in the
 169 wxPython.wx module before will still be in the wx package namespace
 170 after this change.  So from your code you would use it as wx.Window.</p>
 171 <p>A few notes about how all of this was accomplished might be
 172 interesting...  SWIG is now run twice for each module that it is
 173 generating code for.  The first time it outputs an XML representaion
 174 of the parse tree, which can be up to 20MB and 300K lines in size!
 175 That XML is then run through a little Python script that creates a
 176 file full of SWIG %rename directives that take the wx off of the
 177 names, and also generates the Python compatibility file described
 178 above that puts the wx back on the names.  SWIG is then run a second
 179 time to generate the C++ code to implement the extension module, and
 180 uses the %rename directives that were generated in the first step.</p>
 181 <p>Not every name is handled correctly (but the bulk of them are) and so
 182 some work has to be done by hand, especially for the reverse-renamers.
 183 So expect a few flaws here and there until everything gets sorted out.</p>
 184 <p>In summary, the wx package and names without the &quot;wx&quot; prefix are now
 185 the official form of the wxPython classes.  For example:</p>
 186 <pre class="literal-block">
 187 import wx
 188
 189 class MyFrame(wx.Frame):
 190     def __init__(self, parent, title):
 191         wx.Frame.__init__(self, parent, -1, title)
 192         p = wx.Panel(self, -1)
 193         b = wx.Button(p, -1, &quot;Do It&quot;, (10,10))
 194         self.Bind(wx.EVT_BUTTON, self.JustDoIt, b)
 195
 196     def JustDoIt(self, evt):
 197         print &quot;It's done!&quot;
 198
 199 app = wx.PySimpleApp()
 200 f = MyFrame(None, &quot;What's up?&quot;)
 201 f.Show()
 202 app.MainLoop()
 203 </pre>
 204 <p>You shouldn't need to migrate all your modules over to use the new
 205 package and names right away as there are modules in place that try to
 206 provide as much backwards compatibility of the names as possible.  If
 207 you rewrote the above sample using &quot;from wxPython.wx import * &quot;, the
 208 old wxNames, and the old style of event binding it will still work
 209 just fine.</p>
 210 </div>
 211 <div class="section" id="new-wx-dc-methods">
 212 <h1><a name="new-wx-dc-methods">New wx.DC Methods</a></h1>
 213 <p>Many of the Draw methods of wx.DC have alternate forms in C++ that take
 214 wxPoint or wxSize parameters (let's call these <em>Type A</em>) instead of
 215 the individual x, y, width, height, etc. parameters (and we'll call
 216 these <em>Type B</em>).  In the rest of the library I normally made the <em>Type
 217 A</em> forms of the methods be the default method with the &quot;normal&quot; name,
 218 and had renamed the <em>Type B</em> forms of the methods to some similar
 219 name.  For example in wx.Window we have these Python methods:</p>
 220 <pre class="literal-block">
 221 SetSize(size)               # Type A
 222 SetSizeWH(width, height)    # Type B
 223 </pre>
 224 <p>For various reasons the new <em>Type A</em> methods in wx.DC were never added
 225 and the existing <em>Type B</em> methods were never renamed.  Now that lots
 226 of other things are also changing in wxPython it has been decided that
 227 it is a good time to also do the method renaming in wx.DC too in order
 228 to be consistent with the rest of the library.  The methods in wx.DC
 229 that are affected are listed here:</p>
 230 <pre class="literal-block">
 231 FloodFillXY(x, y, colour, style = wx.FLOOD_SURFACE)
 232 FloodFill(point, colour,  style = wx.FLOOD_SURFACE)
 233
 234 GetPixelXY(x, y)
 235 GetPixel(point)
 236
 237 DrawLineXY(x1, y1, x2, y2)
 238 DrawLine(point1, point2)
 239
 240 CrossHairXY(x, y)
 241 CrossHair(point)
 242
 243 DrawArcXY(x1, y1, x2, y2, xc, yc)
 244 DrawArc(point1, point2, center)
 245
 246 DrawCheckMarkXY(x, y, width, height)
 247 DrawCheckMark(rect)
 248
 249 DrawEllipticArcXY(x, y, w, h, start_angle, end_angle)
 250 DrawEllipticArc(point, size, start_angle, end_angle)
 251
 252 DrawPointXY(x, y)
 253 DrawPoint(point)
 254
 255 DrawRectangleXY(x, y, width, height)
 256 DrawRectangle(point, size)
 257 DrawRectangleRect(rect)
 258
 259 DrawRoundedRectangleXY(x, y, width, height, radius)
 260 DrawRoundedRectangle(point, size, radius)
 261 DrawRoundedRectangleRect(rect, radius)
 262
 263 DrawCircleXY(x, y, radius)
 264 DrawCircle(point, radius)
 265
 266 DrawEllipseXY(x, y, width, height)
 267 DrawEllipse(point, size)
 268 DrawEllipseRect(rect)
 269
 270 DrawIconXY(icon, x, y)
 271 DrawIcon(icon, point)
 272
 273 DrawBitmapXY(bmp, x, y, useMask = FALSE)
 274 DrawBitmap(bmp, point, useMask = FALSE)
 275
 276 DrawTextXY(text, x, y)
 277 DrawText(text, point)
 278
 279 DrawRotatedTextXY(text, x, y, angle)
 280 DrawRotatedText(text, point, angle)
 281
 282
 283 BlitXY(xdest, ydest, width, height, sourceDC, xsrc, ysrc,
 284        rop = wxCOPY, useMask = FALSE, xsrcMask = -1, ysrcMask = -1)
 285 Blit(destPt, size, sourceDC, srcPt,
 286      rop = wxCOPY, useMask = FALSE, srcPtMask = wx.DefaultPosition)
 287
 288 SetClippingRegionXY(x, y, width, height)
 289 SetClippingRegion(point, size)
 290 SetClippingRect(rect)
 291 SetClippingRegionAsRegion(region);
 292 </pre>
 293 <p>If you have code that draws on a DC and you are using the new wx
 294 namespace then you <strong>will</strong> get errors because of these changes, but
 295 it should be easy to fix the code.  You can either change the name of
 296 the <em>Type B</em> method called to the names shown above, or just add
 297 parentheses around the parameters as needed to turn them into tuples
 298 and let the SWIG typemaps turn them into the wx.Point or wx.Size
 299 object that is expected.  Then you will be calling the new <em>Type A</em>
 300 method.  For example, if you had this code before:</p>
 301 <pre class="literal-block">
 302 dc.DrawRectangle(x, y, width, height)
 303 </pre>
 304 <p>You could either continue to use the <em>Type B</em> method bu changing the
 305 name to DrawRectabgleXY, or just change it to the new <em>Type A</em> by
 306 adding some parentheses like this:</p>
 307 <pre class="literal-block">
 308 dc.DrawRectangle((x, y), (width, height))
 309 </pre>
 310 <p>Or if you were already using a point and size:</p>
 311 <pre class="literal-block">
 312 dc.DrawRectangle(p.x, p.y, s.width, s.height)
 313 </pre>
 314 <p>Then you can just simplify it like this:</p>
 315 <pre class="literal-block">
 316 dc.DrawRectangle(p, s)
 317 </pre>
 318 <p>Now before you start yelling and screaming at me for breaking all your
 319 code, take note that I said above &quot;...using the new wx namespace...&quot;
 320 That's because if you are still importing from wxPython.wx then there
 321 are some classes defined there with Draw and etc. methods that have
 322 2.4 compatible signatures.  However if/when the old wxPython.wx
 323 namespace is removed then these classes will be removed too so you
 324 should plan on migrating to the new namespace and new DC Draw methods
 325 before that time.</p>
 326 </div>
 327 <div class="section" id="building-extending-and-embedding-wxpython">
 328 <h1><a name="building-extending-and-embedding-wxpython">Building, Extending and Embedding wxPython</a></h1>
 329 <p>wxPython's setup.py script now expects to use existing libraries for
 330 the contribs (gizmos, stc, xrc, etc.) rather than building local
 331 copies of them.  If you build your own copies of wxPython please be
 332 aware that you now need to also build the ogl, stc, xrc, and gizmos
 333 libraries in addition to the main wx lib.  [[TODO: update the
 334 BUILD.*.txt files too!]]</p>
 335 <p>The wxPython.h and other header files are now in
 336 .../wxPython/include/wx/wxPython instead of in wxPython/src.  You should
 337 include it via the &quot;wx/wxPython/wxPython.h&quot; path and add
 338 .../wxPython/include to your list of include paths.  [[TODO:  Install
 339 these headers on Linux...]]</p>
 340 <p>You no longer need to call wxClassInfo::CleanUpClasses() and
 341 wxClassInfo::InitializeClasses() in your extensions or when embedding
 342 wxPython.</p>
 343 </div>
 344 <div class="section" id="two-or-three-phase-create">
 345 <h1><a name="two-or-three-phase-create">Two (or Three!) Phase Create</a></h1>
 346 <p>If you use the Precreate/Create method of instantiating a window, (for
 347 example, to set an extended style flag, or for XRC handlers) then
 348 there is now a new method named PostCreate to help with transplanting
 349 the brain of the prewindow instance into the derived window instance.
 350 For example:</p>
 351 <pre class="literal-block">
 352 class MyDialog(wx.Dialog):
 353     def __init__(self, parent, ID, title, pos, size, style):
 354         pre = wx.PreDialog()
 355         pre.SetExtraStyle(wx.DIALOG_EX_CONTEXTHELP)
 356         pre.Create(parent, ID, title, pos, size, style)
 357         self.PostCreate(pre)
 358 </pre>
 359 </div>
 360 <div class="section" id="sizers">
 361 <h1><a name="sizers">Sizers</a></h1>
 362 <p>The hack allowing the old &quot;option&quot; keyword parameter has been removed.
 363 If you use keyworkd args with wxSizer Add, Insert, or Prepend methods
 364 then you will need to use the &quot;proportion&quot; name instead of &quot;option&quot;.</p>
 365 <p>When adding a spacer to a sizer you now need to use a wxSize or a
 366 2-integer sequence instead of separate width and height parameters.</p>
 367 <p>The wxGridBagSizer class (very similar to the RowColSizer in the
 368 library) has been added to C++ and wrapped for wxPython.  It can also
 369 be used from XRC.</p>
 370 <p>You should not use AddWindow, AddSizer, AddSpacer (and similar for
 371 Insert, Prepend, and etc.) methods any longer.  Just use Add and the
 372 wrappers will figure out what to do.</p>
 373 </div>
 374 <div class="section" id="platforminfo">
 375 <h1><a name="platforminfo">PlatformInfo</a></h1>
 376 <p>Added wx.PlatformInfo which is a tuple containing strings that
 377 describe the platform and build options of wxPython.  This lets you
 378 know more about the build than just the __WXPORT__ value that
 379 wx.Platform contains, such as if it is a GTK2 build.  For example,
 380 instead of:</p>
 381 <pre class="literal-block">
 382 if wx.Platform == &quot;__WXGTK__&quot;:
 383     ...
 384 </pre>
 385 <p>you should do this:</p>
 386 <pre class="literal-block">
 387 if &quot;__WXGTK__&quot; in wx.PlatformInfo:
 388      ...
 389 </pre>
 390 <p>and you can specifically check for a wxGTK2 build by looking for
 391 &quot;gtk2&quot; in wx.PlatformInfo.  Unicode builds are also detectable this
 392 way.  If there are any other platform/toolkit/build flags that make
 393 sense to add to this tuple please let me know.</p>
 394 <p>BTW, wx.Platform will probably be deprecated in the future.</p>
 395 </div>
 396 <div class="section" id="other-stuff">
 397 <h1><a name="other-stuff">Other Stuff</a></h1>
 398 <p>Instead of over a dozen separate extension modules linked together
 399 into a single extension module, the &quot;core&quot; module is now just a few
 400 extensions that are linked independently, and then merged together
 401 later into the main namespace via Python code.</p>
 402 <p>Because of the above and also because of the way the new SWIG works,
 403 the &quot;internal&quot; module names have changed, but you shouldn't have been
 404 using them anyway so it shouldn't bother you. ;-)</p>
 405 <p>The help module no longer exists and the classes therein are now part
 406 of the core module imported with wxPython.wx or the wx package.</p>
 407 <p>wxPyDefaultPosition and wxPyDefaultSize are gone.  Use the
 408 wxDefaultPosition and wxDefaultSize objects instead.</p>
 409 <p>Similarly, the wxSystemSettings backwards compatibiility aliases for
 410 GetSystemColour, GetSystemFont and GetSystemMetric have also gone into
 411 the bit-bucket.  Use GetColour, GetFont and GetMetric instead.</p>
 412 <p>The wx.NO_FULL_REPAINT_ON_RESIZE style is now the default style for
 413 all windows.  The name still exists for compatibility, but it is set
 414 to zero.  If you want to disable the setting (so it matches the old
 415 default) then you need to use the new wx.FULL_REPAINT_ON_RESIZE style
 416 flag otherwise only the freshly exposed areas of the window will be
 417 refreshed.</p>
 418 <p>wxPyTypeCast has been removed.  Since we've had the OOR (Original
 419 Object Return) for a couple years now there should be no need to use
 420 wxPyTypeCast at all.</p>
 421 <p>If you use the old wxPython package and wxPython.wx namespace then
 422 there are compatibility aliases for much of the above items.</p>
 423 <p>The wxWave class has been renamed to wxSound, and now has a slightly
 424 different API.</p>
 425 <p>Instead of a very small 20x20 the default window size is now a more
 426 reasonable size, (currently 400x250 but that may change...)  If you
 427 don't specify a size, and the window/control class does not have any
 428 definition of it's own &quot;best size&quot; (most controls do) then the new
 429 default will be used.  If you have code that accidentally depends on
 430 the smaller size then things will look a bit odd.  To work around this
 431 just give those windows an explicit size when created.</p>
 432 </div>
 433 </div>
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