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<h3><a name=QLayout>QLayout</a></h3>
<p> Calling resize(0,0) or resize(1,1) will no longer work magically.
Remove all such calls. The default size of toplevel widgets will be their
<a href="qwidget.html#4511d1">sizeHint()</a>.
<p> The default implementation of QWidget::sizeHint() will no longer
return just an invalid size; if the widget has a layout, it will return
the layout's preferred size.
<p> The special maximum MaximumHeight/Width is now QWIDGETSIZE_MAX,
not QCOORD_MAX.
<p> <a href="qboxlayout.html#ebba99">QBoxLayout::addWidget()</a>
now interprets the <em>alignment</em> parameter more aggressively.  A
non-default alignment now indicates that the widget should not grow to
fill the available space, but should be sized according to sizeHint().
If a widget is too small, set the alignment to 0. (Zero indicates no
alignment, and is the default.)
<p> The class QGManager is removed. Subclasses of QLayout need to be rewritten
to use the new, much simpler <a href="qlayout.html">QLayout API</a>.
<p> For typical layouts, all use of
<a href="qwidget.html#c0b5fb">setMinimumSize()</a>
and
<a href="qwidget.html#87e3f4">setFixedSize()</a>
can be removed.
<a href="qlayout.html#1cb33d">activate()</a> is no longer necessary.
<p>
You might like to look at the QGrid, QVBox, and QHBox widgets - they offer
a simple way to build nested widget structures.
<p>
<h3><a name=QListView>QListView</a></h3>
<p>In Qt 1.x mouse events to the viewport where redirected to the
event handlers for the listview; in Qt 2.x, this functionality is
in QScrollView where mouse (and other position-oriented) events are
redirected to viewportMousePressEvent() etc, which in turn translate
the event to the coordinate system of the contents and call
contentsMousePressEvent() etc, thus providing events in the most
convenient coordinate system.  If you overrode QListView::MouseButtonPress(),
QListView::mouseDoubleClickEvent(), QListView::mouseMoveEvent(), or
QListView::mouseReleaseEvent() you must instead override
viewportMousePressEvent(),
viewportMouseDoubleClickEvent(), viewportMouseMoveEvent(), or
viewportMouseReleaseEvent() respectively.  New code will usually override
contentsMousePressEvent() etc.
<p>The signal QListView::selectionChanged(QListViewItem *) can now be
emitted with a null pointer as parameter. Programs that use the
argument without checking for 0, may crash.
<p>
<h3><a name=QMultiLineEdit>QMultiLineEdit</a></h3>
<p>
The protected function
<pre> <a href="qmultilineedit.html#a97ed4">QMultiLineEdit::textWidth</a>(<a href="qstring.html">QString</a>*)</pre>
<p>
changed to
<pre> <a href="qmultilineedit.html#a97ed4">QMultiLineEdit::textWidth</a>(const QString&amp;)</pre>
.
This is unlikely to be a problem, and you'll get a compile error
if you called it.
<p>
<h3><a name=QClipboard>QClipboard</a></h3>
<p>
<pre> <a href="qclipboard.html#905cbc">QClipboard::pixmap</a>()</pre>
 now returns a QPixmap, not a QPixmap*.
The pixmap
will be <a href="qpixmap.html#7803c4">null</a> if no pixmap is on the
clipboard.  QClipboard now offers powerful MIME-based types on the
clipboard, just like drag-and-drop (in fact, you can reuse most of your
drag-and-drop code with clipboard operations).
<p>
<h3><a name=QDropSite>QDropSite</a></h3>
<p>
<P>
QDropSite is obsolete.  If you simply passed <tt>this</tt>, just remove
the inheritance of QDropSite and call
<a href="qwidget.html#8169cb">setAcceptDrops(TRUE)</a> in the class
constructor.
If you passed something other than <tt>this</tt>,
your code will not work.  A common case is passing
the
<a href="qscrollview.html#26f2bf">viewport()</a> of a QListView,
in which case,
override the
<a href="qscrollview.html#f54ca8">viewportDragMoveEvent()</a>,
etc.
functions rather than QListView's dragMoveEvent() etc.  For other
cases, you will need to use an event filter to act on the drag/drop events
of another widget (as is the usual way to intercept foreign events).
<p>
<h3><a name=QScrollView>QScrollView</a></h3>
<p>
The parameters in the signal
<a href="qscrollview.html#479944">contentsMoving(int,int)</a>
are now positive rather than negative values, coinciding with
<a href="qscrollview.html#15a368">setContentsPos()</a>.  Search for
connections you make to this signal, and either change the slot they are
connected to such that it also expects positive rather than negative
values, or introduce an intermediate slot and signal that negates them.
<p>
If you used drag and drop with QScrollView, you may experience the problem
described for <a href=#QDropSite>QDropSite</a>.
<p>
<h3><a name=QTextStream>QTextStream</a></h3>
<p>
<pre> operator&lt;&lt;(<a href="qtextstream.html">QTextStream</a>&amp;, QChar&amp;)</pre>
 does not skip whitespace.
<pre> operator&lt;&lt;(<a href="qtextstream.html">QTextStream</a>&amp;, char&amp;)</pre>
 does,
    as was the case with Qt 1.x.  This is for backward compatibility.
<p>
<h3><a name=QUriDrag>QUriDrag</a></h3>
<p>
The class QUrlDrag is renamed to QUriDrag, and the API has been
broadened to include additional conversion routines, including
conversions to Unicode filenames (see the class documentation
for details).  Note that in Qt 1.x
the QUrlDrag class used the non-standard MIME type "url/url",
while QUriDrag uses the standardized "text/uri-list" type.  Other
identifiers affected by the Url to Uri change are
QUrlDrag::setUrls() and QUrlDrag::urlToLocalFile().
<p>
<h3><a name=QPainter>QPainter</a></h3>
<p> The GrayText painter flag has been removed. Use
<a href="qpainter.html#0183e4">setPen( palette().disabled().foreground() )</a>
instead.
<p> The RasterOp enum
(CopyROP,
        OrROP,
        XorROP,
        NotAndROP,
        EraseROP,
        NotCopyROP,
        NotOrROP,
        NotXorROP,
        AndROP, NotEraseROP,
        NotROP,
        ClearROP,
        SetROP,
        NopROP,
        AndNotROP,
        OrNotROP,
        NandROP,
        NorROP, LastROP)
is now part of the Qt namespace class, so if you
use it outside a member function, you'll need to prefix with Qt::.
<p>
<h3><a name=QPicture>QPicture</a></h3>
<p>The binary storage format of QPicture is changed, but the Qt 2.x
QPicture class can both read and write Qt 1.x format QPictures. No
special handling is required for reading; QPicture will automatically
detect the version number. In order to write a Qt 1.x format QPicture,
set the formatVersion parameter to 1 in the QPicture constructor.
<p>For writing Qt 1.x format QPictures, the compatibility issues of <a
href=#QDataStream>QDataStream</a> applies.
<p>It is safe to try to read a QPicture file generated with Qt 2.x
(without formatVersion set to 1) with a program compiled with Qt
1.x. The program will not crash, it will just issue the warning
"QPicture::play: Incompatible version 2.x" and refuse to load the
picture.
<p>
<h3><a name=QPoint>QPoint, QPointArray, QSize and QRect</a></h3>
<p>The basic coordinate datatype in these classes, QCOORD, is now 32
bit (int) instead of a 16 bit (short). The const values QCOORD_MIN and
QCOORD_MAX have changed accordingly.
<p>QPointArray is now actually, not only seemingly, a QArray of QPoint
objects. The semi-internal workaround classes QPointData and QPointVal
are removed since they are no longer needed; QPoint is used directly
instead. The function <pre> <a href="qpointarray.html#0dbaa7">QPointArray::shortPoints</a>()</pre>
<p>
provides the point array converted to short (16bit) coordinates for
use with external functions that demand that format.
<p>
<h3><a name=QImage>QImage</a></h3>
<p>
QImage uses QRgb for the colors - see <a href=#QRgb>the changes to that</a>.
<p>
<h3><a name=QPixmap>QPixmap</a></h3>
<p>
<pre> <a href="qpixmap.html#8c5f15">QPixmap::convertToImage</a>()</pre>
 with bitmaps now guarantees that color0 pixels
become color(0) in the resulting QImage.  If you worked around the lack of
this, you may be able to simplify your code.  If you made assumptions
about the previous undefined behavior, the symptom will be inverted
bitmaps (eg. "inside-out" masks).
<p>
<pre> QPixmap::optimize(TRUE)</pre>
<p>
is replaced by
<pre> <a href="qpixmap.html#e6ae80">QPixmap::setOptimization</a>(QPixmap::NormalOptim)</pre>
<p>
or
<pre> <a href="qpixmap.html#e6ae80">QPixmap::setOptimization</a>(QPixmap::BestOptim)</pre>
<p>
- see the documentation
to choose which is best for your application.  NormalOptim is most like
the Qt 1.x "TRUE" optimization.
<p>
<h3><a name=QMenuData>QMenuData / QPopupMenu</a></h3>
<p>
In Qt 1.x, new menu items were assigned either an application-wide
unique identifier or an identifier equal to the index of the item, depending on the
<a href="qmenudata.html#a0155e">insertItem(...)</a> function used.
In Qt 2.x this confusing
situation has been cleaned up: generated identifiers are always
unique across the entire application.
<p>
If your code depends on generated ids
being equal to the item's index, a quick fix is to use
<pre> <a href="qmenudata.html#49862d">QMenuData::indexOf</a>(int id)</pre>
<p>
in the handling function instead. You may alternatively pass
<pre> <a href="qmenudata.html#e3e249">QMenuData::count</a>()</pre>
<p>
as identifier when you insert the items.
<p>
Furthermore, QPopupMenus can (and should!) be created with a parent
widget now, for example the main window that is used to display the
popup. This way, the popup will automatically be destroyed together
with its main window. Otherwise you'll have to take care of the
ownership manually.
<p>
QPopupMenus are also reusable in 2.x. They may occur in different
locations within one menu structure or be used as both a menubar
drop-down and as a context popup-menu.  This should make it possible to
significantly simplify many applications.
<p>
Last but not least, QPopupMenu no longer inherits QTableView. Instead,
it directly inherits QFrame.
<p>
<h3><a name=QValidator>QValidator (QLineEdit, QComboBox, QSpinBox) </a></h3>
<p>
<pre> <a href="qvalidator.html#da4f8c">QValidator::validate</a>(...)</pre>
<p>
and
<pre> <a href="qvalidator.html#3fa523">QValidator::fixup</a>( <a href="qstring.html">QString</a> &amp; )</pre>
<p>
are now const
functions. If your subclass reimplements validate() as a
non-const function,
you will get a compile error (validate was pure virtual).
<p>
In QLineEdit, QComboBox, and QSpinBox,
setValidator(...) now takes a const pointer to a QValidator, and
validator() returns a const pointer. This change highlights the fact
that the widgets do not take the ownership of the validator (a validator is
a QObject on its own, with its own parent - you can easily set the same validator
object on many different widgets), so changing the state of
such an object or deleting it is very likely a bug.
<p>
<h3><a name=QFile>QFile, QFileInfo, QDir</a></h3>
<p>
File and directory names are now always Unicode strings (ie. QString).  If you used QString
in the past for the simplicity it offers, you'll probably have little consequence.  However,
if you pass filenames to system functions rather than using Qt functions (eg. if you use the
Unix <tt>unlink()</tt> function rather than <tt>QFile::remove()</tt>, your code will probably
only work for Latin1 locales (eg. Western Europe, the U.S.).  To ensure your code will support
filenames in other locales, either use the Qt functions, or convert the filenames via
<pre> QFile::encodeFilename()</pre>
 and <pre> QFile::decodeFilename()</pre>
 - but do it
<em>just</em> as you call the system function - code that mixes encoded and unencoded filenames
is very error prone.  See the comments in QString, such as regarding QT_NO_ASCII_CAST that
can help find potential problems.
<p>
<h3><a name=QFontMetrics>QFontMetrics</a></h3>
<p>
boundingRect(char) is replaced by
boundingRect(QChar), but since
char auto-converts to QChar, you're not likely to run into problems
with this.
<p>
<h3><a name=QWindow>QWindow</a></h3>
<p>
This class (which was just QWidget under a different name) has been
removed.  If you used it, do a global search-and-replace of the word
"QWindow" with "QWidget".
<p>
<h3><a name=QEvent>QEvent</a></h3>
<p> The global #define macros in qevent.h have been replaced by an
enum in QEvent.  Use e.g. QEvent::Paint instead of Event_Paint. Same
for all of:
Event_None,
Event_Timer,
Event_MouseButtonPress,
Event_MouseButtonRelease,
Event_MouseButtonDblClick,
Event_MouseMove,
Event_KeyPress,
Event_KeyRelease,
Event_FocusIn,
Event_FocusOut,
Event_Enter,
Event_Leave,
Event_Paint,
Event_Move,
Event_Resize,
Event_Create,
Event_Destroy,
Event_Show,
Event_Hide,
Event_Close,
Event_Quit,
Event_Accel,
Event_Clipboard,
Event_SockAct,
Event_DragEnter,
Event_DragMove,
Event_DragLeave,
Event_Drop,
Event_DragResponse,
Event_ChildInserted,
Event_ChildRemoved,
Event_LayoutHint,
Event_ActivateControl,
Event_DeactivateControl,
and
Event_User.
<p> The Q_*_EVENT macros in qevent.h have been deleted.  Use an
explicit cast instead. The macros were:
Q_TIMER_EVENT,
Q_MOUSE_EVENT,
Q_KEY_EVENT,
Q_FOCUS_EVENT,
Q_PAINT_EVENT,
Q_MOVE_EVENT,
Q_RESIZE_EVENT,
Q_CLOSE_EVENT,
Q_SHOW_EVENT,
Q_HIDE_EVENT,
and
Q_CUSTOM_EVENT.
<p> QChildEvents are now sent for all QObjects, not just QWidgets.
You may need to add extra checking if you use a QChildEvent without
much testing of its values.
<p>
<h3>All the removed functions</h3>
<p>
All <a href="removed20.html">these functions</a> have been removed in
Qt 2.x.  Most are simply cases where "const char*" has changed to
"const QString&", or when an enumeration type has moved into the Qt::
namespace (which, technically, is a new name, but your code will
compile just the same anyway).  This list is provided for completeness.

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