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| author | Timothy Pearson <[email protected]> | 2011-07-10 15:24:15 -0500 |
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| committer | Timothy Pearson <[email protected]> | 2011-07-10 15:24:15 -0500 |
| commit | bd0f3345a938b35ce6a12f6150373b0955b8dd12 (patch) | |
| tree | 7a520322212d48ebcb9fbe1087e7fca28b76185c /doc/html/porting2.html | |
| download | qt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.tar.gz qt3-bd0f3345a938b35ce6a12f6150373b0955b8dd12.zip | |
Add Qt3 development HEAD version
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diff --git a/doc/html/porting2.html b/doc/html/porting2.html new file mode 100644 index 0000000..cfa84fd --- /dev/null +++ b/doc/html/porting2.html @@ -0,0 +1,965 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> +<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/porting2.doc:36 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>Porting to Qt 2.x</title> +<style type="text/css"><!-- +fn { margin-left: 1cm; text-indent: -1cm; } +a:link { color: #004faf; text-decoration: none } +a:visited { color: #672967; text-decoration: none } +body { background: #ffffff; color: black; } +--></style> +</head> +<body> + +<table border="0" cellpadding="0" cellspacing="0" width="100%"> +<tr bgcolor="#E5E5E5"> +<td valign=center> + <a href="index.html"> +<font color="#004faf">Home</font></a> + | <a href="classes.html"> +<font color="#004faf">All Classes</font></a> + | <a href="mainclasses.html"> +<font color="#004faf">Main Classes</font></a> + | <a href="annotated.html"> +<font color="#004faf">Annotated</font></a> + | <a href="groups.html"> +<font color="#004faf">Grouped Classes</font></a> + | <a href="functions.html"> +<font color="#004faf">Functions</font></a> +</td> +<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Porting to Qt 2.x</h1> + + + +<p> <p> +You're probably looking at this page because you want to port +your application from Qt 1.x to Qt 2.x, but to be sure, let's +review the good reasons to do this: +<ul> +<li>To get access to all the new Qt 2.x features like the rich text +HTML subset for formatted labels, tooltips, online help etc. +and the much easier to use layout classes and widgets. +<li>To make your application truly international, with support +for Unicode and translations for the languages of the world. +<li>To allow your application to fit into the new look of the +Unix desktop with configurable, very powerful "themes". The +extended style system also integrates Qt applications better +on MS-Windows desktops. Qt will automatically chose the right +colors and fonts and obey global system setting changes. +<li>To stay up-to-date with the version of Qt that gets all the +new features and bug-fixes. +<li>To get more speed and smoother widgets display with all the +new anti-flicker changes in Qt. +<li>Most of all though, you want to port to Qt 2.x +so that your Wheel Mouse works! +</ul> +<p> <p> +The Qt 2.x series is not binary compatible with the 1.x series. +This means programs compiled for Qt 1.x must be recompiled to work +with Qt 2.x. Qt 2.x is also not completely <em>source</em> compatible +with 1.x, however all points of incompatibility cause +compiler errors (rather than mysterious results), or produce run-time +messages. The result is that Qt 2.x includes many additional features, +discards obsolete functionality that is easily converted to use the new +features, and that porting an application from Qt 1.x to Qt 2.x is +a simple task well worth the amount of effort required. +<p> To port code using Qt 1.x to use Qt 2.x: +<p> <ul> +<li> Briefly read the porting notes below to get an idea of what to expect. +<li> Be sure your code compiles and runs well on all your target platforms with Qt 1.x. +<li> Recompile with Qt 2.x. For each error, search below for related +identifiers (eg. function names, class names) - this documented is +structured to mention all relevant identifiers to facilitate such +searching, even if that makes it a little verbose. +<li> If you get stuck, ask on the qt-interest mailing list, or +Trolltech Technical Support if you're a Professional Edition +licensee. +</ul> +<p> Many very major projects, such as <a href="http://www.kde.org/">KDE</a> +have been port, so there is plenty of expertise in the collective conscious +that is the Qt Developer Community! +</p> +<p> <hr> +<p> <h2 align=center>The Porting Notes</h2> +<p> <ul> +<li><b><a href="#Namespace">Namespace</a></b> +<li><b><a href="#Virtual">Virtual Functions</a></b> +<li><b><a href="#Collection">Collection classes</a></b> +<li><b><a href="#DefaultParent">No Default 0 Parent Widget</a></b> +<li><b><a href="#DebugVsRelease">Debug vs. Release</a></b> +<li><b><a href="#QApplication">QApplication</a></b> +<li><b><a href="#QClipboard">QClipboard</a></b> +<li><b><a href="#QColor">QColor</a></b> +<li><b><a href="#QDataStream">QDataStream</a></b> +<li><b><a href="#QDialog">QDialog</a></b> +<li><b><a href="#QDropSite">QDropSite</a></b> +<li><b><a href="#QEvent">QEvent</a></b> +<li><b><a href="#QFile">QFile</a></b> +<li><b><a href="#QFontMetrics">QFontMetrics</a></b> +<li><b><a href="#QIODevice">QIODevice</a></b> +<li><b><a href="#QLabel">QLabel</a></b> +<li><b><a href="#QLayout">QLayout</a></b> +<li><b><a href="#QListView">QListView</a></b> +<li><b><a href="#QMenuData">QMenuData</a></b> +<li><b><a href="#QMenuData">QPopupMenu</a></b> +<li><b><a href="#QMultiLineEdit">QMultiLineEdit</a></b> +<li><b><a href="#QPainter">QPainter</a></b> +<li><b><a href="#QPicture">QPicture</a></b> +<li><b><a href="#QPoint">QPoint, <a href="qpointarray.html">QPointArray</a>, <a href="qsize.html">QSize</a> and <a href="qrect.html">QRect</a></a></b> +<li><b><a href="#QPixmap">QPixmap</a></b> +<li><b><a href="#QRgb">QRgb</a></b> +<li><b><a href="#QScrollView">QScrollView</a></b> +<li><b><a href="#QStrList">QStrList</a></b> +<li><b><a href="#QString">QString</a></b> +<li><b><a href="#QTextStream">QTextStream</a></b> +<li><b><a href="#QUriDrag">QUriDrag / QUrlDrag</a></b> +<li><b><a href="#QValidator">QComboBox</a></b> +<li><b><a href="#QValidator">QLineEdit</a></b> +<li><b><a href="#QValidator">QSpinBox</a></b> +<li><b><a href="#QValidator">QValidator</a></b> +<li><b><a href="#QWidget">QWidget</a></b> +<li><b><a href="#QWindow">QWindow</a></b> +</ul> +<p> <hr> +<p> <h3><a name="Namespace">Namespace</a></h3> +<p> <p> Qt 2.x is namespace-clean, unlike 1.x. Qt now uses very few +global identifiers. Identifiers like <code>red, blue, LeftButton, +AlignRight, Key_Up, Key_Down, NoBrush</code> etc. are now part of a +special class <code>Qt</code> (defined in qnamespace.h), +which is inherited by +most Qt classes. Member functions of classes that inherit from <a href="qwidget.html">QWidget</a>, +etc. are totally unaffected, but code that is +<em>not</em> in functions of classes inherited from <code>Qt</code>, +you must qualify these identifiers like this: <code>Qt::red, +Qt::LeftButton, Qt::AlignRight</code>, etc. +<p> <p>The <code>qt/bin/qt20fix</code> script helps to fix the code that +needs adaption, though most code does not need changing. +<p> Compiling with -DQT1COMPATIBILITY will help you get going with Qt 2.x +- it allows all the old "dirty namespace" identifiers from Qt 1.x to +continue working. Without it, you'll get compile errors that can +easily be fixed by searching this page for the clean identifiers. +<p> <h3><a name="DefaultParent">No Default 0 Parent Widget</a></h3> +<p> In Qt 1.x, all widget constructors were defined with a default value +of 0 for the parent widget. However, only the main window of the +application should be created with a 0 parent, all other widgets +should have parents. Having the 0 default made it too simple to create +bugs by forgetting to specify the parent of non-mainwindow +widgets. Such widgets would typically never be deleted (causing memory +leaks), and they would become top-level widgets, confusing the window +managers. Therefore, in Qt 2.x the 0 default parent has been removed +for the widget classes that are not likely to be used as main windows. +<p> Note also that programs no longer need (or should) use 0 parent just +to indicate that a widget should be top-level. See +<pre> QWidget::isTopLevel() </pre> + for details. See also the notes about +<a href="#QMenuData">QPopupMenu</a> and <a href="#QDialog">QDialog</a> +below. +<p> <h3><a name="Virtual">Virtual Functions</a></h3> +<p> <p> Some virtual functions have changed signature in Qt 2.x. +If you override them in derived classes, you must change the signature +of your functions accordingly. +<p> <!-- warwick can check for additions to this with his qt-2-report --> +<ul> +<li><pre> QWidget::setStyle(GUIStyle)</pre> + +<li><pre> QListView::addColumn(const char *, int)</pre> + +<li><pre> QListView::setColumnText(int, const char *)</pre> + +<li><pre> QListViewItem::setText(int, const char *)</pre> + +<li><pre> QMultiLineEdit::insertLine(const char *, int)</pre> + +<li><pre> QMultiLineEdit::insertAt(const char *, int, int, bool)</pre> + +<li><pre> QSpinBox::setPrefix(const char *)</pre> + +<li><pre> QSpinBox::setSuffix(const char *)</pre> + +<li><pre> QToolButton::setTextLabel(const char *, bool)</pre> + +<li><pre> QDoubleValidator::validate(QString &, int &)</pre> + +<li><pre> QIntValidator::validate(QString &, int &)</pre> + +<li><pre> QValidator::fixup(QString &)</pre> + +<li><pre> QSlider::paintSlider(QPainter *, const <a href="qrect.html">QRect</a> &)</pre> + +</ul> +<p> This is one class of changes that are +not detected by the compiler, +so you should mechanically search for each of +these function names in your header files, eg. +<p> <pre> +egrep -w 'setStyle|addColumn|setColumnText|setText...' *.h +</pre> + +<p> Of course, you'll get a few false positives (eg. if you have a setText +function that is not in a subclass of <a href="qlistviewitem.html">QListViewItem</a>). +<p> <h3><a name="Collection">Collection classes</a></h3> +<p> <p> The <a href="collection.html#collection-classes">collection classes</a> include generic +classes such as QGDict, QGList, and +the subclasses such as <a href="qdict.html">QDict</a> and QList. +<p> <p> The macro-based Qt collection classes are obsolete; use the +template-based classes instead. Simply remove includes of qgeneric.h and +replace e.g. Q_DECLARE(<a href="qcache.html">QCache</a>,QPixmap) with QCache<QPixmap>. +<p> <p> The GCI global typedef is replaced by QCollection::Item. Only if you +make your own subclasses of the undocumented generic collection classes +will you have GCI in your code. +This change has been made to avoid collisions with other namespaces. +<p> <p> The GCF global typedef is removed (it was not used in Qt). +<p> <h3><a name="DebugVsRelease">Debug vs. Release</a></h3> +<p> <p>The Q_ASSERT macro is now a null expression if the QT_CHECK_STATE flag +is not set (i.e. if the QT_NO_CHECK flag is defined). +<p> <p>The debug() function now outputs nothing if Qt was compiled with +the QT_NO_DEBUG macro defined. +<p> <h3><a name="QString">QString</a></h3> +<p> <a href="qstring.html">QString</a> has undergone major changes internally, and although it is highly +backward compatible, it is worth studying in detail when porting to Qt 2.x. +The Qt 1.x QString class has been renamed to <a href="qcstring.html">QCString</a> in Qt 2.x, though if +you use that you will incur a performance penalty since all Qt functions +that took const char* now take const QString&. +<p> <p> +To take full advantage of the new <a href="i18n.html#internationalization">Internationalization</a> +functionality in Qt 2.x, the following steps are required: +<p> <ul> +<li> Start converting all uses of "const char*" in parameters to +"const QString&" - this can often be done mechanically, eg. +using Perl. Convert usage of char[] for temporary string +building to QString (much software already uses QString for +this purpose as it offers many more facilities). +<p> If you find that you are mixing usage of QCString, QString, +and <a href="qbytearray.html">QByteArray</a>, this causes lots of unnecessary copying and +might indicate that the true nature of the data you are +dealing with is uncertain. If the data is NUL-terminated +8-bit data, use QCString; if it is unterminated (ie. +contains NULs) 8-bit data, use QByteArray; if it is text, +use <a href="qstring.html">QString</a>. +</p> +<li> Put a breakpoint in <pre> QString::latin1()</pre> + +to catch places where +Unicode information is being converted to ASCII (loosing +information if your user in not using Latin1). Qt has +a small number of calls to this - ignore those. As a stricter +alternative, compile your code with QT_NO_ASCII_CAST defined, +which hides the automatic conversion of QString to const char*, +so you can catch problems at compile time. +</p> +<li> See the Qt <a href="i18n.html">Internationalization page</a> +for information about the full process of internationalizing +your software. +</ul> +<p> <p> +Points to note about the new QString are: +<p> <dl compact> +<dt><b>Unicode</b></dt> +<dd> +Qt now uses Unicode throughout. +data() now returns a <em>const</em> reference to an ASCII version +of the string - you cannot directly access the +string as an array of bytes, because it isn't one. Often, latin1() is +what you want rather than data(), or just leave it to convert to +const char* automatically. data() is only used now to aide porting to Qt 2.x, +and ideally you'll only need latin1() or implicit conversion when interfacing +to facilities that do not have Unicode support. +<p> <dt><b>Automatic-expanding</b></dt> +<dd> +A big advantage of the new <a href="qstring.html">QString</a> is that it automatically expands +when you write to an indexed position. +<p> <dt><b>QChar and <a href="qcharref.html">QCharRef</a></b></dt> +<dd> +<a href="qchar.html">QChar</a> are the Unicode characters that make up a QString. A QCharRef is +a temporary reference to a QChar in a QString that when assigned to +ensures that the <a href="shclass.html#implicit-sharing">implicit sharing</a> semantics of the QString are maintained. +You are unlikely to use QCharRef in your own code - but so that you +understand compiler error messages, just know that <tt>mystring[123]</tt> +is a QCharRef whenever <tt>mystring</tt> is not a constant string. A QCharRef +has basically the same functionality as a QChar, except it is more restricted +in what you can assign to it and cast it to (to avoid programming errors). +<p> <dt><b>Use QString</b></dt> +<dd> +Try to always use QString. If you <em>must</em>, use <a href="qcstring.html">QCString</a> which is the +old implementation from Qt 1.x. +<p> <dt><b>Unicode vs. ASCII</b></dt> +<dd> +Every conversion to and from ASCII is wasted time, so try to use <a href="qstring.html">QString</a> +as much as possible rather than const char*. This also ensures you have +full 16-bit support. +<p> <dt><b>Convertion to ASCII</b></dt> +<dd> +The return value from operator const char*() is transient - don't expect +it to remain valid while you make deep function calls. +It is valid for as long as you don't modify or destroy the QString. +<p> <dt><b>QString is simpler</b></dt> +<dd> +Expect your code to become simpler with the new QString, especially +places where you have used a char* to wander over the string rather +than using indexes into the string. +<p> <dt><b>Some hacks don't work</b></dt> +<dd> +This hack: +use_sub_string( &my_string[index] ) +should be replaced by: +use_sub_string( my_string.mid(index) ) +<p> <dt><b>QString(const char*, int) is removed</b></dt> +<dd> +The QString constructor taking a const char* and an integer is removed. +Use of this constructor was error-prone, since the length included the +'\0' terminator. Use <a href="qstring.html#left">QString::left</a>(int) or <a href="qstring.html#fromLatin1">QString::fromLatin1</a>( const char*, +int ) -- in both cases the int parameter signifies the number of characters. +<p> <dt><b>QString(int) is private</b></dt> +<dd> +The <a href="qstring.html">QString</a> constructor taking an integer is now private. This function +is not meaningful anymore, since QString does all space allocation +automatically. 99% of cases can simple be changed to use the +default constructor, QString(). +<p> +In Qt 1.x the constructor was used in two ways: accidentally, +by attempting to convert a char to a QString (the char converts to int!) - +giving strange bugs, and as a way to make a QString big enough prior to +calling <pre> QString::sprintf()</pre> + . In Qt 2.x, the accidental bug case is +prevented (you will get a compilation error) and QString::sprintf has +been made safe - you no longer need to pre-allocate space (though for +other reasons, sprintf is still a poor choice - eg. it doesn't pass Unicode). +The only remaining common case is conversion of 0 (NULL) to QString, which +would usually give expected results in Qt 1.x. For Qt 2.x the correct +syntax is to use <a href="qstring.html#QString-null">QString::null</a>, though note that +the default constructor, QString(), creates a null string too. +Assignment of 0 to a <a href="qstring.html">QString</a> is ambiguous - assign +QString::null; you'll mainly find these in code that has been converted +from const char* types to QString. +This also prevents a common error case from Qt 1.x - in +that version, mystr = 'X' would <em>not</em> produce the expected +results and was always a programming error; in Qt 2.x, it works - making +a single-character string. +<p> <p> +Also see <a href="#QStrList">QStrList</a>. +<p> <dt><b>Signals and Slots</b></dt> +<dd> +Many signal/slots have changed from const char* to QString. You will +get run-time errors when you try to <pre> QObject::connect()</pre> + +to the old +signals and slots, usually with a message indicating the const QString& +replacement signal/slot. +<p> <dt><b>Optimize with Q2HELPER</b></dt> +<dd> +In qt/src/tools/qstring.cpp there is a Q2HELPER - define it for some +extra debugging/optimizing features (don't leave it it - it kills performance). +You'll get an extra function, qt_qstring_stats(), which will print a +summary of how much your application is doing Unicode and ASCII +back-and-forth conversions. +<p> <dt><b>QString::detach() is obsolete and removed</b></dt> +<dd> +Since <a href="qstring.html">QString</a> is now always shared, this function does nothing. +Remove calls to QString::detach(). +<p> <dt><b>QString::resize(int size) is obsolete and removed</b></dt> +<dd> +Code using this to truncate a string should use +<a href="qstring.html#truncate">truncate(size-1)</a>. +Code using qstr.resize(0) should use qstr = QString::null. +Code calling resize(n) prior to using +<a href="qstring.html#operator[]">operator[]</a> up to n just remove +the resize(n) completely. +<p> <dt><b>QString::size() is obsolete and removed</b></dt> +<dd> +Calls to this function must be replaced by +<a href="qstring.html#length">length()</a>+1. +<p> <dt><b>QString::setStr(const char*) is removed</b></dt> +<dd>Try to understand why you were using this. +If you just meant assignment, use that. Otherwise, +you are probably using QString as an array of bytes, in which case use +<a href="qbytearray.html">QByteArray</a> or <a href="qcstring.html">QCString</a> instead. +<p> <dt><b>QString is not an array of bytes</b></dt> +<dd> +Code that uses <a href="qstring.html">QString</a> as an array of bytes should use QByteArray +or a char[], <em>then</em> convert that to a QString if needed. +<p> <dt><b>"string = 0"</b></dt> +<dd> +Assigning 0 to a QString should be assigning the null string, +ie. string = QString::null. +<p> <dt><b>System functions</b></dt> +<dd> +You may find yourself needing latin1() for passing to the operating system +or other libraries, and be tempted to use QCString to save the conversion, +but you are better off using Unicode throughout, then when the operating +system supports Unicode, you'll be prepared. Some Unix operating systems +are now beginning to have basic Unicode support, and Qt will be tracking +these improvements as they become more widespread. +<p> <dt><b>Bugs removed</b></dt> +<dd> +toShort() returns 0 (and sets *ok to false) on error. +toUInt() now works for big valid unsigned integers. +insert() now works into the same string. +<p> <dt><b>NULL pointers</b></dt> +<dd> +When converting "const char*" usage to QString in order to make your +application fully Unicode-aware, use QString::null for the null value +where you would have used 0 with char pointers. +<p> <dt><b>QString is not null terminated</b></dt> +<dd> +This means that inserting a 0-character +in the middle of the string does <em>not</em> change the length(). ie. +<pre> + <a href="qstring.html">QString</a> s = "fred"; + s[1] = '\0'; + // s.<a href="qstring.html#length">length</a>() == 4 + // s == "f\0ed" + // s.<a href="qstring.html#latin1">latin1</a>() == "f" + s[1] = 'r'; + // s == "fred" + // s.<a href="qstring.html#latin1">latin1</a>() == "fred" + </pre> + +Especially look out for this type of code: +<pre> + <a href="qstring.html">QString</a> s(2); + s[0] = '?'; + s[1] = 0; + </pre> + +This creates a string 2 characters long. +To find these problems while converting, you might like to +add <a href="qapplication.html#Q_ASSERT">Q_ASSERT</a>(strlen(d->ascii)==d->len) inside +<pre> QString::latin1()</pre> + . +<p> <dt><b>QString or Standard C++ string?</b></dt> +<dd> +<p> +The Standard C++ Library string is not Unicode. Nor is wstring defined +to be so (for the small number of platforms where it is defined at all). +This is the same mistake made over and over +in the history of C - only when non-8-bit characters are <em>the norm</em> +do programmers find them usable. Though it is possible to convert between +string and <a href="qstring.html">QString</a>, it is less efficient than using QString throughout. +For example, when using: +<pre> + QLabel::<a href="qlabel.html#setText">setText</a>( const <a href="qstring.html">QString</a>& ) +</pre> + +if you use string, like this: +<pre> + void myclass::dostuffwithtext( const string& str ) + { + mylabel.setText( QString(str.c_str()) ); + } +</pre> + +that will create a (ASCII only) copy of str, stored in mylabel. +But this: +<pre> + void myclass::dostuffwithtext( const <a href="qstring.html">QString</a>& str ) + { + mylabel.setText( str ); + } +</pre> + +will make an <a href="shclass.html#implicitly-shared">implicitly shared</a> reference to str in the <a href="qlabel.html">QLabel</a> - no copying +at all. This function might be 10 nested function calls away from something +like this: +<pre> + void toplevelclass::initializationstuff() + { + doStuff( tr("Okay") ); + } +</pre> + +At this point, in Qt 2.x, the tr() does a very fast dictionary lookup +through memory-mapped message files, returning some Unicode <a href="qstring.html">QString</a> for +the appropriate language (the default being to just make a QString out +of the text, of course - you're not <em>forced</em> to use any of these +features), and that <em>same</em> memory mapped Unicode will be passed +though the system. All occurrences of the translation of "Okay" can +potentially be shared. +<p> </dl> +<p> <h3><a name="QApplication">QApplication</a></h3> +<p> In the function <pre> QApplication::setColorSpec()</pre> + , +PrivateColor and TrueColor are obsolete. Use ManyColor instead. +<p> <h3><a name="QColor">QColor</a></h3> +<p> <p> +All colors +(color0, +color1, +black, +white, +darkGray, +gray, +lightGray, +red, +green, +blue, +cyan, +magenta, +yellow, +darkRed, +darkGreen, +darkBlue, +darkCyan, +darkMagenta, +and +darkYellow) +are in the Qt namespace. +In members of classes that inherit the Qt namespace-class (eg. <a href="qwidget.html">QWidget</a> +subclasses), you can use the unqualified names as before, but in global +functions (eg. main()), you need to qualify them: Qt::red, Qt::white, etc. +See also the <a href="#QRgb">QRgb</a> section below. +<p> <h3><a name="QRgb">QRgb</a></h3> +<p> In QRgb (a typedef of long), the order of the RGB channels has changed to +be in the more efficient order (for typical contemporary hardware). If your +code made assumptions about the order, you will get blue where you expect +red and vice versa (you'll not notice the problem if you use shades of +gray, green, or magenta). You should port your code to use the +creator function <a href="qcolor.html#qRgb">qRgb</a>(int r,int g,int b) and the +access functions <a href="qcolor.html#qRed">qRed</a>(QRgb), <a href="qcolor.html#qBlue">qBlue</a>(QRgb), and <a href="qcolor.html#qGreen">qGreen</a>(QRgb). +If you are using the alpha channel, it hasn't moved, but you should use +the functions <a href="qcolor.html#qRgba">qRgba</a>(int,int,int,int) and <a href="qcolor.html#qAlpha">qAlpha</a>(QRgb). Note also that +<a href="qcolor.html#pixel">QColor::pixel</a>() does <i>not</i> return a QRgb (it never did on all platforms, +but your code may have assumed so on your platform) - this may also produce +strange color results - use <a href="qcolor.html#rgb">QColor::rgb</a>() if you want a QRgb. +<p> <h3><a name="QDataStream">QDataStream</a></h3> +<p> <p>The QDatastream serialization format of most Qt classes is changed +in Qt 2.x. Use <pre> QDataStream::setVersion( 1 )</pre> + to get a +datastream object that can read and write Qt 1.x format data streams. +<p> <p>If you want to write Qt 1.x format datastreams, note the following +compatibility issues: +<ul> +<li>QString: Qt 1.x has no Unicode support, so strings will be +serialized by writing the classic C string returned by <pre> + QString::<a href="qstring.html#latin1">latin1</a>().</pre> + +<li><a href="#QPoint">QPoint & al.</a>: Coordinates will be +truncated to the Qt 1.x 16 bit format. +</ul> +<p> <h3><a name="QWidget">QWidget</a></h3> +<p> <h4>QWidget::recreate()</h4> +<p> +This function is now called <a href="qwidget.html#reparent">reparent()</a>. +<p> <h4>QWidget::setAcceptFocus(bool)</h4> +<p> +This function is removed. +Calls like QWidget::setAcceptFocus(TRUE) should be replaced by +<pre> QWidget::setFocusPolicy(StrongFocus)</pre> + , and +calls like QWidget::setAcceptFocus(FALSE) should be replaced by +<pre> QWidget::setFocusPolicy(NoFocus)</pre> + . +Additional policies are TabFocus and ClickFocus. +<p> <h4>QWidget::paintEvent()</h4> +<p> +paintEvent(0) is not permitted - subclasses need not check for +a null event, and might crash. +Never pass 0 as the argument to paintEvent(). You probably +just want repaint() or update() instead. +<p> +When processing a paintEvent, painting is only permitted within +the update region specified in the event. Any painting outside will be +clipped away. This shouldn't break any code (it was always like this +on MS-Windows) but makes many explicit calls to +<a href="qpainter.html#setClipRegion">QPainter::setClipRegion</a>() superfluous. Apart from the improved +consistency, the change is likely to reduce flicker and to make Qt +event slightly faster. +<p> <h3><a name="QIODevice">QIODevice</a></h3> +<p> +The protected member QIODevice::index is renamed to QIODevice::ioIndex +to avoid warnings and to allow compilation with bad C libraries that +#define index to strchr. If you have made a subclass of <a href="qiodevice.html">QIODevice</a>, +check every occurrence of the string "index" in the implementation, since +a compiler will not always catch cases like <pre>(uint)index</pre> + +that need to be changed. +<p> <h3><a name="QLabel">QLabel</a></h3> +<p> <h4><pre> QLabel::setMargin()</pre> + </h4> +<p> +<pre> QLabel::setMargin()</pre> + and<pre> QLabel::margin()</pre> + +have been renamed to <pre> QLabel::setIndent()</pre> + and +<pre> QLabel::indent()</pre> + , respectively. This was done to avoid +collision with <a href="qframe.html#setMargin">QFrame::setMargin</a>(), which is now virtual. +<p> <h4><pre> QLabel::setMovie()</pre> + </h4> +<p> +Previously, setting a movie on a label cleared the value of text(). +Now it doesn't. If you somehow used <tt>QLabel::text()</tt> +to detect if a +movie was set, you might have trouble. This is unlikely. +<p> <h3><a name="QDialog">QDialog</a></h3> +<p> <p> The semantics of the parent pointer changed for modeless dialogs: +In Qt-2.x, dialogs are always top level windows. The parent, however, +takes the ownership of the dialog, i.e. it will delete the dialog at +destruction if it has not been explicitly deleted +already. Furthermore, the window system will be able to tell that both +the dialog and the parent belong together. Some X11 window managers +will for instance provide a common taskbar entry in that case. +<p> <p> +If the dialog belongs to a top level main window +of your application, pass this main window as parent to the dialog's +constructor. Old code (with 0 pointer) will still run. Old code that +included QDialogs as child widgets will no longer work (it never really did). +If you think you might be doing this, put a breakpoint in +<a href="qdialog.html#QDialog">QDialog::QDialog</a>() conditional on parent not being 0. +<p> <h3><a name="QStrList">QStrList</a></h3> +<p> Many methods that took a <a href="qstrlist.html">QStrList</a> can now instead take a <a href="qstringlist.html">QStringList</a>, +which is a real list of <a href="qstring.html">QString</a> values. +<p> To use QStringList rather than QStrList, change loops that look like this: +<pre> + <a href="qstrlist.html">QStrList</a> list = ...; + const char* s; + for ( s = list.<a href="qptrlist.html#first">first</a>(); s; s = list.<a href="qptrlist.html#next">next</a>() ) { + process(s); + } +</pre> + +to be like this: +<pre> + <a href="qstringlist.html">QStringList</a> list = ...; + QStringList::ConstIterator i; + for ( i = list.<a href="qvaluelist.html#begin">begin</a>(); i != list.<a href="qvaluelist.html#end">end</a>(); ++i ) { + process(*i); + } +</pre> + +<p> In general, the QStrList functions are less efficient, building a temporary QStringList. +<p> The following functions now use QStringList rather than QStrList +for return types/parameters. +<p> <ul> +<li><tt>void <a href="qfiledialog.html#setFilters">QFileDialog::setFilters</a>(const <a href="qstrlist.html">QStrList</a>&)</tt> +becomes <tt>void QFileDialog::setFilters(const <a href="qstringlist.html">QStringList</a>&)</tt> +<li><tt>QStrList <a href="qfiledialog.html#getOpenFileNames">QFileDialog::getOpenFileNames</a>(...)</tt> +becomes <tt>QStringList QFileDialog::getOpenFileNames(...)</tt> +<li><tt>bool QUrlDrag::decodeLocalFiles(<a href="qmimesource.html">QMimeSource</a>*, QStrList&)</tt> +becomes <tt>bool <a href="quridrag.html#decodeLocalFiles">QUriDrag::decodeLocalFiles</a>(QMimeSource*, QStringList&)</tt> +<li><tt>const QStrList *QDir::entryList(...) const</tt> +becomes <tt>QStringList <a href="qdir.html#entryList">QDir::entryList</a>(...) const</tt> +(note that the return type is no longer a pointer). You may also +choose to use encodedEntryList(). +</ul> +<p> The following functions are added: +<ul> +<li><tt>QComboBox::insertStringList(const QStringList &, int index=-1)</tt> +<li><tt>QListBox::insertStringList(const QStringList &,int index=-1)</tt> +</ul> +<p> The rarely used static function <tt>void +QFont::listSubstitutions(<a href="qstrlist.html">QStrList</a>*)</tt> is replaced by <tt>QStringList +<a href="qfont.html#substitutions">QFont::substitutions</a>()</tt>. +<p> <h3><a name="QLayout">QLayout</a></h3> +<p> <p> Calling resize(0,0) or resize(1,1) will no longer work magically. +Remove all such calls. The default size of top level widgets will be their +<a href="qwidget.html#sizeHint">sizeHint()</a>. +<p> <p> The default implementation of <a href="qwidget.html#sizeHint">QWidget::sizeHint</a>() will no longer +return just an invalid size; if the widget has a layout, it will return +the layout's preferred size. +<p> <p> The special maximum MaximumHeight/Width is now QWIDGETSIZE_MAX, +not QCOORD_MAX. +<p> <p> <a href="qboxlayout.html#addWidget">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> <p> The class QGManager is removed. Subclasses of <a href="qlayout.html">QLayout</a> need to be rewritten +to use the new, much simpler <a href="qlayout.html">QLayout API</a>. +<p> <p> For typical layouts, all use of +<a href="qwidget.html#setMinimumSize">setMinimumSize()</a> +and +<a href="qwidget.html#setFixedSize">setFixedSize()</a> +can be removed. +<a href="qlayout.html#activate">activate()</a> is no longer necessary. +<p> <p> +You might like to look at the <a href="qgrid.html">QGrid</a>, <a href="qvbox.html">QVBox</a>, and <a href="qhbox.html">QHBox</a> widgets - they offer +a simple way to build nested widget structures. +<p> <h3><a name="QListView">QListView</a></h3> +<p> <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 <a href="qscrollview.html">QScrollView</a> 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(), +<a href="qwidget.html#mouseDoubleClickEvent">QListView::mouseDoubleClickEvent</a>(), <a href="qwidget.html#mouseMoveEvent">QListView::mouseMoveEvent</a>(), or +<a href="qwidget.html#mouseReleaseEvent">QListView::mouseReleaseEvent</a>() you must instead override +viewportMousePressEvent(), +viewportMouseDoubleClickEvent(), viewportMouseMoveEvent(), or +viewportMouseReleaseEvent() respectively. New code will usually override +contentsMousePressEvent() etc. +<p> <p>The signal <a href="qlistview.html#selectionChanged">QListView::selectionChanged</a>(<a href="qlistviewitem.html">QListViewItem</a> *) 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> <p> +The protected function +<pre> QMultiLineEdit::textWidth(QString*)</pre> + +changed to +<pre> QMultiLineEdit::textWidth(const <a href="qstring.html">QString</a>&)</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> <p> +<pre> QClipboard::pixmap()</pre> + now returns a <a href="qpixmap.html">QPixmap</a>, not a QPixmap*. +The pixmap +will be <a href="qpixmap.html#isNull">null</a> if no pixmap is on the +clipboard. <a href="qclipboard.html">QClipboard</a> 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#setAcceptDrops">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#viewport">viewport()</a> of a <a href="qlistview.html">QListView</a>, +in which case, +override the +<a href="qscrollview.html#contentsDragMoveEvent">contentsDragMoveEvent()</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#contentsMoving">contentsMoving(int,int)</a> +are now positive rather than negative values, coinciding with +<a href="qscrollview.html#setContentsPos">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 <a href="qscrollview.html">QScrollView</a>, you may experience the problem +described for <a href="#QDropSite">QDropSite</a>. +<p> <h3><a name="QTextStream">QTextStream</a></h3> +<p> <p> +<pre> operator<<(QTextStream&, QChar&)</pre> + does not skip whitespace. +<pre> operator<<(QTextStream&, char&)</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 <a href="quridrag.html">QUriDrag</a>, 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> <p> The GrayText painter flag has been removed. Use +<a href="qpainter.html#setPen">setPen( palette().disabled().foreground() )</a> +instead. +<p> <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> <p>The binary storage format of <a href="qpicture.html">QPicture</a> 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> <p>For writing Qt 1.x format QPictures, the compatibility issues of <a +href="#QDataStream">QDataStream</a> applies. +<p> <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, <a href="qpointarray.html">QPointArray</a>, <a href="qsize.html">QSize</a> and <a href="qrect.html">QRect</a></a></h3> +<p> <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> <p>QPointArray is now actually, not only seemingly, a QArray of <a href="qpoint.html">QPoint</a> +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> QPointArray::shortPoints()</pre> + +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> <a href="qimage.html">QImage</a> uses QRgb for the colors - see <a href="#QRgb">the changes to that</a>. +<p> <h3><a name="QPixmap">QPixmap</a></h3> +<p> <pre> QPixmap::convertToImage()</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> <p> +<pre> QPixmap::optimize(TRUE)</pre> + +is replaced by +<pre> QPixmap::setOptimization(QPixmap::NormalOptim)</pre> + +or +<pre> QPixmap::setOptimization(QPixmap::BestOptim)</pre> + +- 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 / <a href="qpopupmenu.html">QPopupMenu</a></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#insertItem">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> QMenuData::indexOf(int id)</pre> + +in the handling function instead. You may alternatively pass +<pre> QMenuData::count()</pre> + +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, <a href="qpopupmenu.html">QPopupMenu</a> no longer inherits QTableView. Instead, +it directly inherits <a href="qframe.html">QFrame</a>. +<p> <h3><a name="QValidator">QValidator (<a href="qlineedit.html">QLineEdit</a>, <a href="qcombobox.html">QComboBox</a>, <a href="qspinbox.html">QSpinBox</a>) </a></h3> +<p> <pre> QValidator::validate(...)</pre> + +and +<pre> QValidator::fixup( <a href="qstring.html">QString</a> & )</pre> + +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 <a href="qvalidator.html">QValidator</a>, 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 <a href="qobject.html">QObject</a> 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, <a href="qfileinfo.html">QFileInfo</a>, <a href="qdir.html">QDir</a></a></h3> +<p> File and directory names are now always Unicode strings (ie. <a href="qstring.html">QString</a>). 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(<a href="qchar.html">QChar</a>), 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 <a href="qwidget.html">QWidget</a> 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> <p> The global #define macros in qevent.h have been replaced by an +enum in <a href="qevent.html">QEvent</a>. 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> <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> <p> QChildEvents are now sent for all QObjects, not just QWidgets. +You may need to add extra checking if you use a <a href="qchildevent.html">QChildEvent</a> 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 <a href="qstring.html">QString</a>&", 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. +<p> +<!-- eof --> +<p><address><hr><div align=center> +<table width=100% cellspacing=0 border=0><tr> +<td>Copyright © 2007 +<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a> +<td align=right><div align=right>Qt 3.3.8</div> +</table></div></address></body> +</html> |