📄 sec-gtkarg.html
字号:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html> <head> <title> GtkArg and the Type System </title> <meta name="GENERATOR" content= "Modular DocBook HTML Stylesheet Version 1.45"> <link rel="HOME" title="GTK+ / Gnome Application Development" href="ggad.html"> <link rel="UP" title="The GTK+ Object and Type System" href= "cha-objects.html"> <link rel="PREVIOUS" title="Initializing a New Class" href= "sec-classinit.html"> <link rel="NEXT" title="Object Arguments" href= "hc-objectargs.html"> </head> <body bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink= "#840084" alink="#0000FF"> <div class="NAVHEADER"> <table width="100%" border="0" bgcolor="#ffffff" cellpadding= "1" cellspacing="0"> <tr> <th colspan="4" align="center"> <font color="#000000" size="2">GTK+ / Gnome Application Development</font> </th> </tr> <tr> <td width="25%" bgcolor="#ffffff" align="left"> <a href="sec-classinit.html"><font color="#0000ff" size="2"><b><<< Previous</b></font></a> </td> <td width="25%" colspan="2" bgcolor="#ffffff" align= "center"> <font color="#0000ff" size="2"><b><a href="ggad.html"> <font color="#0000ff" size="2"><b> Home</b></font></a></b></font> </td> <td width="25%" bgcolor="#ffffff" align="right"> <a href="hc-objectargs.html"><font color="#0000ff" size="2"><b>Next >>></b></font></a> </td> </tr> </table> </div> <div class="SECT1"> <h1 class="SECT1"> <a name="SEC-GTKARG"><span class="STRUCTNAME">GtkArg</span> and the Type System</a> </h1> <p> Before delving further into <span class="STRUCTNAME"> GtkObject</span>, you will need more details on GTK+'s type system. The type system is used in many contexts: </p> <ul> <li> <p> It allows signals and callbacks with any signature to be dynamically registered and dynamically queried. Function argument lists can be constructed at runtime. </p> </li> <li> <p> It allows object attributes (values that you can "get" or "set") to be dynamically queried and manipulated. </p> </li> <li> <p> It exports information about enumerations and bitfields (lists of permitted values, and human-readable names). </p> </li> <li> <p> It is possible to identify types at runtime and traverse the object class hierarchy. </p> </li> </ul> <p> Because of its type system, GTK+ is particularly easy to manipulate from dynamically-typed, interactive languages. There are bindings available for nearly all popular languages, and the bindings can be lightweight (since GTK+ already includes much of the needed functionality, and types can be handled generically so the amount of glue code is reduced). You can find a complete list of functions for querying and using GTK+'s type system in <tt class= "FILENAME">gtk/gtktypeutils.h</tt>; most of these are not useful in applications. Only the functions of general interest are described in this book. </p> <p> GTK+ has a number of so-called <i class="FIRSTTERM"> fundamental</i> types which are automatically registered during <tt class="FUNCTION">gtk_init()</tt> (or <tt class= "FUNCTION">gnome_init()</tt>). The fundamental types include all the primitive C types, some GTK+ types such as <span class="STRUCTNAME">GTK_TYPE_SIGNAL</span>, and <span class="STRUCTNAME">GTK_TYPE_OBJECT</span>. Fundamental types are essentially the "base classes" understood by the GTK+ type system; for example, the fundamental type of any enumeration is <span class="STRUCTNAME"> GTK_TYPE_ENUM</span>, and the fundamental type of any <span class="STRUCTNAME">GtkObject</span> subclass is <span class="STRUCTNAME">GTK_TYPE_OBJECT</span>. Fundamental types are supposed to cover all the "special cases" in the GTK+ type system; all types ultimately derive from some fundamental type. A type's fundamental type is extracted from a <span class="STRUCTNAME">GtkType</span> with the <tt class="FUNCTION">GTK_FUNDAMENTAL_TYPE()</tt> macro. The fundamental types are shown in <a href= "sec-gtkarg.html#TABLE-FUNDTYPES">Table 1</a>. </p> <p> There is a second category of <span class="STRUCTNAME"> GtkType</span> values: <i class="FIRSTTERM">builtin</i> types are registered by GTK+ and <tt class="APPLICATION"> libgnomeui</tt> during library initialization and are thus always available. Builtin types include enumerations, flags, and some structs (<span class= "STRUCTNAME">GdkWindow</span>, or <span class="STRUCTNAME"> GdkImlibImage</span>, for example). Builtin types are distinct from fundamental types because the GTK+ object system does not have to understand them; for the purposes of getting and setting argument values, they can be treated as fundamental types. They are somewhat arbitrarily distinguished from user-registered enumeration or flag types. (The difference between builtin types and user types is the time of registration.) </p> <p> Builtin types are all accessible via macros that come with GTK+ and Gnome. These begin with <span class="STRUCTNAME"> GTK_TYPE_</span>, as in: <span class="STRUCTNAME"> GTK_TYPE_WINDOW</span>, <span class="STRUCTNAME"> GTK_TYPE_GDK_WINDOW</span>, <span class="STRUCTNAME"> GTK_TYPE_RELIEF_STYLE</span>, <span class="STRUCTNAME"> GTK_TYPE_GNOME_DIALOG</span>. As you can see, the name of the type macro is derived from the name of the <span class= "STRUCTNAME">GtkObject</span>, struct, or enumeration; if the object name begins with "Gtk," the "Gtk" is dropped. The above examples map to the <tt class="CLASSNAME"> GtkWindow</tt> widget, <span class="STRUCTNAME"> GdkWindow</span> struct, <span class="STRUCTNAME"> GtkReliefStyle</span> enumeration, and <span class= "STRUCTNAME">GnomeDialog</span> widget, respectively. </p> <p> The final major category of <span class="STRUCTNAME"> GtkType</span> values consists of the registered <span class="STRUCTNAME">GtkObject</span> types. These are registered the first time the <span class="STRUCTNAME"> _get_type()</span> routine for each object is called. </p> <div class="TABLE"> <a name="TABLE-FUNDTYPES"></a> <p> <b>Table 1. The GTK+ Fundamental Types</b> </p> <table border="1" bgcolor="#E0E0E0" cellspacing="0" cellpadding="4" class="CALSTABLE"> <tr> <th align="LEFT" valign="TOP"> <span class="STRUCTNAME">GtkType</span> Constant </th> <th align="LEFT" valign="TOP"> Corresponding C Type </th> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_INVALID</span> </td> <td align="LEFT" valign="TOP"> None </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_NONE</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">void</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_CHAR</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gchar</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_UCHAR</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">guchar</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_BOOL</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gboolean</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_INT</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gint</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_UINT</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">guint</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_LONG</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">glong</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_ULONG</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gulong</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_FLOAT</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gfloat</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_DOUBLE</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gdouble</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_STRING</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gchar*</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_ENUM</span> </td> <td align="LEFT" valign="TOP"> Any enumeration </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_FLAGS</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">guint</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_BOXED</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gpointer</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_POINTER</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gpointer</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_SIGNAL</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GtkSignalFunc</span>, <span class="STRUCTNAME">gpointer</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_ARGS</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gint</span>, <span class= "STRUCTNAME">GtkArg*</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_CALLBACK</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GtkCallbackMarshal</span>, <span class="STRUCTNAME">gpointer</span>, <span class="STRUCTNAME">GtkDestroyNotify</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_C_CALLBACK</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GtkFunction</span>, <span class="STRUCTNAME">gpointer</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_FOREIGN</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">gpointer</span>, <span class="STRUCTNAME">GtkDestroyNotify</span> </td> </tr> <tr> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GTK_TYPE_OBJECT</span> </td> <td align="LEFT" valign="TOP"> <span class="STRUCTNAME">GtkObject*</span> </td> </tr> </table> </div> <p> Some of the fundamental types require further explanation. In brief:⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -