Commit 09e06dff authored by BST 2000  Tony Gale's avatar BST 2000 Tony Gale Committed by Tony Gale

Finish Section 6. Add Section 7.

Wed Jun 28 17:49:05 BST 2000  Tony Gale <gale@gtk.org>

        * docs/faq/gtk-faq.sgml: Finish Section 6. Add Section 7.
parent edacfcb7
Wed Jun 28 17:49:05 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Finish Section 6. Add Section 7.
Wed Jun 28 13:31:55 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Start of Section 6.
......
Wed Jun 28 17:49:05 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Finish Section 6. Add Section 7.
Wed Jun 28 13:31:55 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Start of Section 6.
......
Wed Jun 28 17:49:05 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Finish Section 6. Add Section 7.
Wed Jun 28 13:31:55 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Start of Section 6.
......
Wed Jun 28 17:49:05 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Finish Section 6. Add Section 7.
Wed Jun 28 13:31:55 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Start of Section 6.
......
Wed Jun 28 17:49:05 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Finish Section 6. Add Section 7.
Wed Jun 28 13:31:55 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Start of Section 6.
......
Wed Jun 28 17:49:05 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Finish Section 6. Add Section 7.
Wed Jun 28 13:31:55 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Start of Section 6.
......
Wed Jun 28 17:49:05 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Finish Section 6. Add Section 7.
Wed Jun 28 13:31:55 BST 2000 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Start of Section 6.
......
......@@ -2499,7 +2499,389 @@ gtk_misc_set_alignment(GTK_MISK(label), 1.0f, 1.0f);
a GtkLabel widget, you need to change the background color of
its parent, i.e. the object that you pack it into.</para>
</sect2>
<!-- ----------------------------------------------------------------- -->
<sect2>
<title>How do I set the color and font of a GtkLabel using a
Resource File?</title>
<para>The widget name path constructed for a Label consists of
the widget names of its object hierarchy as well, e.g.</para>
<para><literallayout>
<literal>window (name: humphrey)</literal>
<literal> hbox</literal>
<literal> label (name: mylabel)</literal>
</literallayout></para>
<para>The widget path your pattern needs to match would be:
<literal>humphrey.GtkHBox.mylabel</literal></para>
<para>The resource file may look something like:</para>
<programlisting role="C">
style "title"
{
fg[NORMAL] = {1.0, 0.0, 0.0}
font = "-adobe-helvetica-bold-r-normal--*-140-*-*-*-*-*-*"
}
widget "*mylabel" style "title"
</programlisting>
<para>In your program, you would also need to give a name to
the Label widget, which can be done using:</para>
<programlisting role="C">
label = gtk_label_new("Some Label Text");
gtk_widget_set_name(label, "mylabel");
gtk_widget_show(label);
</programlisting>
</sect2>
<!-- ----------------------------------------------------------------- -->
<sect2>
<title>How do I configure Tooltips in a Resource File?</title>
<para>The tooltip's window is named "gtk-tooltips",
GtkTooltips in itself is not a GtkWidget (though a GtkObject)
and as such is not attempted to match any widget styles.</para>
<para>So, you resource file should look something like:</para>
<programlisting role="C">
style "postie"
{
bg[NORMAL] = {1.0, 1.0, 0.0}
}
widget "gtk-tooltips*" style "postie"
</programlisting>
</sect2>
<!-- ----------------------------------------------------------------- -->
<sect2>
<title>I can't add more than (something like) 2000 chars in a
GtkEntry. What's wrong?</title>
<para>There is now a known problem in the GtkEntry widget. In
the <literal>gtk_entry_insert_text()</literal> function, the
following lines limit the number of chars in the entry to
2047.</para>
<programlisting role="C">
/* The algorithms here will work as long as, the text size (a
* multiple of 2), fits into a guint16 but we specify a shorter
* maximum length so that if the user pastes a very long text, there
* is not a long hang from the slow X_LOCALE functions. */
if (entry->text_max_length == 0)
max_length = 2047;
else
max_length = MIN (2047, entry->text_max_length);
</programlisting>
</sect2>
<!-- ----------------------------------------------------------------- -->
<sect2>
<title>How do I make a GtkEntry widget activate on pressing
the Return key?</title>
<para>The Entry widget emits an 'activate' signal when you
press return in it. Just attach to the activate signal on the
entry and do whatever you want to do. Typical code would
be:</para>
<programlisting role="C">
entry = gtk_entry_new();
gtk_signal_connect (GTK_OBJECT(entry), "activate",
GTK_SIGNAL_FUNC(entry_callback),
NULL);
</programlisting>
</sect2>
<!-- ----------------------------------------------------------------- -->
<sect2>
<title>How do I validate/limit/filter the input to a
GtkEntry?</title>
<para>If you want to validate the text that a user enters into
a GtkEntry widget you can attach to the "insert_text" signal
of the entry, and modify the text within the callback
function. The example below forces all characters to
uppercase, and limits the range of characters to A-Z. Note
that the entry is cast to an object of type GtkEditable, from
which GtkEntry is derived.</para>
<programlisting role="C">
#include &lt;ctype.h&gt;
#include &lt;gtk/gtk.h&gt;
void insert_text_handler (GtkEntry *entry,
const gchar *text,
gint length,
gint *position,
gpointer data)
{
GtkEditable *editable = GTK_EDITABLE(entry);
int i, count=0;
gchar *result = g_new (gchar, length);
for (i=0; i < length; i++) {
if (!isalpha(text[i]))
continue;
result[count++] = islower(text[i]) ? toupper(text[i]) : text[i];
}
if (count > 0) {
gtk_signal_handler_block_by_func (GTK_OBJECT (editable),
GTK_SIGNAL_FUNC (insert_text_handler),
data);
gtk_editable_insert_text (editable, result, count, position);
gtk_signal_handler_unblock_by_func (GTK_OBJECT (editable),
GTK_SIGNAL_FUNC (insert_text_handler),
data);
}
gtk_signal_emit_stop_by_name (GTK_OBJECT (editable), "insert_text");
g_free (result);
}
int main (int argc,
char *argv[])
{
GtkWidget *window;
GtkWidget *entry;
gtk_init (&amp;argc, &amp;argv);
/* create a new window */
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_title(GTK_WINDOW (window), "GTK Entry");
gtk_signal_connect(GTK_OBJECT (window), "delete_event",
(GtkSignalFunc) gtk_exit, NULL);
entry = gtk_entry_new();
gtk_signal_connect(GTK_OBJECT(entry), "insert_text",
GTK_SIGNAL_FUNC(insert_text_handler),
NULL);
gtk_container_add(GTK_CONTAINER (window), entry);
gtk_widget_show(entry);
gtk_widget_show(window);
gtk_main();
return(0);
}
</programlisting>
</sect2>
<!-- ----------------------------------------------------------------- -->
<sect2>
<title>How do I use horizontal scrollbars with a GtkText
widget?</title>
<para>The short answer is that you can't. The current version
of the GtkText widget does not support horizontal
scrolling. There is an intention to completely rewrite the
GtkText widget, at which time this limitation will be
removed.</para>
</sect2>
<!-- ----------------------------------------------------------------- -->
<sect2>
<title>How do I change the font of a GtkText widget?</title>
<para>There are a couple of ways of doing this. As GTK+ allows
the appearance of applications to be changed at run time using
resources you can use something like the following in the
appropriate file:</para>
<programlisting role="C">
style "text"
{
font = "-adobe-helvetica-medium-r-normal--*-100-*-*-*-*-*-*"
}
</programlisting>
<para>Another way to do this is to load a font within your
program, and then use this in the functions for adding text to
the text widget. You can load a font using, for example:</para>
<programlisting role="C">
GdkFont *font;
font = gdk_font_load("-adobe-helvetica-medium-r-normal--*-140-*-*-*-*-*-*");
</programlisting>
</sect2>
<!-- ----------------------------------------------------------------- -->
<sect2>
<title>How do I set the cursor position in a GtkText
object?</title>
<para>Notice that the response is valid for any object that
inherits from the GtkEditable class.</para>
<para>Are you sure that you want to move the cursor position?
Most of the time, while the cursor position is good, the
insertion point does not match the cursor position. If this
apply to what you really want, then you should use the
<literal>gtk_text_set_point()</literal> function. If you want
to set the insertion point at the current cursor position, use
the following:</para>
<programlisting role="C">
gtk_text_set_point(GTK_TEXT(text),
gtk_editable_get_position(GTK_EDITABLE(text)));
</programlisting>
<para>If you want the insertion point to follow the cursor at
all time, you should probably catch the button press event,
and then move the insertion point. Be careful : you'll have to
catch it after the widget has changed the cursor position
though. Thomas Mailund Jensen proposed the following
code:</para>
<programlisting role="C">
static void
insert_bar (GtkWidget *text)
{
/* jump to cursor mark */
gtk_text_set_point (GTK_TEXT (text),
gtk_editable_get_position (GTK_EDITABLE (text)));
gtk_text_insert (GTK_TEXT (text), NULL, NULL, NULL,
"bar", strlen ("bar"));
}
int
main (int argc, char *argv[])
{
GtkWidget *window, *text;
gtk_init (&amp;argc, &amp;argv);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
text = gtk_text_new (NULL, NULL);
gtk_text_set_editable (GTK_TEXT (text), TRUE);
gtk_container_add (GTK_CONTAINER (window), text);
/* connect after everything else */
gtk_signal_connect_after (GTK_OBJECT(text), "button_press_event",
GTK_SIGNAL_FUNC (insert_bar), NULL);
gtk_widget_show_all(window);
gtk_main();
return 0;
}
</programlisting>
<para>Now, if you really want to change the cursor position,
you should use the
<literal>gtk_editable_set_position()</literal>
function.</para>
</sect2>
</sect1>
</chapter>
<!-- ***************************************************************** -->
<chapter>
<title>About GDK</title>
<sect1>
<title></title>
<!-- ----------------------------------------------------------------- -->
<sect2>
<title>What is GDK?</title>
<para>GDK is basically a wrapper around the standard Xlib
function calls. If you are at all familiar with Xlib, a lot of
the functions in GDK will require little or no getting used
to. All functions are written to provide an way to access Xlib
functions in an easier and slightly more intuitive manner. In
addition, since GDK uses GLib (see below), it will be more
portable and safer to use on multiple platforms.</para>
<!-- Examples, anybody? I've been mulling some over. NF -->
</sect2>
<!-- ----------------------------------------------------------------- -->
<sect2>
<title>How do I use color allocation?</title>
<para>One of the nice things about GDK is that it's based on
top of Xlib; this is also a problem, especially in the area of
color management. If you want to use color in your program
(drawing a rectangle or such, your code should look something
like this:</para>
<programlisting role="C">
{
GdkColor *color;
int width, height;
GtkWidget *widget;
GdkGC *gc;
...
/* first, create a GC to draw on */
gc = gdk_gc_new(widget->window);
/* find proper dimensions for rectangle */
gdk_window_get_size(widget->window, &amp;width, &amp;height);
/* the color we want to use */
color = (GdkColor *)malloc(sizeof(GdkColor));
/* red, green, and blue are passed values, indicating the RGB triple
* of the color we want to draw. Note that the values of the RGB components
* within the GdkColor are taken from 0 to 65535, not 0 to 255.
*/
color->red = red * (65535/255);
color->green = green * (65535/255);
color->blue = blue * (65535/255);
/* the pixel value indicates the index in the colormap of the color.
* it is simply a combination of the RGB values we set earlier
*/
color->pixel = (gulong)(red*65536 + green*256 + blue);
/* However, the pixel valule is only truly valid on 24-bit (TrueColor)
* displays. Therefore, this call is required so that GDK and X can
* give us the closest color available in the colormap
*/
gdk_color_alloc(gtk_widget_get_colormap(widget), color);
/* set the foreground to our color */
gdk_gc_set_foreground(gc, color);
/* draw the rectangle */
gdk_draw_rectangle(widget->window, gc, 1, 0, 0, width, height);
...
}
</programlisting>
</sect2>
</sect1>
</chapter>
......
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