当我们制作一套软体, 您会希望在视窗内放超过一个以上的按钮. 我们第一个范例"hello world"仅用一个物件, 因此我们能够很简单使用gtk_container_add来"封装"该物件到视窗中. 但当您希够望放更多的物件到视窗中, 要如何控制它们的位置? 这里就要用到"封装"(Packing).
大部份的封装是由产生boxes来达成的. 这些是看不见的widget containers, 我们可以用两种形式来将我们的物件封装进去, vertical box及horizontal box. 当我们封装物件到一个horizontal box时, 物件是依我们呼叫的顺序由右至左平行的被新增进去. 在vertical box, 物件是由上至下. 您可以将物件插入box, 也可以将boxes插入box, 任意的组合用以产生所想要的效果.
要产生horizontal box,我们使用gtk_hbox_new(), 而vertical boxe使用gtk_vbox_new(). gtk_box_pack_start()及gtk_box_pack_end()函数 是用来将物件放到containers里面. gtk_box_pack_start()函数会开始由左至右, 由上至下来封装物件. gtk_box_pack_end()则相反, 由下至上, 由右至左. 使用这些函数允许我们对右边或对左边较正, 而且可以用许多种方式来较正来取得所想要的效果. 一个object可以是另一个container或物件. 而且事实上, 许多物件本身也是containers. 像按钮就是, 不过我们一般只在按钮中用一个标签.
使用这些呼叫, GTK知道要把物件放到那里去, 并且会自动缩放及其它比例上的调整. 还有许多其它选项可以控制如何将物件封装在一起. 正如您所想的, 这些方法可以给您许多的弹性来制作视窗.
由於这样的弹性, packing boxes在一开始使用的话会有点搞糊涂. 还有许多其它的选项,一开始还看不太出来它们如何凑在一起. 最後您会知道, 他们基本上有五种不同的型式.
每一行包含一个horizontal box (hbox)及好几个按钮. 所有按钮都是以同样的方式来包入hbox内.
这是gtk_box_pack_start的宣告.
void gtk_box_pack_start (GtkBox *box,
GtkWidget *child,
gint expand,
gint fill,
gint padding);
第一个参数是您要把object放进去的box, 第二个是该object. 现在这些物件将会都是按钮.
expand参数在gtk_box_pack_start()或gtk_box_pack_end()中控制 物件如何在box中排列. expand = TRUE的话它们会填满box中所有额外的空间. expand = FALSE的话, 该box会缩小到刚好该物件的大小. 设expand=FALSE您可做好左右较正. 否则它们会填满整个box. 同样的效果可用tk_box_pack_start或pack_end functions来达成.
fill参数在gtk_box_pack中控制额外空间. fill=TRUE该物件会自行产生额外空间, fill=FALSE则由box产生一个在物件周围的填白区域. 这只有在expand=TRUE时, 才会有作用.
当产生一个新的box, 该函数看起来像这样:
GtkWidget * gtk_hbox_new (gint homogeneous,
gint spacing);
homogeneous参数在gtk_hbox_new (and the same for gtk_vbox_new) 控制每个物件是否有同样的宽或高. 若homogeneous=TRUE, 则expand也会被开启.
空白(spacing)及填白(padding)有什麽不同呢 空白是加在物件之间, 填白只加在物件的一边. 看以下这张图可能会明白一点:
这里是一些用来产生以上影像的程式. 我做了蛮多的注解, 希望您不会有问题. 将它编译然後玩玩它.
#include "gtk/gtk.h"
void
destroy (GtkWidget *widget, gpointer *data)
{
gtk_main_quit ();
}
/* Make a new hbox filled with button-labels. Arguments for the
* variables we're interested are passed in to this function.
* We do not show the box, but do show everything inside. */
GtkWidget *make_box (gint homogeneous, gint spacing,
gint expand, gint fill, gint padding)
{
GtkWidget *box;
GtkWidget *button;
char padstr[80];
/* create a new hbox with the appropriate homogeneous and spacing
* settings */
box = gtk_hbox_new (homogeneous, spacing);
/* create a series of buttons with the appropriate settings */
button = gtk_button_new_with_label ("gtk_box_pack");
gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
gtk_widget_show (button);
button = gtk_button_new_with_label ("(box,");
gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
gtk_widget_show (button);
button = gtk_button_new_with_label ("button,");
gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
gtk_widget_show (button);
/* create a button with the label depending on the value of
* expand. */
if (expand == TRUE)
button = gtk_button_new_with_label ("TRUE,");
else
button = gtk_button_new_with_label ("FALSE,");
gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
gtk_widget_show (button);
/* This is the same as the button creation for "expand"
* above, but uses the shorthand form. */
button = gtk_button_new_with_label (fill ? "TRUE," : "FALSE,");
gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
gtk_widget_show (button);
sprintf (padstr, "%d);", padding);
button = gtk_button_new_with_label (padstr);
gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
gtk_widget_show (button);
return box;
}
int
main (int argc, char *argv[])
{
GtkWidget *window;
GtkWidget *button;
GtkWidget *box1;
GtkWidget *box2;
GtkWidget *separator;
GtkWidget *label;
GtkWidget *quitbox;
int which;
/* Our init, don't forget this! :) */
gtk_init (&argc, &argv);
if (argc != 2) {
fprintf (stderr, "usage: packbox num, where num is 1, 2, or 3.\n");
/* this just does cleanup in GTK, and exits with an exit status of 1. */
gtk_exit (1);
}
which = atoi (argv[1]);
/* Create our window */
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
/* You should always remember to connect the destroy signal to the
* main window. This is very important for proper intuitive
* behavior */
gtk_signal_connect (GTK_OBJECT (window), "destroy",
GTK_SIGNAL_FUNC (destroy), NULL);
gtk_container_border_width (GTK_CONTAINER (window), 10);
/* We create a vertical box (vbox) to pack the horizontal boxes into.
* This allows us to stack the horizontal boxes filled with buttons one
* on top of the other in this vbox. */
box1 = gtk_vbox_new (FALSE, 0);
/* which example to show. These correspond to the pictures above. */
switch (which) {
case 1:
/* create a new label. */
label = gtk_label_new ("gtk_hbox_new (FALSE, 0);");
/* Align the label to the left side. We'll discuss this function and
* others in the section on Widget Attributes. */
gtk_misc_set_alignment (GTK_MISC (label), 0, 0);
/* Pack the label into the vertical box (vbox box1). Remember that
* widgets added to a vbox will be packed one on top of the other in
* order. */
gtk_box_pack_start (GTK_BOX (box1), label, FALSE, FALSE, 0);
/* show the label */
gtk_widget_show (label);
/* call our make box function - homogeneous = FALSE, spacing = 0,
* expand = FALSE, fill = FALSE, padding = 0 */
box2 = make_box (FALSE, 0, FALSE, FALSE, 0);
gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
gtk_widget_show (box2);
/* call our make box function - homogeneous = FALSE, spacing = 0,
* expand = FALSE, fill = FALSE, padding = 0 */
box2 = make_box (FALSE, 0, TRUE, FALSE, 0);
gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
gtk_widget_show (box2);
/* Args are: homogeneous, spacing, expand, fill, padding */
box2 = make_box (FALSE, 0, TRUE, TRUE, 0);
gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
gtk_widget_show (box2);
/* creates a separator, we'll learn more about these later,
* but they are quite simple. */
separator = gtk_hseparator_new ();
/* pack the separator into the vbox. Remember each of these
* widgets are being packed into a vbox, so they'll be stacked
* vertically. */
gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 5);
gtk_widget_show (separator);
/* create another new label, and show it. */
label = gtk_label_new ("gtk_hbox_new (TRUE, 0);");
gtk_misc_set_alignment (GTK_MISC (label), 0, 0);
gtk_box_pack_start (GTK_BOX (box1), label, FALSE, FALSE, 0);
gtk_widget_show (label);
/* Args are: homogeneous, spacing, expand, fill, padding */
box2 = make_box (TRUE, 0, TRUE, FALSE, 0);
gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
gtk_widget_show (box2);
/* Args are: homogeneous, spacing, expand, fill, padding */
box2 = make_box (TRUE, 0, TRUE, TRUE, 0);
gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
gtk_widget_show (box2);
/* another new separator. */
separator = gtk_hseparator_new ();
/* The last 3 arguments to gtk_box_pack_start are: expand, fill, padding. */
gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 5);
gtk_widget_show (separator);
break;
case 2:
/* create a new label, remember box1 is a vbox as created
* near the beginning of main() */
label = gtk_label_new ("gtk_hbox_new (FALSE, 10);");
gtk_misc_set_alignment (GTK_MISC (label), 0, 0);
gtk_box_pack_start (GTK_BOX (box1), label, FALSE, FALSE, 0);
gtk_widget_show (label);
/* Args are: homogeneous, spacing, expand, fill, padding */
box2 = make_box (FALSE, 10, TRUE, FALSE, 0);
gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
gtk_widget_show (box2);
/* Args are: homogeneous, spacing, expand, fill, padding */
box2 = make_box (FALSE, 10, TRUE, TRUE, 0);
gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
gtk_widget_show (box2);
separator = gtk_hseparator_new ();
/* The last 3 arguments to gtk_box_pack_start are: expand, fill, padding. */
gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 5);
gtk_widget_show (separator);
label = gtk_label_new ("gtk_hbox_new (FALSE, 0);");
gtk_misc_set_alignment (GTK_MISC (label), 0, 0);
gtk_box_pack_start (GTK_BOX (box1), label, FALSE, FALSE, 0);
gtk_widget_show (label);
/* Args are: homogeneous, spacing, expand, fill, padding */
box2 = make_box (FALSE, 0, TRUE, FALSE, 10);
gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
gtk_widget_show (box2);
/* Args are: homogeneous, spacing, expand, fill, padding */
box2 = make_box (FALSE, 0, TRUE, TRUE, 10);
gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
gtk_widget_show (box2);
separator = gtk_hseparator_new ();
/* The last 3 arguments to gtk_box_pack_start are: expand, fill, padding. */
gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 5);
gtk_widget_show (separator);
break;
case 3:
/* This demonstrates the ability to use gtk_box_pack_end() to
* right justify widgets. First, we create a new box as before. */
box2 = make_box (FALSE, 0, FALSE, FALSE, 0);
/* create the label that will be put at the end. */
label = gtk_label_new ("end");
/* pack it using gtk_box_pack_end(), so it is put on the right side
* of the hbox created in the make_box() call. */
gtk_box_pack_end (GTK_BOX (box2), label, FALSE, FALSE, 0);
/* show the label. */
gtk_widget_show (label);
/* pack box2 into box1 (the vbox remember ? :) */
gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
gtk_widget_show (box2);
/* a separator for the bottom. */
separator = gtk_hseparator_new ();
/* this explicitly sets the separator to 400 pixels wide by 5 pixels
* high. This is so the hbox we created will also be 400 pixels wide,
* and the "end" label will be separated from the other labels in the
* hbox. Otherwise, all the widgets in the hbox would be packed as
* close together as possible. */
gtk_widget_set_usize (separator, 400, 5);
/* pack the separator into the vbox (box1) created near the start
* of main() */
gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 5);
gtk_widget_show (separator);
}
/* Create another new hbox.. remember we can use as many as we need! */
quitbox = gtk_hbox_new (FALSE, 0);
/* Our quit button. */
button = gtk_button_new_with_label ("Quit");
/* setup the signal to destroy the window. Remember that this will send
* the "destroy" signal to the window which will be caught by our signal
* handler as defined above. */
gtk_signal_connect_object (GTK_OBJECT (button), "clicked",
GTK_SIGNAL_FUNC (gtk_widget_destroy),
GTK_OBJECT (window));
/* pack the button into the quitbox.
* The last 3 arguments to gtk_box_pack_start are: expand, fill, padding. */
gtk_box_pack_start (GTK_BOX (quitbox), button, TRUE, FALSE, 0);
/* pack the quitbox into the vbox (box1) */
gtk_box_pack_start (GTK_BOX (box1), quitbox, FALSE, FALSE, 0);
/* pack the vbox (box1) which now contains all our widgets, into the
* main window. */
gtk_container_add (GTK_CONTAINER (window), box1);
/* and show everything left */
gtk_widget_show (button);
gtk_widget_show (quitbox);
gtk_widget_show (box1);
/* Showing the window last so everything pops up at once. */
gtk_widget_show (window);
/* And of course, our main function. */
gtk_main ();
/* control returns here when gtk_main_quit() is called, but not when
* gtk_exit is used. */
return 0;
}
我们来看看另一个封装的方法 - 用表格. 在很多状况下, 这是极其有用的.
使用表格, 我们产生格线来将物件放入. 物件会照我们安排的位置排入.
我们第一个要看的是gtk_table_new这个函数:
GtkWidget* gtk_table_new (gint rows,
gint columns,
gint homogeneous);
第一个参数是多少列, 第二个是多少栏.
homogeneous参数用来决定表格如何来定大小. 若homogeneous为TRUE, table boxes会被重定为在其中最大物件的大小. 若homogeneous为FALSE, 则其大小为, "高"为列中最高的物件, 及"宽"栏中最宽的物件大小.
列及栏的编号为从0到n. n是我们在gtk_table_new中所指定的值. 所以, 如果您指定rows = 2及columns = 2, 整个排列会看起来像这样:
0 1 2
0+----------+----------+
| | |
1+----------+----------+
| | |
2+----------+----------+
坐标系统开始於左上角. 要把物件放进box中, 可用以下函数:
void gtk_table_attach (GtkTable *table,
GtkWidget *child,
gint left_attach,
gint right_attach,
gint top_attach,
gint bottom_attach,
gint xoptions,
gint yoptions,
gint xpadding,
gint ypadding);
第一个参数("table")是您才刚产生的表格, 而第二个("child")是您想放进去的物件.
而left_attach及right_attach参数指定要把物件放在那里, 及用多少个boxes. 如果您想要用右下角的表格, 可以这样填表. left_attach = 1, right_attach = 2, top_attach = 1, bottom_attach = 2.
现在, 如果您想要物件来使用上面2x2的表格, 您可以使用left_attach = 0, right_attach =2, top_attach = 0, bottom_attach = 1.
xoptions及yoptions是用来指定封装选项, 可以同时组合多个选项(用or).
这些选项是:
填空就像boxes, 产生一个在物件周边空白的区域.
gtk_table_attach()有许多选项. 这里有个捷径:
void gtk_table_attach_defaults (GtkTable *table,
GtkWidget *widget,
gint left_attach,
gint right_attach,
gint top_attach,
gint bottom_attach);
X及Y选项内定为GTK_FILL | GTK_EXPAND, X及Y填空则设为0. 其馀的参数则相同於以上的函数.
我们另外有gtk_table_set_row_spacing()及gtk_table_set_col_spacing(). 这些会在指定的栏及列插入空白.
void gtk_table_set_row_spacing (GtkTable *table,
gint row,
gint spacing);
void gtk_table_set_col_spacing (GtkTable *table,
gint column,
gint spacing);
对栏来说, 空格是在栏的右边. 而列则是在下面.
您也可以用以下函数来产生固定的空格.
void gtk_table_set_row_spacings (GtkTable *table,
gint spacing);
及,
void gtk_table_set_col_spacings (GtkTable *table,
gint spacing);
使用这些函数, 其最後一栏及最後一列并没有空格存在.
目前并无说明, 请参照testgtk.c