<li><a class="section" href="#font">Handling text and fonts</a>
<ol>
<li><a class="subsection" href="#fontstruct">The Font structure</a>
- <li>Loading a Font
- <li>Assigning a Font to a Graphic Context
- <li>Drawing text in a window
+ <li><a class="subsection" href="#openingfont">Opening a Font</a>
+ <li><a class="subsection" href="#assigningfont">Assigning a Font to a Graphic Context</a>
+ <li><a class="subsection" href="#drawingtext">Drawing text in a drawable</a>
+ <li><a class="subsection" href="#fontcompleteexample">Complete example</a>
</ol>
<li>Windows hierarchy
<ol>
<li><a class="subsection" href="#DoesBackingStore">DoesBackingStore</a>
<li><a class="subsection" href="#EventMaskOfScreen">EventMaskOfScreen</a>
</ol>
- <li><a class="subsection" href="#misc">Miscellaneaous macros</a>
+ <li><a class="subsection" href="#misc">Miscellaneous macros</a>
<ol>
<li><a class="subsection" href="#DisplayOfScreen">DisplayOfScreen</a>
<li><a class="subsection" href="#DisplayCells">DisplayCells / CellsOfScreen</a>
with the <a href="http://xcb.freedesktop.org">XCB</a>
library. keep in mind that XCB, like the
<a href="http://tronche.com/gui/x/xlib/introduction">Xlib</a>
- library, isn't what post programmers wanting to write X
+ library, isn't what most programmers wanting to write X
applications are looking for. They should use a much higher
level GUI toolkit like Motif,
<a href="http://www.lesstif.org">LessTiff</a>,
<a href="http://www.gtk.org">GTK</a>,
- <a href="http://www.trolltech.com">QT</a> or
- <a href="http://www.enlightenment.org">EWL</a>, or use
+ <a href="http://www.trolltech.com">QT</a>,
+ <a href="http://www.enlightenment.org">EWL</a>,
+ <a href="http://www.enlightenment.org">ETK</a>, or use
<a href="http://cairographics.org">Cairo</a>.
However,
we need to start somewhere. More than this, knowing how things
diff = end - start;
/* free var */
- for (i = 0; i < count; ++i)
- free (names[i]);
free (atoms);
free (cs);
printf ("ratio : %f\n", diff_x / diff);
free (atoms_x);
+ for (i = 0; i < count; ++i)
+ free (names[i]);
free (names);
XCloseDisplay (disp);
change its attributes (for example, changing the foreground
color we use to draw a line, or changing the attributes of the
font we use to display strings. See Subsections Drawing with a
- color and Assigning a Font to a Graphic Context). This is done
- by using this function:
+ color and
+ <a href="#assigningfont">Assigning a Font to a Graphic Context</a>).
+ This is done by using this function:
</p>
<pre class="code">
xcb_void_cookie_t xcb_change_gc (xcb_connection_t *c, /* The XCB Connection */
/* We draw the polygonal line */
xcb_poly_line (c, XCB_COORD_MODE_PREVIOUS, win, foreground, 4, polyline);
- /* We draw the segements */
+ /* We draw the segments */
xcb_poly_segment (c, win, foreground, 2, segments);
/* We draw the rectangles */
</pre>
<p>
If the window has already been created, we can use the
- <span class="code">xcb_configure_window()</span> function to set
+ <span class="code">xcb_change_window_attributes()</span> function to set
the events that the window will receive. The subsection
<a href="#winconf">Configuring a window</a> shows its
prototype. As an example, here is a piece of code that
/* The connection c and the window win are supposed to be defined */
-xcb_configure_window (c, win, XCB_CW_EVENT_MASK, values);
+xcb_change_window_attributes (c, win, XCB_CW_EVENT_MASK, values);
</pre>
<div class="emph">
<p>
- Note: A common bug programmers do is adding code to handle new
+ Note: A common bug programmers have is adding code to handle new
event types in their program, while forgetting to add the
masks for these events in the creation of the window. Such a
- programmer then should sit down for hours debugging his
+ programmer would then sit there for hours debugging their
program, wondering "Why doesn't my program notice that I
released the button?", only to find that they registered for
button press events but not for button release events.
keyboard focus using the window manager (often by clicking
on the title bar of the desired window). Once our window
has the keyboard focus, every key press or key release will
- cause an event to be sent to our program (if it regsitered
+ cause an event to be sent to our program (if it registered
for these event types...).
</p>
<li class="subsubtitle"><a name="keypress">Keyboard press and release events</a>
<ol>
<li class="subtitle"><a name="fontstruct">The Font structure</a>
<p>
- In order to support flexible fonts, a font structure is
+ In order to support flexible fonts, a font type is
defined. You know what ? It's an Id:
</p>
<pre class="code">
<p>
It is used to contain information about a font, and is passed
to several functions that handle fonts selection and text drawing.
+ We ask the X server to attribute an Id to our font with the
+ function:
+ </p>
+ <pre class="code">
+xcb_font_t xcb_generate_id (xcb_connection_t *c);
+</pre>
+ <br>
+ <li class="subtitle"><a name="openingfont">Opening a Font</a>
+ <p>
+ To open a font, we use the following function:
+ </p>
+ <pre class="code">
+xcb_void_cookie_t xcb_open_font (xcb_connection_t *c,
+ xcb_font_t fid,
+ uint16_t name_len,
+ const char *name);
+</pre>
+ <p>
+ The <span class="code">fid</span> parameter is the font Id
+ defined by <span class="code">xcb_generate_id()</span> (see
+ above). The <span class="code">name</span> parameter is the
+ name of the font you want to open. Use the command
+ <span class="code">xlsfonts</span> in a terminal to know which
+ are the fonts available on your computer. The parameter
+ <span class="code">name_len</span> is the length of the name
+ of the font (given by <span class="code">strlen()</span>).
+ </p>
+ <li class="subtitle"><a name="assigningfont">Assigning a Font to a Graphic Context</a>
+ <p>
+ Once a font is opened, you have to create a Graphic Context
+ that will contain the informations about the color of the
+ foreground and the background used when you draw a text in a
+ Drawable. Here is an example of a Graphic Context that will
+ allow us to draw an opened font with a black foreground and a
+ white background:
</p>
+ <pre class="code">
+ /*
+ * c is the connection
+ * screen is the screen where the window is displayed
+ * window is the window in which we will draw the text
+ * font is the opened font
+ */
+
+ uint32_t value_list[3];
+ xcb_gcontext_t gc;
+ uint32_t mask;
+
+ gc = xcb_generate_id (c);
+ mask = XCB_GC_FOREGROUND | XCB_GC_BACKGROUND | XCB_GC_FONT;
+ value_list[0] = screen->black_pixel;
+ value_list[1] = screen->white_pixel;
+ value_list[2] = font;
+ xcb_create_gc (c, gc, window, mask, value_list);
+
+ /* The font is not needed anymore, so we close it */
+ xcb_close_font (c, font);
+</pre>
+ <li class="subtitle"><a name="drawingtext">Drawing text in a drawable</a>
<p>
- <b>TODO:</b> example for picking a font and displaying some text.
- Even better, also demonstrate translating keypresses to text.
+ To draw a text in a drawable, we use the following function:
</p>
+ <pre class="code">
+xcb_void_cookie_t xcb_image_text_8 (xcb_connection_t *c,
+ uint8_t string_len,
+ xcb_drawable_t drawable,
+ xcb_gcontext_t gc,
+ int16_t x,
+ int16_t y,
+ const char *string);
+</pre>
+ <p>
+ The <span class="code">string</span> parameter is the text to
+ draw. The location of the drawing is given by the parameters
+ <span class="code">x</span> and <span class="code">y</span>.
+ The base line of the text is exactly the parameter
+ <span class="code">y</span>.
+ </p>
+ <li class="subtitle"><a name="fontcompleteexample">Complete example</a>
+ <p>
+ This example draw a text at 10 pixels (for the base line) of
+ the bottom of a window. Pressing the Esc key exits the program.
+ </p>
+ <pre class="code">
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <xcb/xcb.h>
+
+#define WIDTH 300
+#define HEIGHT 100
+
+
+
+static xcb_gc_t gc_font_get (xcb_connection_t *c,
+ xcb_screen_t *screen,
+ xcb_window_t window,
+ const char *font_name);
+
+static void text_draw (xcb_connection_t *c,
+ xcb_screen_t *screen,
+ xcb_window_t window,
+ int16_t x1,
+ int16_t y1,
+ const char *label);
+
+static void
+text_draw (xcb_connection_t *c,
+ xcb_screen_t *screen,
+ xcb_window_t window,
+ int16_t x1,
+ int16_t y1,
+ const char *label)
+{
+ xcb_void_cookie_t cookie_gc;
+ xcb_void_cookie_t cookie_text;
+ xcb_generic_error_t *error;
+ xcb_gcontext_t gc;
+ uint8_t length;
+
+ length = strlen (label);
+
+ gc = gc_font_get(c, screen, window, "7x13");
+
+ cookie_text = xcb_image_text_8_checked (c, length, window, gc,
+ x1,
+ y1, label);
+ error = xcb_request_check (c, cookie_text);
+ if (error) {
+ fprintf (stderr, "ERROR: can't paste text : %d\n", error->error_code);
+ xcb_disconnect (c);
+ exit (-1);
+ }
+
+ cookie_gc = xcb_free_gc (c, gc);
+ error = xcb_request_check (c, cookie_gc);
+ if (error) {
+ fprintf (stderr, "ERROR: can't free gc : %d\n", error->error_code);
+ xcb_disconnect (c);
+ exit (-1);
+ }
+}
+
+static xcb_gc_t
+gc_font_get (xcb_connection_t *c,
+ xcb_screen_t *screen,
+ xcb_window_t window,
+ const char *font_name)
+{
+ uint32_t value_list[3];
+ xcb_void_cookie_t cookie_font;
+ xcb_void_cookie_t cookie_gc;
+ xcb_generic_error_t *error;
+ xcb_font_t font;
+ xcb_gcontext_t gc;
+ uint32_t mask;
+
+ font = xcb_generate_id (c);
+ cookie_font = xcb_open_font_checked (c, font,
+ strlen (font_name),
+ font_name);
+
+ error = xcb_request_check (c, cookie_font);
+ if (error) {
+ fprintf (stderr, "ERROR: can't open font : %d\n", error->error_code);
+ xcb_disconnect (c);
+ return -1;
+ }
+
+ gc = xcb_generate_id (c);
+ mask = XCB_GC_FOREGROUND | XCB_GC_BACKGROUND | XCB_GC_FONT;
+ value_list[0] = screen->black_pixel;
+ value_list[1] = screen->white_pixel;
+ value_list[2] = font;
+ cookie_gc = xcb_create_gc_checked (c, gc, window, mask, value_list);
+ error = xcb_request_check (c, cookie_gc);
+ if (error) {
+ fprintf (stderr, "ERROR: can't create gc : %d\n", error->error_code);
+ xcb_disconnect (c);
+ exit (-1);
+ }
+
+ cookie_font = xcb_close_font_checked (c, font);
+ error = xcb_request_check (c, cookie_font);
+ if (error) {
+ fprintf (stderr, "ERROR: can't close font : %d\n", error->error_code);
+ xcb_disconnect (c);
+ exit (-1);
+ }
+
+ return gc;
+}
+
+int main ()
+{
+ xcb_screen_iterator_t screen_iter;
+ xcb_connection_t *c;
+ const xcb_setup_t *setup;
+ xcb_screen_t *screen;
+ xcb_generic_event_t *e;
+ xcb_generic_error_t *error;
+ xcb_void_cookie_t cookie_window;
+ xcb_void_cookie_t cookie_map;
+ xcb_window_t window;
+ uint32_t mask;
+ uint32_t values[2];
+ int screen_number;
+
+ /* getting the connection */
+ c = xcb_connect (NULL, &screen_number);
+ if (!c) {
+ fprintf (stderr, "ERROR: can't connect to an X server\n");
+ return -1;
+ }
+
+ /* getting the current screen */
+ setup = xcb_get_setup (c);
+
+ screen = NULL;
+ screen_iter = xcb_setup_roots_iterator (setup);
+ for (; screen_iter.rem != 0; --screen_number, xcb_screen_next (&screen_iter))
+ if (screen_number == 0)
+ {
+ screen = screen_iter.data;
+ break;
+ }
+ if (!screen) {
+ fprintf (stderr, "ERROR: can't get the current screen\n");
+ xcb_disconnect (c);
+ return -1;
+ }
+
+ /* creating the window */
+ window = xcb_generate_id (c);
+ mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
+ values[0] = screen->white_pixel;
+ values[1] =
+ XCB_EVENT_MASK_KEY_RELEASE |
+ XCB_EVENT_MASK_BUTTON_PRESS |
+ XCB_EVENT_MASK_EXPOSURE |
+ XCB_EVENT_MASK_POINTER_MOTION;
+ cookie_window = xcb_create_window_checked (c,
+ screen->root_depth,
+ window, screen->root,
+ 20, 200, WIDTH, HEIGHT,
+ 0, XCB_WINDOW_CLASS_INPUT_OUTPUT,
+ screen->root_visual,
+ mask, values);
+ cookie_map = xcb_map_window_checked (c, window);
+
+ /* error managing */
+ error = xcb_request_check (c, cookie_window);
+ if (error) {
+ fprintf (stderr, "ERROR: can't create window : %d\n", error->error_code);
+ xcb_disconnect (c);
+ return -1;
+ }
+ error = xcb_request_check (c, cookie_map);
+ if (error) {
+ fprintf (stderr, "ERROR: can't map window : %d\n", error->error_code);
+ xcb_disconnect (c);
+ return -1;
+ }
+
+ xcb_flush(c);
+
+ while (1) {
+ e = xcb_poll_for_event(c);
+ if (e) {
+ switch (e->response_type & ~0x80) {
+ case XCB_EXPOSE: {
+ char *text;
+
+ text = "Press ESC key to exit...";
+ text_draw (c, screen, window, 10, HEIGHT - 10, text);
+ break;
+ }
+ case XCB_KEY_RELEASE: {
+ xcb_key_release_event_t *ev;
+
+ ev = (xcb_key_release_event_t *)e;
+
+ switch (ev->detail) {
+ /* ESC */
+ case 9:
+ free (e);
+ xcb_disconnect (c);
+ return 0;
+ }
+ }
+ }
+ free (e);
+ }
+ }
+
+ return 0;
+}
+</pre>
</ol>
<li class="title"><a name="wm">Interacting with the window manager</a>
<p>
const void *data); /* Data */
</pre>
<p>
- The <span class="code">mode</span> parameter coud be one of
+ The <span class="code">mode</span> parameter could be one of
the following values (defined in enumeration xcb_prop_mode_t in
the xproto.h header file):
</p>
latter case, each time the mouse moves onto your window, the
screen color map will be replaced by your window's color map,
and you'll see all the other windows on screen change their
- colors into something quite bizzare. In fact, this is the
+ colors into something quite bizarre. In fact, this is the
effect you get with X applications that use the "-install"
command line option.
</p>
<li class="title"><a name="mousecursor">Messing with the mouse cursor</a>
<p>
It it possible to modify the shape of the mouse pointer (also
- called the X pointer) when in certain states, as we otfen see in
+ called the X pointer) when in certain states, as we often see in
programs. For example, a busy application would often display
- the sand clock over its main window, to give the user a visual
- hint that he should wait. Let's see how we can change the mouse
+ the hourglass cursor over its main window, to give the user a visual
+ hint that they should wait. Let's see how we can change the mouse
cursor of our windows.
</p>
<ol>
</p>
<p>
So we first open that font (see <a href="#loadfont">Loading a Font</a>)
- and create the new cursor. As for every X ressource, we have to
+ and create the new cursor. As for every X resource, we have to
ask for an X id with <span class="code">xcb_generate_id</span>
first:
</p>
while (1) {
e = xcb_poll_for_event(c);
if (e) {
- switch (e->response_type) {
+ switch (e->response_type & ~0x80) {
case XCB_EXPOSE: {
char *text;
projects / free-sw / xcb / libxcb / blobdiff