- <li class="subtitle"><a name="pixmapswhat">What is a X Bitmap? An X Pixmap?</a></li>
- <p>
- An X bitmap is a two-color image stored in a format specific
- to the X window system. When stored in a file, the bitmap data
- looks like a C source file. It contains variables defining the
- width and the height of the bitmap, an array containing the
- bit values of the bitmap (the size of the array is
- weight*height), and an optional hot-spot location (that will
- be explained later, when discussing mouse cursors).
- </p>
- <p>
- An X pixmap is a format used to stored images in the memory of
- an X server. This format can store both black and white images
- (such as x bitmaps) as well as color images. It is the only
- image format supported by the X protocol, and any image to be
- drawn on screen, should be first translated into this format.
- </p>
- <p>
- In actuality, an X pixmap can be thought of as a window that
- does not appear on the screen. Many graphics operations that
- work on windows, will also work on pixmaps. Indeed, the type
- of X pixmap in XCB is an Id like a window:
- </p>
- <pre class="code">
-typedef struct {
- CARD32 xid;
-} XCBPIXMAP;
-</pre>
- <p>
- In order to make the difference between a window and a pixmap,
- XCB introduces a drawable type, which is a <b>union</b>
- </p>
- <pre class="code">
-typedef union {
- XCBWINDOW window;
- XCBPIXMAP pixmap;
-} XCBDRAWABLE;
-</pre>
- <p>
- in order to avoid confusion between a window and a pixmap. The
- operations that will work indifferently on a window or a pixmap
- will require a <span class="code">XCBDRAWABLE</span>
- </p>
- <div class="emph">
- <p>
- Remark: In Xlib, there is no specific difference between a
- <span class="code">Drawable</span>, a
- <span class="code">Pixmap</span> or a
- <span class="code">Window</span>: all are 32 bit long
- integer.
- </p>
- </div>
- <li class="subtitle"><a name="pixmapscreate">Creating a pixmap</a></li>
- <p>
- Sometimes we want to create an un-initialized pixmap, so we
- can later draw into it. This is useful for image drawing
- programs (creating a new empty canvas will cause the creation
- of a new pixmap on which the drawing can be stored). It is
- also useful when reading various image formats: we load the
- image data into memory, create a pixmap on the server, and
- then draw the decoded image data onto that pixmap.
- </p>
- <p>
- To create a new pixmap, we first ask the X server to give an
- Id to our pixmap, with this function:
- </p>
- <pre class="code">
-XCBPIXMAP XCBPIXMAPNew (XCBConnection *c);
-</pre>
- <p>
- Then, XCB supplies the following function to create new pixmaps:
- </p>
- <pre class="code">
-XCBVoidCookie XCBCreatePixmap (XCBConnection *c, /* Pointer to the XCBConnection structure */
- CARD8 depth, /* Depth of the screen */
- XCBPIXMAP pid, /* Id of the pixmap */
- XCBDRAWABLE drawable,
- CARD16 width, /* Width of the window (in pixels) */
- CARD16 height); /* Height of the window (in pixels) */
-</pre>
- <p>
- <b>TODO</b>: Explain the drawable parameter, and give an
- example (like xpoints.c)
- </p>
- <li class="subtitle"><a name="pixmapsdraw"></a>Drawing a pixmap in a window</li>
- <p>
- Once we got a handle to a pixmap, we can draw it on some
- window, using the following function:
- </p>
- <pre class="code">
-XCBVoidCookie XCBCopyArea (XCBConnection *c, /* Pointer to the XCBConnection structure */
- XCBDRAWABLE src_drawable, /* The Drawable we want to paste */
- XCBDRAWABLE dst_drawable, /* The Drawable on which we copy the previous Drawable */
- XCBGCONTEXT gc, /* A Graphic Context */
- INT16 src_x, /* Top left x coordinate of the region we want to copy */
- INT16 src_y, /* Top left y coordinate of the region we want to copy */
- INT16 dst_x, /* Top left x coordinate of the region where we want to copy */
- INT16 dst_y, /* Top left y coordinate of the region where we want to copy */
- CARD16 width, /* Width of the region we want to copy */
- CARD16 height); /* Height of the region we want to copy */
-</pre>
- <p>
- As you can see, we could copy the whole pixmap, as well as
- only a given rectangle of the pixmap. This is useful to
- optimize the drawing speed: we could copy only what we have
- modified in the pixmap.
- </p>
- <p>
- <b>One important note should be made</b>: it is possible to
- create pixmaps with different depths on the same screen. When
- we perform copy operations (a pixmap onto a window, etc), we
- should make sure that both source and target have the same
- depth. If they have a different depth, the operation would
- fail. The exception to this is if we copy a specific bit plane
- of the source pixmap using the
- <span class="code">XCBCopyPlane</span> function. In such an
- event, we can copy a specific plain to the target window (in
- actuality, setting a specific bit in the color of each pixel
- copied). This can be used to generate strange graphic effects
- in widow, but that is beyond the scope of this tutorial.
- </p>
- <li class="subtitle"><a name="pixmapsfree"></a>Freeing a pixmap</li>
- <p>
- Finally, when we are done using a given pixmap, we should free
- it, in order to free resources of the X server. This is done
- using this function:
- </p>
- <pre class="code">
-XCBVoidCookie XCBFreePixmap (XCBConnection *c, /* Pointer to the XCBConnection structure */
- XCBPIXMAP pixmap); /* A given pixmap */
-</pre>
- <p>
- Of course, after having freed it, we must not try accessing
- the pixmap again.
- </p>
- <p>
- <b>TODO</b>: Give an example, or a link to xpoints.c
- </p>
+ <li class="subtitle"><a name="pixmapswhat">What is a X Bitmap? An X Pixmap?</a>
+ <p>
+ An X bitmap is a two-color image stored in a format specific
+ to the X window system. When stored in a file, the bitmap data
+ looks like a C source file. It contains variables defining the
+ width and the height of the bitmap, an array containing the
+ bit values of the bitmap (the size of the array is
+ (width+7)/8*height and the bit and byte order are LSB), and
+ an optional hot-spot location (that will
+ be explained later, when discussing mouse cursors).
+ </p>
+ <p>
+ An X pixmap is a format used to stored images in the memory of
+ an X server. This format can store both black and white images
+ (such as x bitmaps) as well as color images. It is the only
+ image format supported by the X protocol, and any image to be
+ drawn on screen, should be first translated into this format.
+ </p>
+ <p>
+ In actuality, an X pixmap can be thought of as a window that
+ does not appear on the screen. Many graphics operations that
+ work on windows, will also work on pixmaps. Indeed, the type
+ of X pixmap in XCB is an Id like a window:
+ </p>
+ <pre class="code">
+typedef uint32_t xcb_pixmap_t;
+</pre>
+ <p>
+ Like Xlib, there is no difference between a Drawable, a Window
+ or a Pixmap:
+ </p>
+ <pre class="code">
+typedef uint32_t xcb_drawable_t;
+</pre>
+ <p>
+ in order to avoid confusion between a window and a pixmap. The
+ operations that will work the same on a window or a pixmap
+ will require a <span class="code">xcb_drawable_t</span>
+ </p>
+ <div class="emph">
+ <p>
+ Remark: In Xlib, there is no specific difference between a
+ <span class="code">Drawable</span>, a
+ <span class="code">Pixmap</span> or a
+ <span class="code">Window</span>: all are 32 bit long
+ integer. XCB wraps all these different IDs in structures to
+ provide some measure of type-safety.
+ </p>
+ </div>
+ <li class="subtitle"><a name="pixmapscreate">Creating a pixmap</a>
+ <p>
+ Sometimes we want to create an un-initialized pixmap, so we
+ can later draw into it. This is useful for image drawing
+ programs (creating a new empty canvas will cause the creation
+ of a new pixmap on which the drawing can be stored). It is
+ also useful when reading various image formats: we load the
+ image data into memory, create a pixmap on the server, and
+ then draw the decoded image data onto that pixmap.
+ </p>
+ <p>
+ To create a new pixmap, we first ask the X server to give an
+ Id to our pixmap, with this function:
+ </p>
+ <pre class="code">
+xcb_pixmap_t xcb_generate_id (xcb_connection_t *c);
+</pre>
+ <p>
+ Then, XCB supplies the following function to create new pixmaps:
+ </p>
+ <pre class="code">
+xcb_void_cookie_t xcb_create_pixmap (xcb_connection_t *c, /* Pointer to the xcb_connection_t structure */
+ uint8_t depth, /* Depth of the screen */
+ xcb_pixmap_t pid, /* Id of the pixmap */
+ xcb_drawable_t drawable,
+ uint16_t width, /* Width of the window (in pixels) */
+ uint16_t height); /* Height of the window (in pixels) */
+</pre>
+ <p>
+ <b>TODO</b>: Explain the drawable parameter, and give an
+ example (like <a href="xpoints.c">xpoints.c</a>)
+ </p>
+ <li class="subtitle"><a name="pixmapsdraw"></a>Drawing a pixmap in a window
+ <p>
+ Once we got a handle to a pixmap, we can draw it on some
+ window, using the following function:
+ </p>
+ <pre class="code">
+xcb_void_cookie_t xcb_copy_area (xcb_connection_t *c, /* Pointer to the xcb_connection_t structure */
+ xcb_drawable_t src_drawable, /* The Drawable we want to paste */
+ xcb_drawable_t dst_drawable, /* The Drawable on which we copy the previous Drawable */
+ xcb_gcontext_t gc, /* A Graphic Context */
+ int16_t src_x, /* Top left x coordinate of the region we want to copy */
+ int16_t src_y, /* Top left y coordinate of the region we want to copy */
+ int16_t dst_x, /* Top left x coordinate of the region where we want to copy */
+ int16_t dst_y, /* Top left y coordinate of the region where we want to copy */
+ uint16_t width, /* Width of the region we want to copy */
+ uint16_t height); /* Height of the region we want to copy */
+</pre>
+ <p>
+ As you can see, we could copy the whole pixmap, as well as
+ only a given rectangle of the pixmap. This is useful to
+ optimize the drawing speed: we could copy only what we have
+ modified in the pixmap.
+ </p>
+ <p>
+ <b>One important note should be made</b>: it is possible to
+ create pixmaps with different depths on the same screen. When
+ we perform copy operations (a pixmap onto a window, etc), we
+ should make sure that both source and target have the same
+ depth. If they have a different depth, the operation would
+ fail. The exception to this is if we copy a specific bit plane
+ of the source pixmap using the
+ <span class="code">xcb_copy_plane_t</span> function. In such an
+ event, we can copy a specific plane to the target window (in
+ actuality, setting a specific bit in the color of each pixel
+ copied). This can be used to generate strange graphic effects
+ in a window, but that is beyond the scope of this tutorial.
+ </p>
+ <li class="subtitle"><a name="pixmapsfree"></a>Freeing a pixmap
+ <p>
+ Finally, when we are done using a given pixmap, we should free
+ it, in order to free resources of the X server. This is done
+ using this function:
+ </p>
+ <pre class="code">
+xcb_void_cookie_t xcb_free_pixmap (xcb_connection_t *c, /* Pointer to the xcb_connection_t structure */
+ xcb_pixmap_t pixmap); /* A given pixmap */
+</pre>
+ <p>
+ Of course, after having freed it, we must not try accessing
+ the pixmap again.
+ </p>
+ <p>
+ <b>TODO</b>: Give an example, or a link to xpoints.c
+ </p>
+ </ol>
+ <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
+ 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
+ cursor of our windows.
+ </p>
+ <ol>
+ <li class="subtitle"><a name="mousecursorcreate">Creating and destroying a mouse cursor</a>
+ <p>
+ There are two methods for creating cursors. One of them is by
+ using a set of predefined cursors, that are supplied by the X
+ server, the other is by using a user-supplied bitmap.
+ </p>
+ <p>
+ In the first method, we use a special font named "cursor", and
+ the function <span class="code">xcb_create_glyph_cursor</span>:
+ </p>
+ <pre class="code">
+xcb_void_cookie_t xcb_create_glyph_cursor (xcb_connection_t *c,
+ xcb_cursor_t cid,
+ xcb_font_t source_font, /* font for the source glyph */
+ xcb_font_t mask_font, /* font for the mask glyph or XCB_NONE */
+ uint16_t source_char, /* character glyph for the source */
+ uint16_t mask_char, /* character glyph for the mask */
+ uint16_t fore_red, /* red value for the foreground of the source */
+ uint16_t fore_green, /* green value for the foreground of the source */
+ uint16_t fore_blue, /* blue value for the foreground of the source */
+ uint16_t back_red, /* red value for the background of the source */
+ uint16_t back_green, /* green value for the background of the source */
+ uint16_t back_blue) /* blue value for the background of the source */
+</pre>
+ <p>
+ <b>TODO</b>: Describe <span class="code">source_char</span>
+ and <span class="code">mask_char</span>, for example by giving
+ an example on how to get the values. There is a list there:
+ <a href="http://tronche.com/gui/x/xlib/appendix/b/">X Font Cursors</a>
+ </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
+ ask for an X id with <span class="code">xcb_generate_id</span>
+ first:
+ </p>
+ <pre class="code">
+xcb_font_t font;
+xcb_cursor_t cursor;
+
+/* The connection is set */
+
+font = xcb_generate_id (conn);
+xcb_open_font (conn, font, strlen ("cursor"), "cursor");
+
+cursor = xcb_generate_id (conn);
+xcb_create_glyph_cursor (conn, cursor, font, font,
+ 58, 58 + 1,
+ 0, 0, 0,
+ 0, 0, 0);
+</pre>
+ <p>
+ We have created the cursor "right hand" by specifying 58 to
+ the <span class="code">source_fon</span>t argument and 58 + 1
+ to the <span class="code">mask_font</span>.
+ </p>
+ <p>
+ The cursor is destroyed by using the function
+ </p>
+ <pre class="code">
+xcb_void_cookie_t xcb_free_cursor (xcb_connection_t *c,
+ xcb_cursor_t cursor);
+</pre>
+ <p>
+ In the second method, we create a new cursor by using a pair
+ of pixmaps, with depth of one (that is, two colors
+ pixmaps). One pixmap defines the shape of the cursor, while
+ the other works as a mask, specifying which pixels of the
+ cursor will be actually drawn. The rest of the pixels will be
+ transparent.
+ </p>
+ <p>
+ <b>TODO</b>: give an example.
+ </p>
+ <li class="subtitle"><a name="mousecursorset">Setting a window's mouse cursor</a>
+ <p>
+ Once the cursor is created, we can modify the cursor of our
+ window by using <span class="code">xcb_change_window_attributes</span>
+ and using the <span class="code">XCB_CWCURSOR</span> attribute:
+ </p>
+ <pre class="code">
+uint32_t mask;
+uint32_t value_list;
+
+/* The connection and window are set */
+/* The cursor is already created */
+
+mask = XCB_CWCURSOR;
+value_list = cursor;
+xcb_change_window_attributes (conn, window, mask, &value_list);
+</pre>
+ <p>
+ Of course, the cursor and the font must be freed.
+ </p>
+ <li class="subtitle"><a name="mousecursorexample">Complete example</a>
+ <p>
+ The following example displays a window with a
+ button. When entering the window, the window cursor is changed
+ to an arrow. When clicking once on the button, the cursor is
+ changed to a hand. When clicking again on the button, the
+ cursor window gets back to the arrow. The Esc key exits the
+ application.
+ </p>
+ <pre class="code">
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <xcb/xcb.h>
+
+#define WIDTH 300
+#define HEIGHT 150
+
+
+
+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 button_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);
+
+static void cursor_set (xcb_connection_t *c,
+ xcb_screen_t *screen,
+ xcb_window_t window,
+ int cursor_id);
+
+
+static void
+button_draw (xcb_connection_t *c,
+ xcb_screen_t *screen,
+ xcb_window_t window,
+ int16_t x1,
+ int16_t y1,
+ const char *label)
+{
+ xcb_point_t points[5];
+ xcb_void_cookie_t cookie_gc;
+ xcb_void_cookie_t cookie_line;
+ xcb_void_cookie_t cookie_text;
+ xcb_generic_error_t *error;
+ xcb_gcontext_t gc;
+ int16_t width;
+ int16_t height;
+ uint8_t length;
+ int16_t inset;
+
+ length = strlen (label);
+ inset = 2;
+
+ gc = gc_font_get(c, screen, window, "7x13");
+
+ width = 7 * length + 2 * (inset + 1);
+ height = 13 + 2 * (inset + 1);
+ points[0].x = x1;
+ points[0].y = y1;
+ points[1].x = x1 + width;
+ points[1].y = y1;
+ points[2].x = x1 + width;
+ points[2].y = y1 - height;
+ points[3].x = x1;
+ points[3].y = y1 - height;
+ points[4].x = x1;
+ points[4].y = y1;
+ cookie_line = xcb_poly_line_checked (c, XCB_COORD_MODE_ORIGIN,
+ window, gc, 5, points);
+
+ error = xcb_request_check (c, cookie_line);
+ if (error) {
+ fprintf (stderr, "ERROR: can't draw lines : %d\n", error->error_code);
+ xcb_disconnect (c);
+ exit (-1);
+ }
+
+ cookie_text = xcb_image_text_8_checked (c, length, window, gc,
+ x1 + inset + 1,
+ y1 - inset - 1, 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 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;
+}
+
+static void
+cursor_set (xcb_connection_t *c,
+ xcb_screen_t *screen,
+ xcb_window_t window,
+ int cursor_id)
+{
+ uint32_t values_list[3];
+ xcb_void_cookie_t cookie_font;
+ xcb_void_cookie_t cookie_gc;
+ xcb_generic_error_t *error;
+ xcb_font_t font;
+ xcb_cursor_t cursor;
+ xcb_gcontext_t gc;
+ uint32_t mask;
+ uint32_t value_list;
+
+ font = xcb_generate_id (c);
+ cookie_font = xcb_open_font_checked (c, font,
+ strlen ("cursor"),
+ "cursor");
+ error = xcb_request_check (c, cookie_font);
+ if (error) {
+ fprintf (stderr, "ERROR: can't open font : %d\n", error->error_code);
+ xcb_disconnect (c);
+ exit (-1);
+ }
+
+ cursor = xcb_generate_id (c);
+ xcb_create_glyph_cursor (c, cursor, font, font,
+ cursor_id, cursor_id + 1,
+ 0, 0, 0,
+ 0, 0, 0);
+
+ gc = xcb_generate_id (c);
+ mask = XCB_GC_FOREGROUND | XCB_GC_BACKGROUND | XCB_GC_FONT;
+ values_list[0] = screen->black_pixel;
+ values_list[1] = screen->white_pixel;
+ values_list[2] = font;
+ cookie_gc = xcb_create_gc_checked (c, gc, window, mask, values_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);
+ }
+
+ mask = XCB_CW_CURSOR;
+ value_list = cursor;
+ xcb_change_window_attributes (c, window, mask, &value_list);
+
+ xcb_free_cursor (c, cursor);
+
+ 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);
+ }
+}
+
+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;
+ uint8_t is_hand = 0;
+
+ /* 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;
+ }
+
+ cursor_set (c, screen, window, 68);
+
+ xcb_flush(c);
+
+ while (1) {
+ e = xcb_poll_for_event(c);
+ if (e) {
+ switch (e->response_type & ~0x80) {
+ case XCB_EXPOSE: {
+ char *text;
+
+ text = "click here to change cursor";
+ button_draw (c, screen, window,
+ (WIDTH - 7 * strlen(text)) / 2,
+ (HEIGHT - 16) / 2, text);
+
+ text = "Press ESC key to exit...";
+ text_draw (c, screen, window, 10, HEIGHT - 10, text);
+ break;
+ }
+ case XCB_BUTTON_PRESS: {
+ xcb_button_press_event_t *ev;
+ int length;
+
+ ev = (xcb_button_press_event_t *)e;
+ length = strlen ("click here to change cursor");
+
+ if ((ev->event_x >= (WIDTH - 7 * length) / 2) &&
+ (ev->event_x <= ((WIDTH - 7 * length) / 2 + 7 * length + 6)) &&
+ (ev->event_y >= (HEIGHT - 16) / 2 - 19) &&
+ (ev->event_y <= ((HEIGHT - 16) / 2)))
+ is_hand = 1 - is_hand;
+
+ is_hand ? cursor_set (c, screen, window, 58) : cursor_set (c, screen, window, 68);
+ }
+ 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>