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diff --git a/doc/tutorial/index.html b/doc/tutorial/index.html index de7849a..ac173a0 100644 --- a/doc/tutorial/index.html +++ b/doc/tutorial/index.html @@ -59,9 +59,10 @@ <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> @@ -977,8 +978,9 @@ main () 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 */ @@ -2046,7 +2048,7 @@ main () <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"> @@ -2055,11 +2057,304 @@ typedef uint32_t xcb_font_t; <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> + <p> + <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 exemple 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> + 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> - <b>TODO:</b> example for picking a font and displaying some text. - Even better, also demonstrate translating keypresses to text. + 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) { + 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> |