First Commit

1 files changed, 173 insertions, 0 deletions

diff --git a/help/simple-text.c b/help/simple-text.c
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+++ b/help/simple-text.c
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+/*
+ * simple-text.c - demonstrate drawing of text strings on a window. All
+ *		   drawings are done in black color over a white background.
+ */
+
+#include <X11/Xlib.h>
+
+#include <stdio.h>
+#include <stdlib.h>		/* getenv(), etc. */
+#include <unistd.h>		/* sleep(), etc.  */
+
+/*
+ * function: create_simple_window. Creates a window with a white background
+ *           in the given size.
+ * input:    display, size of the window (in pixels), and location of the window
+ *           (in pixels).
+ * output:   the window's ID.
+ * notes:    window is created with a black border, 2 pixels wide.
+ *           the window is automatically mapped after its creation.
+ */
+Window
+create_simple_window(Display* display, int width, int height, int x, int y)
+{
+  int screen_num = DefaultScreen(display);
+  int win_border_width = 2;
+  Window win;
+
+  /* create a simple window, as a direct child of the screen's */
+  /* root window. Use the screen's black and white colors as   */
+  /* the foreground and background colors of the window,       */
+  /* respectively. Place the new window's top-left corner at   */
+  /* the given 'x,y' coordinates.                              */
+  win = XCreateSimpleWindow(display, RootWindow(display, screen_num),
+                            x, y, width, height, win_border_width,
+                            BlackPixel(display, screen_num),
+                            WhitePixel(display, screen_num));
+
+  /* make the window actually appear on the screen. */
+  XMapWindow(display, win);
+
+  /* flush all pending requests to the X server. */
+  XFlush(display);
+
+  return win;
+}
+
+GC
+create_gc(Display* display, Window win, int reverse_video)
+{
+  GC gc;				/* handle of newly created GC.  */
+  unsigned long valuemask = 0;		/* which values in 'values' to  */
+					/* check when creating the GC.  */
+  XGCValues values;			/* initial values for the GC.   */
+  unsigned int line_width = 2;		/* line width for the GC.       */
+  int line_style = LineSolid;		/* style for lines drawing and  */
+  int cap_style = CapButt;		/* style of the line's edje and */
+  int join_style = JoinBevel;		/*  joined lines.		*/
+  int screen_num = DefaultScreen(display);
+
+  gc = XCreateGC(display, win, valuemask, &values);
+  if (gc < 0) {
+	fprintf(stderr, "XCreateGC: \n");
+  }
+
+  /* allocate foreground and background colors for this GC. */
+  if (reverse_video) {
+    XSetForeground(display, gc, WhitePixel(display, screen_num));
+    XSetBackground(display, gc, BlackPixel(display, screen_num));
+  }
+  else {
+    XSetForeground(display, gc, BlackPixel(display, screen_num));
+    XSetBackground(display, gc, WhitePixel(display, screen_num));
+  }
+
+  /* define the style of lines that will be drawn using this GC. */
+  XSetLineAttributes(display, gc,
+                     line_width, line_style, cap_style, join_style);
+
+  /* define the fill style for the GC. to be 'solid filling'. */
+  XSetFillStyle(display, gc, FillSolid);
+
+  return gc;
+}
+
+void
+main(int argc, char* argv[])
+{
+  Display* display;		/* pointer to X Display structure.           */
+  int screen_num;		/* number of screen to place the window on.  */
+  Window win;			/* pointer to the newly created window.      */
+  unsigned int display_width,
+               display_height;	/* height and width of the X display.        */
+  unsigned int win_width,
+	       win_height;	/* height and width for the new window.      */
+  char *display_name = getenv("DISPLAY");  /* address of the X display.      */
+  GC gc;			/* GC (graphics context) used for drawing    */
+				/*  in our window.			     */
+  XFontStruct* font_info;       /* Font structure, used for drawing text.    */
+  char* font_name = "*-helvetica-*-12-*"; /* font to use for drawing text.   */
+
+  /* open connection with the X server. */
+  display = XOpenDisplay(display_name);
+  if (display == NULL) {
+    fprintf(stderr, "%s: cannot connect to X server '%s'\n",
+            argv[0], display_name);
+    exit(1);
+  }
+
+  /* get the geometry of the default screen for our display. */
+  screen_num = DefaultScreen(display);
+  display_width = DisplayWidth(display, screen_num);
+  display_height = DisplayHeight(display, screen_num);
+
+  /* make the new window occupy 1/9 of the screen's size. */
+  win_width = (display_width / 3);
+  win_height = (display_height / 3);
+  printf("window width - '%d'; height - '%d'\n", win_width, win_height);
+
+  /* create a simple window, as a direct child of the screen's   */
+  /* root window. Use the screen's white color as the background */
+  /* color of the window. Place the new window's top-left corner */
+  /* at the given 'x,y' coordinates.                             */
+  win = create_simple_window(display, win_width, win_height, 0, 0);
+
+  /* allocate a new GC (graphics context) for drawing in the window. */
+  gc = create_gc(display, win, 0);
+  XSync(display, False);
+
+  /* try to load the given font. */
+  font_info = XLoadQueryFont(display, font_name);
+  if (!font_info) {
+      fprintf(stderr, "XLoadQueryFont: failed loading font '%s'\n", font_name);
+      exit(-1);
+  }
+
+  /* assign the given font to our GC. */
+  XSetFont(display, gc, font_info->fid);
+
+  {
+    /* variables used for drawing the text strings. */
+    int x, y;
+    char* text_string;
+    int string_width;
+    int font_height;
+
+    /* find the height of the characters drawn using this font.        */
+    font_height = font_info->ascent + font_info->descent;
+
+    /* draw a "hello world" string on the top-left side of our window. */
+    text_string = "hello world";
+    x = 0;
+    y = font_height;
+    XDrawString(display, win, gc, x, y, text_string, strlen(text_string));
+
+    /* draw a "middle of the road" string in the middle of our window. */
+    text_string = "middle of the road";
+    /* find the width, in pixels, of the text that will be drawn using */
+    /* the given font.                                                 */
+    string_width = XTextWidth(font_info, text_string, strlen(text_string));
+    x = (win_width - string_width) / 2;
+    y = (win_height + font_height) / 2;
+    XDrawString(display, win, gc, x, y, text_string, strlen(text_string));
+  }
+
+  /* flush all pending requests to the X server. */
+  XFlush(display);
+
+  /* make a delay for a short period. */
+  sleep(4);
+
+  /* close the connection to the X server. */
+  XCloseDisplay(display);
+}