/* * simple-drawing.c - demonstrate drawing of pixels, lines, arcs, etc. * on a window. All drawings are done in black color * over a white background. */ #include #include #include /* getenv(), etc. */ #include /* 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; } int 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 width, 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. */ /* 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. */ width = (display_width / 3); height = (display_height / 3); printf("window width - '%d'; height - '%d'\n", width, 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, width, height, 0, 0); /* allocate a new GC (graphics context) for drawing in the window. */ gc = create_gc(display, win, 0); XSync(display, False); /* draw one pixel near each corner of the window */ XDrawPoint(display, win, gc, 5, 5); XDrawPoint(display, win, gc, 5, height-5); XDrawPoint(display, win, gc, width-5, 5); XDrawPoint(display, win, gc, width-5, height-5); /* draw two intersecting lines, one horizontal and one vertical, */ /* which intersect at point "50,100". */ XDrawLine(display, win, gc, 50, 0, 50, 200); XDrawLine(display, win, gc, 0, 100, 200, 100); /* now use the XDrawArc() function to draw a circle whose diameter */ /* is 30 pixels, and whose center is at location '50,100'. */ XDrawArc(display, win, gc, 50-(30/2), 100-(30/2), 30, 30, 0, 360*64); { XPoint points[] = { {0, 0}, {15, 15}, {0, 15}, {0, 0} }; int npoints = sizeof(points)/sizeof(XPoint); /* draw a small triangle at the top-left corner of the window. */ /* the triangle is made of a set of consecutive lines, whose */ /* end-point pixels are specified in the 'points' array. */ XDrawLines(display, win, gc, points, npoints, CoordModeOrigin); } /* draw a rectangle whose top-left corner is at '120,150', its width is */ /* 50 pixels, and height is 60 pixels. */ XDrawRectangle(display, win, gc, 120, 150, 50, 60); /* draw a filled rectangle of the same size as above, to the left of the */ /* previous rectangle. */ XFillRectangle(display, win, gc, 60, 150, 50, 60); /* 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); return(0); }