I'm writing a simple X11 clock app, it can be scaled by resizing the window,
I want to draw some numbers (1..12) around the clock face, and the numbers should be scaled too.
So I can't use XLoadQueryFont, which only accept descrete pre-defined font sizes, can't be scaled.
I tried Xft, but failed to do XftDrawString, which raised error BadPicture.
And it seems big mess when mixing drawing codes of Xlib (like XSetForeground) and Xft (color as parameter).
So I guess maybe I can get XFontStruct from XftFont? I only need to use Xft to find a appropriate font matching arbitray font-size.
xft(3) said, XftFont contains a pointer to XFontStruct:
XftFont contains general font metrics and a pointer to either the core XFontStruct data or a structure holding FreeType and X Render Extension data.
while in the header file (xft.h), I didn' find the pointer:
typedef struct _XftFont {
int ascent;
int descent;
int height;
int max_advance_width;
FcCharSet *charset;
FcPattern *pattern;
} XftFont;
The clock app:
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xft/Xft.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <math.h>
#include <time.h>
#include <sys/time.h>
#define MWM_HINTS_DECORATIONS (1L << 1)
#define MWM_DECOR_ALL (1L << 0) /* [v] */
typedef struct
{
unsigned long flags;
unsigned long functions;
unsigned long decorations;
long input_mode;
unsigned long status;
} MotifWmHints;
static MotifWmHints *
get_motif_wm_hints(Display *display,
Window window)
{
Atom property;
int result;
Atom actual_type;
int actual_format;
unsigned long nitems;
unsigned long bytes_after;
unsigned char *data;
property = XInternAtom(display, "_MOTIF_WM_HINTS", False);
result = XGetWindowProperty(display, window, property,
0, LONG_MAX, False, AnyPropertyType,
&actual_type, &actual_format,
&nitems, &bytes_after, &data);
if (result == Success && data != NULL)
{
size_t data_size;
size_t max_size;
MotifWmHints *hints;
data_size = nitems * sizeof(long);
max_size = sizeof(*hints);
hints = calloc(1, max_size);
memcpy(hints, data, data_size > max_size ? max_size : data_size);
XFree(data);
return hints;
}
return NULL;
}
void removeBorder(Display *display,
Window window)
{
MotifWmHints *hints;
Atom property;
int nelements;
hints = get_motif_wm_hints(display, window);
if (hints == NULL)
{
hints = calloc(1, sizeof(*hints));
hints->decorations = 0;
}
hints->flags |= MWM_HINTS_DECORATIONS;
hints->decorations = 0;
property = XInternAtom(display, "_MOTIF_WM_HINTS", False);
nelements = sizeof(*hints) / sizeof(long);
XChangeProperty(display, window, property, property, 32, PropModeReplace,
(unsigned char *)hints, nelements);
free(hints);
}
int clock_margin_h = 80;
int clock_margin_v = 80;
int clock_radius = 100;
Colormap colormap;
XColor blue_color;
XColor red_color;
XftDraw *draw = NULL;
XftFont *font = NULL;
void drawClock(Display *display, Window window, int hour, int minute, int second, int usec)
{
int screen = DefaultScreen(display);
int clock_center_x = clock_radius + clock_margin_h;
int clock_center_y = clock_radius + clock_margin_v;
float hour_len = 0.4;
float minute_len = 0.6;
float second_len = 0.8;
XGCValues values;
GC gc = XCreateGC(display, window, 0, &values);
// Draw clock face
XSetForeground(display, gc, blue_color.pixel);
XFillArc(display, window, gc, clock_center_x - clock_radius, clock_center_y - clock_radius,
2 * clock_radius, 2 * clock_radius, 0, 360 * 64);
double hour_angle = (-(hour + minute / 60.0) / 12 + 1 / 4.0) * M_PI * 2;
double minute_angle = (-minute / 60.0 + 1 / 4.0) * M_PI * 2;
double second_angle = (-(second + usec / 1000000.0) / 60.0 + 1 / 4.0) * M_PI * 2;
// Draw hour hand (white color)
XSetForeground(display, gc, WhitePixel(display, screen));
XDrawLine(display, window, gc, clock_center_x, clock_center_y,
clock_center_x + hour_len * clock_radius * cos(hour_angle),
clock_center_y - hour_len * clock_radius * sin(hour_angle));
// Draw minute hand (white color)
XDrawLine(display, window, gc, clock_center_x, clock_center_y,
clock_center_x + minute_len * clock_radius * cos(minute_angle),
clock_center_y - minute_len * clock_radius * sin(minute_angle));
// Draw second hand (red color)
XSetForeground(display, gc, red_color.pixel);
XDrawLine(display, window, gc, clock_center_x, clock_center_y,
clock_center_x + second_len * clock_radius * cos(second_angle),
clock_center_y - second_len * clock_radius * sin(second_angle));
// Draw numbers 1-12 around the clock face
if (font)
{
// XSetFont(display, gc, font_info->fid);
// XSetForeground(display, gc, WhitePixel(display, screen));
XftDraw *draw = XftDrawCreate(display, window,
DefaultVisual(display, screen),
DefaultColormap(display, screen));
XftColor color;
color.color.red = 65535;
color.color.green = 65535;
color.color.blue = 65535;
color.color.alpha = 65535;
for (int i = 1; i <= 12; i++)
{
double angle = (-(i) / 12.0 + 1 / 4.0) * M_PI * 2;
int x = clock_center_x + 1 * clock_radius * cos(angle) - 5;
int y = clock_center_y - 1 * clock_radius * sin(angle) + 10;
char number[10];
sprintf(number, "%d", i);
// XDrawString(display, window, gc, x, y, number, strlen(number));
XftDrawStringUtf8(draw, &color, font, x, y, number, strlen(number));
}
XftDrawDestroy(draw);
}
else
{
fprintf(stderr, "Error: Unable to load font\n");
}
XFreeGC(display, gc);
}
void updateClock(Display *display, Window window)
{
time_t now = time(NULL);
struct tm *local_time = localtime(&now);
struct timeval tvTime;
gettimeofday(&tvTime, NULL);
int hour = local_time->tm_hour % 12;
int minute = local_time->tm_min;
int second = local_time->tm_sec;
drawClock(display, window, hour, minute, second, tvTime.tv_usec);
}
int error_logger(
Display *display,
XErrorEvent *event)
{
char msg[200];
XGetErrorText(display, event->error_code, msg, sizeof(msg));
fprintf(stderr, "[serial %d] [type %d] error %d (%s): request %d.%d\n", //
event->serial,
event->type,
event->error_code,
msg,
event->request_code,
event->minor_code);
}
static int wait_fd(int fd, long usec)
{
struct timeval tv;
fd_set in_fds;
FD_ZERO(&in_fds);
FD_SET(fd, &in_fds);
tv.tv_sec = usec / 1000000;
tv.tv_usec = usec % 1000000;
return select(fd + 1, &in_fds, 0, 0, &tv);
}
int XNextEventTimeout(Display *display, XEvent *event, double seconds)
{
if (XPending(display) || wait_fd(ConnectionNumber(display), seconds))
{
XNextEvent(display, event);
return 0;
}
else
{
// event->type = 0;
return 1;
}
}
int main()
{
XSetErrorHandler(error_logger);
Display *display = XOpenDisplay(NULL);
if (display == NULL)
{
fprintf(stderr, "Error: Could not open display\n");
return 1;
}
Window root = DefaultRootWindow(display);
int screen = DefaultScreen(display);
Window origFocusWindow;
int origRevert;
XGetInputFocus(display, &origFocusWindow, &origRevert);
// Create a window with transparent background
XVisualInfo vinfo;
XMatchVisualInfo(display, screen, 32, TrueColor, &vinfo);
XSetWindowAttributes attr;
colormap = XCreateColormap(display, root, vinfo.visual, AllocNone);
attr.colormap = colormap;
attr.border_pixel = 0;
attr.background_pixel = 0;
// attr.override_redirect = False;
int left = 100, top = 100;
int width = (clock_radius + clock_margin_h) * 2;
int height = (clock_radius + clock_margin_v) * 2;
int border_width = 0;
Window window = XCreateWindow(display, root, left, top, width, height, border_width,
vinfo.depth, InputOutput, vinfo.visual,
CWColormap | CWBorderPixel | CWBackPixel, &attr);
// removeBorder(display, window);
Colormap colormap = DefaultColormap(display, screen);
XAllocNamedColor(display, colormap, "blue", &blue_color, &blue_color);
XAllocNamedColor(display, colormap, "red", &red_color, &red_color);
font = XftFontOpenName(display, screen, "Sans:size=10");
// Set window background to transparent
// XSetWindowBackground(display, window, 0);
XClearWindow(display, window);
XMapWindow(display, window);
XSelectInput(display, window, ExposureMask | StructureNotifyMask);
// XMapWindow(display, focusWindow);
// XRaiseWindow(display, focusWindow);
// XSelectInput(display, focusWindow, ExposureMask | KeyPressMask);
// XSync(display, True);
// int r = XSetInputFocus(display, focusWindow, RevertToParent, CurrentTime);
while (1)
{
XEvent event;
int timeout = XNextEventTimeout(display, &event, 100 * 1000);
if (timeout)
{
updateClock(display, window);
continue;
}
switch (event.type)
{
case ConfigureNotify:
XConfigureEvent xce = event.xconfigure;
if (xce.width < xce.height)
clock_radius = xce.width / 2 - clock_margin_h;
else
clock_radius = xce.height / 2 - clock_margin_v;
int font_height = clock_radius / 12;
if (font)
{
XftFontClose(display, font);
font = NULL;
}
char font_name[80];
sprintf(font_name, "Sans:size=%d", font_height);
font = XftFontOpenName(display, screen, font_name);
updateClock(display, window);
break;
case Expose:
updateClock(display, window);
Window focusWindow;
int revert;
XGetInputFocus(display, &focusWindow, &revert);
if (focusWindow == window)
{
XSetInputFocus(display, origFocusWindow, RevertToParent, CurrentTime);
}
break;
case MapNotify:
case ClientMessage:
break;
default:
printf("other event: %d\n", event.type);
}
}
XCloseDisplay(display);
return 0;
}
How to get XFontStruct from XftFont?
You don't. You cannot, and you don't need to. Xft is a client-size font rendering system. The core X fonts are server sise, they have no idea about what you have client-side.
I tried Xft, but failed to do XftDrawString, which raised error BadPicture.
The error is because of a visual mismatch. You are using the default visual at some places and a found and matched one at other places. Use the same visual for the same window. As a simple quick and dirty fix, make vinfo global and use vinfo.visual throughout.
xft(3) said, XftFont contains a pointer to XFontStruct:
You have an outdated version of the man page. Not only the header file doesn't reference XFontStruct, the entire libXft source has no mention of it. A very old release of libXft, included with XOrg X11R6.7 release, mentions XFontStruct in the manual page, but nowhere in the source code. The mention is gone in X11R6.9 release. I could not find older versions of libXft anywhere on the internet (nor could its author).
So I guess maybe I can get XFontStruct from XftFont?
No. Don't try that. Use client-side font rendering. It works.