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/*
* buzzsaver.c
*
* Created 2019-01-16 by James Magahern <james@magahern.com>
*/
#include <cairo/cairo.h>
#include <cairo-xlib.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
int poll_events(Display *display, Window window)
{
const bool block_for_next_event = false;
char keybuf[8];
KeySym key;
XEvent e;
for (;;) {
if (block_for_next_event || XPending(display)) {
// XNextEvent blocks the caller until an event arrives
XNextEvent(display, &e);
} else {
return 0;
}
// TODO: listen for window resize events and resize cairo surface
switch (e.type) {
case ButtonPress:
return -e.xbutton.button;
case KeyPress:
XLookupString(&e.xkey, keybuf, sizeof(keybuf), &key, NULL);
return key;
default:
fprintf(stderr, "Dropping unhandled XEevent.type = %d.\n", e.type);
}
}
}
int main(int argc, char **argv)
{
int width = 300;
int height = 300;
Display *display = XOpenDisplay(NULL);
if (display == NULL) {
fprintf(stderr, "Error opening display\n");
exit(1);
}
Window root_window = DefaultRootWindow(display);
Window window = XCreateSimpleWindow(
display, // display
root_window, // parent window
0, 0, // x, y
width, height, // width, height
0, // border_width
0, // border
0 // background
);
// Enable key events
XSelectInput(display, window, ButtonPressMask | KeyPressMask | StructureNotifyMask);
// Map window to display
XMapWindow(display, window);
// Create cairo surface
int screen = DefaultScreen(display);
Visual *visual = DefaultVisual(display, screen);
cairo_surface_t *surface = cairo_xlib_surface_create(
display,
window,
visual,
width,
height
);
if (surface == NULL) {
fprintf(stderr, "Error creating cairo surface\n");
exit(1);
}
// Docs say this must be called whenever the size of the window changes
cairo_xlib_surface_set_size(surface, width, height);
// Create cairo surface
cairo_t *cr = cairo_create(surface);
// Main run loop
struct timespec sleep_time = { 0, 5000000 };
for (;;) {
cairo_push_group(cr);
cairo_set_source_rgba(cr, 1.0, 0.0, 0.0, 1.0);
cairo_fill_preserve(cr);
cairo_paint(cr);
cairo_pop_group_to_source(cr);
cairo_paint(cr);
cairo_surface_flush(surface);
poll_events(display, window);
nanosleep(&sleep_time, NULL);
}
return 0;
}
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