From e7a652e35eba129d335da0341dacfa1b99e7eb7b Mon Sep 17 00:00:00 2001
From: James Magahern <james@magahern.com>
Date: Wed, 16 Jan 2019 01:19:35 -0800
Subject: Got a basic window going

---
 buzzsaver.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 buzzsaver.c

diff --git a/buzzsaver.c b/buzzsaver.c
new file mode 100644
index 0000000..e56e17e
--- /dev/null
+++ b/buzzsaver.c
@@ -0,0 +1,113 @@
+/*
+ * 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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