From 763efda3098f8098b18ce37f29e67f6485f0836f Mon Sep 17 00:00:00 2001
From: Stijn Buys <ingar@telenet.be>
Date: Wed, 25 May 2022 18:26:40 +0200
Subject: Initial commit

---
 genclockimg.c | 152 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)
 create mode 100644 genclockimg.c

(limited to 'genclockimg.c')

diff --git a/genclockimg.c b/genclockimg.c
new file mode 100644
index 0000000..e85a4ee
--- /dev/null
+++ b/genclockimg.c
@@ -0,0 +1,152 @@
+/*
+	genclockimg
+	generates a clock face PNG image
+*/
+#include <cairo.h>
+#include <popt.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+
+#include <math.h>
+
+int main (int argc, const char **argv)
+{
+
+	/* configuration options */
+	int img_width;
+	int img_height;
+	char *img_filename;
+	char img_filename_default[] = "out.png\0";
+	char *timestr;
+	
+	/* timestamp represeting what time to draw */
+	time_t clock_timestamp;
+	struct tm *clock_localtime;
+	int h;
+	int m;
+
+	/* cairo surface and context */
+	cairo_surface_t *surface;
+	cairo_t *context;
+	
+	/* popt options table */
+	struct poptOption options_table[] = {
+		{"out", 'o', POPT_ARG_STRING, &img_filename, 0, "output filename",  NULL },
+		{"width", 'w', POPT_ARG_INT, &img_width, 0, "output image width", NULL },
+		{"height", 'h', POPT_ARG_INT, &img_height, 0, "output image height", NULL },
+		{"hours", '\0', POPT_ARG_INT, &h, 0, "hour to display", NULL },
+		{"minutes", '\0', POPT_ARG_INT, &m, 0, "minutes to display", NULL },
+		{"time", 't', POPT_ARG_STRING, &timestr, 0, "time to display as HH:MM", NULL},
+		POPT_AUTOHELP
+		{NULL, '\0', 0, NULL, 0, NULL, NULL}
+	};
+	/* popt context */
+	poptContext options_context;
+		
+	/* default filename is out.png */
+	img_filename = NULL;
+	
+	timestr = NULL;
+	
+	/* default image size is 128x128 */
+	img_width = 128;
+	img_height = 128;
+
+	/* default timestamp is current localtime */
+	clock_timestamp = time(NULL);
+	clock_localtime = localtime(&clock_timestamp);
+	h = clock_localtime->tm_hour % 12;
+	m = clock_localtime->tm_min;
+	
+	/* parse command line options */
+	options_context = poptGetContext(NULL, argc, argv, options_table, 0);
+
+	int result;
+	while ((result = poptGetNextOpt(options_context)) > 0 ) {		
+	}
+	if (result < -1) {
+      /* an error occurred during option processing */
+      fprintf(stderr, "%s: %s\n", poptBadOption(options_context, POPT_BADOPTION_NOALIAS), poptStrerror(result));
+      exit(1);
+	}
+	
+	if (img_filename == NULL) {
+		img_filename = img_filename_default;
+	}
+	
+	if (timestr != NULL ) {
+		/* note: clock_localtime is already initialized here */
+		strptime(timestr, "%H:%M", clock_localtime);
+		h = clock_localtime->tm_hour % 12;
+		m = clock_localtime->tm_min;
+	}
+	
+	/* keep hours and minutes into range */
+	h %= 12;
+	m %= 60;	
+	
+	/* create the cairo drawing context and an RGBA drawing surface */	
+	surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, img_width, img_height);
+	context = cairo_create(surface);	
+
+	/* draw image */
+	cairo_set_source_rgba(context, 0.0, 0.0, 0.0, 0.0);
+	cairo_rectangle(context, 0, 0, img_width, img_height);
+	cairo_fill(context);
+	
+	int x1 = img_width / 2 -1;
+	int y1 = img_height / 2 -1;
+
+	float r;
+	if (img_width < img_height) {
+		r = img_width / 2;
+	} else {
+		r = img_height /2;
+	}
+	float angle = 2.0f * M_PI / 12.0f;
+	
+	/* draw clock face */
+	cairo_set_source_rgba (context, 1.0, 1.0, 1.0, 1.0);
+	cairo_arc(context, x1, y1, r-4, 0, 2 * M_PI);
+	cairo_fill(context);
+	
+	cairo_set_source_rgba (context, 0.0, 0.0, 0.0, 1.0);
+	cairo_set_line_width (context, 1);	
+	cairo_arc(context, x1, y1, r-4, 0, 2 * M_PI);
+	cairo_stroke(context);
+
+	/* draw markers */
+	cairo_set_source_rgba (context, 0.0, 0.0, 0.0, 1.0);
+	cairo_set_line_width (context, 2);	
+	for (int h = 0; h < 12; h++) {
+		cairo_move_to(context, x1 + (r - 10) * cosf(angle * h), y1 + (r - 10) * sinf(angle * h));
+		cairo_line_to(context, x1 + (r - 4) * cosf(angle * h), y1 + (r - 4)* sinf(angle * h));
+	}
+	cairo_stroke(context);
+	
+	/* draw handles */
+	cairo_set_line_width (context, 4);
+	
+	/* hours handle */
+	cairo_move_to(context, x1, y1);
+	cairo_line_to(context, x1 + (r/2 - 4) * sinf(angle * h + angle / 60 * m), y1 - (r/2 - 4) * cosf(angle * h + angle / 60 * m));
+	
+	/* minutes handle */
+	cairo_move_to(context, x1, y1);
+	cairo_line_to(context, x1 + (r - 10) * sinf(M_PI / 30.0f * m ), y1 - (r - 10) * cosf(M_PI / 30.0f * m));
+	cairo_stroke(context);
+	
+	
+	/* write image file */
+	if (cairo_surface_write_to_png(surface, img_filename) != CAIRO_STATUS_SUCCESS) {
+		fprintf(stderr, "Error saving %s\n", img_filename);
+	}
+
+	/* cleanup */
+	cairo_surface_destroy(surface);
+	poptFreeContext(options_context);
+	
+	return 0;
+}
-- 
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