resize images to the terminal window size

1 files changed, 84 insertions, 7 deletions

diff --git a/view.c b/view.c
index af237c9..f028c82 100644
--- a/view.c
+++ b/view.c
@@ -1,6 +1,10 @@
 #include <stdlib.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <assert.h>
 #include <math.h>
 #include <unistd.h>
+#include <termios.h>
 
 #include <glib.h>
 #include <gio/gio.h>
@@ -8,12 +12,73 @@
 #include <gdk-pixbuf/gdk-pixbuf.h>
 #include <gdk-pixbuf/gdk-pixdata.h>
 
-// TODO Unhardcode these
-const int char_width = 8;
-const int char_height = 15;
+static FILE* tty;
+static int tty_fd;
+static struct termios tty_tio;
 
-const int window_width = 8 * 80;
-const int window_height = 15 * 25;
+static int char_width = 8;
+static int char_height = 15;
+static int window_columns = 25;
+static int window_rows = 80;
+static int window_width = 8 * 80;
+static int window_height = 15 * 25;
+
+static bool init_terminal(int fd);
+static void close_terminal();
+
+static bool init_terminal(int fd)
+{
+	const char *name_of_tty = ttyname(fd);
+	if (!name_of_tty) {
+		return FALSE;
+	}
+
+	tty = fopen(name_of_tty, "r+");
+	if (tty == NULL) {
+		g_printerr("Cannot open terminal %s", name_of_tty);
+		return FALSE;
+	}
+	tty_fd = fileno(tty);
+
+	tcgetattr(tty_fd, &tty_tio);
+	struct termios tio = tty_tio;
+
+	tio.c_lflag &= ~(ICANON | ECHO);
+	tio.c_cc[VMIN] = 4;
+	tio.c_cc[VTIME] = 1;
+	tcsetattr(tty_fd, TCSADRAIN, &tio);
+
+	// Try to get window width and height in pixels using a xterm command
+	fprintf(tty, "\033[14;t");
+	fflush(tty);
+
+	if (fscanf(tty, "\033[4;%d;%dt", &window_height, &window_width) != 2) {
+		close_terminal();
+		return FALSE;
+	}
+
+	// Also use a xterm command to get the window size in chars,
+	// (could also use termios...)
+	fprintf(tty, "\033[18;t");
+	fflush(tty);
+
+	if (fscanf(tty, "\033[8;%d;%dt", &window_rows, &window_columns) != 2) {
+		close_terminal();
+		return FALSE;
+	}
+
+	// Now calculate char height & width based on the above data
+	char_width = window_width / window_columns;
+	char_height = window_height / window_rows;
+
+	return TRUE;
+}
+
+static void close_terminal()
+{
+	tcsetattr(tty_fd, TCSADRAIN, &tty_tio);
+	fclose(tty);
+}
 
 static gboolean view_pixbuf(GdkPixbuf *pixbuf)
 {
@@ -52,13 +117,15 @@ static gboolean view_pixbuf(GdkPixbuf *pixbuf)
 	guint8 *data = gdk_pixdata_serialize(&pixdata, &size);
 	gchar *str = g_base64_encode(data, size);
 
-	g_print("\033]v;%s\007", str);
+	fprintf(tty, "\033]v;%s\007", str);
 
 	int rows = ceil(height / (double)char_height);
 	while (rows > 0) {
-		g_print("\n");
+		fprintf(tty, "\n");
 		rows--;
 	}
+
+	fflush(tty);
 	
 	g_free(str);
 	g_free(data);
@@ -80,16 +147,23 @@ int main(int argc, char * argv[])
 		return EXIT_FAILURE;
 	}
 
+	if (!init_terminal((STDOUT_FILENO))) {
+		g_printerr("Refusing to display image on non-graphical terminal\n");
+		return EXIT_FAILURE;
+	}
+
 	if (argc > 1) {
 		int i;
 		for (i = 1; i < argc; i++) {
 			GdkPixbuf *pixbuf = gdk_pixbuf_new_from_file(argv[i], &error);
 			if (pixbuf == NULL) {
 				g_printerr("Failed to open image '%s': %s\n", argv[i], error->message);
+				close_terminal();
 				return EXIT_FAILURE;
 			}
 			if (!view_pixbuf(pixbuf)) {
 				g_printerr("Failed to view image '%s'\n", argv[i]);
+				close_terminal();
 				return EXIT_FAILURE;
 			}
 			g_object_unref(pixbuf);
@@ -99,14 +173,17 @@ int main(int argc, char * argv[])
 		GdkPixbuf *pixbuf = gdk_pixbuf_new_from_stream(input, NULL, &error);
 		if (pixbuf == NULL) {
 			g_printerr("Failed to open stdin image: %s\n", error->message);
+			close_terminal();
 			return EXIT_FAILURE;
 		}
 		if (!view_pixbuf(pixbuf)) {
 			g_printerr("Failed to view stdin image\n");
+			close_terminal();
 			return EXIT_FAILURE;
 		}
 		g_object_unref(pixbuf);
 	}
 
+	close_terminal();
 	return EXIT_SUCCESS;
 }