Handle 180 degrees image rotation

README.md

@@ -136,6 +136,7 @@ of small previews is displayed, making it easy to choose an image to open.
                  (also with Ctrl-arrow keys)
 
     <,>          Rotate image (counter-)clockwise by 90 degrees
+    ?            Rotate image by 180 degrees
     \,|          Flip image horizontally/vertically
 
     a            Toggle anti-aliasing

commands.c

@@ -397,14 +397,17 @@ bool i_fit_to_img(arg_t a)
 
 bool i_rotate(arg_t a)
 {
-	direction_t dir = (direction_t) a;
+	rotate_t rot = (rotate_t) a;
 
 	if (mode == MODE_IMAGE) {
-		if (dir == DIR_LEFT) {
-			img_rotate_left(&img);
+		if (rot == ROTATE_90) {
+			img_rotate(&img, 1);
 			return true;
-		} else if (dir == DIR_RIGHT) {
-			img_rotate_right(&img);
+		} else if (rot == ROTATE_270) {
+			img_rotate(&img, 3);
+			return true;
+		} else if (rot == ROTATE_180) {
+			img_rotate(&img, 2);
 			return true;
 		}
 	}

config.def.h

@@ -114,8 +114,9 @@ static const keymap_t keys[] = {
 	{ false,  XK_E,             i_fit_to_win,         (arg_t) SCALE_HEIGHT },
 	{ false,  XK_W,             i_fit_to_img,         (arg_t) None },
 
-	{ false,  XK_less,          i_rotate,             (arg_t) DIR_LEFT },
-	{ false,  XK_greater,       i_rotate,             (arg_t) DIR_RIGHT },
+	{ false,  XK_less,          i_rotate,             (arg_t) ROTATE_270 },
+	{ false,  XK_greater,       i_rotate,             (arg_t) ROTATE_90 },
+	{ false,  XK_question,      i_rotate,             (arg_t) ROTATE_180 },
 
 	{ false,  XK_backslash,     i_flip,               (arg_t) FLIP_HORIZONTAL },
 	{ false,  XK_bar,           i_flip,               (arg_t) FLIP_VERTICAL },
@@ -131,10 +132,14 @@ static const keymap_t keys[] = {
 			"mogrify -rotate -90 \"$SXIV_IMG\"" },
 	{ true,   XK_greater,       it_shell_cmd,         (arg_t) \
 			"mogrify -rotate +90 \"$SXIV_IMG\"" },
+	{ true,   XK_question,      it_shell_cmd,         (arg_t) \
+			"mogrify -rotate 180 \"$SXIV_IMG\"" },
 	{ true,   XK_comma,         it_shell_cmd,         (arg_t) \
 			"jpegtran -rotate 270 -copy all -outfile \"$SXIV_IMG\" \"$SXIV_IMG\"" },
 	{ true,   XK_period,        it_shell_cmd,         (arg_t) \
 			"jpegtran -rotate  90 -copy all -outfile \"$SXIV_IMG\" \"$SXIV_IMG\"" },
+	{ true,   XK_slash,         it_shell_cmd,         (arg_t) \
+			"jpegtran -rotate 180 -copy all -outfile \"$SXIV_IMG\" \"$SXIV_IMG\"" },
 };
 
 /* mouse button mappings for image mode: */

image.c

@@ -663,29 +663,22 @@ void img_rotate(img_t *img, int d)
 	oy = d == 3 ? img->y : win->h - img->y - img->h * img->zoom;
 
 	imlib_context_set_image(img->im);
+	/* rotates by `90 * d` degrees in the clockwise direction */
 	imlib_image_orientate(d);
 
-	img->x = oy + (win->w - win->h) / 2;
-	img->y = ox + (win->h - win->w) / 2;
+	if (d == 1 || d == 3) {
+		img->x = oy + (win->w - win->h) / 2;
+		img->y = ox + (win->h - win->w) / 2;
 
-	tmp = img->w;
-	img->w = img->h;
-	img->h = tmp;
+		tmp = img->w;
+		img->w = img->h;
+		img->h = tmp;
+		img->checkpan = true;
+	}
 
-	img->checkpan = true;
 	img->dirty = true;
 }
 
-void img_rotate_left(img_t *img)
-{
-	img_rotate(img, 3);
-}
-
-void img_rotate_right(img_t *img)
-{
-	img_rotate(img, 1);
-}
-
 void img_flip(img_t *img, flipdir_t d)
 {
 	if (img == NULL || img->im == NULL)

image.h

@@ -77,9 +77,6 @@ bool img_pan(img_t*, direction_t, int);
 bool img_pan_edge(img_t*, direction_t);
 
 void img_rotate(img_t*, int);
-void img_rotate_left(img_t*);
-void img_rotate_right(img_t*);
-
 void img_flip(img_t*, flipdir_t);
 
 void img_toggle_antialias(img_t*);

sxiv.1

@@ -261,6 +261,9 @@ Rotate image counter-clockwise by 90 degrees.
 .TP
 .B >
 Rotate image clockwise by 90 degrees.
+.TP
+.B ?
+Rotate image by 180 degrees.
 .SS Flip
 .TP
 .B \\\\

types.h

@@ -38,6 +38,12 @@ typedef enum {
 	DIR_DOWN
 } direction_t;
 
+typedef enum {
+	ROTATE_90,
+	ROTATE_270,
+	ROTATE_180
+} rotate_t;
+
 typedef enum {
 	FLIP_HORIZONTAL,
 	FLIP_VERTICAL