Move get_screen_dpi to libdocument

2 files changed, 17 insertions, 0 deletions

diff --git a/libdocument/ev-document-misc.c b/libdocument/ev-document-misc.c
index 14bc3a3..0a23394 100644
--- a/libdocument/ev-document-misc.c
+++ b/libdocument/ev-document-misc.c
@@ -21,6 +21,7 @@
 #include <config.h>
 
 #include <string.h>
+#include <math.h>
 
 #include <gtk/gtk.h>
 
@@ -363,3 +364,17 @@ ev_document_misc_invert_pixbuf (GdkPixbuf *pixbuf)
 		}
 	}
 }
+
+gdouble
+ev_document_misc_get_screen_dpi (GdkScreen *screen)
+{
+	gdouble dp, di;
+
+	/*diagonal in pixels*/
+	dp = hypot (gdk_screen_get_width (screen), gdk_screen_get_height (screen));
+
+	/*diagonal in inches*/
+	di = hypot (gdk_screen_get_width_mm(screen), gdk_screen_get_height_mm (screen)) / 25.4;
+
+	return (dp / di);
+}
diff --git a/libdocument/ev-document-misc.h b/libdocument/ev-document-misc.h
index 8e92983..61d070d 100644
--- a/libdocument/ev-document-misc.h
+++ b/libdocument/ev-document-misc.h
@@ -54,6 +54,8 @@ cairo_surface_t *ev_document_misc_surface_rotate_and_scale (cairo_surface_t *sur
 void             ev_document_misc_invert_surface (cairo_surface_t *surface);
 void		 ev_document_misc_invert_pixbuf  (GdkPixbuf       *pixbuf);
 
+gdouble          ev_document_misc_get_screen_dpi (GdkScreen *screen);
+
 G_END_DECLS
 
 #endif /* EV_DOCUMENT_MISC_H */