adding docs & rotate_image

src/wand/magick.rs

@@ -66,6 +66,7 @@ impl MagickWand {
         }
     }
 
+    /// Add all images from another wand to this wand at the current index.
     pub fn add_image(&mut self, other_wand: &MagickWand) -> Result<(), &'static str> {
         match unsafe { bindings::MagickAddImage(self.wand, other_wand.wand) } {
             bindings::MagickBooleanType::MagickTrue => Ok(()),
@@ -238,6 +239,15 @@ impl MagickWand {
         }
     }
 
+    /// Rotate the currently selected image by the given number of degrees,
+    /// filling any empty space with the background color of a given PixelWand
+    pub fn rotate_image(&self, background: &PixelWand, degrees: f64) -> Result<(), &'static str> {
+        match unsafe { bindings::MagickRotateImage(self.wand, background.wand, degrees) } {
+            bindings::MagickBooleanType::MagickTrue => Ok(()),
+            _ => Err("failed to rotate image")
+        }
+    }
+
     /// Trim the image removing the backround color from the edges.
     pub fn trim_image(&self, fuzz: f64) -> Result<(), &'static str> {
         let result = unsafe {