Add an advanced feature to change resize behavior

Added the "Fit" resize method as an option, to respond to issue #35

2 files changed, 17 insertions, 2 deletions

diff --git a/README.md b/README.md
index d597c91..70dde87 100644
--- a/README.md
+++ b/README.md
@@ -157,7 +157,12 @@ Regardless of the number of resources you have, Hugo will only deploy the ones a
 
 ## Advanced Features
 
-Image resizing: normally you specify `thumb_width` and `full_width` in your configuration, and the qualities, to modify how Autophugo scales your images.  Autophugo uses these values to build a string for Hugo's Resize function.  You can specify that string directly though...  Set `thumb_size` or `full_size` directly in your config to bypass the other ones.  The format of the string is [documented here](https://gohugo.io/content-management/image-processing/).
+Image resizing: normally you specify `thumb_width` and `full_width` in your configuration, and the qualities, to modify how Autophugo scales your images.  Autophugo uses these values to build a string for Hugo's Resize function.  You can specify that string directly though...  Set `thumb_size` or `full_size` directly in your config to bypass the other ones.  The format of the string is [documented here](https://gohugo.io/content-management/image-processing/).  You can specify `full_size` and `thumb_size` for the entire site, or in the `_index.md` for a specific subalbum.
+
+You can also change the method Hugo uses to resize your full-sized images (the option is not available for thumbnails).  Hugo has both `Resize` and `Fit` methods that are appropriate for resizing the full-sized images.  By default Autophugo uses `Resize`.  By setting `full_resize_method` to `Fit` or `Resize` you can change that.  You must also specify a `full_size` if you change to the `Fit` method.  That's because both the height and width must be specified, and with `Resize` you only need one or the other.  Again, the format of the `full_size` string is [documented here](https://gohugo.io/content-management/image-processing/).  Here are some examples:
+
+* Scale an image down, keeping aspect ratio, to a max height of 960px and a max width of 960px, with a 90% quality: `full_resize_method = "fit"`, `full_size = "960x960 q90"`
+* Scale an image to a width of 960px, allowing whatever height is required for the original aspect ratio, with a 90% quality: `full_resize_method = "resize"`, `full_size = "960x q90"`
 
 ## Comparison to Phugo
 
diff --git a/layouts/_default/list.html b/layouts/_default/list.html
index caaefe6..1a9786a 100644
--- a/layouts/_default/list.html
+++ b/layouts/_default/list.html
@@ -9,6 +9,7 @@
 
     {{- /* Calculate thumb_ and full_size from params, unless one is provided in the config. */}}
     {{- $thumb_size := default (printf "%dx q%d" $thumb_width $thumb_quality) ($.Param "thumb_size") }}
+    {{- $full_resize_method := lower (default "resize" ($.Param "full_resize_method")) -}}
     {{- $full_size := default (printf "%dx q%d" $full_width $full_quality) ($.Param "full_size") }}
 
     {{- /* Build the list of sections and thumbnails */}}
@@ -130,7 +131,16 @@
         {{- $weight := $img_dat.Get "weight" }}
         {{- $taxonomies := $img_dat.Get "taxonomies" }}
         {{- $thumb := $elem_val.Resize $thumb_resize_cmd }}
-        {{- $full := $elem_val.Resize $full_resize_cmd }}
+
+        {{- $.Scratch.Set "full_resized" $thumb }}
+        {{- if (eq $full_resize_method "resize") }}
+            {{- $.Scratch.Set "full_resized" ($elem_val.Resize $full_resize_cmd) }}
+        {{- else if (eq $full_resize_method "fit") }}
+            {{- $.Scratch.Set "full_resized" ($elem_val.Fit $full_resize_cmd) }}
+        {{- else }}
+            {{- errorf "Invalid 'full_resize_method' specified!  Must be resize or fit." }}
+        {{- end }}
+        {{- $full := $.Scratch.Get "full_resized" }}
 
         {{- $new_img := dict "type" "image" "index" $elem_index "image" $elem_val "thumb" $thumb "full" $full "alt" $alt "phototitle" $phototitle "description" $description "weight" $weight  "orig" $elem_val "taxonomies" $taxonomies }}