Add support for squared thumbnails

Disabled by default, only very simple center crop implemented.
The SQUARED_SIMPLE_SHAVE_AMOUNT constant may be slightly adjusted
according to future experience. It's a really dumb algorithm which
may not be suitable for every picture.

Looking for a fast and smart algorithm to determine image weight center
and radius, i.e. focus on object of interest. The OpenCV's face recognition
features are worth to test and consider, though I fear the speed issues.

1 files changed, 27 insertions, 5 deletions

diff --git a/src/jpeg-utils.cpp b/src/jpeg-utils.cpp
index 3bde7b6..d46e064 100644
--- a/src/jpeg-utils.cpp
+++ b/src/jpeg-utils.cpp
@@ -231,9 +231,10 @@ free_exif_data (TExifData *data)
  */
 gboolean
 resize_image (const gchar *src, const gchar *dst,
-	          int size_x, int size_y,
-	          int quality,
-                  gboolean thumbnail)
+              int size_x, int size_y,
+              int quality,
+              gboolean thumbnail,
+              ThumbnailSquareType squared_thumbnail_type)
 {
   #define ThrowWandException(wand) \
   { \
@@ -248,14 +249,35 @@ resize_image (const gchar *src, const gchar *dst,
 
   MagickBooleanType status;
   MagickWand *magick_wand;
+  unsigned long w;
+  unsigned long h;
+  unsigned long amount;
 
   /*  Read an image.  */
   magick_wand = NewMagickWand();
   status = MagickReadImage (magick_wand, src);
   if (status == MagickFalse)
-	  ThrowWandException (magick_wand);
-  if (thumbnail)
+    ThrowWandException (magick_wand);
+
+  /*  Process thumbnail if required  */
+  if (thumbnail) {
+    switch (squared_thumbnail_type) {
+      case THUMBNAIL_SQUARE_TYPE_SIMPLE:
+        w = MagickGetImageWidth (magick_wand);
+        h = MagickGetImageHeight (magick_wand);
+        amount = MAX (w, h) * SQUARED_SIMPLE_SHAVE_AMOUNT / 100;
+        MagickShaveImage (magick_wand, amount, amount);
+
+        w = MagickGetImageWidth (magick_wand);
+        h = MagickGetImageHeight (magick_wand);
+        amount = MIN (w, h);
+        MagickCropImage (magick_wand, amount, amount, (w - amount) / 2, (h - amount) / 2);
+        break;
+      default:
+        break;
+    }
     MagickThumbnailImage (magick_wand, size_x, size_y);
+  }
   else
     MagickResizeImage (magick_wand, size_x, size_y, LanczosFilter, 1.0);
   MagickSetImageCompressionQuality (magick_wand, quality);