theming: Make custom image size handling fully flexible

This commit brings full flexibility of custom image size definition and
usage. When a custom image size is defined, it automatically maps to the
album <item> tag arguments. Alternatively, this automatic name matching
can be overriden by <size tagname="..."> theme setup tags.

This allows us to supply image of different sizes that can be also used
in templates.

Legacy behaviour of "fullsize" and "preview" image size fallback is
retained (though not recommended in new theming setups).

1 files changed, 8 insertions, 6 deletions

diff --git a/templates/default.xml b/templates/default.xml
index 3948538..2ac8354 100644
--- a/templates/default.xml
+++ b/templates/default.xml
@@ -3,6 +3,11 @@
 
   <!-- image size definitions -->
   <image_sizes>
+    <!-- Every image size automatically corresponds to the <item> tag parameter
+         of the same name in album source files. E.g. image size named "hires"
+         would correspond to <item hires=".."> tags. Use the image size parameter
+         "tagname" to override that.   -->
+
     <!-- "original", "preview" and "thumbnail" sizes are somewhat special here
          in order to keep compatibility with previous versions. In case when
          "original" size is not available due to <nofullsize> tag present,
@@ -26,9 +31,7 @@
 
     <!-- The "preview" size is considered default and should be displayed
          on a first visit.  -->
-    <!-- Corresponds with optional <item preview="..."> tag in album source file.
-         No resizing is made when the attribute is present (legacy behaviour).  -->
-    <size name="preview">
+    <size name="preview" tagname="preview">
       <!-- Note that "preview" sizes can be further overriden by album legacy
            <images> tag and also per-image by "width"/"height" <item> tag
            attributes. Same goes for quality. -->
@@ -44,16 +47,15 @@
     </size>
 
     <!-- Thumbnail section is mandatory. -->
-    <!-- Corresponds with optional <item thumbnail> tag in album source file.
-         Note that thumbnail images are always resized even for custom supplied files.  -->
     <!-- The "type" attribute has to be set to "thumbnail" to be treated as such. -->
+    <!-- Note that thumbnail images are always resized even for custom supplied files.  -->
     <!-- An optional "style" attribute affects cropping:
            * normal  - image is resized to fit the dimension limits, maintaining
                        aspect ratio without any crop (default)
            * squared - image is cropped to a squared size and resized to fit
            * fixed   - image is cropped to a specified dimension and cropped to
                        fit the specified aspect ratio
-         An optional album item <thumbnail crop> tags may affect crop area.  -->
+         An optional album item <thumbnail crop> tags may affect the crop area.  -->
     <size name="thumbnail" type="thumbnail" style="normal">
       <landscape w="180" h="120" />
       <portrait w="120" h="180" />