[gimp-help] Add Panorama Projection filter

[Julien Hardlin <jhardlin src gnome org>]

commit 0b5b0432718876e718df146386345ba7962757e4
Author: Julien Hardelin <jhardlin orange fr>
Date:   Fri Feb 22 18:00:15 2019 +0100

    Add Panorama Projection filter

 .../C/filters/examples/map/pan-project-origin.jpg  | Bin 0 -> 30020 bytes
 .../filters/examples/map/pan-project-result-1.jpg  | Bin 0 -> 34229 bytes
 .../filters/examples/map/pan-project-result-2.jpg  | Bin 0 -> 42101 bytes
 images/C/filters/map/pan-project-dialog.png        | Bin 0 -> 25973 bytes
 src/filters/map.xml                                |   2 +
 src/filters/map/panorama-projection.xml            | 120 +++++++++++++++++++++
 6 files changed, 122 insertions(+)
---
diff --git a/images/C/filters/examples/map/pan-project-origin.jpg 
b/images/C/filters/examples/map/pan-project-origin.jpg
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diff --git a/images/C/filters/examples/map/pan-project-result-1.jpg 
b/images/C/filters/examples/map/pan-project-result-1.jpg
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diff --git a/images/C/filters/examples/map/pan-project-result-2.jpg 
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diff --git a/images/C/filters/map/pan-project-dialog.png b/images/C/filters/map/pan-project-dialog.png
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diff --git a/src/filters/map.xml b/src/filters/map.xml
index fac36a081..3f6201e69 100644
--- a/src/filters/map.xml
+++ b/src/filters/map.xml
@@ -2,6 +2,7 @@
 <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
                        "http://www.docbook.org/xml/4.3/docbookx.dtd";>
 <!-- section history:
+  2019-02-21 j.h: add panorama-projection
   2019-02-18 j.h: add little-planet.xml
   2007-08-08 ude: moved Van Gogh (LIC) to artistic filters
   2005-10-05 created by julien hardelin
@@ -14,6 +15,7 @@
   <xi:include href="map/fractal-trace.xml"/>
   <xi:include href="map/illusion.xml"/>
   <xi:include href="map/little-planet.xml"/>
+  <xi:include href="map/panorama-projection.xml"/>
   <xi:include href="map/make-seamless.xml"/>
   <xi:include href="map/map-object.xml"/>
   <xi:include href="map/papertile.xml"/>
diff --git a/src/filters/map/panorama-projection.xml b/src/filters/map/panorama-projection.xml
new file mode 100644
index 000000000..60edbf225
--- /dev/null
+++ b/src/filters/map/panorama-projection.xml
@@ -0,0 +1,120 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE sect2 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
+                       "http://www.docbook.org/xml/4.3/docbookx.dtd";>
+<!-- section history:
+  2019-02-21 j.h: create
+-->
+
+<sect2 xmlns:xi="http://www.w3.org/2001/XInclude"; 
+  id="gimp-filter-panorama-projection">
+  <title>Panorama Projection</title>
+
+  <indexterm>
+    <primary>Filters</primary>
+    <secondary>Map</secondary>
+    <tertiary>Panorama Projection</tertiary>
+  </indexterm>
+  <indexterm>
+    <primary>Panorama Projection</primary>
+  </indexterm>
+
+  <sect3>
+    <title>Overview</title>
+    <para>
+      This filter converts a 360° x 180° image, also known as equirectangular 
+      image, into a panorama.
+    </para>
+  </sect3>
+  <sect3>
+    <title>Activate the filter</title>
+    <para>
+      This filter is found in the image window menu under
+      <menuchoice>
+        <guimenu>Filters</guimenu>
+        <guisubmenu>Map</guisubmenu>
+        <guimenuitem>Panorama Projection…</guimenuitem>
+      </menuchoice>.
+    </para>
+  </sect3>
+
+  <sect3>
+    <title>Options</title>
+    <figure>
+      <title><quote>Panorama Projection</quote> filter options</title>
+      <mediaobject>
+        <imageobject>
+          <imagedata format="PNG"
+            fileref="images/filters/map/pan-project-dialog.png"/>
+        </imageobject>
+      </mediaobject>
+    </figure>
+    <para>
+      These options are the same as <xref linkend="gimp-filter-little-planet"/> 
+      options.
+    </para>
+  </sect3>
+  
+  <sect3>
+    <title>Using Panorama Projection filter</title>
+    <tip>
+      <para>
+        You can find free equirectangular images at <ulink 
+url="https://commons.wikimedia.org/wiki/Category:360°_panoramas_with_equirectangular_projection"/>.
+      </para>
+    </tip>
+    <para>
+      Of course, you can get only a part of the original image in your panorama. 
+      The first thing you have to do is creating a new image with the size of 
+      your future panorama. Then, open the original image.
+      <mediaobject>
+        <imageobject>
+          <imagedata format="JPG"
+            fileref="images/filters/examples/map/pan-project-origin.jpg"/>
+        </imageobject>
+        <caption>
+          <para>
+          <subscript>
+            Parc_de_Belleville,_Paris_June_2007.jpg by Alexandre Duret-Lutz under 
+<ulink url="https://creativecommons.org/licenses/by-sa/4.0";>  CC by-sa 4.0</ulink>
+          </subscript>
+          </para>
+          <para>
+          GIMP opened this 4000x2000 pixels original image in a 1000x500 px frame 
+          at zoom 12.5. This is a screenshot scaled to 400x200 px.
+          </para>
+        </caption>
+      </mediaobject>
+    </para>
+    <para>
+      Open the Panorama Projection filter. Only the central part of the image is 
+      visible. Pan across the image to find your panorama using the Pan option or 
+      click and dragging. You can zoom in to have a wider view.
+    </para>
+    <figure>
+      <title><quote>Panorama Projection</quote> filter applied</title>
+      <mediaobject>
+        <imageobject>
+          <imagedata format="JPG"
+            fileref="images/filters/examples/map/pan-project-result-1.jpg"/>
+        </imageobject>
+        <caption>
+          <para>
+            Pan = 0.00
+          </para>
+        </caption>
+      </mediaobject>
+      <mediaobject>
+        <imageobject>
+          <imagedata format="JPG"
+            fileref="images/filters/examples/map/pan-project-result-2.jpg"/>
+        </imageobject>
+        <caption>
+          <para>
+            Pan = 66.00
+          </para>
+        </caption>
+      </mediaobject>
+    </figure>
+  </sect3>
+</sect2>
+