1 files changed, 186 insertions, 0 deletions
diff --git a/src/layer-fns.cpp b/src/layer-fns.cpp
new file mode 100644
index 000000000..fadcd0f1e
--- /dev/null
+++ b/src/layer-fns.cpp
@@ -0,0 +1,186 @@
+/*
+ * Inkscape::SelectionDescriber - shows messages describing selection
+ *
+ * Authors:
+ *   MenTaLguY <mental@rydia.net>
+ *
+ * Copyright (C) 2004 MenTaLguY
+ *
+ * Released under GNU GPL, read the file 'COPYING' for more information
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include "document.h"
+#include "sp-item-group.h"
+#include "xml/repr.h"
+#include "algorithms/find-last-if.h"
+
+namespace Inkscape {
+
+/** 
+ *  Creates a new layer.  Advances to the next layer id indicated
+ *  by the string "layerNN", then creates a new group object of 
+ *  that id with attribute inkscape:groupmode='layer', and finally
+ *  appends the new group object to \a root after object \a layer.
+ *
+ *  \pre \a root should be either \a layer or an ancestor of it
+ */
+SPObject *create_layer(SPObject *root, SPObject *layer) {
+    SPDocument *document=SP_OBJECT_DOCUMENT(root);
+
+    static int layer_suffix=1;
+    gchar *id=NULL;
+    do {
+        g_free(id);
+        id = g_strdup_printf("layer%d", layer_suffix++);
+    } while (document->getObjectById(id));
+
+    Inkscape::XML::Node *repr=sp_repr_new("svg:g");
+    repr->setAttribute("inkscape:groupmode", "layer");
+    repr->setAttribute("id", id);
+    g_free(id);
+
+    if ( root == layer ) {
+        SP_OBJECT_REPR(root)->appendChild(repr);
+    } else {
+        Inkscape::XML::Node *layer_repr=SP_OBJECT_REPR(layer);
+        sp_repr_parent(layer_repr)->addChild(repr, layer_repr);
+    }
+
+    return document->getObjectByRepr(repr);
+}
+
+namespace {
+
+bool is_layer(SPObject &object) {
+    return SP_IS_GROUP(&object) &&
+           SP_GROUP(&object)->layerMode() == SPGroup::LAYER;
+}
+
+SPObject *next_sibling_layer(SPObject *layer) {
+    using std::find_if;
+
+    return find_if<SPObject::SiblingIterator>(
+        SP_OBJECT_NEXT(layer), NULL, &is_layer
+    );
+}
+
+SPObject *previous_sibling_layer(SPObject *layer) {
+    using Inkscape::Algorithms::find_last_if;
+
+    SPObject *sibling(find_last_if<SPObject::SiblingIterator>(
+        SP_OBJECT_PARENT(layer)->firstChild(), layer, &is_layer
+    ));
+
+    return ( sibling != layer ) ? sibling : NULL;
+}
+
+SPObject *first_descendant_layer(SPObject *layer) {
+    using std::find_if;
+
+    SPObject *first_descendant=NULL;
+    while (layer) {
+        layer = find_if<SPObject::SiblingIterator>(
+            layer->firstChild(), NULL, &is_layer
+        );
+        if (layer) {
+            first_descendant = layer;
+        }
+    }
+
+    return first_descendant;
+}
+
+SPObject *last_child_layer(SPObject *layer) {
+    using Inkscape::Algorithms::find_last_if;
+
+    return find_last_if<SPObject::SiblingIterator>(
+        layer->firstChild(), NULL, &is_layer
+    );
+}
+
+SPObject *last_elder_layer(SPObject *root, SPObject *layer) {
+    using Inkscape::Algorithms::find_last_if;
+
+    while ( layer != root ) {
+        SPObject *sibling(previous_sibling_layer(layer));
+        if (sibling) {
+            return sibling;
+        }
+        layer = SP_OBJECT_PARENT(layer);
+    }
+
+    return NULL;
+}
+
+}
+
+/** Finds the next layer under \a root, relative to \a layer in
+ *  depth-first order.
+ *
+ *  @returns NULL if there are no further layers under \a root
+ */
+SPObject *next_layer(SPObject *root, SPObject *layer) {
+    using std::find_if;
+
+    g_return_val_if_fail(layer != NULL, NULL);
+
+    SPObject *sibling(next_sibling_layer(layer));
+    if (sibling) {
+        SPObject *descendant(first_descendant_layer(sibling));
+        if (descendant) {
+            return descendant;
+        } else {
+            return sibling;
+        }
+    } else {
+        SPObject *parent=SP_OBJECT_PARENT(layer);
+        if ( parent != root ) {
+            return parent;
+        } else {
+            return NULL;
+        }
+    }
+}
+
+
+/** Finds the previous layer under \a root, relative to \a layer in
+ *  depth-first order.
+ *
+ *  @returns NULL if there are no prior layers under \a root.
+ */
+SPObject *previous_layer(SPObject *root, SPObject *layer) {
+    using Inkscape::Algorithms::find_last_if;
+
+    g_return_val_if_fail(layer != NULL, NULL);
+
+    SPObject *child(last_child_layer(layer));
+    if (child) {
+        return child;
+    } else if ( layer != root ) {
+        SPObject *sibling(previous_sibling_layer(layer));
+        if (sibling) {
+            return sibling;
+        } else {
+            return last_elder_layer(root, SP_OBJECT_PARENT(layer));
+        }
+    } 
+
+    return NULL;
+}
+
+}
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :