1 files changed, 106 insertions, 0 deletions
diff --git a/tex/context/base/typo-dig.lua b/tex/context/base/typo-dig.lua
new file mode 100644
index 000000000..c1b44e39f
--- /dev/null
+++ b/tex/context/base/typo-dig.lua
@@ -0,0 +1,106 @@
+if not modules then modules = { } end modules ['typo-dig'] = {
+    version   = 1.001,
+    comment   = "companion to typo-dig.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files"
+}
+
+local next, type = next, type
+local format, insert = string.format, table.insert
+local round = math.round
+
+local trace_digits = false  trackers.register("nodes.digits", function(v) trace_digits = v end)
+
+local has_attribute      = node.has_attribute
+local unset_attribute    = node.unset_attribute
+local set_attribute      = node.set_attribute
+local hpack_node         = node.hpack
+local traverse_id        = node.traverse_id
+local insert_before      = node.insert_before
+local insert_after       = node.insert_after
+
+local glyph = node.id("glyph")
+local kern  = node.id("kern")
+
+local new_glue = nodes.glue
+
+local fontdata = fonts.identifiers
+local chardata = fonts.characters
+local quaddata = fonts.quads
+local charbase = characters.data
+
+digits           = digits or { }
+digits.actions   = { }
+digits.attribute = attributes.private("digits")
+
+local actions  = digits.actions
+
+-- at some point we can manipulate the glyph node so then i need
+-- to rewrite this
+
+function nodes.aligned(start,stop,width,how)
+    local prv, nxt, head = start.prev, stop.next, nil
+    start.prev, stop.next = nil, nil
+    if how == "flushright" or how == "middle" then
+        head, start = insert_before(start,start,new_glue(0,65536,65536))
+    end
+    if how == "flushleft" or how == "middle" then
+        head, stop = insert_after(start,stop,new_glue(0,65536,65536))
+    end
+    local packed = hpack_node(start,width,"exactly") -- no directional mess here, just lr
+    if prv then
+        prv.next, packed.prev = packed, prv
+    end
+    if nxt then
+        nxt.prev, packed.next = packed, nxt
+    end
+    return packed, prv, nxt
+end
+
+actions[1] = function(start,attribute)
+    local char = start.char
+    if charbase[char].category == "nd" then
+        local font = start.font
+        local oldwidth, newwidth = start.width, fonts.get_digit_width(font)
+        if newwidth ~= oldwidth then
+            local start = nodes.aligned(start,start,newwidth,"middle") -- return three node pointers
+            return start, true
+        end
+    end
+    return start, false
+end
+
+function digits.process(namespace,attribute,head)
+    local done, current, ok = false, head, false
+    while current do
+        if current.id == glyph then
+            local attr = has_attribute(current,attribute)
+            if attr and attr > 0 then
+                unset_attribute(current,attribute)
+                local action = actions[attr]
+                if action then
+                    if current == head then
+                        head, ok = action(current,attribute)
+                        current = head
+                    else
+                        current, ok = action(current,attribute)
+                    end
+                    done = done and ok
+                end
+            end
+        end
+        current = current and current.next
+    end
+    return head, done
+end
+
+chars.handle_digits = nodes.install_attribute_handler {
+    name = "digits",
+    namespace = digits,
+    processor = digits.process,
+}
+
+function digits.enable()
+    tasks.enableaction("processors","chars.handle_digits")
+end