1 files changed, 73 insertions, 0 deletions
diff --git a/tex/context/base/attr-eff.lua b/tex/context/base/attr-eff.lua
new file mode 100644
index 000000000..2dba1b459
--- /dev/null
+++ b/tex/context/base/attr-eff.lua
@@ -0,0 +1,73 @@
+if not modules then modules = { } end modules ['attr-eff'] = {
+    version   = 1.001,
+    comment   = "companion to attr-eff.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files"
+}
+
+local format = string.format
+
+local attributes, nodes = attributes, nodes
+
+local states         = attributes.states
+local tasks          = nodes.tasks
+local nodeinjections = backends.nodeinjections
+
+attributes.effects = attributes.effects or { }
+local effects      = attributes.effects
+effects.data       = effects.data       or { }
+effects.values     = effects.values     or { }
+effects.registered = effects.registered or { }
+effects.stamp      = "%s:%s:%s"
+effects.attribute  = attributes.private("effect")
+
+storage.register("attributes/effects/registered", effects.registered, "attributes.effects.registered")
+storage.register("attributes/effects/values",     effects.values,     "attributes.effects.values")
+
+local data, registered, values = effects.data, effects.registered, effects.values
+
+-- valid effects: normal inner outer both hidden (stretch,rulethickness,effect)
+
+local function effect(...) effect = nodeinjections.effect return effect(...) end
+
+local function extender(effects,key)
+    if key == "none" then
+        local d = effect(0,0,0)
+        effects.none = d
+        return d
+    end
+end
+
+local function reviver(data,n)
+    local e = values[n] -- we could nil values[n] now but hardly needed
+    local d = effect(e[1],e[2],e[3])
+    data[n] = d
+    return d
+end
+
+setmetatable(effects,      { __index = extender })
+setmetatable(effects.data, { __index = reviver  })
+
+function effects.register(effect,stretch,rulethickness)
+    local stamp = format(effects.stamp,effect,stretch,rulethickness)
+    local n = registered[stamp]
+    if not n then
+        n = #values + 1
+        values[n] = { effect, stretch, rulethickness }
+        registered[stamp] = n
+    end
+    return n
+end
+
+attributes.effects.handler = nodes.install_attribute_handler {
+    name        = "effect",
+    namespace   = effects,
+    initializer = states.initialize,
+    finalizer   = states.finalize,
+    processor   = states.process,
+}
+
+function effects.enable()
+    tasks.enableaction("shipouts","attributes.effects.handler")
+end