1 files changed, 134 insertions, 0 deletions
diff --git a/tex/context/base/mkxl/attr-eff.lmt b/tex/context/base/mkxl/attr-eff.lmt
new file mode 100644
index 000000000..d04408fb9
--- /dev/null
+++ b/tex/context/base/mkxl/attr-eff.lmt
@@ -0,0 +1,134 @@
+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 attributes, nodes, backends, utilities = attributes, nodes, backends, utilities
+local tex = tex
+
+local states            = attributes.states
+local enableaction      = nodes.tasks.enableaction
+local nodeinjections    = backends.nodeinjections
+local texsetattribute   = tex.setattribute
+local allocate          = utilities.storage.allocate
+local setmetatableindex = table.setmetatableindex
+local formatters        = string.formatters
+
+local interfaces        = interfaces
+local implement         = interfaces.implement
+
+local variables         = interfaces.variables
+local v_normal          = variables.normal
+
+attributes.effects      = attributes.effects or { }
+local effects           = attributes.effects
+
+local a_effect          = attributes.private('effect')
+
+effects.data            = allocate()
+effects.values          = effects.values     or { }
+effects.registered      = effects.registered or { }
+effects.attribute       = a_effect
+
+local data              = effects.data
+local registered        = effects.registered
+local values            = effects.values
+
+local f_stamp           = formatters["%s:%s:%s"]
+
+storage.register("attributes/effects/registered", registered, "attributes.effects.registered")
+storage.register("attributes/effects/values",     values,     "attributes.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
+
+setmetatableindex(effects,      extender)
+setmetatableindex(effects.data, reviver)
+
+effects.handler = nodes.installattributehandler {
+    name        = "effect",
+    namespace   = effects,
+    initializer = states.initialize,
+    finalizer   = states.finalize,
+    processor   = states.process,
+}
+
+local function register(specification)
+    local alternative, stretch, rulethickness
+    if specification then
+        alternative   = specification.alternative or v_normal
+        stretch       = specification.stretch or 0
+        rulethickness = specification.rulethickness or 0
+    else
+        alternative   = v_normal
+        stretch       = 0
+        rulethickness = 0
+    end
+    local stamp = f_stamp(alternative,stretch,rulethickness)
+    local n = registered[stamp]
+    if not n then
+        n = #values + 1
+        values[n] = { alternative, stretch, rulethickness }
+        registered[stamp] = n
+    end
+    return n
+end
+
+local enabled = false
+
+local function enable()
+    if not enabled then
+        enableaction("shipouts","attributes.effects.handler")
+        enabled = true
+    end
+end
+
+effects.register = register
+effects.enable   = enable
+
+-- interface
+
+implement {
+    name      = "seteffect",
+    actions   = function(specification)
+        if not enabled then
+            enable()
+        end
+        texsetattribute(a_effect,register(specification))
+    end,
+    arguments = {
+        {
+            { "alternative",   "string"  },
+            { "stretch",       "integer" },
+            { "rulethickness", "dimen"   }
+        }
+    }
+}
+
+implement {
+    name      = "reseteffect",
+    actions   = function()
+        if enabled then
+            texsetattribute(a_effect,register())
+        end
+    end
+}