1 files changed, 106 insertions, 0 deletions
diff --git a/tex/context/base/mkiv/grph-mem.lua b/tex/context/base/mkiv/grph-mem.lua
new file mode 100644
index 000000000..bb48ae8d5
--- /dev/null
+++ b/tex/context/base/mkiv/grph-mem.lua
@@ -0,0 +1,106 @@
+if not modules then modules = { } end modules ['grph-mem'] = {
+    version   = 1.001,
+    comment   = "companion to grph-inc.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files"
+}
+
+-- very experimental and likely to change
+--
+-- \startluacode
+--     figures.setmemstream("whatever",io.loaddata("t:/sources/cow.pdf"))
+-- \stopluacode
+--
+-- \externalfigure[memstream:///t:/sources/cow.pdf]
+-- \externalfigure[memstream:///whatever]
+
+local gsub = string.gsub
+
+local report = logs.reporter("memstream")
+local trace  = false  trackers.register  ("graphics.memstreams", function(v) trace = v end)
+local data   = { }
+local opened = { }
+
+local function setmemstream(name,stream,once)
+    if once and data[name] then
+        if trace then
+            report("not overloading %a",name) --
+        end
+        return data[name]
+    end
+    local memstream, identifier = epdf.openMemStream(stream,#stream,name)
+    if not identifier then
+        report("no valid stream %a",name)
+        identifier = "invalid-memstream"
+    elseif trace then
+        report("setting %a with identifier %a",name,identifier)
+    end
+    data  [name] = identifier
+    opened[name] = memstream
+    return identifier
+end
+
+resolvers.setmemstream = setmemstream
+
+function resolvers.finders.memstream(specification)
+    local name       = specification.path
+    local identifier = data[name]
+    if identifier then
+        if trace then
+            report("reusing %a with identifier %a",name,identifier)
+        end
+        return identifier
+    end
+    local stream = io.loaddata(name)
+    if not stream or stream == "" then
+        if trace then
+            report("no valid file %a",name)
+        end
+        return resolvers.finders.notfound()
+    else
+        return setmemstream(name,stream)
+    end
+end
+
+local flush = { }
+
+function resolvers.resetmemstream(name,afterpage)
+    if afterpage then
+        flush[#flush+1] = name
+    else
+        opened[name] = nil
+    end
+end
+
+luatex.registerpageactions(function()
+    if #flush > 0 then
+        for i=1,#flush do
+            opened[flush[i]] = nil -- we keep of course data[name] because of reuse
+        end
+        flush = { }
+    end
+end)
+
+figures.identifiers.list[#figures.identifiers.list+1] = function(specification)
+    local name = specification.request.name
+    if name then
+        local base = gsub(name,"^memstream:///","")
+        if base ~= name then
+            local identifier = data[base]
+            if identifier then
+                if trace then
+                    report("requested %a has identifier %s",name,identifier)
+                end
+                specification.status.status = 1
+                specification.used.fullname = name
+            else
+                if trace then
+                    report("requested %a is not found",name)
+                end
+            end
+        end
+    end
+end
+
+figures.setmemstream = resolvers.setmemstream