From 8b678f473da7b81842dbc13b50c6303991570521 Mon Sep 17 00:00:00 2001
From: Hans Hagen <pragma@wxs.nl>
Date: Sat, 25 May 2019 11:48:47 +0200
Subject: 2019-05-25 10:53:00

---
 tex/context/base/mkiv/back-trf.lua | 155 +++++++++++++++++++++++++++++++++++++
 1 file changed, 155 insertions(+)
 create mode 100644 tex/context/base/mkiv/back-trf.lua

(limited to 'tex/context/base/mkiv/back-trf.lua')

diff --git a/tex/context/base/mkiv/back-trf.lua b/tex/context/base/mkiv/back-trf.lua
new file mode 100644
index 000000000..721c856a9
--- /dev/null
+++ b/tex/context/base/mkiv/back-trf.lua
@@ -0,0 +1,155 @@
+if not modules then modules = { } end modules ['back-trf'] = {
+    version   = 1.001,
+    comment   = "companion to back-ini.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files"
+}
+
+local sind, cosd, abs = math.sind, math.cosd, math.abs
+local insert, remove = table.insert, table.remove
+local unpack = unpack
+
+local context           = context
+
+local formatters        = string.formatters
+
+local scanners          = tokens.scanners
+local scankeyword       = scanners.keyword
+local scaninteger       = scanners.integer
+local scannumber        = scanners.number
+local scanstring        = scanners.string
+
+local implement         = interfaces.implement
+
+local nodepool          = nodes.pool
+local savenode          = nodepool.save
+local restorenode       = nodepool.restore
+local setmatrixnode     = nodepool.setmatrix
+local literalnode       = nodepool.literal -- has to become some nodeinjection
+
+local stack             = { }
+local restore           = true -- false
+
+updaters.register("backend.update",function()
+    savenode      = nodepool.save
+    restorenode   = nodepool.restore
+    setmatrixnode = nodepool.setmatrix
+    literalnode   = nodepool.literal -- has to become some nodeinjection
+end)
+
+local function stopsomething()
+    local top = remove(stack)
+    if top == false then
+        -- not wrapped
+    elseif top == true then
+        context(restorenode())
+    elseif top then
+        context(setmatrixnode(unpack(top))) -- not really needed anymore
+        context(restorenode())
+    else
+        -- nesting error
+    end
+end
+
+local function startrotation()
+    local a = scannumber()
+    if a == 0 then
+        insert(stack,false)
+    else
+        local s, c = sind(a), cosd(a)
+        if abs(s) < 0.000001 then
+            s = 0 -- otherwise funny -0.00000
+        end
+        if abs(c) < 0.000001 then
+            c = 0 -- otherwise funny -0.00000
+        end
+        context(savenode())
+        context(setmatrixnode(c,s,-s,c))
+        insert(stack,restore and { c, -s, s, c } or true)
+    end
+end
+
+implement { name = "startrotation", actions = startrotation }
+implement { name = "stoprotation",  actions = stopsomething }
+
+local function startscaling() -- at the tex end we use sx and sy instead of rx and ry
+    local rx, ry = 1, 1
+    while true do
+        if scankeyword("rx") then
+            rx = scannumber()
+        elseif scankeyword("ry") then
+            ry = scannumber()
+     -- elseif scankeyword("revert") then
+     --     local top = stack[#stack]
+     --     if top then
+     --         rx = top[1]
+     --         ry = top[4]
+     --     else
+     --         rx = 1
+     --         ry = 1
+     --     end
+        else
+            break
+        end
+    end
+    if rx == 1 and ry == 1 then
+        insert(stack,false)
+    else
+        if rx == 0 then
+            rx = 0.0001
+        end
+        if ry == 0 then
+            ry = 0.0001
+        end
+        context(savenode())
+        context(setmatrixnode(rx,0,0,ry))
+        insert(stack,restore and { 1/rx, 0, 0, 1/ry } or true)
+    end
+end
+
+implement { name = "startscaling", actions = startscaling }
+implement { name = "stopscaling",  actions = stopsomething }
+
+local function startmatrix() -- rx sx sy ry  -- tx, ty
+    local rx, sx, sy, ry = 1, 0, 0, 1
+    while true do
+            if scankeyword("rx") then rx = scannumber()
+        elseif scankeyword("ry") then ry = scannumber()
+        elseif scankeyword("sx") then sx = scannumber()
+        elseif scankeyword("sy") then sy = scannumber()
+        else   break end
+    end
+    if rx == 1 and sx == 0 and sy == 0 and ry == 1 then
+        insert(stack,false)
+    else
+        context(savenode())
+        context(setmatrixnode(rx,sx,sy,ry))
+        insert(stack,store and { -rx, -sx, -sy, -ry } or true)
+    end
+end
+
+implement { name = "startmatrix", actions = startmatrix }
+implement { name = "stopmatrix",  actions = stopsomething }
+
+local function startmirroring()
+    context(setmatrixnode(-1,0,0,1))
+end
+
+implement { name = "startmirroring", actions = startmirroring }
+implement { name = "stopmirroring",  actions = startmirroring } -- not: stopsomething
+
+-- this could also run on top of pack-rul ... todo
+
+local function startclipping()
+ -- context(savenode())
+    context(literalnode("origin",formatters["q 0 w %s W n"](scanstring())))
+end
+
+local function stopclipping()
+ -- context(restorenode())
+    context(literalnode("Q"))
+end
+
+implement { name = "startclipping", actions = startclipping }
+implement { name = "stopclipping",  actions = stopclipping }
-- 
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