1 files changed, 75 insertions, 50 deletions

diff --git a/tex/context/base/scrn-pag.mkvi b/tex/context/base/scrn-pag.mkvi
index aa1bd6999..c982eb402 100644
--- a/tex/context/base/scrn-pag.mkvi
+++ b/tex/context/base/scrn-pag.mkvi
@@ -22,65 +22,52 @@
 \installparameterhandler \??sc {interactionscreen}
 \installsetuphandler     \??sc {interactionscreen}
 
-\def\scrn_canvas_synchronize_simple % this will be done differently (or disappear)
-  {\begingroup
-   \ifx\@@ppleft   \empty
-   \ifx\@@ppright  \empty
-   \ifx\@@pptop    \empty
-   \ifx\@@ppbottom \empty
-   \ifx\@@pcstate\v!start
-     \locationfalse\fi\else
-     \locationfalse\fi\else
-     \locationfalse\fi\else
-     \locationfalse\fi\else
-     \locationfalse\fi
-   \iflocation % without screen settings
-      \ctxcommand{setupcanvas{
-        paperwidth  = \number\paperwidth,
-        paperheight = \number\paperheight
-      }}%
-   \else
-      \ctxcommand{setupcanvas{
-        paperwidth  = \number\printpaperwidth,
-        paperheight = \number\printpaperheight
-      }}%
-   \fi
-   \endgroup}
+\newdimen\canvaswidth
+\newdimen\canvasheight
+\newdimen\canvasbackoffset
+\newdimen\canvastopoffset
 
-\def\scrn_canvas_synchronize_complex
+\def\scrn_canvas_calculate
   {\begingroup
    \edef\currentinteractionscreenwidth {\interactionscreenparameter\c!width }%
    \edef\currentinteractionscreenheight{\interactionscreenparameter\c!height}%
+   \canvasbackoffset\backspace
+   \canvastopoffset\topoffset
    \ifx\currentinteractionscreenwidth\v!fit
-     \!!widtha\leftcombitotal
-     \ifdim\backspace>\!!widtha
+     \global\canvaswidth\leftcombitotal
+     \ifdim\backspace>\canvaswidth
        \ifdim\backspace>\zeropoint\relax
-         \advance\backspace -\!!widtha
+         \global\advance\canvasbackspace -\canvaswidth
        \fi
      \fi
-     \advance\!!widtha\dimexpr
+     \global\advance\canvaswidth\dimexpr
        \rightcombitotal
      + 2\dimexpr
           \interactionscreenparameter\c!backspace
         + \interactionscreenparameter\c!horoffset
         \relax
      \relax
+     \donetrue
    \else\ifx\currentinteractionscreenwidth\v!max
-     \!!widtha\printpaperwidth
+     \global\canvaswidth\printpaperwidth
+     \donetrue
    \else
-     \!!widtha\currentinteractionscreenwidth
-   \fi\fi
-   \ifdim\!!widtha>\paperwidth\ifdim\!!widtha>\zeropoint
-     \global\paperwidth\!!widtha
+     \global\canvaswidth\currentinteractionscreenwidth
+     \donefalse
    \fi\fi
+   \ifdone
+     \ifdim\canvaswidth>\paperwidth\ifdim\canvaswidth>\zeropoint
+       \global\paperwidth\canvaswidth % kills location=middle
+     \fi\fi
+   \fi
    \ifx\currentinteractionscreenheight\v!fit
-     \!!heighta\dimexpr\topheight+\topdistance\relax
-     \ifdim\topspace>\!!heighta
+     \global\canvasheight\dimexpr\topheight+\topdistance\relax
+     \ifdim\topspace>\canvasheight
        \ifdim\topspace>\zeropoint\relax
-         \advance\topspace -\!!heighta
+         \global\advance\canvastopspace -\canvasheight
        \fi
      \fi
-     \advance\!!heighta\dimexpr
+     \global\advance\canvasheight\dimexpr
        \makeupheight
      + \bottomdistance
      + \bottomheight
@@ -89,26 +76,64 @@
         + \interactionscreenparameter\c!veroffset
         \relax
      \relax
+     \donetrue
    \else\ifx\currentinteractionscreenheight\v!max
-     \!!heighta\printpaperheight
+     \global\canvasheight\printpaperheight
+     \donetrue
    \else
-     \!!heighta\currentinteractionscreenheight
-   \fi\fi
-   \ifdim\!!heighta>\paperheight\ifdim\!!heighta>\zeropoint
-     \global\paperheight\!!heighta
+     \global\canvasheight\currentinteractionscreenheight
+     \donefalse
    \fi\fi
-   \ctxcommand{setupcanvas{
+   \ifdone
+     \ifdim\canvasheight>\paperheight\ifdim\canvasheight>\zeropoint
+       \global\paperheight\canvasheight % kills location=middle
+     \fi\fi
+   \fi
+   \endgroup}
+
+\appendtoks
+    \ifproductionrun
+      \scrn_canvas_calculate
+    \fi
+\to \everysetupinteractionscreen
+
+\def\scrn_canvas_synchronize_simple % this will be done differently (or disappear)
+  {\begingroup
+   \ifx\@@ppleft   \empty
+   \ifx\@@ppright  \empty
+   \ifx\@@pptop    \empty
+   \ifx\@@ppbottom \empty
+   \ifx\@@pcstate\v!start
+     \locationfalse\fi\else
+     \locationfalse\fi\else
+     \locationfalse\fi\else
+     \locationfalse\fi\else
+     \locationfalse\fi
+   \iflocation % without screen settings
+      \ctxcommand{setupcanvas{
+        paperwidth  = \number\paperwidth,
+        paperheight = \number\paperheight
+      }}%
+   \else
+      \ctxcommand{setupcanvas{
+        paperwidth  = \number\printpaperwidth,
+        paperheight = \number\printpaperheight
+      }}%
+   \fi
+   \endgroup}
+
+\def\scrn_canvas_synchronize_complex
+  {\ctxcommand{setupcanvas{
       mode        = "\interactionscreenparameter\c!option",
       singlesided = \ifsinglesided true\else false\fi,
       doublesided = \ifdoublesided true\else false\fi,
-      leftoffset  = \number\dimexpr\backoffset\relax,
-      topoffset   = \number\dimexpr\topoffset \relax,
-      width       = \number\dimexpr\!!widtha  \relax,
-      height      = \number\dimexpr\!!heighta \relax,
+      leftoffset  = \number\dimexpr\canvasbackoffset\relax,
+      topoffset   = \number\dimexpr\canvastopoffset\relax,
+      width       = \number\dimexpr\canvaswidth\relax,
+      height      = \number\dimexpr\canvasheight\relax,
       paperwidth  = \number\paperwidth,
       paperheight = \number\paperheight
-   }}%
-   \endgroup}
+   }}}
 
 \let\scrn_canvas_synchronize\scrn_canvas_synchronize_simple