Support custom slide size and scaling constraints.

Readme.org

@@ -2,7 +2,12 @@
 #+Author: Yujie Wen
 #+Email: yjwen.ty@gmail.com
 
-#+OPTIONS: reveal_center:t reveal_progress:t reveal_history:nil reveal_control:t reveal_mathjax:t reveal_rolling_links:t reveal_keyboard:t reveal_overview:t num:nil
+#+OPTIONS: reveal_center:t reveal_progress:t reveal_history:nil reveal_control:t
+#+OPTIONS: reveal_mathjax:t reveal_rolling_links:t reveal_keyboard:t reveal_overview:t num:nil
+#+OPTIONS: reveal_width:1200 reveal_height:800
+#+REVEAL_MARGIN: 0.1
+#+REVEAL_MIN_SCALE: 0.5
+#+REVEAL_MAX_SCALE: 2.5
 #+REVEAL_TRANS: cube
 #+REVEAL_THEME: moon
 #+REVEAL_HLEVEL: 2
@@ -156,7 +161,7 @@ $ git clone https://github.com/yjwen/org-reveal.git
 ,#+REVEAL: split
 #+END_SRC
 
-#+REVEAL: split:force-split
+#+REVEAL: split
 
    Now a new slide begins after =#+REVEAL= keyword.
 
@@ -171,6 +176,20 @@ $ git clone https://github.com/yjwen/org-reveal.git
 
     Available transitions are: default|cube|page|concave|zoom|linear|fade|none.
 
+** Slide Size
+
+   Reveal.js scales slides to best fit the display resolution. But in case
+   the auto-sizes are not satisfiable, you can specify the desired size by
+   option tag =width= and =height=.
+
+   The scaling behavior can also be contrainted by setting following
+   options:
+   * =#+REVEAL_MARGIN:= :: a float number, the factor of empty area
+        surrounding slide contents.
+   * =#+REVEAL_MIN_SCALE:= :: a float number, the minimun scaling down
+        ratio.
+   * =#+REVEAL_MAX_SCALE:= :: a float number, the maximum scaling up
+        ratio.
 ** Extra Stylesheets
 
     Set =REVEAL_EXTRA_CSS= to a stylesheet file path in order to load extra custom

ox-reveal.el

@@ -46,6 +46,11 @@
     (:reveal-rolling-links nil "reveal_rolling_links" org-reveal-rolling-links t)
     (:reveal-keyboard nil "reveal_keyboard" org-reveal-keyboard t)
     (:reveal-overview nil "reveal_overview" org-reveal-overview t)
+    (:reveal-width nil "reveal_width" org-reveal-width t)
+    (:reveal-height nil "reveal_height" org-reveal-height)
+    (:reveal-margin"REVEAL_MARGIN" nil org-reveal-margin t)
+    (:reveal-min-scale "REVEAL_MIN_SCALE" nil org-reveal-min-scale t)
+    (:reveal-max-scale "REVEAL_MAX_SCALE" nil org-reveal-max-scale t)
     (:reveal-root "REVEAL_ROOT" nil org-reveal-root t)
     (:reveal-trans "REVEAL_TRANS" nil org-reveal-transition t)
     (:reveal-speed "REVEAL_SPEED" nil org-reveal-transition-speed t)
@@ -154,6 +159,31 @@ can be include."
   :group 'org-export-reveal
   :type 'boolean)
 
+(defcustom org-reveal-width -1
+  "Slide width"
+  :group 'org-export-reveal
+  :type 'integer)
+
+(defcustom org-reveal-height -1
+  "Slide height"
+  :group 'org-export-reveal
+  :type 'integer)
+
+(defcustom org-reveal-margin -1
+  "Slide margin"
+  :group 'org-export-reveal
+  :type 'string)
+
+(defcustom org-reveal-min-scale -1
+  "Minimum bound for scaling slide."
+  :group 'org-export-reveal
+  :type 'string)
+
+(defcustom org-reveal-max-scale -1
+  "Maximum bound for scaling slide."
+  :group 'org-export-reveal
+  :type 'string)
+
 (defcustom org-reveal-mathjax nil
   "Enable MathJax script."
   :group 'org-export-reveal
@@ -342,6 +372,12 @@ custom variable `org-reveal-root'."
         			rollingLinks: %s,
         			keyboard: %s,
         			overview: %s,
+        			%s // slide width
+        			%s // slide height
+        			%s // slide margin
+        			%s // slide minimum scaling factor
+        			%s // slide maximum scaling factor
+
 
         			theme: Reveal.getQueryHash().theme, // available themes are in /css/theme
         			transition: Reveal.getQueryHash().transition || '%s', // default/cube/page/concave/zoom/linear/fade/none
@@ -353,6 +389,22 @@ custom variable `org-reveal-root'."
              (if (plist-get info :reveal-rolling-links) "true" "false")
              (if (plist-get info :reveal-keyboard) "true" "false")
              (if (plist-get info :reveal-overview) "true" "false")
+             (let ((width (plist-get info :reveal-width)))
+               (if (> width 0) (format "width: %d," width)
+                 ""))
+             (let ((height (plist-get info :reveal-height)))
+               (if (> height 0) (format "height: %d," height)
+                 ""))
+             (let ((margin (string-to-number (plist-get info :reveal-margin))))
+               (if (>= margin 0) (format "margin: %.2f," margin)
+                 ""))
+             (let ((min-scale (string-to-number (plist-get info :reveal-min-scale))))
+               (if (> min-scale 0) (format "minScale: %.2f," min-scale)
+                 ""))
+             (let ((max-scale (string-to-number (plist-get info :reveal-max-scale))))
+               (if (> max-scale 0) (format "maxScale: %.2f," max-scale)
+                 ""))
+             
              (plist-get info :reveal-trans)
              (plist-get info :reveal-speed))
      (format "