js: Distinguish manual resizes from device pixel ratio changes

This adds a new callback, rescale_puzzle(), that's called when the
device pixel ratio changes.  This means that resize_puzzle() can safely
set the nominal canvas size, which means that manual resizing of the
puzzle now sticks.

Still missing: paying attention to the device pixel ratio when choosing
the initial (or reset) size.

1 files changed, 3 insertions, 1 deletions

diff --git a/emccpre.js b/emccpre.js
index 0c555f9..c2af60a 100644
--- a/emccpre.js
+++ b/emccpre.js
@@ -535,12 +535,14 @@ function initPuzzle() {
      * <https://developer.mozilla.org/en-US/docs/Web/API/Window/
      * devicePixelRatio> (CC0) to work on older browsers.
      */
+    var rescale_puzzle = Module.cwrap('rescale_puzzle',
+                                      'void', ['number', 'number']);
     var mql = null;
     var update_pixel_ratio = function() {
         var dpr = window.devicePixelRatio;
         if (mql !== null)
             mql.removeListener(update_pixel_ratio);
-        resize_puzzle(nominal_width * dpr, nominal_height * dpr);
+        rescale_puzzle(nominal_width * dpr, nominal_height * dpr);
         mql = window.matchMedia(`(resolution: ${dpr}dppx)`);
         mql.addListener(update_pixel_ratio);
     }