Add a draggable resize handle to the JS puzzles.

Rather than design an ersatz 'window frame' surrounding the puzzle
canvas, I've simply overlaid the resize handle on the corner of the
puzzle itself (canvas or status bar, depending on whether the latter
exists), trusting that all games in my collection provide a reasonable
border within their drawing area. (OS X already does this with its
resize handle, so it's not as if there's no precedent.)

Unlike the desktop versions, I control the resize behaviour completely
in this environment, so I can constrain the canvas to only ever be
sensible sizes with no dead space round the edges (and, in particular,
preserve the aspect ratio).

Right-clicking the resize handle will restore the puzzle's default
tile size. I had intended to implement a maximise-to-browser-window
button too, but was annoyingly foiled by scrollbars - if you maximise
to the current window width, and as a result the text below the puzzle
scrolls off the bottom, then a vertical scrollbar appears and eats
into the width you just maximised to. Gah.

[originally from svn r9822]

emcc.c

@@ -21,12 +21,6 @@
  *    by using the DOM File API to ask the user to select a file and
  *    permit us to see its contents.
  *
- *  - it ought to be possible to make the puzzle canvases resizable,
- *    by superimposing some kind of draggable resize handle. Also I
- *    quite like the idea of having a few buttons for standard sizes:
- *    reset to default size, maximise to the browser window dimensions
- *    (if we can find those out), and perhaps even go full-screen.
- *
  *  - I should think about whether these webified puzzles can support
  *    touchscreen-based tablet browsers (assuming there are any that
  *    can cope with the reasonably modern JS and run it fast enough to
@@ -194,10 +188,12 @@ void timer_callback(double tplus)
 }
 
 /* ----------------------------------------------------------------------
- * Helper function to resize the canvas, and variables to remember its
+ * Helper functions to resize the canvas, and variables to remember
- * size for other functions (e.g. trimming blitter rectangles).
+ * its size for other functions (e.g. trimming blitter rectangles).
  */
 static int canvas_w, canvas_h;
+
+/* Called when we resize as a result of changing puzzle settings */
 static void resize(void)
 {
     int w, h;
@@ -208,6 +204,26 @@ static void resize(void)
     canvas_h = h;
 }
 
+/* Called from JS when the user uses the resize handle */
+void resize_puzzle(int w, int h)
+{
+    midend_size(me, &w, &h, TRUE);
+    if (canvas_w != w || canvas_h != h) { 
+        js_canvas_set_size(w, h);
+        canvas_w = w;
+        canvas_h = h;
+        midend_force_redraw(me);
+    }
+}
+
+/* Called from JS when the user uses the restore button */
+void restore_puzzle_size(int w, int h)
+{
+    midend_reset_tilesize(me);
+    resize();
+    midend_force_redraw(me);
+}
+
 /*
  * HTML doesn't give us a default frontend colour of its own, so we
  * just make up a lightish grey ourselves.

emcclib.js

@@ -567,6 +567,7 @@ mergeInto(LibraryManager.library, {
             statusbar.style.width = (w - 4) + "px";
             document.getElementById("statusbarholder").style.width = w + "px";
         }
+        resizable_div.style.width = w + "px";
 
         onscreen_canvas.height = h;
         offscreen_canvas.height = h;

emccpre.js

@@ -103,6 +103,10 @@ var permalink_seed, permalink_desc;
 // The undo and redo buttons. Used by js_enable_undo_redo().
 var undo_button, redo_button;
 
+// A div element enclosing both the puzzle and its status bar, used
+// for positioning the resize handle.
+var resizable_div;
+
 // Helper function to find the absolute position of a given DOM
 // element on a page, by iterating upwards through the DOM finding
 // each element's offset from its parent, and thus calculating the
@@ -268,6 +272,83 @@ function initPuzzle() {
     // Default to giving keyboard focus to the puzzle.
     onscreen_canvas.focus();
 
+    // Create the resize handle.
+    var resize_handle = document.createElement("canvas");
+    resize_handle.width = 10;
+    resize_handle.height = 10;
+    {
+        var ctx = resize_handle.getContext("2d");
+        ctx.beginPath();
+        for (var i = 1; i <= 7; i += 3) {
+            ctx.moveTo(8.5, i + 0.5);
+            ctx.lineTo(i + 0.5, 8.5);
+        }
+        ctx.lineWidth = '1px';
+        ctx.lineCap = 'round';
+        ctx.lineJoin = 'round';
+        ctx.strokeStyle = '#000000';
+        ctx.stroke();
+    }
+    resizable_div = document.getElementById("resizable");
+    resizable_div.appendChild(resize_handle);
+    resize_handle.style.position = 'absolute';
+    resize_handle.style.zIndex = 98;
+    resize_handle.style.bottom = "0";
+    resize_handle.style.right = "0";
+    resize_handle.style.cursor = "se-resize";
+    resize_handle.title = "Drag to resize the puzzle. Right-click to restore the default size.";
+    var resize_xbase = null, resize_ybase = null, restore_pending = false;
+    var resize_xoffset = null, resize_yoffset = null;
+    var resize_puzzle = Module.cwrap('resize_puzzle',
+                                     'void', ['number', 'number']);
+    var restore_puzzle_size = Module.cwrap('restore_puzzle_size', 'void', []);
+    resize_handle.oncontextmenu = function(event) { return false; }
+    resize_handle.onmousedown = function(event) {
+        if (event.button == 0) {
+            var xy = element_coords(onscreen_canvas);
+            resize_xbase = xy.x + onscreen_canvas.width / 2;
+            resize_ybase = xy.y;
+            resize_xoffset = xy.x + onscreen_canvas.width - event.pageX;
+            resize_yoffset = xy.y + onscreen_canvas.height - event.pageY;
+        } else {
+            restore_pending = true;
+        }
+        resize_handle.setCapture(true);
+        event.preventDefault();
+    };
+    window.addEventListener("mousemove", function(event) {
+        if (resize_xbase !== null && resize_ybase !== null) {
+            resize_puzzle((event.pageX + resize_xoffset - resize_xbase) * 2,
+                          (event.pageY + resize_yoffset - resize_ybase));
+            event.preventDefault();
+            // Chrome insists on selecting text during a resize drag
+            // no matter what I do
+            if (window.getSelection)
+                window.getSelection().removeAllRanges();
+            else
+                document.selection.empty();        }
+    });
+    window.addEventListener("mouseup", function(event) {
+        if (resize_xbase !== null && resize_ybase !== null) {
+            resize_xbase = null;
+            resize_ybase = null;
+            onscreen_canvas.focus(); // return focus to the puzzle
+        } else if (restore_pending) {
+            // If you have the puzzle at larger than normal size and
+            // then right-click to restore, I haven't found any way to
+            // stop Chrome and IE popping up a context menu on the
+            // revealed piece of document when you release the button
+            // except by putting the actual restore into a setTimeout.
+            // Gah.
+            setTimeout(function() {
+                restore_pending = false;
+                restore_puzzle_size();
+                onscreen_canvas.focus();
+            }, 20);
+        }
+        event.preventDefault();
+    });
+
     // Run the C setup function, passing argv[1] as the fragment
     // identifier (so that permalinks of the form puzzle.html#game-id
     // can launch the specified id).

emccx.json

@@ -21,6 +21,9 @@
     // Callbacks to return values from dialog boxes
     '_dlg_return_sval',
     '_dlg_return_ival',
+    // Callbacks when the resizing controls are used
+    '_resize_puzzle',
+    '_restore_puzzle_size',
     // Main program, run at initialisation time
     '_main'
 ]

html/jspage.pl

@@ -84,10 +84,12 @@ ${unfinishedpara}
   <select id="gametype"></select>
 </p>
 <div align=center>
+  <div id="resizable" style="position:relative; left:0; top:0">
   <canvas style="display: block" id="puzzlecanvas" width="1px" height="1px" tabindex="1">
   </canvas>
   <div id="statusbarholder" style="display: block">
   </div>
+  </div>
   <p>
     Link to this puzzle:
     <a id="permalink-desc">by game ID</a>