Limit the range of tile sizes the openjpeg source can produce.

Tiles that are too large or small are inefficient.

For the Leaflet and SlideAtlas viewers, show an error if the tile size
is larger than 256, as neither of those viewers works properly in that
case.

server/tilesource/openjpeg.py

@@ -75,6 +75,9 @@ class OpenjpegFileTileSource(FileTileSource):
     }
     _xmlTag = b'mxl '
 
+    _minTileSize = 256
+    _maxTileSize = 512
+
     def __init__(self, path, **kwargs):
         """
         Initialize the tile class.  See the base class for other available
@@ -99,10 +102,24 @@ def __init__(self, path, **kwargs):
         except IndexError:
             raise TileSourceException('File cannot be opened via Glymur and OpenJPEG.')
         self.levels = self._openjpeg.codestream.segment[2].num_res + 1
+        self._minlevel = 0
         self.tileWidth = self.tileHeight = 2 ** int(math.ceil(max(
             math.log(float(self.sizeX)) / math.log(2) - self.levels + 1,
             math.log(float(self.sizeY)) / math.log(2) - self.levels + 1)))
-        # read associated images and metadata from boxes
+        # Small and large tiles are both inefficient.  Large tiles don't work
+        # with some viewers (leaflet and Slide Atlas, for instance)
+        if self.tileWidth < self._minTileSize or self.tileWidth > self._maxTileSize:
+            self.tileWidth = self.tileHeight = min(
+                self._maxTileSize, max(self._minTileSize, self.tileWidth))
+            self.levels = math.ceil(math.log(float(max(
+                self.sizeX, self.sizeY)) / self.tileWidth) / math.log(2)) + 1
+            self._minlevel = self.levels - self._openjpeg.codestream.segment[2].num_res - 1
+        self._getAssociatedImages()
+
+    def _getAssociatedImages(self):
+        """
+        Read associated images and metadata from boxes.
+        """
         self._associatedImages = {}
         for box in self._openjpeg.box:
             if box.box_id == self._xmlTag or box.box_id in self._boxToTag:
@@ -203,6 +220,10 @@ def getTile(self, x, y, z, pilImageAllowed=False, **kwargs):
             raise TileSourceException('x is outside layer')
         if y < 0 or y0 >= self.sizeY:
             raise TileSourceException('y is outside layer')
+        scale = None
+        if z < self._minlevel:
+            scale = 2 ** (self._minlevel - z)
+            step = 2 ** (self.levels - 1 - self._minlevel)
         # possible open the file multiple times so multiple threads can access
         # it concurrently.
         with self._openjpegLock:
@@ -218,6 +239,8 @@ def getTile(self, x, y, z, pilImageAllowed=False, **kwargs):
         if len(tile.shape) == 3:
             mode = ['L', 'LA', 'RGB', 'RGBA'][tile.shape[2] - 1]
         tile = PIL.Image.frombytes(mode, (tile.shape[1], tile.shape[0]), tile)
+        if scale:
+            tile = tile.resize((tile.size[0] // scale, tile.size[1] // scale), PIL.Image.LANCZOS)
         if tile.size != (self.tileWidth, self.tileHeight):
             wrap = PIL.Image.new(mode, (self.tileWidth, self.tileHeight))
             wrap.paste(tile, (0, 0))

web_client/views/imageViewerWidget/leaflet.js

@@ -23,6 +23,7 @@ var LeafletImageViewerWidget = ImageViewerWidget.extend({
     },
 
     render: function () {
+        var errmsg;
         // If script or metadata isn't loaded, then abort
         if (!window.L || !this.tileWidth || !this.tileHeight || this.deleted) {
             return this;
@@ -34,7 +35,15 @@ var LeafletImageViewerWidget = ImageViewerWidget.extend({
         }
 
         if (this.tileWidth !== this.tileHeight) {
-            console.error('The Leaflet viewer only supports square tiles.');
+            errmsg = 'The Leaflet viewer only supports square tiles.';
+        }
+        if (this.tileWidth > 256) {
+            errmsg = 'The Leaflet viewer does not support tiles wider than 256 pixels.';
+        }
+        if (errmsg) {
+            this.viewer = $('<div/>').text(errmsg);
+            this.$el.append(this.viewer);
+            console.error(errmsg);
             return this;
         }
 

web_client/views/imageViewerWidget/slideatlas.js

@@ -25,6 +25,7 @@ var SlideAtlasImageViewerWidget = ImageViewerWidget.extend({
     },
 
     render: function () {
+        var errmsg;
         // If script or metadata isn't loaded, then abort
         if (!window.SA || !this.tileWidth || !this.tileHeight || this.deleted) {
             return this;
@@ -36,7 +37,15 @@ var SlideAtlasImageViewerWidget = ImageViewerWidget.extend({
         }
 
         if (this.tileWidth !== this.tileHeight) {
-            console.error('The SlideAtlas viewer only supports square tiles.');
+            errmsg = 'The SlideAtlas viewer only supports square tiles.';
+        }
+        if (this.tileWidth > 256) {
+            errmsg = 'The SlideAtlas viewer does not support tiles wider than 256 pixels.';
+        }
+        if (errmsg) {
+            this.viewer = $('<div/>').text(errmsg);
+            this.$el.append(this.viewer);
+            console.error(errmsg);
             return this;
         }