Improve error message on various sources.

sources/bioformats/large_image_source_bioformats/__init__.py

@@ -278,10 +278,14 @@ def __init__(self, path, **kwargs):  # noqa
 
         if self.levels < 1:
             raise TileSourceError(
-                'OpenSlide image must have at least one level.')
+                'Bioformats image must have at least one level.')
 
         if self.sizeX <= 0 or self.sizeY <= 0:
             raise TileSourceError('Bioformats tile size is invalid.')
+        try:
+            self.getTile(0, 0, self.levels - 1)
+        except Exception as exc:
+            raise TileSourceError('Bioformats cannot read a tile: %r' % exc)
 
     def __del__(self):
         if getattr(self, '_bioimage', None) is not None:

sources/deepzoom/large_image_source_deepzoom/__init__.py

@@ -48,7 +48,7 @@ def __init__(self, path, **kwargs):
             xml = ElementTree.parse(self._largeImagePath).getroot()
             self._info = etreeToDict(xml)['Image']
         except (ElementTree.ParseError, KeyError, UnicodeDecodeError):
-            raise TileSourceError('File cannot be opened via Deepzoom reader.')
+            raise TileSourceError('File cannot be opened via deepzoom reader.')
         except FileNotFoundError:
             if not os.path.isfile(self._largeImagePath):
                 raise TileSourceFileNotFoundError(self._largeImagePath) from None

sources/gdal/large_image_source_gdal/__init__.py

@@ -159,15 +159,15 @@ def __init__(self, path, projection=None, unitsPerPixel=None, **kwargs):
             with self._getDatasetLock:
                 self.sourceSizeX = self.sizeX = self.dataset.RasterXSize
                 self.sourceSizeY = self.sizeY = self.dataset.RasterYSize
-        except AttributeError:
+        except AttributeError as exc:
             if not os.path.isfile(self._largeImagePath):
                 raise TileSourceFileNotFoundError(self._largeImagePath) from None
-            raise TileSourceError('File cannot be opened via GDAL.')
+            raise TileSourceError('File cannot be opened via GDAL: %r' % exc)
         is_netcdf = self._checkNetCDF()
         try:
             scale = self.getPixelSizeInMeters()
-        except RuntimeError:
-            raise TileSourceError('File cannot be opened via GDAL.')
+        except RuntimeError as exc:
+            raise TileSourceError('File cannot be opened via GDAL: %r' % exc)
         if (self.projection or self._getDriver() in {
             'PNG',
         }) and not scale and not is_netcdf:

sources/openjpeg/large_image_source_openjpeg/__init__.py

@@ -99,8 +99,8 @@ def __init__(self, path, **kwargs):
                 if not os.path.isfile(self._largeImagePath):
                     raise FileNotFoundError()
                 raise TileSourceError('File cannot be opened via Glymur and OpenJPEG.')
-        except (glymur.jp2box.InvalidJp2kError, struct.error):
-            raise TileSourceError('File cannot be opened via Glymur and OpenJPEG.')
+        except (glymur.jp2box.InvalidJp2kError, struct.error) as exc:
+            raise TileSourceError('File cannot be opened via Glymur and OpenJPEG: %r' % exc)
         except FileNotFoundError:
             if not os.path.isfile(self._largeImagePath):
                 raise TileSourceFileNotFoundError(self._largeImagePath) from None
@@ -112,8 +112,8 @@ def __init__(self, path, **kwargs):
         self._openjpegHandles.put(self._openjpeg)
         try:
             self.sizeY, self.sizeX = self._openjpeg.shape[:2]
-        except IndexError:
-            raise TileSourceError('File cannot be opened via Glymur and OpenJPEG.')
+        except IndexError as exc:
+            raise TileSourceError('File cannot be opened via Glymur and OpenJPEG: %r' % exc)
         self.levels = int(self._openjpeg.codestream.segment[2].num_res) + 1
         self._minlevel = 0
         self.tileWidth = self.tileHeight = 2 ** int(math.ceil(max(

sources/tifffile/large_image_source_tifffile/__init__.py

@@ -137,6 +137,7 @@ def _biggestSeries(self):
         """
         maxseries = None
         maxsamples = 0
+        ex = 'no maximum series'
         try:
             for idx, s in enumerate(self._tf.series):
                 samples = numpy.prod(s.shape)
@@ -145,9 +146,11 @@ def _biggestSeries(self):
                     maxsamples = samples
         except Exception as exc:
             self.logger.debug('Cannot use tifffile: %r', exc)
+            ex = exc
             maxseries = None
         if maxseries is None:
-            raise TileSourceError('File cannot be opened via tifffile source.')
+            raise TileSourceError(
+                'File cannot be opened via tifffile source: %r' % ex)
         return maxseries, maxsamples
 
     def _findMatchingSeries(self):
@@ -205,7 +208,7 @@ def _findAssociatedImages(self):
         """
         Find associated images from unused pages and series.
         """
-        pagesInSeries = [p for s in self._tf.series for l in s.pages.levels for p in l.pages]
+        pagesInSeries = [p for s in self._tf.series for ll in s.pages.levels for p in ll.pages]
         self._associatedImages = {}
         for p in self._tf.pages:
             if (p not in pagesInSeries and p.keyframe is not None and
@@ -330,7 +333,7 @@ def getInternalMetadata(self, **kwargs):
         """
         result = {}
         pages = [s.pages[0] for s in self._tf.series]
-        pagesInSeries = [p for s in self._tf.series for l in s.pages.levels for p in l.pages]
+        pagesInSeries = [p for s in self._tf.series for ll in s.pages.levels for p in ll.pages]
         pages.extend([page for page in self._tf.pages if page not in pagesInSeries])
         for page in pages:
             for tag in getattr(page, 'tags', []):
@@ -402,11 +405,11 @@ def getTile(self, x, y, z, pilImageAllowed=False, numpyAllowed=False, **kwargs):
         if hasattr(za[0], 'get_basic_selection'):
             bza = za[0]
             # we could cache this
-            for l in range(len(series.levels) - 1, 0, -1):
-                scale = round(max(za[0].shape[xidx] / za[l].shape[xidx],
-                                  za[0].shape[yidx] / za[l].shape[yidx]))
+            for ll in range(len(series.levels) - 1, 0, -1):
+                scale = round(max(za[0].shape[xidx] / za[ll].shape[xidx],
+                                  za[0].shape[yidx] / za[ll].shape[yidx]))
                 if scale <= step and step // scale == step / scale:
-                    bza = za[l]
+                    bza = za[ll]
                     x0 //= scale
                     x1 //= scale
                     y0 //= scale

test/test_source_base.py

@@ -20,9 +20,10 @@
 SourceAndFiles = {
     'bioformats': {
         'read': r'\.(czi|jp2|svs|scn)$',
+        'noread': r'(JK-kidney_B|TCGA-AA-A02O|\.scn$)',
         # We need to modify the bioformats reader similar to tiff's
         # getTileFromEmptyDirectory
-        'skipTiles': r'(JK-kidney_B|TCGA-AA-A02O|TCGA-DU-6399|sample_jp2k_33003|\.scn$)'},
+        'skipTiles': r'(TCGA-DU-6399|sample_jp2k_33003)'},
     'deepzoom': {},
     'dummy': {'any': True, 'skipTiles': r''},
     'gdal': {