Better support for RGB files

- update set_naxispath implementation for RGBImage
- add additional supported mimetypes to pillow- and opencv-based loaders
- RGB video files can be opened (with OpenCv loader) and examined with
  MultiDim plugin or naxis mode (video frames are treated as axis 3)
- small fixes to naxis mode

doc/WhatsNew.rst

@@ -37,6 +37,11 @@ Ver 5.0.0 (unreleased)
 - Added mode help; type 'h' in the viewer window when you are in a mode
   to display a help tab for that mode (reference viewer only)
 - Better support for touchpad gestures in modes
+- Better support for RGB files
+
+  - Support additional types (ico/icns/tga/bmp)
+  - RGB video files can be opened (with OpenCv loader) and examined with
+    MultiDim plugin or naxis mode (video frames is treated as axis 3)
 
 Ver 4.1.0 (2022-06-30)
 ======================

ginga/RGBImage.py

@@ -58,6 +58,23 @@ def get_buffer(self, format, output=None):
         return self.io.get_buffer(self._get_data(), self.get_header(),
                                   format, output=output)
 
+    def set_naxispath(self, naxispath):
+        """Choose a slice out of multidimensional data.
+        """
+        # Currently, RGBImage only supports regular 3D images (H, W, D)
+        # But we support a "fake" 4th axis for RGB video files (for this
+        # you need to use the OpenCv loader)
+        self.logger.debug(f"naxispath is {naxispath}")
+        num = naxispath[0]
+        data = self.io.get_frame(num, metadata=self.metadata)
+
+        if data is None or len(data.shape) not in [3]:
+            raise ImageError(
+                "naxispath does not lead to a 2D RGB slice: {}".format(naxispath))
+
+        self.naxispath = naxispath
+        self.set_data(data)
+
     def copy(self, astype=None):
         other = RGBImage()
         self.transfer(other, astype=astype)

ginga/modes/naxis.py

@@ -48,7 +48,7 @@ def __str__(self):
         return 'naxis'
 
     def start(self):
-        pass
+        self.axis = 3
 
     def stop(self):
         self.onscreen_message(None)
@@ -150,7 +150,7 @@ def ms_naxis(self, viewer, event, data_x, data_y, msg=True):
         if event.state in ('down', 'move'):
             win_wd, win_ht = viewer.get_window_size()
             x_pct = min(max(0.0, x / float(win_wd)), 1.0)
-            idx = int(x_pct * axis_lim - 1)
+            idx = int(round(x_pct * (axis_lim - 1)))
             naxispath[m] = idx
             image.set_naxispath(naxispath)
             if msg:

ginga/rv/plugins/MultiDim.py

@@ -82,7 +82,7 @@ def __init__(self, fv, fitsimage):
         self.play_idx = 0
         self.play_max = 0
         self.play_int_sec = 0.1
-        self.play_min_sec = 1.0 / 30
+        self.play_min_sec = 0.0
         self.play_last_time = 0.0
         self.play_fps = 0
         self.timer = fv.get_timer()

ginga/util/io/io_fits.py

@@ -719,7 +719,10 @@ def close(self):
         self.hdu_db = {}
         self.extver_db = {}
         self.info = None
+        fits_f = self.fits_f
         self.fits_f = None
+        if fits_f is not None:
+            fits_f.close()
 
     def find_first_good_hdu(self):