Enable auto levels by default in SkyFit2

Guides/SkyFit.md

@@ -80,7 +80,7 @@ Next, a dialog asking you to input an approximate azimuth and altitude of the ca
 
 Use arrow keys **<-- Left** and **Right -->** to cycle through images. Find an image which has clearly visible stars and has no clouds. **Green circles** are stars detected on the image using an automatic algorithm, but there might be some which were not automatically detected. You will also notice **red plusses** on the image, those are projected positions of catalog stars, and the projection is done by using the current astrometric parameters. The size of the catalog star marker is proportional to the brightness of the star, which can help you with identifying which star is which. You will notice that the stars on the image and the catalog stars do not match at all. Our goal is to tweak the astrometric parameters until they do match.
 
-If the image is dark, **use U and J keys to change the image gamma.** You can press **CTRL + A** to automatically adjust the image levels.
+If the image is dark, **use U and J keys to change the image gamma.** Automatic adjustment of the image levels is enabled by default - press **CTRL + A** to toggle it off and on, or simply drag the histogram region on the Levels tab to switch to manual levels (starting from the auto-determined values).
 
 First, cycle through images and see if the catalog stars follow the general direction of the movement of the image stars. For example, if your camera is rotated in any way, the movement of catalog stars will not match the movement of the image stars. This can be corrected for by changing the ***rotation*** using keys **Q** and **E**. Rotate the catalog stars until the stars start moving in approximately the same direction. If the stars are going in the opposite direction, the position angle should be 180 degrees.
 

RMS/Routines/CustomPyqtgraphClasses.py

@@ -1204,6 +1204,7 @@ def mousePressEvent(self, event):
         modifier = QtWidgets.QApplication.keyboardModifiers()
         pos = self.vb.mapSceneToView(event.pos())
         if self.item.region.movable and modifier == QtCore.Qt.ControlModifier:
+            self.item.exitAutoLevels()
             if event.button() == QtCore.Qt.LeftButton:
                 self.setLevels(pos.y(), self.getLevels()[1])
             elif event.button() == QtCore.Qt.RightButton:
@@ -1248,14 +1249,26 @@ def toggleAutoLevels(self):
         else:
             self.setLevels(*self.saved_manual_levels)
         self.auto_levels = not self.auto_levels
-        self.region.setMovable(not self.auto_levels)
+
+    def exitAutoLevels(self):
+        """
+        Drop out of auto levels mode, keeping the auto-determined levels as the manual levels
+        """
+        if self.auto_levels:
+            self.auto_levels = False
+            self.saved_manual_levels = self.getLevels()
 
     def paint(self, p, *args):
         # tbh this is an improvement
         pass
 
     def regionChanging(self):
-        pass  # doesn't update when moving it
+        # Doesn't update the image when moving the region, only on release
+
+        # A user drag on the region while auto levels are on drops to manual mode, keeping the
+        #   auto-determined levels as the starting point
+        if self.auto_levels and (self.region.moving or any(l.moving for l in self.region.lines)):
+            self.exitAutoLevels()
 
     def imageChanged(self, autoLevel=False, autoRange=False):
         if not self.auto_levels:

Utils/SkyFit2.py

@@ -3310,6 +3310,10 @@ def setupUI(self, loaded_file=False):
         else:
             self.tab.hist.setLevels(0, 255)
 
+        # Turn on auto levels by default (Ctrl + A toggles back to manual)
+        if not self.tab.hist.auto_levels:
+            self.tab.hist.toggleAutoLevels()
+
         self.tab.settings.updateInvertColours()
         self.tab.settings.updateImageGamma()
         self.tab.star_detection.setCatalogLM(self.cat_lim_mag)
@@ -3636,7 +3640,13 @@ def changeStation(self, dir_path=None, config_override=None):
             # Update ImageItems with new handle before loading platepar (which triggers drawing)
             self.img.changeHandle(self.img_handle)
             self.img_zoom.changeHandle(self.img_handle)
-            self.tab.hist.setLevels(0, 2**(8*self.img.data.itemsize) - 1)
+            if not self.tab.hist.auto_levels:
+                self.tab.hist.setLevels(0, 2**(8*self.img.data.itemsize) - 1)
+
+            # Sync both image items to the histogram levels (setImage assigns each item independent
+            #   min/max levels, and an unchanged histogram won't re-emit them)
+            self.img.setLevels(self.tab.hist.getLevels())
+            self.img_zoom.setLevels(self.tab.hist.getLevels())
 
             # Now that the new image dimensions are available, load this station's mask (or clear a
             #   previous station's mask if this one has none), then render the overlay
@@ -9580,7 +9590,14 @@ def loadState(self, dir_path, state_name, beginning_time=None, mask=None):
             self.img.changeHandle(self.img_handle)
             self.img_zoom.changeHandle(self.img_handle)
 
-            self.tab.hist.setLevels(0, 2**(8*self.img.data.itemsize) - 1)
+            if not self.tab.hist.auto_levels:
+                self.tab.hist.setLevels(0, 2**(8*self.img.data.itemsize) - 1)
+
+            # Sync both image items to the histogram levels (setImage assigns each item independent
+            #   min/max levels, and an unchanged histogram won't re-emit them)
+            self.img.setLevels(self.tab.hist.getLevels())
+            self.img_zoom.setLevels(self.tab.hist.getLevels())
+
             self.img_frame.autoRange(padding=0)
 
             self.updateCalstars()