JAL-2759 performance improvements to hideColumns

[jalview.git] / src / jalview / datamodel / HiddenColumns.java

diff --git a/src/jalview/datamodel/HiddenColumns.java b/src/jalview/datamodel/HiddenColumns.java
index fa5d0a0..3b1a574 100644 (file)
--- a/src/jalview/datamodel/HiddenColumns.java
+++ b/src/jalview/datamodel/HiddenColumns.java
@@ -188,10 +188,28 @@ public class HiddenColumns
         wasAlreadyLocked = true;
       }
 
+      int previndex = 0;
+      int prevHiddenCount = 0;
+      int regionindex = 0;
       if (hiddenColumns == null)
       {
         hiddenColumns = new ArrayList<>();
       }
+      else
+      {
+        // set up cursor reset values
+        HiddenCursorPosition cursorPos = cursor.findRegionForColumn(start);
+        regionindex = cursorPos.getRegionIndex();
+
+        if (regionindex > 0)
+        {
+          // get previous index and hidden count for updating the cursor later
+          previndex = regionindex - 1;
+          int[] prevRegion = hiddenColumns.get(previndex);
+          prevHiddenCount = cursorPos.getHiddenSoFar()
+                  - (prevRegion[1] - prevRegion[0] + 1);
+        }
+      }
 
       /*
        * new range follows everything else; check first to avoid looping over whole hiddenColumns collection
@@ -208,18 +226,23 @@ public class HiddenColumns
          * appropriate
          */
         boolean added = false;
-        for (int i = 0; !added && i < hiddenColumns.size(); i++)
+        if (regionindex > 0)
+        {
+          added = insertRangeAtRegion(regionindex - 1, start, end);
+        }
+        if (!added && regionindex < hiddenColumns.size())
         {
-          added = insertRangeAtRegion(i, start, end);
-        } // for
+          insertRangeAtRegion(regionindex, start, end);
+        }
       }
-      if (!wasAlreadyLocked)
-      {
-        cursor.resetCursor(hiddenColumns);
 
-        // reset the number of columns so they will be recounted
-        numColumns = 0;
-      }
+      // reset the cursor to just before our insertion point: this saves
+      // a lot of reprocessing in large alignments
+      cursor.resetCursor(hiddenColumns, previndex, prevHiddenCount);
+
+      // reset the number of columns so they will be recounted
+      numColumns = 0;
+
     } finally
     {
       if (!wasAlreadyLocked)
@@ -287,6 +310,9 @@ public class HiddenColumns
           break;
         }
         region[1] = Math.max(nextRegion[1], end);
+
+        // in theory this is faster than hiddenColumns.remove(i+1)
+        // benchmarking results a bit ambivalent
         hiddenColumns.subList(i + 1, i + 2).clear();
       }
       added = true;