From 5a1f2750b656571e9086561eb7df5343c7885e4d Mon Sep 17 00:00:00 2001
From: "Maxim.Mossienko" <Maxim.Mossienko@jetbrains.com>
Date: Mon, 22 Apr 2013 15:44:05 +0200
Subject: [PATCH] optimization in getTabbedTextWidth calculation to cache last
 two values calculated: 2-10 speed up due to often caret / scroll position
 calculation (IDEA-105872)

---
 .../openapi/editor/impl/EditorImpl.java       | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java b/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java
index 3c677b34470a..e175db7c2fd6 100644
--- a/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java
+++ b/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java
@@ -69,6 +69,8 @@ import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.openapi.wm.IdeFocusManager;
 import com.intellij.openapi.wm.IdeGlassPane;
+import com.intellij.psi.PsiDocumentManager;
+import com.intellij.psi.PsiFile;
 import com.intellij.ui.GuiUtils;
 import com.intellij.ui.JBColor;
 import com.intellij.ui.LightweightHint;
@@ -642,6 +644,8 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
     myDescent = -1;
     myPlainFontMetrics = null;
 
+    clearTextWidthCache();
+
     boolean softWrapsUsedBefore = mySoftWrapModel.isSoftWrappingEnabled();
 
     mySettings.reinitSettings();
@@ -1416,12 +1420,32 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
     return result + columnsToProcess;
   }
 
+  // TODO: tabbed text width is additive, it should be possible to have buckets, containing arguments / values to start with
+  private final int[] myLastStartOffsets = new int[2];
+  private final int[] myLastTargetColumns = new int[myLastStartOffsets.length];
+  private final int[] myLastXs = new int[myLastStartOffsets.length];
+  private int myLastPosition;
+  private int hits, totals;
+
   private int getTabbedTextWidth(int startOffset, int targetColumn, int xOffset) {
     int x = xOffset;
     if (startOffset == 0 && myPrefixText != null) {
       x += myPrefixWidthInPixels;
     }
     if (targetColumn <= 0) return x;
+
+    ++totals;
+    for(int i = 0; i < myLastStartOffsets.length; ++i) {
+      if (startOffset == myLastStartOffsets[i] && targetColumn == myLastTargetColumns[i]) {
+        ++hits;
+        if ((hits & 0xFF) == 0) {
+          PsiFile file = PsiDocumentManager.getInstance(myProject).getCachedPsiFile(myDocument);
+          LOG.info("Hits:" + hits + "," + totals + "," + (file != null ? file.getViewProvider().getVirtualFile():null));
+        }
+        return myLastXs[i] + xOffset;
+      }
+    }
+
     int offset = startOffset;
     CharSequence text = myDocument.getCharsNoThreadCheck();
     int textLength = myDocument.getTextLength();
@@ -1492,6 +1516,11 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
         x += EditorUtil.getSpaceWidth(fontType, this) * (targetColumn - column);
       }
 
+      myLastTargetColumns[myLastPosition] = targetColumn;
+      myLastStartOffsets[myLastPosition] = startOffset;
+      myLastXs[myLastPosition] = x - xOffset;
+      myLastPosition = (myLastPosition + 1) % myLastStartOffsets.length;
+
       return x;
     }
     finally {
@@ -1499,6 +1528,14 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
     }
   }
 
+  private void clearTextWidthCache() {
+    for(int i = 0; i < myLastStartOffsets.length; ++i) {
+      myLastTargetColumns[i] = -1;
+      myLastStartOffsets[i] = - 1;
+      myLastXs[i] = -1;
+    }
+  }
+
   public int visibleLineToY(int line) {
     if (line < 0) throw new IndexOutOfBoundsException("Wrong line: " + line);
     return line * getLineHeight();
@@ -1601,6 +1638,7 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
   private void changedUpdate(DocumentEvent e) {
     if (myScrollPane == null || myDocument.isInBulkUpdate()) return;
 
+    clearTextWidthCache();
     stopOptimizedScrolling();
     mySelectionModel.removeBlockSelection();
 
@@ -2235,6 +2273,7 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
     // Perform additional activity if soft wrap is added or removed during repainting.
     if (mySoftWrapsChanged) {
       mySoftWrapsChanged = false;
+      clearTextWidthCache();
       validateSize();
 
       // Repaint editor to the bottom in order to ensure that its content is shown correctly after new soft wrap introduction.