IDEA-157087 slow text rendering on OS X when ligatures are enabled

platform/platform-impl/src/com/intellij/openapi/editor/impl/view/ComplexTextFragment.java

@@ -15,6 +15,7 @@
  */
 package com.intellij.openapi.editor.impl.view;
 
+import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.util.BitUtil;
 import org.jetbrains.annotations.NotNull;
 
@@ -27,6 +28,7 @@ import java.awt.geom.Rectangle2D;
  * GlyphVector-based text fragment. Used for non-Latin text or when ligatures are enabled
  */
 class ComplexTextFragment extends TextFragment {
+  private static final Logger LOG = Logger.getInstance(ComplexTextFragment.class);
   private static final double CLIP_MARGIN = 1e4;
   
   @NotNull
@@ -90,18 +92,57 @@ class ComplexTextFragment extends TextFragment {
     }
   }
 
+  boolean isRtl() {
+    return BitUtil.isSet(myGlyphVector.getLayoutFlags(), GlyphVector.FLAG_RUN_RTL);
+  }
+
+  // Drawing a portion of glyph vector using clipping might be not very effective
+  // (we still pass all glyphs to the rendering code, and filtering by clipping might occur late in the processing,
+  // on OS X larger number of glyphs passed for processing is known to slow down rendering significantly).
+  // So we try to merge drawing of adjacent glyph vector fragments, if possible.
+  private static ComplexTextFragment lastFragment;
+  private static int lastStartColumn;
+  private static int lastEndColumn;
+  private static Color lastColor;
+  private static float lastStartX;
+  private static float lastEndX;
+  private static float lastY;
+
+  @SuppressWarnings("AssignmentToStaticFieldFromInstanceMethod")
   @Override
   public void draw(Graphics2D g, float x, float y, int startColumn, int endColumn) {
-    assert startColumn >= 0; 
+    assert startColumn >= 0;
     assert endColumn <= myCharPositions.length;
     assert startColumn < endColumn;
+
+    Color color = g.getColor();
+    assert color != null;
+    float newX = x - getX(startColumn) + getX(endColumn);
+    if (lastFragment == this && lastEndColumn == startColumn && lastEndX == x && lastY == y && color.equals(lastColor)) {
+      lastEndColumn = endColumn;
+      lastEndX = newX;
+      return;
+    }
+
+    flushDrawingCache(g);
+    lastFragment = this;
+    lastStartColumn = startColumn;
+    lastEndColumn = endColumn;
+    lastColor = color;
+    lastStartX = x;
+    lastEndX = newX;
+    lastY = y;
+  }
+
+  private void doDraw(Graphics2D g, float x, float y, int startColumn, int endColumn) {
+    updateStats(endColumn - startColumn, myCharPositions.length);
     if (startColumn == 0 && endColumn == myCharPositions.length) {
       g.drawGlyphVector(myGlyphVector, x, y);
     }
     else {
       Shape savedClip = g.getClip();
       float startX = x - getX(startColumn);
-      // We define clip region here assuming that glyphs do not extend further than CLIP_MARGIN pixels from baseline 
+      // We define clip region here assuming that glyphs do not extend further than CLIP_MARGIN pixels from baseline
       // vertically (both up and down) and horizontally (from the region defined by glyph vector's total advance)
       double xMin = x - (startColumn == 0 ? CLIP_MARGIN : 0);
       double xMax = startX + getX(endColumn) + (endColumn == myCharPositions.length ? CLIP_MARGIN : 0);
@@ -112,8 +153,26 @@ class ComplexTextFragment extends TextFragment {
       g.setClip(savedClip);
     }
   }
-  
-  boolean isRtl() {
-    return BitUtil.isSet(myGlyphVector.getLayoutFlags(), GlyphVector.FLAG_RUN_RTL);
+
+  public static void flushDrawingCache(Graphics2D g) {
+    if (lastFragment != null) {
+      g.setColor(lastColor);
+      lastFragment.doDraw(g, lastStartX, lastY, lastStartColumn, lastEndColumn);
+      lastFragment = null;
+    }
+  }
+
+  private static long ourDrawingCount;
+  private static long ourCharsProcessed;
+  private static long ourGlyphsProcessed;
+
+  private static void updateStats(int charCount, int glyphCount) {
+    if (!LOG.isDebugEnabled()) return;
+    ourCharsProcessed += charCount;
+    ourGlyphsProcessed += glyphCount;
+    if ((++ourDrawingCount) % 10000 == 0) {
+      LOG.debug("Text rendering stats: " + ourCharsProcessed + " chars, " + ourGlyphsProcessed + " glyps, ratio - " +
+                ((float) ourGlyphsProcessed) / ourCharsProcessed);
+    }
   }
 }

platform/platform-impl/src/com/intellij/openapi/editor/impl/view/EditorPainter.java

@@ -35,7 +35,6 @@ import com.intellij.openapi.wm.impl.IdeBackgroundUtil;
 import com.intellij.ui.ColorUtil;
 import com.intellij.ui.Gray;
 import com.intellij.ui.JBColor;
-import com.intellij.util.Processor;
 import com.intellij.util.ui.JBUI;
 import com.intellij.util.ui.UIUtil;
 import gnu.trove.TFloatArrayList;
@@ -400,6 +399,7 @@ class EditorPainter implements TextDrawingCallback {
       });
       visLinesIterator.advance();
     }
+    ComplexTextFragment.flushDrawingCache(g);
   }
 
   private float paintLineLayoutWithEffect(Graphics2D g, LineLayout layout, float x, float y, 
@@ -832,6 +832,7 @@ class EditorPainter implements TextDrawingCallback {
               break;
             }
           }
+          ComplexTextFragment.flushDrawingCache(g);
         }
       }
     }