IDEA-97406 support LINE_UNDERSCORE as well as WAVE_UNDERSCORE

platform/platform-api/src/com/intellij/ui/EffectPainter.java

@@ -26,6 +26,27 @@ import java.awt.geom.*;
  * @author Sergey.Malenkov
  */
 public enum EffectPainter implements RegionPainter<Paint> {
+  /**
+   * @see com.intellij.openapi.editor.markup.EffectType#LINE_UNDERSCORE
+   */
+  LINE_UNDERSCORE {
+    @Override
+    public void paint(Graphics2D g, int x, int y, int width, int height, Paint paint) {
+      // we assume here that Y is a baseline of a text
+      if (!Registry.is("ide.text.effect.line.new")) {
+        g.setPaint(paint);
+        g.drawLine(x, y + 1, x + width, y + 1);
+      }
+      else if (paint != null && width > 0 && height > 0) {
+        g.setPaint(paint);
+        int h = height < 4 ? 2 : height >> 1;
+        double pos = Registry.doubleValue("ide.text.effect.line.new.pos");
+        y += (int)((double)height - h * pos);
+        g.setPaint(paint);
+        g.drawLine(x, y, x + width, y);
+      }
+    }
+  },
   /**
    * @see com.intellij.openapi.editor.markup.EffectType#WAVE_UNDERSCORE
    */

platform/platform-api/src/com/intellij/ui/SimpleColoredComponent.java

@@ -837,8 +837,7 @@ public class SimpleColoredComponent extends JComponent implements Accessible, Co
       }
       // 3. Underline
       if (attributes.isUnderline()) {
-        final int underlineAt = textBaseline + 1;
-        UIUtil.drawLine(g, offset, underlineAt, offset + fragmentWidth, underlineAt);
+        EffectPainter.LINE_UNDERSCORE.paint(g, offset, textBaseline, fragmentWidth, metrics.getDescent(), g.getColor());
       }
       // 4. Bold Dotted Line
       if (attributes.isBoldDottedLine()) {

platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java

@@ -2428,7 +2428,7 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
           drawBoldLineUnderScore(g, end.x, y - 1, charWidth - 1);
         }
         else if (attributes.getEffectType() != EffectType.BOXED) {
-          UIUtil.drawLine(g, end.x, y, end.x + charWidth - 1, y);
+          EffectPainter.LINE_UNDERSCORE.paint((Graphics2D)g, end.x, y - 1, charWidth - 1, getDescent(), attributes.getEffectColor());
         }
       }
     }
@@ -3546,8 +3546,7 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
       }
 
       if (effectType == EffectType.LINE_UNDERSCORE) {
-        g.setColor(effectColor);
-        UIUtil.drawLine(g, xStart, y + 1, xEnd, y + 1);
+        EffectPainter.LINE_UNDERSCORE.paint((Graphics2D)g, xStart, y, xEnd - xStart, getDescent(), effectColor);
         g.setColor(savedColor);
       }
       else if (effectType == EffectType.BOLD_LINE_UNDERSCORE) {

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

@@ -429,7 +429,7 @@ class EditorPainter implements TextDrawingCallback {
     int xEnd = (int)xTo;
     g.setColor(effectColor);
     if (effectType == EffectType.LINE_UNDERSCORE) {
-      UIUtil.drawLine(g, xStart, y + 1, xEnd, y + 1);
+      EffectPainter.LINE_UNDERSCORE.paint(g, xStart, y, xEnd - xStart, myView.getDescent(), effectColor);
     }
     else if (effectType == EffectType.BOLD_LINE_UNDERSCORE) {
       int height = JBUI.scale(Registry.intValue("editor.bold.underline.height", 2));

platform/util/resources/misc/registry.properties

@@ -761,6 +761,10 @@ cidr.xcode.derived.data.override.description=Ignore Xcode DerivedData location s
 editor.rainbow.identifiers=false
 editor.rainbow.identifiers.description=Rainbow identifiers in editor
 
+ide.text.effect.line.new=false
+ide.text.effect.line.new.description=Enables new line painter for text
+ide.text.effect.line.new.pos=0.5
+ide.text.effect.line.new.pos.description=Changes a line position
 ide.text.effect.wave.new=false
 ide.text.effect.wave.new.description=Enables new wave painter for text
 ide.text.effect.wave.new.scale=false