Package com.intellij.codeInsight.daemon.impl

Class IconLineMarkerProvider

java.lang.Object

com.intellij.codeInsight.daemon.GutterIconDescriptor

com.intellij.codeInsight.daemon.LineMarkerProviderDescriptor

com.intellij.codeInsight.daemon.impl.IconLineMarkerProvider

All Implemented Interfaces:

LineMarkerProvider

public class IconLineMarkerProvider
extends LineMarkerProviderDescriptor

Shows small (16x16 or less) icons as gutters.

Works in places where it's possible to resolve from literal expression to an icon image.

Nested Class Summary

Nested classes/interfaces inherited from class com.intellij.codeInsight.daemon.GutterIconDescriptor

GutterIconDescriptor.Option

Constructor Summary

Constructors

Constructor and Description
IconLineMarkerProvider()

Method Summary

Modifier and Type	Method and Description
LineMarkerInfo<?>	getLineMarkerInfo(PsiElement element) Get line markers for this PsiElement.
java.lang.String	getName() Human-readable provider name for UI.
boolean	isEnabledByDefault()

Methods inherited from class com.intellij.codeInsight.daemon.GutterIconDescriptor

getIcon, getId, getOptions, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.intellij.codeInsight.daemon.LineMarkerProvider

collectSlowLineMarkers

Constructor Detail

IconLineMarkerProvider

public IconLineMarkerProvider()

Method Detail

getLineMarkerInfo

public LineMarkerInfo<?> getLineMarkerInfo(PsiElement element)

Description copied from interface: LineMarkerProvider

Get line markers for this PsiElement.

NOTE for implementers: Please create line marker info for leaf elements only - i.e. the smallest possible elements. For example, instead of returning method marker for PsiMethod, create the marker for the PsiIdentifier which is a name of this method.

More technical details:

Highlighting (specifically, LineMarkersPass) queries all LineMarkerProviders in two passes (for performance reasons):

• first pass for all elements in visible area
• second pass for all the rest elements

If provider returned nothing for both areas, its line markers are cleared.

So imagine a LineMarkerProvider which (incorrectly) written like this:

 
   class MyBadLineMarkerProvider implements LineMarkerProvider {
     public LineMarkerInfo getLineMarkerInfo(PsiElement element) {
       if (element instanceof PsiMethod) { // ACTUALLY DONT!
          return new LineMarkerInfo(element, element.getTextRange(), icon, null,null, alignment);
       }
       else {
         return null;
       }
     }
     ...
   }
 
 

Note that it create LineMarkerInfo for the whole method body. Following will happen when this method is half-visible (e.g. its name is visible but a part of its body isn't):

• the first pass would remove line marker info because the whole PsiMethod isn't visible
• the second pass would try to add line marker info back because LineMarkerProvider was called for the PsiMethod at last

As a result, line marker icon will blink annoyingly. Instead, write this:

 
   class MyGoodLineMarkerProvider implements LineMarkerProvider {
     public LineMarkerInfo getLineMarkerInfo(PsiElement element) {
       if (element instanceof PsiIdentifier &&
           (parent = element.getParent()) instanceof PsiMethod &&
           ((PsiMethod)parent).getMethodIdentifier() == element)) { // aha, we are at method name
            return new LineMarkerInfo(element, element.getTextRange(), icon, null,null, alignment);
       }
       else {
         return null;
       }
     }
     ...
   }
 
 

getName

public java.lang.String getName()

Description copied from class: GutterIconDescriptor

Human-readable provider name for UI.

Specified by:

getName in class GutterIconDescriptor

Returns:

null if no configuration needed

isEnabledByDefault

public boolean isEnabledByDefault()

Overrides:

isEnabledByDefault in class GutterIconDescriptor