mirror of
https://github.com/JetBrains/intellij-sdk-code-samples.git
synced 2025-07-30 02:07:50 +08:00
115 lines
4.3 KiB
Markdown
115 lines
4.3 KiB
Markdown
---
|
|
layout: editable
|
|
title: Line Marker Provider
|
|
---
|
|
|
|
Line markers help to annotate any code with icons on the gutter.
|
|
These icons may provide navigation to related code.
|
|
|
|
### 1. Define a line marker provider
|
|
|
|
Let's annotate usages of our properties within Java code and provide navigation to the definition of these properties.
|
|
|
|
```java
|
|
package com.simpleplugin;
|
|
|
|
import com.intellij.codeInsight.daemon.RelatedItemLineMarkerInfo;
|
|
import com.intellij.codeInsight.daemon.RelatedItemLineMarkerProvider;
|
|
import com.intellij.codeInsight.navigation.NavigationGutterIconBuilder;
|
|
import com.intellij.openapi.project.Project;
|
|
import com.intellij.psi.PsiElement;
|
|
import com.intellij.psi.PsiLiteralExpression;
|
|
import com.simpleplugin.psi.SimpleProperty;
|
|
import org.jetbrains.annotations.NotNull;
|
|
|
|
import java.util.Collection;
|
|
import java.util.List;
|
|
|
|
public class SimpleLineMarkerProvider extends RelatedItemLineMarkerProvider {
|
|
@Override
|
|
protected void collectNavigationMarkers(@NotNull PsiElement element, Collection<? super RelatedItemLineMarkerInfo> result) {
|
|
if (element instanceof PsiLiteralExpression) {
|
|
PsiLiteralExpression literalExpression = (PsiLiteralExpression) element;
|
|
String value = (String) literalExpression.getValue();
|
|
if (value != null && value.startsWith("simple:")) {
|
|
Project project = element.getProject();
|
|
final List<SimpleProperty> properties = SimpleUtil.findProperties(project, value.substring(7));
|
|
if (properties.size() > 0) {
|
|
NavigationGutterIconBuilder<PsiElement> builder =
|
|
NavigationGutterIconBuilder.create(SimpleIcons.FILE).
|
|
setTargets(properties).
|
|
setTooltipText("Navigate to a simple property");
|
|
result.add(builder.createLineMarkerInfo(element));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
|
|
## More technical details for implementers
|
|
|
|
* Please return line marker info for exact element you were asked for.
|
|
For example, do not return class marker info if ```getLineMarkerInfo()``` was called for a method.
|
|
|
|
* Please return relevant line marker info for as small element as possible.
|
|
For example, do not return method marker for ```PsiMethod```. Instead, return it for the ```PsiIdentifier``` which is a name of this method.
|
|
|
|
### Even more technical details:
|
|
|
|
What happens when LineMarkerProvider returns something for too big PsiElement?
|
|
|
|
```java
|
|
public class MyLineMarkerProvider implements LineMarkerProvider {
|
|
public LineMarkerInfo getLineMarkerInfo(@NotNull PsiElement element) {
|
|
if (element instanceof PsiMethod) return new LineMarkerInfo(element, ...);
|
|
return null;
|
|
}
|
|
}
|
|
```
|
|
|
|
Inspection (specifically, ```LineMarkersPass```) for performance reasons queries all ```LineMarkerProviders``` in two passes:
|
|
|
|
* first pass for all elements in visible area
|
|
|
|
* second pass for all the rest elements
|
|
|
|
If providers return nothing for either area, its line markers are cleared.
|
|
So if e.g. a method is half-visible (its name is visible but part of its body isn't) and
|
|
some poorly written ```LineMarkerProvider``` returned info for the ```PsiMethod``` instead of ```PsiIdentifier``` then:
|
|
|
|
* the first pass removes line marker info because whole ```PsiMethod``` is not visible.
|
|
|
|
* the second pass tries to add line marker info back because ```LineMarkerProvider``` is called for the ```PsiMethod``` at last.
|
|
|
|
As a result, line marker icon would blink annoyingly.
|
|
To fix this, rewrite ```LineMarkerProvider``` to return info for ```PsiIdentifier``` instead of ```PsiMethod```:
|
|
|
|
```java
|
|
public class MyLineMarkerProvider implements LineMarkerProvider {
|
|
public LineMarkerInfo getLineMarkerInfo(@NotNull PsiElement element) {
|
|
if (element instanceof PsiIdentifier && element.getParent() instanceof PsiMethod) return new LineMarkerInfo(element, ...);
|
|
return null;
|
|
}
|
|
}
|
|
```
|
|
|
|
### 2. Register the line marker provider
|
|
|
|
```xml
|
|
<codeInsight.lineMarkerProvider language="JAVA" implementationClass="com.simpleplugin.SimpleLineMarkerProvider"/>
|
|
```
|
|
|
|
### 3. Run the project
|
|
|
|
Now you see the icon on the gutter and can navigate to the property definition.
|
|
|
|
|
|
|
|
--------------
|
|
|
|
[Previous](annotator.html)
|
|
[Top](cls_tutorial.html)
|
|
[Next](completion_contributor.html)
|