[md] cosmetics

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Anna Bulenkova 2015-01-27 10:30:48 +01:00
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Basics of working with the Editor.
Basics of working with the Editor
===========
### [Source code] (https://github.com/JetBrains/intellij-sdk/tree/master/code_samples/editor_basics)
@ -8,12 +8,12 @@ Basics of working with the Editor.
This tutorial will lead you through the series of steps showing how to work with the Editor in IntelliJ IDEA, how access and modify text it contains,
and how to handle events sent to the Editor.
#Editor. Working with text.
#Working with text
The following set of steps will show how to access a text selection and change it.
##Prerequirements.
##Prerequirements
###Creating a new action.
###Creating a new action
In this example access to the Editor is made through an action as a plug-in point.
To create an action we need derive
[AnAction.java] (https://github.com/JetBrains/intellij-community/blob/master/platform/editor-ui-api/src/com/intellij/openapi/actionSystem/AnAction.java)
@ -22,7 +22,7 @@ class.
public class EditorIllustration extends AnAction {
}
###Registering an action.
###Registering an action
To register the action we should add a corresponding attribute to the *<actions>* section of the plugin configuration file
[plugin.xml] (https://github.com/JetBrains/intellij-sdk/blob/master/code_samples/editor_basics/resources/META-INF/plugin.xml)
@ -35,7 +35,7 @@ To register the action we should add a corresponding attribute to the *<actions>
If an action is registered in the group EditorPopupMenu, like the sample above shows,
it will be available from the context menu when the focus is located in the editor.
###Defining action's visibility.
###Defining action's visibility
To determine conditions by which the action will be visible and available for being executed we need to override it's
*public void update(final AnActionEvent e)* method.
@ -53,7 +53,7 @@ If we want to work with a selected part of the text, it's reasonable to make the
Further steps will show how to check these conditions through obtaining instances of Project and Editor and how to set up a desired level of action's visibility.
##Getting an instance of the Active Editor.
##Getting an instance of the Active Editor
A reference to an instance of the Editor can be obtained by calling ```CommonDataKeys.EDITOR```,
obtaining a project reference is performed the same way ```CommonDataKeys.PROJECT```.
@ -81,7 +81,7 @@ object is available ```final Editor editor = actionEvent.getData(CommonDataKeys.
------------------
##Obtaining a caret model and selection.
##Obtaining a caret model and selection
After making sure we have a project open and an instance of the Editor we need to check if any selection is available and set action's visibility accordingly to these conditions.
[SelectionModel] () got from the Editor allows to do it by calling it's ```hasSelection()``` method.
Here's how our ```update(final AnActionEvent e)``` method should look like at the end:
@ -115,7 +115,7 @@ package and include:
------------
##Obtainitg a Document.
##Obtainitg a Document
The action is visible and available now. In order to make it do something we need to override it's
```public void actionPerformed(final AnActionEvent anActionEvent)``` method.
@ -147,7 +147,7 @@ We also need to figure out where the selected part of the text is located.
final int end = selectionModel.getSelectionEnd();
}
##Modifying text.
##Modifying text
Generally replacement can be done by calling
```void replaceString(int startOffset, int endOffset, @NotNull CharSequence s);``` of the Document, however,
the operation of replacement must be executed safely, this mean the Document must be locked and any changes should be performed under the
@ -191,15 +191,15 @@ To see how text replacement works, check out
[Editor Basics] (https://github.com/JetBrains/intellij-sdk/blob/master/code_samples/editor_basics/src/org/jetbrains/plugins/editor/basics/)
plugin, make the project, and run it, then invoke the *EditorIllustration* action which is available in the context menu of the editor.
#Editor coordinates system. Positions and offsets.
#Editor coordinates system. Positions and offsets
Every caret in the editor has a set of properties describing it's coordinates. These properties can be accessed by obtaining a
[caret model instance] (https://github.com/JetBrains/intellij-community/blob/master/platform/editor-ui-api/src/com/intellij/openapi/editor/CaretModel.java).
Working with caret positions and it's logical and visual properties will be explained in the sample below.
##Prerequirements.
##Prerequirements
Access to the Editor is performed through an action.
##Accessing caret positions.
##Accessing caret positions
To get an access to caret positions an instance of CaretModel should be obtained.
public class EditorAreaIllustration extends AnAction {
@ -215,7 +215,7 @@ To get an access to caret positions an instance of CaretModel should be obtained
}
}
##Logical position.
##Logical position
[LogicalPosition.java] (https://github.com/JetBrains/intellij-community/blob/master/platform/editor-ui-api/src/com/intellij/openapi/editor/LogicalPosition.java)
represents a line and a column of the current logical position of the caret. Logical positions ignore folding -
for example, if the top 10 lines of the document are folded, the 10th line in the document will have the line number 10 in its logical position.
@ -240,7 +240,7 @@ Rationale is that single logical pair matches soft wrap-introduced virtual space
correspond to the same logical position. It's convenient to store exact visual location details within the logical
position in order to relief further 'logical position' -> 'visual position' mapping.
##Visual position.
##Visual position
[VisualPosition.java] (https://github.com/JetBrains/intellij-community/blob/master/platform/editor-ui-api/src/com/intellij/openapi/editor/VisualPosition.java)
represent a visual position and may very from the corresponding logical position.
Visual positions take folding into account - for example,
@ -261,7 +261,7 @@ if the top 10 lines of the document are folded, the 10th line in the document wi
}
}
##Offset.
##Offset
An absolute offset for a given caret position is accessible through CaretModel as well
public class EditorAreaIllustration extends AnAction {
@ -280,7 +280,7 @@ An absolute offset for a given caret position is accessible through CaretModel a
}
}
##Displaying position values.
##Displaying position values
To display the actual values of logical anf visual positions we add an
```Messages.showInfoMessage()``` call that will show them in form of notification after the action is performed.
@ -315,16 +315,16 @@ Find the action in the context menu:
Perform the action to see caret positions:
![Show coordinates action](img/coordinates_demo.png)
#Actions activated by editor events.
#Actions activated by editor events
IntelliJ IDEA SDK provides a set of embedded mechanisms for handling events related to the Editor.
##Handling keystrokes in the Editor.
##Handling keystrokes in the Editor
To handle keystrokes and provide custom reactions interface
[TypedActionHandler]()
may be used.
Series of steps below shows how to change standard behaviour of the editor and make it react on typing differently instead of simply displaying a typed character in the editor area.
###Implementing *TypedActionHandler*.
###Implementing *TypedActionHandler*
First we need to implement an instance of
[TypedActionHandler]():
@ -334,7 +334,7 @@ First we need to implement an instance of
}
}
###Implementing logic for handling keystrokes.
###Implementing logic for handling keystrokes
```public void execute(@NotNull Editor editor, char c, @NotNull DataContext dataContext);```
method should contain the main logical part for handling keystrokes. It will be called every time a key is pressed.
In the following example our typed handler is meant insert a string at the zero offset in the editor after a keystroke occurs:
@ -354,7 +354,7 @@ In the following example our typed handler is meant insert a string at the zero
}
}
###Setting up *TypedActionHandler*.
###Setting up *TypedActionHandler*
To enable a custom implementation of *TypedActionHandler* in the plugin we need to create a new instance of it and pass to
```public TypedActionHandler setupHandler(TypedActionHandler handler);``` method of the
@ -371,14 +371,14 @@ class. By doing it we replace the typing handler with the specified handler.
After compiling and running the code snippet above typing in the editor will be handled with inserting an extra string at the 0 position.
##Working with EditorActionHandler.
##Working with EditorActionHandler
Class
[EditorActionHandler.java] (https://github.com/JetBrains/intellij-community/blob/master/platform/platform-api/src/com/intellij/openapi/editor/actionSystem/EditorActionHandler.java)
stays for actions activated by keystrokes in the editor.
Series of steps below show how access *EditorActionManager* and pass it actions to be executed.
In this example we will use *EditorActionHandler* to insert one extra caret above the current caret if available.
###Prerequirements.
###Prerequirements
Create an action:
public class EditorHandlerIllustration extends AnAction {
@ -400,7 +400,7 @@ Register action in
</action>
</action>
###Setting visibility.
###Setting visibility
Our action should be visible only in case if the following conditions are met:
there's a project open, there's an editor available, and there's at least one caret active in the editor:
@ -416,7 +416,7 @@ there's a project open, there's an editor available, and there's at least one ca
}
}
###Obtaining *EditorActionHandler*.
###Obtaining *EditorActionHandler*
To manipulate with standard Editor's actions first we need to obtain
an instance of
@ -437,7 +437,7 @@ an instance of
}
}
###Making *EditorActionHandler* execute actions.
###Making *EditorActionHandler* execute actions
To execute an action we need to call the ```public final void execute(@NotNull Editor editor, @Nullable final Caret contextCaret, final DataContext dataContext);```
method of a corresponding *EditorActionHandler*