New feature: Indicators

[pyscripter]

This is inspired by Scintilla indicators. Their most common usage is to indicate syntax errors or spelling mistakes by decorating the text. Scintilla defines 20 such indicators, the most familiar of which is the squiggly lines drawn to indicate errors. This would simplify the implementation of plugins such as the Spelling addin of SynEdit.

The suggestion is to implement this using events:

TSynIndicator = record
  GUID: TGUID
  Style: TSynIndicatorStyle;
  Color: TColor;
  Alpha: Single;
end;

TSynIndicatorRange = record
  Indicator: TSynIndicator;
  BeginChar, EndChar: Integer;
end;

TSynIndicatorRangeArray = TArray<TSynRangeIndicator>;
// events
TSynGetIndicatorsForLine  = procedure(Sender: TObject; const Line: Integer;  IndicatorRanges: TSynIndicatorRangeArray;
// returns true if handled
TSynOnIdicatorHover = function(Sender; TObject; const MousePos; TPoint;  Line: Integer; IndicatorRange: TSynIndicatorRange): Boolean;

The first event will provide information about indicators to SynEdit text painting and the second event could give the opportunity to for example show a hint or popup menu or take some other action when when the user hovers the mouse on an indicator range.
These events can be implemented on the SynEdit or plugin level,

What do you think?

[pyscripter]

Implementation

The first implementation has been added to the main repo. This is the core of the implementation in SynEditMiscClasses:

  TSynIndicatorStyle = (sisTextDecoration, sisSquiggleMicrosoftWord,
    sisSquiggleWordPerfect, sisRectangle, sisFilledRectangle,
    sisRoundedRectangle, sisRoundedFilledRectangle);

  TSynIndicatorSpec = record
    Style: TSynIndicatorStyle;
    Foreground,
    Background: TD2D1ColorF;
    FontStyle: TFontStyles;
  end;

  TSynIndicator = record
    Id: TGuid;
    CharStart, CharEnd : Integer;
    constructor Create(aId: TGuid; aCharStart, aCharEnd: Integer);
  end;

  TSynIndicators = class
  public
    procedure RegisterSpec(Id: TGuid; Spec: TSynIndicatorSpec);
    function GetSpec(Id: TGUID): TSynIndicatorSpec;
    procedure Add(Line: Integer; Indicator: TSynIndicator);
    procedure Clear; overload;
    procedure Clear(Id: TGuid); overload;
    function LineIndicators(Line: Integer): TArray<TSynIndicator>;
    function IndicatorAtPos(Pos: TBufferCoord; var Indicator: TSynIndicator): Boolean;
    function IndicatorAtMousePos(MousePos: TPoint; var Indicator: TSynIndicator): Boolean;

SynEdit defines a public property

property Indicators: TSynIndicators;

Usage

You need to define and register an indicator spec, e.g.:

  const TestIndicatorID: TGUID  = '{A5D68F5B-7E52-4649-BD69-365B68B39A52}';

  IndicatorSpec: TSynIndicatorSpec =
    (Style: sisTextDecoration;
     Foreground: (r: 1; g:0; b: 0; a: 1);
     Background: (r: 0; g:0; b: 1; a: 0.5);
     FontStyle: [fsBold]);

 Editor.Indicators.RegisterSpec(TestIndicatorID, IndicatorSpec);

There are two options for adding/managing indicators:

via a Plugin

The plugin needs to handle LinePut and LinesInserted to add indicators using for instance:

   Editor.Indicators.Add(aIndex, TSynIndicator.Create(TestIndicatorID, charStart, charEnd);

Note that SynEdit deletes indicators when their lines are deleted or edited and automatically adjusts the positions of other indicators. Also SynEdit automatically invalidates indicators on removal.

via an event handler

A new event is defined that can directly provide indicators to the painting routine:

type
  TGetLineIndicatorsEvent = procedure(Sender: TObject; const Line: Integer;
    var LineIndicators: TArray<TSynIndicator>) of Object;

  property OnGetLineIndicators: TGetLineIndicatorsEvent
    read FOnGetLineIndicators write FOnGetLineIndicators;

Indicator styles

sisTextDecoration

Can change style, font color and background color of the the indicated text. The background can be solid or alpha blended:

sisSquiggleMicrosoftWord

sisSquiggleWordPerfect

sisRectangle

sisFilledRectangle

sisRoundedRectangle

sisRoundedFilledRectangle

Indicator hints and pop up menus

You can show an indicator specific hint or an an indicator specific popup by handling the OnShowHint and/or the OnContextPopup events and test for an indicator using IndicatorAtMousePos method.

Bracket highlighting

You can use indicators instead of handling the PaintTransient event to implement bracket highlighting. This is going to be a lot more efficient. I am planning to implement bracket highlighting out-of-the-box, but more on this later.

Demo

I will modify the spell checking component to use indicators and provide a demo.

@MShark67 @JaFi-cz @dados What do you think?

[pyscripter]

The plugin is responsible for adding removing indicators, in the case of spelling, spelling errors. It can do it by handling for instance the LinePut, LinesInserted events. See section on usage.

[pyscripter]

@JaFi-cz By the way I am thinking of replacing the spell checking with the following. The main drawback is that you need Windows 8 or later. But there are clear advantages...

[JaFi-cz]

I am little sceptical. In the past you were able to use Office spell check, but MS stops it. I am not sure, if he won't do the same in the future for this spellcheck or request fees for ussage.
And Just now I am slowly preparing last version supporting Windows XP. Windows 7 is still used, even they are not supported. So I won't stop Windows 7 support now.

Anyway, is MS spell check implementation fast enough to support on the fly check?

[pyscripter]

Just to clarify this is a built-in feature of Windows and has nothing to do with Microsoft Office. You install dictionaries through Windows settings. Windows takes care for storing words added to the dictionaries etc. And yes it is free, full featured and fast. Look at the demo.

[pyscripter]

@JaFi-cz Modified SynSpellCheck.pas to use Indicators. Have a look.

You can use the OnShowHint and OnContextPopUp to show special hints and popup menus for spelling errors. I will do a demo of that.

[dados]

Out of the box bracket highlighting is just an excellent idea.
Indicators is something that I might look into using. Could be really nice and should make any program look more intelligent :)
I really don't have any opinion on spell checking as I cannot see myself using it.

I would be happy running some tests with a provided demo

[MShark67]

This looks really cool. I did some tests just using the OnGetLineIndicators event and it worked well. I hit an issue if you caret right such that the indicated string is partially shown as LeftChar progresses. A range check error and some painting and caret movement issues. Let me know if you need more steps to reproduce.

[pyscripter]

Reproduced. I see also some painting errors with some styles when scrolling left and right. Will look into it.

[pyscripter]

Fixed

[ClementDoss]

Hi!
I would like to use indicators when searching for a text. I would like to highlight the words the user is searching. Do you have a sample code?

Thanks

[pyscripter]

Have a look at SynSpellCheck,pas which now uses indicators. More is coming.

[MShark67]

Quick question! I may be misunderstanding the CharStart and CharEnd values. I was thinking that if I had a one character indicator, that started at position 1, that CharStart would be 1 and that CharEnd would be 1. It seems like now it has to be CharStart 1 and CharEnd 2 for it to work. Is that intended?

[pyscripter]

This was changed in the last commit. It is now analogous to BlockBegin, BlockEnd used for selection. So, CharEnd points to the character after the last character.

[MShark67]

Excellent, thanks!