Redesign of the SynEdit component: what changed

Revision 1 to 2. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		For more info on SynEdit go to: [[SynEdit]]
2	2
3	3		------------------------------------------------------------------------
4	4
5	5		# Introduction
6	6
7	7		This is an attempt to restructure the monolithic TCustomSynEdit class into more general base classes, which can be shared amongst various editor or viewer components. Such an approach will allow to encapsulate the basic functionality, so that derived classes cannot break that vital functionality.
8	8
9	9		The goal of the redesign is a set of classes, useful in creating [[source code editor\|source code editors]] and other browsers or editors.
10	10
11	11		# Class Tree
12	12
13		-	~~- <b>CustomSynViewer</b> (TODO)~~
	13	+	- CustomSynViewer (TODO)
14	14
15		-	~~:*<b>TextBuffer</b> (Partly done, currently TSynEditStringList)~~
	15	+	:*TextBuffer (Partly done, currently TSynEditStringList)
16	16
17	17
18	18
19	19		Holds the entire text. Eventually it should be possible that more than one SynEdit/SynViewer share the same TextBuffer. The TextBufffer provides the necessary callback hooks so all SynEdits can follow any changes
20	20
21	21		SynEdit does not allow direct access to the TextBuffer. For the public SynEdit.Lines property a special wrapper is in place controlling access.
22	22
23	23		The TextBuffer supports methods for Editing and viewing.
24	24
25	25		Act as a wrapper to the TextBuffer. They allow SynEdit/SynView to see the content of the Textbuffer in certain ways (such as Folded, with expanded Tabs information or with trailing spaces).
26	26
27	27		:* some of them are:
28	28
29	29
30	30
31	31		TSynEditStringTrimmingList
32	32
33	33		SynEditStringDoubleWidthChars
34	34
35	35		TSynEditStringTabExpander
36	36
37	37		TSynEditFoldedView
38	38
39	39
40	40		Not yet fully integrated
41	41
42	42		TODO: Integrate Highlighter Access into the TextViews
43	43
44		-	~~- <b>Highlighter</b>~~
	44	+	- Highlighter
45	45
46	46		Provides Highlight information, such as pascal or html specific highlighting. ([[SynEdit Highlighter\|more]])
47	47
48		-	~~- <b>Markup</b>~~
	48	+	- Markup
49	49
50	50		Provides additional highlight info, such as current selection, matching brackets...
51	51
52		-	~~- <b>ViewPort</b> (TODO)~~
	52	+	- ViewPort (TODO)
53	53
54	54
55	55		Defines the visible rectangle of the Text. (Screen content). This is given through TopLine, LeftChar, CharsInWindow, LinesInWindow.
56	56
57	57		Translation of Screen to TextBuffer can be handled here. All Scrolling can be handled here. In a way this represents the ScreenGrid.
58	58
59		-	~~- <b>TextGrid</b> (TODO)~~
60		-	~~- <b>Gutter</b>~~
	59	+	- TextGrid (TODO)
	60	+	- Gutter
61	61
62		-	~~:*<b>GutterPart</b>~~
	62	+	:*GutterPart
63	63
64		-	~~- <b>HighlightTokenPrinter</b> (TODO)~~
	64	+	- HighlightTokenPrinter (TODO)
65	65
66	66
67	67		Combines Text, Highlight, Markup, ... and sends it to the ViewPort/TextGrid
68	68
69		-	~~- <b>CustomSynEdit</b>~~
	69	+	- CustomSynEdit
70	70
71	71
72	72		Implements edit actions
73	73
74		-	~~- <b>IDESynEdit</b> (TODO)~~
	74	+	- IDESynEdit (TODO)
75	75
76	76
77	77		Instantiates a SynEdit, with a specific set of Views and Markup modules
78	78
79	79		# Work in Process
80	80
81	81		Plugins
82	82		The structure and integration of plug-ins needs some review, and is entirely subject to review. Applies to Syncron/TemplateEdit and/or to older SynPlugins (Code-Completion, ...)
83	83
84	84		# Older Content
85	85
86	86		Below is some older content. It may no longer reflect the actual process.
87	87
88	88		I just came across the RichView control, that already is based on a general scrolling window component RVScroll. This component will become the root of my redesign.
89	89
90	90		Once the scrollbar details are encapsulated, we can derive a basic grid component. According to our goal, of an [[source code editor]], the cells in this grid later shall contain characters, of an monospaced font. Unlike the TCustomGrid component, our grid is only a logical organization of the drawing surface. Instead of fixed rows or columns, a gutter can be shown to the left of the grid.
91	91
92	92		The next level will implement the character grid class, with a demo implementation of an simple text file viewer. The handling of fonts (determination of the cell size), a caret, and lines of arbitrary length will be implemented in this class.
93	93
94	94		In the next higher levels changes to the text are implemented, and finally the additional Lazarus specific functionality.
95	95
96	96		## Related Classes
97	97
98	98		Much specific functionality can be implemented in helper classes, so that the editor component can be customized by replacing the SynEdit helpers with other objects. One obvious helper is dedicated to the gutter display, another one to the display of the lines in the character grid, and the text lines are provided and managed by a third helper.
99	99
100	100		### Gutter
101	101
102	102		A gutter pane to the left of the grid can be used to display additional information. Where SynEdit displays line numbers and markers, some other application may display e.g. a table of contents in the gutter.
103	103
104	104		### Grid Painters
105	105
106	106		The basic grid delegates painting to the gutter object and a virtual PaintGrid method. In the case of a character grid, the PaintGrid method organizes the display of entire grid rows, calling another virtual PaintRow method for the actual painting. The PaintRow method again can call a PaintCell method, or it delegates the display of the text in the line to an text painter object.
107	107
108	108		### Grid Contents
109	109
110	110		The contents of a character grid typically are stored in some TStrings object, accessible as strings by line/row numbers. For proper display, all tabs must be expanded into spaces, what suggests an alternative method to retrieve the display strings from the string list. This method also can provide Unicode strings, in order to simplify the column index calculations. Syntax highlighting requires a synchronization between the parser, the highlighting painter, and the list of strings. When wordwrap or block folding can affect the number of visible lines, a translation between display rows and line numbers (string indices) has to be implemented in a dedicated content class. Such specialized content classes should be used only together with appropriate control classes.
111	111
112	112		When multiple source files shall be presented in a tabbed editor window (notebook?), the contents of the control should be easily exchangable. When also the same file can be shown in multiple edit controls, at the same time, the actual caret position and further context information must be stored in the content objects, apart from the common text and file information. Changes to an shared text must be reported to all active edit/content objects. Such features require a proper separation of the configuration and context information, into control settings, display content state, and physical text source state.
113	113
114	114		# See also
115	115
116	116		- [[SynEdit]]
117	117		- [[SynEdit Highlighter]]
118	118
119	119		---
120	120		From the Free Pascal wiki, page "Redesign of the SynEdit component", as it stood on 2013-09-30 after a change by Jwdietrich, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).
121	121		Category: Components
122	122		Category: SynEdit

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