250 lines
11 KiB
HTML
250 lines
11 KiB
HTML
<?xml version="1.0"?>
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
|
|
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
|
<html xmlns="http://www.w3.org/1999/xhtml">
|
|
<head>
|
|
<meta name="generator" content="HTML Tidy, see www.w3.org" />
|
|
<meta name="generator" content="SciTE" />
|
|
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
|
|
<title>
|
|
Scintilla and SciTE
|
|
</title>
|
|
</head>
|
|
<body bgcolor="#FFFFFF" text="#000000">
|
|
<table bgcolor="#000000" width="100%" cellspacing="0" cellpadding="0" border="0">
|
|
<tr>
|
|
<td>
|
|
<img src="SciTEIco.png" border="3" height="64" width="64" alt="Scintilla icon" />
|
|
</td>
|
|
<td>
|
|
<a href="index.html" style="color:white;text-decoration:none"><font size="5">Scintilla
|
|
Component Design</font></a>
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
<h2>
|
|
Top level structure
|
|
</h2>
|
|
<p>
|
|
Scintilla consists of three major layers of C++ code
|
|
</p>
|
|
<ul>
|
|
<li>
|
|
Portability Library
|
|
</li>
|
|
<li>
|
|
Core Code
|
|
</li>
|
|
<li>
|
|
Platform Events and API
|
|
</li>
|
|
</ul>
|
|
<p>
|
|
The primary purpose of this structure is to separate the platform dependent code from the
|
|
platform independent core code. This makes it easier to port Scintilla to a new platform and
|
|
ensures that most readers of the code do not have to deal with platform details. To minimise
|
|
portability problems and avoid code bloat, a conservative subset of C++ is used in Scintilla
|
|
with no exception handling, run time type information or use of the standard C++
|
|
library and with limited use of templates.
|
|
</p>
|
|
<p>
|
|
The currently supported platforms, Windows, GTK+/Linux and wxWindows are fairly similar in
|
|
many ways.
|
|
Each has windows, menus and bitmaps. These features generally work in similar ways so each
|
|
has a way to move a window or draw a red line. Sometimes one platform requires a sequence of
|
|
calls rather than a single call. At other times, the differences are more profound. Reading
|
|
the Windows clipboard occurs synchronously but reading the GTK+ clipboard requires a request
|
|
call that will be asynchronously answered with a message containing the clipboard data.
|
|
The wxWindows platform is available from the <a href="http://wxwindows.org/">wxWindows site</a>
|
|
</p>
|
|
<br />
|
|
<h3>
|
|
Portability Library
|
|
</h3>
|
|
<p>
|
|
This is a fairly small and thin layer over the platform's native capabilities.
|
|
</p>
|
|
<p>
|
|
The portability library is defined in Platform.h and is implemented once for each platform.
|
|
PlatWin.cxx defines the Windows variants of the methods and PlatGTK.cxx the GTK+ variants.
|
|
</p>
|
|
<p>
|
|
Several of the classes here hold platform specific object identifiers and act as proxies to
|
|
these platform objects. Most client code can thus manipulate the platform objects without
|
|
caring which is the current platform. Sometimes client code needs access to the underlying
|
|
object identifiers and this is provided by the GetID method. The underlying types of the
|
|
platform specific identifiers are typedefed to common names to allow them to be transferred
|
|
around in client code where needed.
|
|
</p>
|
|
<h4>
|
|
Point, PRectangle
|
|
</h4>
|
|
<p>
|
|
These are simple classes provided to hold the commonly used geometric primitives. A
|
|
PRectangle follows the Mac / Windows convention of not including its bottom and right sides
|
|
instead of including all its sides as is normal in GTK+. It is not called Rectangle as this may be
|
|
the name of a macro on Windows.
|
|
</p>
|
|
<h4>
|
|
Colour, ColourPair, Palette
|
|
</h4>
|
|
<p>
|
|
Colour holds a platform specific colour identifier - COLORREF for Windows and GdkColor for
|
|
GTK+. The red, green and blue components that make up the colour are limited to the 8 bits of
|
|
precision available on Windows. ColourPairs are used because not all possible colours are
|
|
always available. Using an 8 bit colour mode, which is a common setting for both Windows and
|
|
GTK+, only 256 colours are possible on the display. Thus when an application asks for a dull
|
|
red, say #400000, it may only be allocated an already available colour such as #800000 or
|
|
#330000. With 16 or 2 colour modes even less choice is available and the application will
|
|
have to use the limited set of already available colours.
|
|
</p>
|
|
A Palette object holds a set of colour pairs and can make the appropriate calls to ask to
|
|
allocate these colours and to see what the platform has decided will be allowed.
|
|
<h4>
|
|
Font
|
|
</h4>
|
|
<p>
|
|
Font holds a platform specific font identifier - HFONT for Windows, GdkFont* for GTK+. It
|
|
does not own the identifier and so will not delete the platform font object in its
|
|
destructor. Client code should call Destroy at appropriate times.
|
|
</p>
|
|
<h4>
|
|
Surface
|
|
</h4>
|
|
<p>
|
|
Surface is an abstraction over each platform's concept of somewhere that graphical drawing
|
|
operations can be done. It may wrap an already created drawing place such as a window or be
|
|
used to create a bitmap that can be drawn into and later copied onto another surface. On
|
|
Windows it wraps a HDC and possibly a HBITMAP. On GTK+ it wraps a GdkDrawable* and possibly a
|
|
GdkPixmap*. Other platform specific objects are created (and correctly destroyed) whenever
|
|
required to perform drawing actions.
|
|
</p>
|
|
<p>
|
|
Drawing operations provided include drawing filled and unfilled polygons, lines, rectangles,
|
|
ellipses and text. The height and width of text as well as other details can be measured.
|
|
Operations can be clipped to a rectangle. Most of the calls are stateless with all parameters
|
|
being passed at each call. The exception to this is line drawing which is performed by
|
|
calling MoveTo and then LineTo.
|
|
</p>
|
|
<h4>
|
|
Window
|
|
</h4>
|
|
<p>
|
|
Window acts as a proxy to a platform window allowing operations such as showing, moving,
|
|
redrawing, and destroying to be performed. It contains a platform specific window identifier
|
|
- HWND for Windows, GtkWidget* for GTK+.
|
|
</p>
|
|
<h4>
|
|
ListBox
|
|
</h4>
|
|
<p>
|
|
ListBox is a subclass of Window and acts as a proxy to a platform listbox adding methods for
|
|
operations such as adding, retrieving, and selecting items.
|
|
</p>
|
|
<h4>
|
|
Menu
|
|
</h4>
|
|
<p>
|
|
Menu is a small helper class for constructing popup menus. It contains the platform specific
|
|
menu identifier - HMENU for Windows, GtkItemFactory* for GTK+. Most of the work in
|
|
constructing menus requires access to platform events and so is done in the Platform Events
|
|
and API layer.
|
|
</p>
|
|
<h4>
|
|
Platform
|
|
</h4>
|
|
<p>
|
|
The Platform class is used to access the facilities of the platform. System wide parameters
|
|
such as double click speed and chrome colour are available from Platform. Utility functions
|
|
such as DebugPrintf are also available from Platform.
|
|
</p>
|
|
<h3>
|
|
Core Code
|
|
</h3>
|
|
<p>
|
|
The bulk of Scintilla's code is platform independent. This is made up of the CellBuffer,
|
|
ContractionState, Document, Editor, Indicator, LineMarker, Style, ViewStyle, KeyMap,
|
|
ScintillaBase, CallTip,
|
|
and AutoComplete primary classes.
|
|
</p>
|
|
<h4>
|
|
CellBuffer
|
|
</h4>
|
|
<p>
|
|
A CellBuffer holds text and styling information, the undo stack, the assignment of line
|
|
markers to lines, and the fold structure.
|
|
</p>
|
|
<p>
|
|
A cell contains a character byte and its associated style byte. The current state of the
|
|
cell buffer is the sequence of cells that make up the text and a sequence of line information
|
|
containing the starting position of each line and any markers assigned to each line.
|
|
</p>
|
|
<p>
|
|
The undo stack holds a sequence of actions on the cell buffer. Each action is one of a text
|
|
insertion, a text deletion or an undo start action. The start actions are used to group
|
|
sequences of text insertions and deletions together so they can be undone together. To
|
|
perform an undo operation, each insertion or deletion is undone in reverse sequence.
|
|
Similarly, redo reapplies each action to the buffer in sequence. Whenever a character is
|
|
inserted in the buffer either directly through a call such as InsertString or through undo or
|
|
redo, its styling byte is initially set to zero. Client code is responsible for styling each
|
|
character whenever convenient. Styling information is not stored in undo actions.
|
|
</p>
|
|
<h4>
|
|
Document
|
|
</h4>
|
|
<p>
|
|
A document contains a CellBuffer and deals with some higher level abstractions such as
|
|
words, DBCS character sequences and line end character sequences. It is responsible for
|
|
managing the styling process and for notifying other objects when changes occur to the
|
|
document.
|
|
</p>
|
|
<h4>
|
|
Editor
|
|
</h4>
|
|
<p>
|
|
The Editor object is central to Scintilla. It is responsible for displaying a document and
|
|
responding to user actions and requests from the container. It uses ContractionState, Indicator,
|
|
LineMarker, Style, and ViewStyle objects to display the document and a KeyMap class to
|
|
map key presses to functions.
|
|
The visibility of each line is kept in the ContractionState which is also responsible for mapping
|
|
from display lines to documents lines and vice versa.
|
|
</p>
|
|
<p>
|
|
There may be multiple Editor objects attached to one Document object. Changes to a
|
|
document are broadcast to the editors through the DocWatcher mechanism.
|
|
</p>
|
|
<h4>
|
|
ScintillaBase
|
|
</h4>
|
|
<p>
|
|
ScintillaBase is a subclass of Editor and adds extra windowing features including display of
|
|
calltips, autocompletion lists and context menus. These features use CallTip and AutoComplete
|
|
objects. This class is optional so a lightweight implementation of Scintilla may bypass it if
|
|
the added functionality is not required.
|
|
</p>
|
|
<h3>
|
|
Platform Events and API
|
|
</h3>
|
|
<p>
|
|
Each platform uses different mechanisms for receiving events. On Windows, events are
|
|
received through messages and COM. On GTK+, callback functions are used.
|
|
</p>
|
|
<p>
|
|
For each platform, a class is derived from ScintillaBase (and thus from Editor). This is
|
|
ScintillaWin on Windows and ScintillaGTK on GTK+. These classes are responsible for
|
|
connecting to the platforms event mechanism and also to implement some virtual methods in
|
|
Editor and ScintillaBase which are different on the platforms. For example, this layer has to
|
|
support this difference between the synchronous Windows clipboard and the asynchronous GTK+
|
|
clipboard.
|
|
</p>
|
|
<p>
|
|
The external API is defined in this layer as each platform has different preferred styles of
|
|
API - messages on Windows and function calls on GTK+. This also allows multiple APIs to be
|
|
defined on a platform. The currently available API on GTK+ is similar to the Windows API and
|
|
does not follow platform conventions well. A second API could be implemented here that did
|
|
follow platform conventions.
|
|
</p>
|
|
</body>
|
|
</html>
|
|
|