101 lines
3.3 KiB
Plaintext
101 lines
3.3 KiB
Plaintext
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wxRichTextCtrl README
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=====================
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Welcome to wxRichTextCtrl. It includes the following functionality:
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* Text entry, paragraph wrapping
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* Scrolling, keyboard navigation
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* Application of character styles:
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bold, italic, underlined, font face, text colour
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* Application of paragraph styles:
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left/right indentation, sub-indentation (first-line indent),
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paragraph spacing (before and after), line spacing,
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left/centre/right alignment, numbered bullets
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* Insertion of images
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* Copy/paste
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* Undo/Redo with optional batching and undo history suppression
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* Named paragraph and character styles management and application
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* File handlers allow addition of file formats
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* Text saving and loading, XML saving and loading, HTML saving (unfinished)
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Sorry, this is a Windows-only demo for now but the code should
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compile on other platforms.
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Design
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======
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Data is represented by a hierarchy of objects, all derived from
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wxRichTextObject.
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The top of the hierarchy is the buffer, a kind of wxRichTextParagraphLayoutBox.
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These boxes will allow flexible placement of text boxes on a page, but
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for now there will be a single box representing the document,
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and this box will a wxRichTextParagraphLayoutBox which contains further
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wxRichTextParagraph objects, each of which can include text and images.
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Each object maintains a range (start and end position) measured
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from the start of the main parent box.
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A paragraph object knows its range, and a text fragment knows its range
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too. So, a character or image in a page has a position relative to the
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start of the document, and a character in an embedded text box has
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a position relative to that text box. For now, we will not be dealing with
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embedded objects but it's something to bear in mind for later.
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Before display, a changed buffer must have Layout() called on it,
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to do wrapping, alignment etc. Ranges representing wrapped lines are stored
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with each paragraph.
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Since wxRichTextBuffer is separate from wxRichTextCtrl, the storage
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and rendering facilities can be used by other controls.
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API
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===
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It's basically the wxTextCtrl with some additions. There is a new
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wxTextAttrEx class deriving from wxTextAttr, to accomodate new
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style attributes. This could be merged with wxTextAttr. There
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is also a wxRichTextAttr which is similar to wxTextAttrEx but
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doesn't store the font as a wxFont: this allows much more
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efficient operations, especially when querying styles in a
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UI update handler. We would not want to create several new wxFonts
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when querying for italics, bold, etc. every few milliseconds.
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See "Functionality specific to wxRichTextCtrl" section in richtextctrl.h.
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One addition is Set/GetBasicStyle, which is needed in addition to
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Set/GetDefaultStyle to get the overall style for the buffer
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from which content will inherit (after apply the default style).
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wxRichTextRange is a new class representing start and end positions.
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It's used in the implementation so that pieces of content
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know their range, and also in the API in preference to using
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two positions.
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What next?
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==========
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- Decision about where to put it: wxCode, wxWidgets
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- Makefiles/bakefiles
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- Refining the API
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- Documentation
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- Bug fixing/improvements
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See todo.txt for a list of bugs, improvements and features,
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and also TODO throughout the source.
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==
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Julian Smart, October 18th 2005
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