texthelp -- Shared Text Editing Helper Library

Shared infrastructure for text editing widgets, built as texthelp.lib (DXE3 module). Provides clipboard operations, cursor blink management, word boundary detection, cross-widget selection clearing, and a complete single-line text editing engine.

Used by: TextInput, TextArea, Spinner, ComboBox, AnsiTerm.

API Reference

Cursor Blink

void wgtUpdateCursorBlink(void);

Toggles the global cursor blink state (sCursorBlinkOn) based on clock() timing. Called from the event dispatch layer during paint. Widgets that show a text cursor check sCursorBlinkOn to decide whether to draw or hide the cursor.

Selection Management

void clearOtherSelections(WidgetT *except);

Clears text/item selections in all widgets except the specified one. Called when a widget gains focus or starts a new selection, ensuring only one widget has an active selection at a time.

Word / Character Helpers

bool isWordChar(char c);

Returns true if c is a word character (alphanumeric or underscore). Used for double-click word selection and Ctrl+arrow word navigation.

int32_t wordStart(const char *buf, int32_t pos);

Scans backward from pos to find the start of the current word.

int32_t wordEnd(const char *buf, int32_t len, int32_t pos);

Scans forward from pos to find the end of the current word.

Single-Line Text Editing Engine

Four functions implement the complete editing behavior shared across TextInput, Spinner, ComboBox, and other single-line text widgets:

void widgetTextEditOnKey(WidgetT *w, int32_t key, int32_t mod,
    char *buf, int32_t bufSize, int32_t *pLen,
    int32_t *pCursor, int32_t *pScrollOff,
    int32_t *pSelStart, int32_t *pSelEnd,
    char *undoBuf, int32_t *pUndoLen, int32_t *pUndoCursor,
    int32_t fieldWidth);

Handles all keyboard input: character insertion, deletion (Backspace, Delete), cursor movement (arrows, Home, End), word navigation (Ctrl+arrows), selection (Shift+arrows, Ctrl+Shift+arrows, Ctrl+A), clipboard (Ctrl+C/X/V), and undo (Ctrl+Z).

void widgetTextEditMouseClick(WidgetT *w, int32_t vx, int32_t vy,
    int32_t textLeftX, const BitmapFontT *font,
    const char *buf, int32_t len, int32_t scrollOff,
    int32_t *pCursorPos, int32_t *pSelStart, int32_t *pSelEnd,
    bool wordSelect, bool dragSelect);

Handles mouse click positioning: converts pixel coordinates to cursor position, handles word selection (double-click), and drag-select.

void widgetTextEditDragUpdateLine(int32_t vx, int32_t leftEdge,
    int32_t maxChars, const BitmapFontT *font, int32_t len,
    int32_t *pCursorPos, int32_t *pScrollOff, int32_t *pSelEnd);

Updates cursor and selection during mouse drag operations.

void widgetTextEditPaintLine(DisplayT *d, const BlitOpsT *ops,
    const BitmapFontT *font, const ColorSchemeT *colors,
    int32_t textX, int32_t textY, const char *buf,
    int32_t visLen, int32_t scrollOff, int32_t cursorPos,
    int32_t selStart, int32_t selEnd, uint32_t fg, uint32_t bg,
    bool showCursor, int32_t cursorMinX, int32_t cursorMaxX);

Renders a single line of text with selection highlighting and cursor.

Constants

Name	Value	Description
`TEXT_INPUT_PAD`	3	Padding inside text input border

Exported Symbols

Matches prefixes: _clipboard*, _clearOther*, _isWordChar*, _multiClick*, _widgetText*, _wordStart*, _wordEnd*.

Files

File	Description
`textHelp.h`	Public API header
`textHelp.c`	Complete implementation
`Makefile`	Builds `bin/libs/texthelp.lib` + dep file

Build

make            # builds bin/libs/texthelp.lib + texthelp.dep
make clean      # removes objects, library, and dep file

Depends on: libtasks.lib, libdvx.lib (via texthelp.dep).

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