TextHistory Class Reference

Undo/redo history management for text editing with efficient diff-based storage. More...

#include <gin_texthistory.h>

Public Member Functions
void	setHistoryLimit (int numItems)
void	undo ()
void	redo ()
bool	canUndo ()
bool	canRedo ()
bool	addText (const juce::String &)
const juce::String &	getCurrentText ()

Public Attributes
std::function< void()>	onStateChanged

Detailed Description

Undo/redo history management for text editing with efficient diff-based storage.

TextHistory provides unlimited undo/redo functionality for text documents using a diff-based approach (binary patches) for memory-efficient storage. Instead of storing complete text snapshots, only the differences between states are stored.

Key Features:

• Unlimited undo/redo with configurable history limit
• Efficient diff-based storage (binary patches)
• Change notification via callback
• Minimal memory footprint
• Linear history (no branching)

The implementation uses binary diff patches (forward and backward) to efficiently store changes, making it suitable for large documents or long editing sessions.

Usage:

TextHistory history;
history.setHistoryLimit(100); // Keep last 100 changes
 
// Register for state changes
history.onStateChanged = []() {
    DBG("History state changed");
};
 
// Add text changes
history.addText("Initial text");
history.addText("Modified text");
history.addText("Final text");
 
// Undo changes
if (history.canUndo())
{
    history.undo();
    juce::String text = history.getCurrentText(); // Returns "Modified text"
}
 
// Redo changes
if (history.canRedo())
{
    history.redo();
    juce::String text = history.getCurrentText(); // Returns "Final text"
}

Implementation Details:

• Uses binary diff algorithm for patch generation
• Maintains stack of forward/backward patches
• Stack pointer tracks current position in history
• Adding new text while mid-history discards forward history

See also

juce::UndoManager for alternative undo/redo approach

Member Function Documentation

setHistoryLimit()

void TextHistory::setHistoryLimit

(

int

numItems

)

undo()

void TextHistory::undo

(

)

redo()

void TextHistory::redo

(

)

canUndo()

bool TextHistory::canUndo

(

)

canRedo()

bool TextHistory::canRedo

(

)

addText()

bool TextHistory::addText

(

const juce::String &

)

getCurrentText()

const juce::String & TextHistory::getCurrentText

(

)

Member Data Documentation

onStateChanged

std::function<void ()> TextHistory::onStateChanged

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The documentation for this class was generated from the following file:

• gin_texthistory.h