Method Backspace

plugins/Cardinal/src/DearImGuiColorTextEditor/TextEditor.cpp:1820–1896

}

void TextEditor::Backspace()
{
	assert(!mReadOnly);

	if (mLines.empty())
		return;

	UndoRecord u;
	u.mBefore = mState;

	if (HasSelection())
	{
		u.mRemoved = GetSelectedText();
		u.mRemovedStart = mState.mSelectionStart;
		u.mRemovedEnd = mState.mSelectionEnd;

		DeleteSelection();
	}
	else
	{
		auto pos = GetActualCursorCoordinates();
		SetCursorPosition(pos);

		if (mState.mCursorPosition.mColumn == 0)
		{
			if (mState.mCursorPosition.mLine == 0)
				return;

			u.mRemoved = '\n';
			u.mRemovedStart = u.mRemovedEnd = Coordinates(pos.mLine - 1, GetLineMaxColumn(pos.mLine - 1));
			Advance(u.mRemovedEnd);

			auto& line = mLines[mState.mCursorPosition.mLine];
			auto& prevLine = mLines[mState.mCursorPosition.mLine - 1];
			auto prevSize = GetLineMaxColumn(mState.mCursorPosition.mLine - 1);
			prevLine.insert(prevLine.end(), line.begin(), line.end());

			ErrorMarkers etmp;
			for (auto& i : mErrorMarkers)
				etmp.insert(ErrorMarkers::value_type(i.first - 1 == mState.mCursorPosition.mLine ? i.first - 1 : i.first, i.second));
			mErrorMarkers = std::move(etmp);

			RemoveLine(mState.mCursorPosition.mLine);
			--mState.mCursorPosition.mLine;
			mState.mCursorPosition.mColumn = prevSize;
		}
		else
		{
			auto& line = mLines[mState.mCursorPosition.mLine];
			auto cindex = GetCharacterIndex(pos) - 1;
			auto cend = cindex + 1;
			while (cindex > 0 && IsUTFSequence(line[cindex].mChar))
				--cindex;

			//if (cindex > 0 && UTF8CharLength(line[cindex].mChar) > 1)
			//	--cindex;

			u.mRemovedStart = u.mRemovedEnd = GetActualCursorCoordinates();