Method loadFilePreNextPage

src/cceditor/filemanager.cpp:699–754

加载下一页或者上一页。(二进制模式）

//加载下一页或者上一页。(二进制模式）
int  FileManager::loadFilePreNextPage(int dir, QString& filePath, HexFileMgr* & hexFileOut)
{
	if (m_hexFileMgr.contains(filePath))
	{
		hexFileOut = m_hexFileMgr.value(filePath);

		//小于LITTLE_FILE_MAX的已经一次性全部在内存，没有上下页可以翻到
		if (hexFileOut->onetimeRead)
		{
			return 1;
		}
		qint64 pos = hexFileOut->fileOffset;

		if (dir == 1 && (pos >= 0))
		{
			//上一页
			pos = pos - hexFileOut->contentRealSize - ONE_PAGE_BYTES;
			if (pos < 0)
			{
				pos = 0;
			}
		}
		else if(dir == 2 && (pos < hexFileOut->fileSize))
		{
		
		}
		else
		{
			return 1;//没有上下页，已经是最后一页或最前一页
		}

		char* buf = new char[ONE_PAGE_BYTES+1];

		hexFileOut->file->seek(pos);
		qint64 ret = hexFileOut->file->read(buf, ONE_PAGE_BYTES);
		if (ret <= 0)
		{
			return -1;
		}
		else
		{
			//读取成功
			hexFileOut->fileOffset = hexFileOut->file->pos();

			if (hexFileOut->contentBuf != nullptr)
			{
				delete[]hexFileOut->contentBuf;
			}

			hexFileOut->contentBuf = buf;
			hexFileOut->contentRealSize = ret;
		}
		return 0;
	}
	return -1;
}

const int ONE_PAGE_TEXT_SIZE = 1000 * 1024;