建议完善看漫画往回一页的流畅性

[lkyxgh]

功能描述（请清晰的、详细的描述你想要的功能）

现在有预加载，一页页往后看是顺畅的，但是如果往回则会有一阵的空白和卡顿，建议改善。问了AI，给出建议是read_view.py里，修改def CheckLoadPicture(self)，实测效果可以，建议完善。附AI给的替换代码，替换旧的就能用。

附加信息（其他的与功能相关的附加信息）

def CheckLoadPicture(self):
    if not self.maxPic or not self.bookId:
        return

    # 扩展预加载范围，包括前向和后向
    forward_range = min(self.curIndex + config.PreLoading, self.maxPic)
    backward_range = max(self.curIndex - config.PreLoading//2, 0)  # 增加向后预加载
    
    preLoadSet = set(range(backward_range, forward_range))
    
    # 保留当前页及其邻近页面
    currentKeys = set(self.pictureData.keys())
    removeKeys = currentKeys - preLoadSet
    
    # 批量移除不需要的任务
    removeTaskIds = []
    for key in removeKeys:
        p = self.pictureData[key]
        if p.waifu2xTaskId > 0:
            removeTaskIds.append(p.waifu2xTaskId)
    
    # 清理不需要的数据
    for key in removeKeys:
        self.pictureData.pop(key, None)
    
    if removeTaskIds:
        self.ClearWaitConvertIds(removeTaskIds)

    # 优化下载和转换任务调度
    download_tasks = []
    convert_tasks = []
    
    for i in sorted(preLoadSet):
        if i >= self.maxPic or i < 0:
            continue
            
        p = self.pictureData.get(i)
        
        # 添加下载任务
        if not p:
            download_tasks.append(i)
        elif p.state in [p.DownloadReset, p.DownloadError]:
            download_tasks.append(i)
        elif p.state == p.Downloading:
            continue
            
        # 添加转换任务
        if p and p.isWaifu2x and p.data and not p.cacheWaifu2xImage:
            if p.waifuState in [p.WaifuStateCancle, p.WaifuWait]:
                p.waifuState = p.WaifuStateStart
                convert_tasks.append(i)

    # 控制并发数量
    max_download_concurrent = 3
    max_convert_concurrent = 2
    
    # 批量添加下载任务（优先处理临近当前页的）
    near_tasks = [i for i in download_tasks if abs(i - self.curIndex) <= 2]
    far_tasks = [i for i in download_tasks if abs(i - self.curIndex) > 2]
    
    # 优先处理靠近当前页的下载任务
    for i in (near_tasks + far_tasks)[:max_download_concurrent]:
        self.AddDownload(i)
    
    # 批量添加转换任务
    for i in convert_tasks[:max_convert_concurrent]:
        p = self.pictureData.get(i)
        if p and p.waifu2xTaskId <= 0:
            self.AddCovertData(i)

    # 处理QImage转换任务
    preQImage = list(range(self.curIndex - 1, self.curIndex + config.PreLook))
    preRealQImage = list(range(self.curIndex - 1, self.curIndex + config.PreLook))
    
    for i in preRealQImage:
        if i < 0 or i >= self.maxPic:
            continue
        p = self.pictureData.get(i)
        if not p or not p.data:
            continue
        assert isinstance(p, QtFileData)
        
        # 优先处理当前页和临近页的图像转换
        if i == self.curIndex or abs(i - self.curIndex) <= 1:
            # 立即处理当前页和相邻页
            if not (not p.waifuData or p.cacheWaifu2xImage or p.cacheWaifu2xImageTaskId > 0):
                self.CheckToQImage(i, p, True)
            if not (p.cacheImage or p.cacheImageTaskId > 0):
                self.CheckToQImage(i, p, False)
        else:
            # 后续处理其他页面
            IsConvert = (p.cacheWaifu2xImageTaskId > 0 or not not p.cacheWaifu2xImage)
            if not (not p.waifuData or p.cacheWaifu2xImage or p.cacheWaifu2xImageTaskId > 0):
                IsConvert = self.CheckToQImage(i, p, True)

            if (not IsConvert or not p.isWaifu2x) and not (p.cacheImage or p.cacheImageTaskId > 0):
                self.CheckToQImage(i, p, False)

    # 清理不需要的QImage缓存
    for i in set(self.pictureData.keys()) - set(preQImage):
        p = self.pictureData.get(i)
        if not p:
            continue
        assert isinstance(p, QtFileData)
        if p.cacheImageTaskId > 0:
            self.ClearQImageTaskById(p.cacheImageTaskId)
            p.cacheImageTaskId = 0
        if p.cacheWaifu2xImageTaskId > 0:
            self.ClearQImageTaskById(p.cacheWaifu2xImageTaskId)
            p.cacheWaifu2xImageTaskId = 0
        p.cacheImage = None
        p.cacheWaifu2xImage = None

效果演示（可以提供可借鉴的图片）

实测是顺畅的。

[tonquer]

你是用双页模式，还是滚动模式

[lkyxgh]

默认模式，一页页看的

[tonquer]

更新1.3.1