func (s *CIService) DocPreview(ctx context.Context, name string, opt *DocPreviewOptions) (*Response, error)

opt := &cos.DocPreviewOptions{
    Page: 1,
}
resp, err := c.CI.DocPreview(context.Background(), "form.pdf", opt)

type DocPreviewOptions struct {
    SrcType             string
    Page                int
    ImageParams         string
    Sheet               int
    DstType             string
    Password            string
    Comment             int
    ExcelPaperDirection int
    Quality             int
    Zoom                int
}