tencent cloud

Feature Description

The file preview feature allows generating images from multiple types of files for preview and performing basic processing operations on the output images synchronously. It addresses the display problems of file content on webpages and enables easy online file preview on PC, app, and other terminals. It is widely suitable for diverse business scenarios, such as online education, enterprise OA, and website transcoding.

Note：

• To use this feature, you need to activate the service first. Then, you can call a specific file preview API to preview files in the bucket synchronously or asynchronously.
• File preview is a paid feature billed by CI. For billing details, see Billing Overview.
• The conversion logic of file transcoding is the same as that of local printing. If you need to change the conversion orientation (such as outputting an Excel file with many columns horizontally to one page), you need to change the source file print settings.

Request

Sample request

GET /<ObjectKey>?ci-process=doc-preview&page=<page>&srcType=<srcType>&ImageParams=<ImageParams> HTTP/1.1
Host: <BucketName-APPID>.cos.<Region>.myqcloud.com
Date: GMT Date
Authorization: Auth String

Note：

• Authorization: Auth String (for more information, see Request Signature).
• For private buckets, the request needs to carry the signature for file download.

Request headers

This API only uses common request headers. For more information, see Common Request Headers.

Common request parameters

Parameter	Description	Type	Required
ObjectKey	Object name, such as folder/document.pdf.	String	Yes
ci-process	CI's processing capability, which is fixed at doc-preview for file preview.	String	Yes
srcType	Source data type. Currently, the file conversion feature determines the source data type according to the file extension of the COS object. If the object has no extension, you can set this value.	String	No
page	Number of the page to be converted, which is counted from 1 by default. For spreadsheets, page indicates to convert the xth image in the xth sheet.	Int	No
dstType	Type of the output target file. Valid values: png jpg pdf (the page number cannot be selected, and the page parameter does not take effect) txt If the input file format cannot be recognized, the jpg format will be used by default.	String	No
password	Password to open the Office file. If you need to convert a password-protected file, set this field.	String	No
comment	Whether to hide comments and apply track changes. 0: hide comments and apply track changes; 1: show comments and track changes. Default value: 0.	Int	No

Parameters for spreadsheet files (Excel)

Parameter	Description	Type	Required
sheet	Sheet parameter, indicating to convert the xth sheet. Default value: 1.	Int	No
excelPaperDirection	Paper orientation of the spreadsheet. 0: vertical; other values: horizontal. Default value: 0.	Int	No
excelRow	The value 1 indicates that all rows will be formatted on one page. Default value: 0.	Int	No
excelCol	The value 1 indicates that all columns will be formatted on one page. Default value: 0.	Int	No
excelPaperSize	Paper (canvas) size. Valid values: 0 (A4), 1 (A2), 2 (A0). Default value: 0. This parameter should be used together with excelRow or excelCol.	Int	No

Parameters for transcoding into .txt files

Parameter	Description	Type	Required
txtPagination	Whether to convert to long text. When this parameter is set to true, the text in the pages to be exported can be combined before export, and the pagination range can be controlled by Ranges. The default value is false, indicating to generate .txt files by page. This parameter takes effect only if ExportType is txt.	Bool	No

Parameters for transcoding to .png/.jpg images

Name	Description	Type	Required
ImageParams	Processing parameters for the output image. All parameters of basic image processing are supported. To specify multiple parameters, separate them by pipeline operator. In this way, the image can be processed by multiple parameters in sequence in the same request.	String	No
quality	Quality of the generated preview image. Value range: [1, 100]. Default value: 100. For example, if the value is 100, the quality of the generated image will be 100%.	Int	No
scale	Scaling parameter of the preview image. Value range: [10, 200]. Default value: 100. For example, if the value is 200, the image will be scaled up (enlarged) by 200%.	Int	No
imageDpi	Renders the image based on the specified DPI. This parameter works together with scale. Value range: 96–600. Default value: 96. The width of the output image must be less than 65500 px.	Int	No

Note：

• Currently supported input file types include:
• Presentation files: PPTX, PPT, POT, POTX, PPS, PPSX, DPS, DPT, PPTM, POTM, PPSM.
• Text files: DOC, DOT, WPS, WPT, DOCX, DOTX, DOCM, DOTM.
• Spreadsheet files: XLS, XLT, ET, ETT, XLSX, XLTX, CSV, XLSB, XLSM, XLTM, ETS.
  A spreadsheet file may be split into multiple pages, with multiple images generated.
• Other files: PDF, LRC, C, CPP, H, ASM, S, JAVA, ASP, BAT, BAS, PRG, CMD, RTF, TXT, LOG, XML, HTM, HTML.
• The input file size cannot exceed 200 MB.
• The number of pages in the input file cannot exceed 5,000.

Request body

The request body of this request is empty.

Response

Response headers

This API only returns common response headers. For more information, see Common Response Headers.

Response parameter description

Parameter	Description	Type
X-Total-Page	Total number of pages in the file (or images converted from sheets in the spreadsheet file) returned in the HTTP header. This value will be empty in case of an exception.	Int
Content-Type	Different values will be returned based on the actual image format, such as image/jpeg and image/webp.	String
X-ErrNo	The error code returned in case of an exception, which can be viewed in the HTTP header.	String
X-Total-Sheet	Total number of sheets in the spreadsheet file returned in the HTTP header.	Int
X-Sheet-Name	Name of the current sheet in the spreadsheet file returned in the HTTP header.	String

Error codes

There are no special error messages for this request. For common error messages, see Error Codes.

Samples

Sample 1: Previewing a general file

Request

GET /sample.pdf?ci-process=doc-preview&page=1 HTTP/1.1
Host: examplebucket-1250000000.cos.ap-shanghai.myqcloud.com

Response 1: Preview succeeds

HTTP/1.1 200 OK
Content-Type: image/jpeg
Content-Length: 645
Date: Tue, 03 Apr 2018 09:06:16 GMT
X-Total-Page: 100
[Image data after transcoding]

Response 2: The file does not exist

HTTP/1.1 404 OK
Connection: close
Content-Length: 455
Content-Type: application/xml
Date: Thu, 09 Apr 2020 13:44:52 GMT
X-ErrNo: -3004

Response 3: The specified page does not exist

HTTP/1.1 404 OK
Connection: close
Content-Length: 455
Content-Type: application/xml
Date: Thu, 09 Apr 2020 13:44:52 GMT
X-ErrNo: -3013

Sample 2: Previewing a file and processing the image by scaling it and adding a text watermark

Request

GET /sample.pdf?ci-process=doc-preview&page=1&ImageParams=imageMogr2/thumbnail/!50p|watermark/2/text/5pWw5o2u5LiH6LGh/fill/I0ZGRkZGRg==/fontsize/30/dx/20/dy/20 HTTP/1.1
Host: examplebucket-1250000000.cos.ap-shanghai.myqcloud.com

Response 1: Preview succeeds

HTTP/1.1 200 OK
Content-Type: image/jpeg
Content-Length: 645
Date: Tue, 03 Apr 2018 09:06:16 GMT
X-Total-Page: 100
[Image data after transcoding]

Response 2: The file does not exist

HTTP/1.1 404 OK
Connection: close
Content-Length: 455
Content-Type: application/xml
Date: Thu, 09 Apr 2020 13:44:52 GMT
X-ErrNo: -3004

Response 3: The specified page does not exist

HTTP/1.1 404 OK
Connection: close
Content-Length: 455
Content-Type: application/xml
Date: Thu, 09 Apr 2020 13:44:52 GMT
X-ErrNo: -3013