调整页面尺寸
更改纸张尺寸，可以缩放内容，也可以在四周裁切。
这款工具完全在你的浏览器中运行。文件从不上传，你可以在浏览器的网络标签中亲自验证这一点。 亲自验证：打开浏览器的网络标签观察。你会看到一个查询你是否还有剩余任务的小请求，只包含工具名称和一段哈希，绝不会包含文件。
这款工具的作用
This rebuilds a document on a different sheet size. Fit scales each page's content to the new sheet, so nothing is lost and the type gets smaller or larger with it. Crop keeps the content at its original scale and changes the paper around it, so nothing is rescaled and anything outside the new box is cut away. The content is placed as vector artwork, so text stays text and images keep their resolution either way.
Two situations account for most of it. A document made for one market's paper turns up in another - a Letter file that has to print on A4, or the reverse - and the printer either refuses it or shrinks it unpredictably. Or a poster, drawing or spreadsheet export arrives at A3 and needs to be readable on an ordinary sheet.
工作原理
- Drop the PDF onto this page.
- Choose the target size, or pick Custom and type the width and height in millimetres.
- Set the orientation. Keep follows whatever shape each page already has, so a document mixing portrait text with landscape tables stays sensible.
- Choose Fit to scale the content onto the new sheet, or Crop to leave it at full size and trim the sheet around it.
- Press Resize and the download starts on its own.
Fit and Crop are the whole tool, and choosing the wrong one is the usual complaint about resize tools elsewhere. Fit measures the page against the new sheet, scales it by whichever dimension is tighter, and centres it - so an A4 page onto A5 comes out at 71 per cent of its size, entirely intact and harder to read. Crop draws the page at its original scale on the new sheet and centres it, so the type stays exactly the size it was and whatever falls outside the sheet is gone.
Sizes are entered in millimetres because that is how paper is sold, and converted to points on the way in - a PDF has no notion of millimetres at all, only of 1/72 of an inch. A4 is 210 by 297 mm, Letter is 216 by 279, and the custom fields accept anything from 10 mm to 2000 mm, which covers a business card at one end and a plotter drawing at the other.
Orientation is decided per page rather than for the document. With orientation on Keep, a page currently wider than it is tall gets the target size turned landscape, and an upright page gets it upright. That is what stops a report with a few landscape tables coming out with those tables squeezed into portrait sheets.
The page range under advanced options selects which pages are resized, and the output contains only those pages - it is a selection, not a filter that leaves the rest alone. Use it when you want the selected pages on a new size as a document of their own, and leave it empty for the ordinary case of resizing everything.
Each page is drawn onto its new sheet as artwork, which keeps the content vector and the text selectable but does not carry annotations across. Everything happens with pdf-lib in your browser, so a set of confidential drawings is re-sheeted without anything being uploaded.
这款工具做不到的事
- Links, form fields and annotations are not carried over, because each page is drawn as artwork onto a new sheet.
常见问题
- 「适应」和「裁切」有什么区别？
- 「适应」把整页缩放到新纸张并居中，什么都不会丢失，但一切都会变大小——A4 页面移到 A5 后，文字会变成 71%。「裁切」把内容保持在原尺寸、只更改四周的纸张，所以文字大小不变，超出新纸张之外的部分会被切掉。
- 调整尺寸会让文字或图像变模糊吗？
- 不会。页面是作为矢量图版嵌入的，而不是重新渲染，所以文字仍可选中、放大到任何倍率都清晰，图像也保留原始数据。把扫描件放大会让它的像素变大，那是扫描件本身的性质，而不是这个工具做的事。
- 我的文档混有纵向和横向页面。会怎么样？
- 把方向设为「保持」时，每一页都以自己的方向变成目标尺寸——纵向页变成纵向 A4，横向页变成横向 A4。想让所有页面统一朝向，就明确选择纵向或横向，打印机需要统一纸张时用这个。
- 我可以设一个精确的尺寸吗？
- 可以。选「自定义尺寸」，以毫米为单位输入宽和高，范围从 10 到 2000。数值按每英寸 25.4 毫米换算成 PDF 点，所以 210×297 正好是 A4，100×150 是一张明信片。
- 文档会被上传吗？
- 不会。换纸由 pdf-lib 在你浏览器的 Web Worker 里完成，所以什么都不会离开你的机器。这个页面加载之后，工具在完全没有网络的情况下也能用。