Chrome：如何打印原始大小的PDF（100％，不缩放） [英] Chrome: How to print PDF with original size (100%, no scaling/shrinking)

问题描述

今天，我在Chrome的打印行为中遇到了一个奇怪的错误。
当我尝试使用Chrome打印动态创建的PDF（在Firefox中也是 ）时，PDF中的每个图像都会变小一点（8mm）。
在Adobe Reader / Acrobat / MacOSX默认打印机对话框中都不会发生这种情况。

现在让我更详细地解释我的代码：

dynamic PDF：

我使用 prawn 来动态创建PDF使用此代码的A4（横向格式）：

  require'prawn'
 requireprawn / measurement_extensions
 
类CustomPdf<对虾::文档
 
 def初始化（标签）＃A4 
 super（{
：page_size =>A4，
：page_layout =>：风景，
：margin => 0，
：print_scaling =>：none}）
 
 imagemy_image.png，：width => 213.mm，：at => [3.mm，3.mm] 
 end 
 end 
  

嵌套图像在PDF里面：

嵌套在PDF中的图像的大小为 213mm x 70mm ，
300 DPI 。在像素：2515x827。

我使用RMagick创建图像，但尺寸，dpi和所有目前为止似乎没有问题。所以目前没有进一步的解释。

预期结果：

打印的PDF将显示213cm宽度。

实际结果：

打印的PDF将显示205mm宽的图像。

我到目前为止所做的尝试

• 设置 prawn page_size 到低于A4的东西（因为图片不像A4那么大）。


• 玩弄 print_scaling
code>（有三种模式，：none ，：AppDefault ，： something_except_the_other_ones
如果Imgur将分辨率更改为72，则可以从存储库拉示例图像（链接： https://github.com/posixpascal/chrome-printing-bug/blob/master/example.png ） / p>



以下是一个示例PDF





直接链接：直接链接





GitHub PDF查看器： https： //github.com/posixpascal/chrome-printing-bug/blob/master/output.pdf





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https://github.com/posixpascal/chrome - 打印错误





不幸的是，我无法改变图像的宽度（甚至不是一个像素）。
有人经历过同样的问题吗？





有什么想法？这是一个有趣的谜题，我猜... ... x





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当我用Chrome打印一个普通的图像或网站时，打印PDF时没有使用原稿尺寸或100％尺寸选项。





我也尝试制作网页而不是PDF，设置图像的宽度为 213mm ，这也不起作用...

这是我使用Windows系统和Mac（Yosemite）所看到的测试结果



Windows：



在Chome上打印PDF：完美 - 213毫米



印刷在IE：完美 - 213毫米。这之前（205-210左右）较少。所以改变了默认的打印设置： b
$ b




选择打印选项 - >使用打印对话框 - >选择打印机 - >打印首选项 - >高级 - >纸张大小 - >改变手动缩放 - >测试A4，A5等.-> A5（由于某种原因给了我213）










改变纸张大小并测试相同的：尺寸为213毫米。





这样做是这样的：打印在205毫米。





经过对虾的printscaling测试：appdefault - >以213 mm打印。





在Firefox上测试相同 - >低于205 - 210毫米。所以我真的不知道它是否是一个Chrome的问题，因为它在Firefox上的行为奇怪我。所以最终，这些都是我在测试完我的代码之后的发现。


Today I encountered one weird bug in Chrome's printing behavior. When I try to print a dynamically created PDF using Chrome (also in Firefox), every image inside the PDF gets a little bit smaller (8mm). This doesn't happen neither in Adobe Reader/Acrobat/MacOSX Default Printer Dialog.

Let me explain more about my code so far:

dynamic PDF:

I use prawn to dynamically create a PDF A4 (landscape format) using this code:

require 'prawn'
require "prawn/measurement_extensions"

class CustomPdf < Prawn::Document

  def initialize(label) # A4
    super({
       :page_size =>  "A4", 
       :page_layout => :landscape, 
       :margin => 0, 
       :print_scaling => :none})

    image "my_image.png", :width => 213.mm, :at => [3.mm, 3.mm]
  end
end

nested image inside the PDF:

The Image nested inside the PDF has a size of 213mm x 70mm with 300 DPI. In Pixel: 2515x827.

I create the Image using RMagick but the size, dpi and everything so far seems to be alright. So no further explanation at the moment.

Expected result:

The printed PDF will show an image with 213cm width.

Actual result:

The printed PDF will show an image with 205mm width.

What I tried so far

• Setting the prawn page_size to something lower than A4 (since the Image isn't bigger as A4 as well...).
• Playing around with print_scaling(there are 3 modes, :none, :AppDefault, :something_except_the_other_ones (Read more about it here)
• Giving the image a fixed height (70mm)
• Playing around with various settings provided by the Chrome Printer Dialog
• Tested under Windows Chrome (it's 213mm there, weird), maybe it's related to MacOSX Chrome?
• Tested under IE11 (205mm) unfortunately.

Neither of these did anything. I looked through the Bugreporters of Chromium and found 2 people who might share the same problem as I do:

• https://code.google.com/p/chromium/issues/detail?id=97972
• https://code.google.com/p/chromium/issues/detail?id=67091

The last one was touched 2013 but no one said anything that actually worked for my case.

---

Examples

Here is an example 300 DPI image which width is 2515 px: If Imgur changes the resolution to 72, you can pull the example image from the repository (link: https://github.com/posixpascal/chrome-printing-bug/blob/master/example.png)

Here is an example PDF

Direct Link: Direct Link

GitHub PDF Viewer: https://github.com/posixpascal/chrome-printing-bug/blob/master/output.pdf

---

Github Repository with example image & pdf generator script https://github.com/posixpascal/chrome-printing-bug

Unfortunately I can't change the width of the image (not even a pixel). Someone experienced the same problem?

Any ideas? It's an interesting puzzle I guess... :x

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When I print a plain image or a website with Chrome there is a 'Use Original Size' or '100% size' option which I don't have when printing the PDF.

I also tried making a webpage instead of a PDF and set the image width to 213mm which didn't work either...

解决方案

This is my test results from what i have seen by using a windows system and a Mac ( Yosemite )

Windows :

Printed the PDF in Chome : Perfect - 213 mm

Printed in IE : Perfect - 213 mm. This was less before ( around 205-210ish ). So changed the default print settings :

Selected the Print option -> Used Print Dialog -> Selected the printer -> Print Preferences -> Advanced -> Paper Size -> Changed scaling manually -> tested A4, A5 and so on.-> A5 ( for some reason gave me 213 )

So i moved onto the Mac.

Mac Findings:

Changed Paper Size and tested the same : Size was 213 mm.

This was done like this : Apple Print

So naturally, i tested printing it through Chrome directly instead of opening the PDF through OSX -> Printed at 205 mm.

Tested with printscaling on prawn at :appdefault -> Printed at 213 mm.

Tested the same on Firefox -> lower than 205 - 210 mm.

So i dont really know if its a Chrome issue because its acting weird on Firefox for me.

So ultimately, these are my findings after testing out the code on my end.

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