Suggestions for debugging print stylesheets?
Solution 1
There is an option for that in Chrome's inspector.
- Open the DevTools inspector (mac: Cmd + Shift + C , windows: Ctrl + Shift + C)
- Click on the Toggle device mode icon , located on the upper left corner of the DevTools panel. (windows: Ctrl+Shift+M, mac: Cmd+Shift+M).
- Click on the More overrides icon in the top right corner of the browser viewport to open the devtools drawer.
-
Then, select Media in the emulation drawer, and check the CSS media checkbox.
This should do the trick.
Update: The menus have changed in DevTools. It can now be found by clicking on the "three-dots" menu in the top right corner > More Tools > Rendering Settings > Emulate media > print.
Source: Google DevTools page*
Solution 2
I'm assuming you want as much control of the printed window as possible without using a HTML to PDF approach... Use @media screen to debug - @media print for final css
Modern browsers can give you a quick visual for what's going to happen at print time using inches and pts in a @media query
.
@media screen and (max-width:8.5in) { /* resize your window until the event is triggered */
html { width:8.5in; }
body { font: 9pt/1.5 Arial, sans-serif; } /* Roughly 12px font */
...
}
Once your browser is displaying "inches" you'll have a better idea of what to expect. This approach should all but end the print preview method. All printers will work with pt
and in
units, and using the @media technique will allow you to quickly see what's going to happen and adjust accordingly. Firebug (or equivalent) will absolutely expedite that process. When you've added your changes to @media, you've got all the code you need for a linked CSS file using media = "print"
attribute - just copy/paste the @media screen rules to the referenced file.
Good luck. The web wasn't built for print. Creating a solution that delivers all of your content, styles equal to what's seen in the browser can be impossible at times. For instance, a fluid layout for a predominantly 1280 x 1024 audience doesn't always translate easily to a nice and neat 8.5 x 11 laser print.
W3C reference for purusal: http://www.w3.org/TR/css3-mediaqueries/
Solution 3
Chrome 48 you can debug print styles within the Rendering tab.
Click the menu icon top right of inspector and Rendering Settings.
Edit
For Chrome 58 the location has changed to Web Inspector > Menu > More Tools > Rendering
Solution 4
In Chrome v41, it's there, but in a slightly different spot.
Solution 5
There's an easy way to debug your print stylesheet without switching any media attribute in your HTML code (of course, as pointed out, it doesn't solve the width / pages issue):
- Use Firefox + Web Developer extension.
- In the Web Developer menu, choose CSS / Display CSS by Media Type / Print
- Go back to Web Developer menu, choose Options / Persist Features
Now you are viewing the print CSS and you can reload your page indefinitely. Once you're done, uncheck "Persist Features" and reload, you'll get the screen CSS again.
HTH.
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Jim Puls
I tried to come up with something pithy and sarcastic to put in this space, but didn't come up with anything. These days, Swift developer by day, JavaScript developer by night. Past lives have involved Objective-C, PHP, Ruby, Java, and, um, Perl.
Updated on April 09, 2021Comments
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Jim Puls about 3 years
I've recently been working on a print stylesheet for a website, and I realized that I was at a loss for effective ways to tweak it. It's one thing to have a reload cycle for working on the on-screen layout:
- change code
- command-tab
- reload
but that whole process gets much more arduous when you're trying to print:
- change code
- command-tab
- reload
- squint at print-preview image
- open PDF in Preview for further inspection
Are there tools I'm missing out on here? Does WebKit's inspector have a "pretend this is paged media" checkbox? Is there some magic that Firebug (shudder) can do?
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Halil Özgür over 13 yearsHow about the "Print preview" function of a browser which supports it (e.g. Firefox)? I've (mostly accurately) debugged some web pages for print with it.
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outis about 12 yearspossible duplicate of How do you debug printable CSS?
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Marcello Nuccio about 8 yearsIn Firefox, open the "Developer Toolbar" with Shift+F2, type "media emulate print" (or "emu" + Tab + "print"), Enter.
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Admin over 6 years
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Volker E. over 6 years@MarcelloNuccio This should be an answer. stackoverflow.com/a/28873496/1696030 got quite some positive votes for comparison. “Developer Toolbar” is a little bit misleading as it's a command line interface.
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anarcat over 5 yearswell @MarcelloNuccio's answer was useful for me because I was looking for an answer in Firefox (!) but the original question was for Webkit/Chrome so it doesn't qualify here...
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Jim Puls over 14 yearsExcept the normal browsing mode doesn't have pages, so I have no idea how content will flow. Normal browsing mode has a width of a certain number of pixels, while a page has a width of a certain number of inches or centimeters. There are fundamental implementation-independent differences between screen and print. Debugging between those is what I'm after.
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heartpunk over 13 yearsOn chrome the rendering is quite different using this suggestion alone. Won't work.
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Dawson over 13 years"Page" width isn't hard to nail down, it's height that's really difficult. Both browsers and printers will play a role in the 11in headache. Web pages are continuous length. Without a guarantee of output device type and browser, I don't think you'll ever hit it on the mark every time. Using a HTML to PDF approach would work, but that's beyond the scope of your question.
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heartpunk over 13 yearsrenders different than print preview, substantially. perhaps this is a quirk in my css. in any case, it doesn't solve the problem. thanks though.
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heartpunk over 13 yearsgood to know, but it would require using a different rendering engine than what we develop for, and still requires more than a reload. thanks though.
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Ken Liu over 13 yearsThe problem with this approach is that if a user simply selects "Print..." in their browser, this javascript function will never get invoked.
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Blowsie over 13 yearsyou don't need to display the print function to the user, you can simply use it for debugging purposes if you wish
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chucknelson about 13 yearsJust wanted to comment that this method is pretty clever. Much easier to resize the window slightly to "toggle" print styles than to use a print preview function. While you still have to do that sometimes for IE compatibility and such, this is great for initial iteration of print styles.
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Dawson about 13 years@Chuck. Thanks Man. Hey, I realized my demo was off-line, so I created a fiddle for it. jsfiddle.net/dNEmT
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Aurelien over 11 yearsThanks, that's what I was looking for, couldn't find it :/ The shortcut doesn't work anymore though. I just do F12 + gear icon in the bottom right corner, then the setting is under the Overrides tab,
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Rafael Nogueira over 11 yearsMerci Aurelien for pointing out the wring shortcuts. Just corrected
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Blazes about 11 yearsThanks! The emulate css is very handy.
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maazza almost 11 yearsunfortunately it is not 100% accurate :(
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duality_ over 10 yearsYeah, completely different for me too. I followed this jsfiddle (jsfiddle.net/2wk6Q/3) and print preview shows pages with red margins, but this is just totally different.
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wasatz over 10 yearsI wish I could up this post twice. It might not be 100% accurate, but it's accurate enough to solve a lot of strange and annoying problems.
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gen_Eric over 10 yearsIn Chrome
32.0.1700.14 beta-m Aura
, "Emulate CSS media [print]" is missing :( -
Jonathan Arkell over 10 yearsAre you sure you don't need to select "Screen" instead of "Device"?
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Rikki about 10 yearsThis is very neat. Is there anyway to get it to show where the page breaks are?
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Rafael Nogueira about 10 years@Rikki: The inspector would need to know which page size you are printing to, how big the printing zone is, the margins, etc.
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Rikki about 10 years@rflnogueira: so? :-) When you "Emulate screen", it lets you set the resolution, so it's feasible it could let you set the paper size for emulating printing. Or it could use the current print settings; an inspector for the print preview would be invaluable!
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Rafael Nogueira about 10 years@Rikki: You could try suggesting that to the Chrome team: chromium.org/getting-involved/bug-triage
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GlyphGryph almost 10 yearsThis doesn't show up for me in Chrome unless I edit the options menu "override" to display this tab. On latest Chrome, but on a Mac, so might be related
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joetinger over 9 years37.0.2062.124 it is under Emulation -> Media
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duozmo over 9 yearsAs of Chrome 38, emulation is turned on with 'device mode' in the Developer Tools (cell phone icon). You alter emulation settings in the 'drawer' inside Developer Tools (command-prompt icon, looks like ⟩≡).
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ORyan over 9 yearsThis is an over engineered solution to something the browser already does. Just use a
media="print"
andmedia="screen"
respectively for your stylesheets and just use the browser menu or key combos to invoke print preview. (In this case it's no different than opening a popup) And if you are just debugging, apply themedia="screen"
attribute to your print styles until you are done debugging. -
Lorin Rivers over 8 yearsIt took me a little time to identify the "Media" tab. I kept looking for it in the "Device" tab.
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Erik Čerpnjak over 8 yearsI must say that this "workaround" works best for me. Maybe I am lucky and thats why there are only small differences between native print screen and the web developers print screen but it definately helped me find out why gaps appear and whats most important - i can go throught the code with firebug and see what is going on
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Hrvoje Golcic over 8 yearsKeep in mind that this works only for print, not for example for (print and orientation). Just to note that
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chharvey over 8 yearsThis answer needs to be corrected. As of Chrome 48, the print stylesheet emulator is no longer under "Emulation" but under "Rendering."
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user1477388 over 8 yearsChrome 49 : F12 (developer console) -> ESC (console) -> Rendering -> Emulate print media
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T.J. Crowder about 8 yearsSteps 2 and 3 are just wrong for the current Chrome (and the Chrome as of your most recent edit). This has absolutely nothing to do with device mode. Just open dev tools, open the panel (Esc or choose "show console" from the menu), and tick "Emulate print media". That's it.
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Mr_Chimp about 8 yearsThis is now hidden away under the three-dots menu in the console section of dev tools.
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allicarn almost 8 yearsThree-dots menu (right side) in the inspector > More Tools > Rendering Settings > Emulate media > print
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James Gray over 7 yearsIn v53 it's on the Rendering tab instead, at the bottom there's a checkbox for Emulate Media which will enable a dropdown that you can select Print in, similar to the provided screenshot
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Chris Bier over 7 years@allicarn +1 I added this to the answer above so it's easier for folks to find.
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Gavin S. Yancey about 7 yearsIt's important to note that this won't remove background colors and images, which actual printing will do.
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Volker E. over 6 yearsAlready back in 2011 this was proprietary, purchase-only software only on limited platforms, which you needed to pay for to get the requested functionality to debug the open web.
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zazvorniki over 6 yearsYou just saved me days of print.css debugging. You are awesome!