1257791 - Printing to PDF using Cairo on Windows fails with blank page.

Status: VERIFIED FIXED

(Core :: Printing: Output, defect)

Description

[Bob Owen (:bobowen)]

I broke this when I refactored the DPI and printing scale setting into the nsDeviceContextSpec.

I'd incorrectly thought that an nsDeviceContextSpecWin meant a surface type of gfxSurfaceType::Win32 or gfxSurfaceType::Win32Printing, but it can be gfxSurfaceType::PDF as well.

This PDF functionality on Windows is not actually used by Firefox itself as far as I know, but it is used by at least one addon - Print Edit.

Comment 1

[Bob Owen (:bobowen)]

I've not triggered too many jobs here as the Windows test queue is huge and I think very few tests actually hit this code.
https://treeherder.mozilla.org/#/jobs?repo=try&revision=f06cb5ca36da

Comment 2

[Bob Owen (:bobowen)]

Attachment: Return correct DPI and printing scale from nsDeviceContextSpecWin when printing to PDF

I also noticed that printerName is being leaked in nsDeviceContextSpecWin::Init, but I filed bug 1257841 for that as I'm going to want to uplift this to Beta.

Comment 3

[Jim Mathies [:jimm]]

Comment on attachment 8732152 [details] [diff] [review]
Return correct DPI and printing scale from nsDeviceContextSpecWin when printing to PDF

Review of attachment 8732152 [details] [diff] [review]:
-----------------------------------------------------------------

::: widget/windows/nsDeviceContextSpecWin.cpp
@@ +275,5 @@
>  
>  float
> +nsDeviceContextSpecWin::GetDPI()
> +{
> +  return mOutputFormat == nsIPrintSettings::kOutputFormatPDF ? 72.0f : 144.0f;

comment me please

@@ +284,5 @@
>  {
>    MOZ_ASSERT(mPrintSettings);
>  
> +  if (mOutputFormat == nsIPrintSettings::kOutputFormatPDF) {
> +    return 1.0f;

ditto

Comment 4

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/7a5de08942ca

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/7a5de08942ca

Comment 6

[Bob Owen (:bobowen)]

Comment on attachment 8732152 [details] [diff] [review]
Return correct DPI and printing scale from nsDeviceContextSpecWin when printing to PDF

Approval Request Comment
[Feature/regressing bug #]:
Bug 1156742.

[User impact if declined]:
Addons (in particular Print Edit) that use the print to PDF functionality on Windows won't work.

[Describe test coverage new/current, TreeHerder]:
There is no automated testing for printing, but this has been tested manually with the Print Edit addon.

[Risks and why]: 
Low - simple change that restores the previous settings for printing to PDF of Windows.

[String/UUID change made/needed]:
Non

Comment 7

[Sylvestre Ledru [:Sylvestre]]

Comment on attachment 8732152 [details] [diff] [review]
Return correct DPI and printing scale from nsDeviceContextSpecWin when printing to PDF

Potentially important issue, taking it.
Should be in 46 beta 5

Comment 8

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/releases/mozilla-aurora/rev/15f0abad8bec

Comment 9

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/releases/mozilla-beta/rev/7bd218c7e831

Comment 10

[Cornel Ionce [:noni] [Hubs QA]]

Verified as fixed on Windows 10x64 using the Print Edit add-on on the following branches:
* Latest 48.0a1 Nightly, build ID 20160413030239,
* Latest 47.0a2 Aurora, build ID 20160413004016,
* Firefox 46.0b10, build ID 20160411042519.