Add `BrowserWindow.printToPDF` API Implementation #1835

hokein · 2015-06-01T05:27:23Z

This PR implements a API allowing user to save the browser window page as PDF in local disk. The API provides Chromium Preview feature in Electron. Fixes #1157, #805.

Currently, the API definition:

WebContents.printToPDF(options, callback)

options Object
- marginsType Integer - Specify the type of margins to use
  - 0 - default
  - 1 - none
  - 2 - minimum
- printBackground Boolean - Whether to print CSS background.
- printSelectionOnly Boolean - Whether to print selection only.
- landscape Boolean - true for landscape, false for portrait.
callback Function - function(error, buffer) {}
- error Error
- buffer node:Buffer - Contains the pdf data

This PR also exposes print API to WebContents and WebView.

TODO

Implement on Windows
Implement on OS X
Implement on Linux

hokein · 2015-06-01T09:32:29Z

@zcbenz This PR is ready for review now.

YurySolovyov · 2015-06-03T12:02:58Z

I think it is better to use node-style callback convention like:

function(err, result) {
    // code
}

Where err is error object with error info or null

P.s. in this case there might be nothing reasonable to pass as result variable, but my point was about node's error-first callbacks convention.

zcbenz · 2015-06-08T07:52:49Z

We can make print and printToPDF methods of WebContents so it would be possible to print webview too.

zcbenz · 2015-06-08T08:03:44Z

chromium_src/chrome/browser/printing/print_preview_message_handler.cc

+  atom::NativeWindow* window = atom::NativeWindow::FromWebContents(
+      web_contents());
+  base::FilePath save_path;
+  if (!file_dialog::ShowSaveDialog(window, "Save As",


The filename should be passed as a parameter of printToPdf, users might want to do the printing silently.

zcbenz · 2015-06-08T08:50:09Z

It seems that the only difference between print and printToPdf is: printToPdf writes the PDF file to disk while print creates a new print job? So I think we can simply implement the printToPdf by hacking the PrintViewManagerBase::OnDidPrintPage function?

hokein · 2015-06-10T10:42:49Z

I have refined the API definition. Please take a look again.

It seems that the only difference between print and printToPdf is: printToPdf writes the PDF file to disk while print creates a new print job? So I think we can simply implement the printToPdf by hacking the PrintViewManagerBase::OnDidPrintPage function?

It's not easy to hack the PrintViewManagerBase::OnDidPrintPage function to achieve it. Another difference is the printing setting and its processing procedure. But I have simplifed the code.

YurySolovyov · 2015-06-10T10:47:41Z

@hokein still not using node-style callbacks?

hokein · 2015-06-10T12:12:56Z

@YuriSolovyov Done, thanks for the hint.

YurySolovyov · 2015-06-10T12:16:25Z

@hokein great! but docs seem to be out-of-sync though...

zcbenz · 2015-06-12T03:16:40Z

atom/browser/native_window.cc

@@ -28,6 +28,8 @@
 #include "brightray/browser/inspectable_web_contents.h"
 #include "brightray/browser/inspectable_web_contents_view.h"
 #include "chrome/browser/printing/print_view_manager_basic.h"
+#include "chrome/browser/printing/print_preview_message_handler.h"
+#include "chrome/browser/ui/browser_dialogs.h"


These headers are not needed.

anaisbetts · 2015-06-12T03:24:40Z

This is great work @hokein!

zcbenz · 2015-06-12T03:25:54Z

chromium_src/chrome/browser/printing/print_preview_message_handler.cc

+
+  unsigned char* data_begin = static_cast<unsigned char*>(shared_buf->memory());
+  std::vector<unsigned char> data(data_begin, data_begin + data_size);
+  return base::RefCountedBytes::TakeVector(&data);


The base::RefCountedBytes* has to be put in an scoped_refptr, otherwise the class itself will never be deleted. For this case I think we can return a scoped_ptr<char[]>, since the ownership of data is moved not shared.

Actually the data(PDF content) in RefCountedBytes is manipulated in node::Bufer using through node::Buffer::Use here.

Now I have simplified this code and logic byusing node::Buffer::New, which avoid generating the vector data by ourselves. see commit: hokein@149c00b

frankhale · 2015-06-12T03:34:18Z

Thank you @hokein for all your effort!!!

robhoefakker · 2015-06-15T23:47:05Z

Wow this API works really well! Thanks @hokein :)

zcbenz · 2015-06-16T08:22:23Z

chromium_src/chrome/browser/printing/print_preview_message_handler.cc

+  v8::Locker locker(isolate);
+  v8::HandleScope handle_scope(isolate);
+  if (data) {
+    v8::Local<v8::Value> buffer = node::Buffer::New(isolate,


Calling node::Buffer::New will copy all the data and cause hangs, I think that's why we switched to use node::Buffer::Use?

The pdf file content is returned through base::SharedMemory by renderer process. We cannot pass the memory-map raw data to node::Buffer directly.

You can copy the data in IO thread and then pass the copied data back to UI thread and call node::Buffer::Use.

Also expose in webview.

Also move the print implementation from window to webContents.

zcbenz · 2015-06-17T04:22:54Z

👍

Add `BrowserWindow.printToPDF` API Implementation

Godisemo · 2015-07-25T15:15:16Z

Would it be possible to specify the size of the resulting pdf? I am making an application for creating charts, and want a way to export the window's content to a pdf. Say if the window has dimensions 200x600 px would it be possible to create a pdf with dimensions 20x60 cm?

hokein · 2015-07-26T02:40:12Z

@Godisemo

Would it be possible to specify the size of the resulting pdf?

No. Current the API only generates PDF with A4 paper size. It's resonable to support more paper size(A3, Letter, Legal, Tabloid), which is also supported in Chromium Print Preview.

But I don't think allowing the API to generate PDF with arbitray paper size is a good idea since PDF is a print-oriented format with a fixed layout, and the printer page size is adopted to the ISO paper size standards, also Chromium Print Preview doesn't support neither.

hokein force-pushed the pdf-api branch from e89523e to c37092d Compare June 2, 2015 00:10

zcbenz reviewed Jun 8, 2015
View reviewed changes

hokein force-pushed the pdf-api branch 2 times, most recently from 3e27d90 to 961a5c3 Compare June 10, 2015 07:37

hokein force-pushed the pdf-api branch from 9f96690 to 40f6a7c Compare June 11, 2015 06:37

zcbenz reviewed Jun 12, 2015
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zcbenz mentioned this pull request Jun 12, 2015

Expose Print API to webContents and webView. #1935

Closed

hokein force-pushed the pdf-api branch from 79ba398 to 272444f Compare June 13, 2015 08:16

zcbenz reviewed Jun 16, 2015
View reviewed changes

hokein added 2 commits June 16, 2015 20:02

Add printToPDF API skeleton.

b360f7d

Add printToPDF Implementation.

7ffa704

hokein added 22 commits June 16, 2015 20:02

Add preview failed error.

cef177a

Fix a landscape option error.

6000779

📝 Add BrowserWindow.printToPDF API docs.

bf5d448

Fix OS X compilation error.

68005f9

Fix Linux compilation error.

36fa4da

Fix a type error in checking function options.

10da361

Cleanup.

2597ded

Move printToPDF API to WebContents.

c0a6cb6

Also expose in webview.

Move PDF printing setting in JS part.

6e099af

Add silent and savePath options.

ab40da3

Return node::Buffer as a printToPDF callback result.

ac62871

Fix a type error.

47439cd

Remove some unused IPC messages.

93243ef

Make callback aligns node.js style.

ccbe554

Fixing type: printBackgrounds => printBackground

559eb20

📝 Update docs.

f22662f

Don't use duprecated node buffer api, fix build error on OS X.

894f9c0

Simplify the pdf-data handled code.

93bbc6c

Fix code style.

57580e0

Expose Print API to webContents and webView.

47eac06

Also move the print implementation from window to webContents.

Also Expose printToPDF to BrowserWindow.

1eba552

Copy pdf data on IO thread to avoid causing main process hangs.

16348fc

hokein force-pushed the pdf-api branch from 4c8155c to 16348fc Compare June 16, 2015 12:11

📝 Add missing printToPDF API in webview.

82b1607

zcbenz added a commit that referenced this pull request Jun 17, 2015

Merge pull request #1835 from hokein/pdf-api

a751f4c

Add `BrowserWindow.printToPDF` API Implementation

zcbenz merged commit a751f4c into electron:master Jun 17, 2015

hokein mentioned this pull request Jul 26, 2015

Add 'pageSize' option in printToPDF API. #2338

Merged

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Add `BrowserWindow.printToPDF` API Implementation #1835

Add `BrowserWindow.printToPDF` API Implementation #1835

hokein commented Jun 1, 2015

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YurySolovyov commented Jun 3, 2015

zcbenz commented Jun 8, 2015

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hokein commented Jun 10, 2015

YurySolovyov commented Jun 10, 2015

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YurySolovyov commented Jun 10, 2015

zcbenz Jun 12, 2015

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anaisbetts commented Jun 12, 2015

zcbenz Jun 12, 2015

hokein Jun 13, 2015

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robhoefakker commented Jun 15, 2015

zcbenz Jun 16, 2015

hokein Jun 16, 2015

zcbenz Jun 16, 2015

hokein Jun 16, 2015

zcbenz commented Jun 17, 2015

Godisemo commented Jul 25, 2015

hokein commented Jul 26, 2015

Add BrowserWindow.printToPDF API Implementation #1835

Add BrowserWindow.printToPDF API Implementation #1835

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hokein commented Jun 1, 2015

TODO

hokein commented Jun 1, 2015

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zcbenz commented Jun 17, 2015

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hokein commented Jul 26, 2015

Add `BrowserWindow.printToPDF` API Implementation #1835

Add `BrowserWindow.printToPDF` API Implementation #1835