refactor: printToPDF should be headless

BUILD.gn

@@ -667,8 +667,6 @@ source_set("electron_lib") {
 
   if (enable_basic_printing) {
     sources += [
-      "shell/browser/printing/print_preview_message_handler.cc",
-      "shell/browser/printing/print_preview_message_handler.h",
       "shell/browser/printing/print_view_manager_electron.cc",
       "shell/browser/printing/print_view_manager_electron.h",
       "shell/renderer/printing/print_render_frame_helper_delegate.cc",

chromium_src/BUILD.gn

@@ -216,6 +216,8 @@ static_library("chrome") {
       "//chrome/browser/printing/printer_query.h",
       "//chrome/browser/printing/printing_service.cc",
       "//chrome/browser/printing/printing_service.h",
+      "//components/printing/browser/print_to_pdf/pdf_print_utils.cc",
+      "//components/printing/browser/print_to_pdf/pdf_print_utils.h",
     ]
 
     if (enable_oop_printing) {

docs/api/web-contents.md

@@ -1428,7 +1428,7 @@ Returns `Promise<PrinterInfo[]>` - Resolves with a [`PrinterInfo[]`](structures/
   * `header` string (optional) - string to be printed as page header.
   * `footer` string (optional) - string to be printed as page footer.
   * `pageSize` string | Size (optional) - Specify page size of the printed document. Can be `A3`,
-  `A4`, `A5`, `Legal`, `Letter`, `Tabloid` or an Object containing `height`.
+  `A4`, `A5`, `Legal`, `Letter`, `Tabloid` or an Object containing `height` and `width`.
 * `callback` Function (optional)
   * `success` boolean - Indicates success of the print call.
   * `failureReason` string - Error description called back if the print fails.
@@ -1459,43 +1459,28 @@ win.webContents.print(options, (success, errorType) => {
 #### `contents.printToPDF(options)`
 
 * `options` Object
-  * `headerFooter` Record<string, string> (optional) - the header and footer for the PDF.
-    * `title` string - The title for the PDF header.
-    * `url` string - the url for the PDF footer.
-  * `landscape` boolean (optional) - `true` for landscape, `false` for portrait.
-  * `marginsType` Integer (optional) - Specifies the type of margins to use. Uses 0 for
-    default margin, 1 for no margin, and 2 for minimum margin.
-  * `scaleFactor` number (optional) - The scale factor of the web page. Can range from 0 to 100.
-  * `pageRanges` Record<string, number> (optional) - The page range to print.
-    * `from` number - Index of the first page to print (0-based).
-    * `to` number - Index of the last page to print (inclusive) (0-based).
-  * `pageSize` string | Size (optional) - Specify page size of the generated PDF. Can be `A3`,
-  `A4`, `A5`, `Legal`, `Letter`, `Tabloid` or an Object containing `height` and `width` in microns.
-  * `printBackground` boolean (optional) - Whether to print CSS backgrounds.
-  * `printSelectionOnly` boolean (optional) - Whether to print selection only.
+  * `landscape` boolean (optional) - Paper orientation.`true` for landscape, `false` for portrait. Defaults to false.
+  * `displayHeaderFooter` boolean (optional) - Whether to display header and footer. Defaults to false.
+  * `printBackground` boolean (optional) - Whether to print background graphics. Defaults to false.
+  * `scale` number(optional)  - Scale of the webpage rendering. Defaults to 1.
+  * `pageSize` string | Size (optional) - Specify page size of the generated PDF. Can be `A0`, `A1`, `A2`, `A3`,
+  `A4`, `A5`, `A6`, `Legal`, `Letter`, `Tabloid`, `Ledger`, or an Object containing `height` and `width` in inches. Defaults to `Letter`.
+  * `margins` Object (optional)
+    * `top` number (optional) - Top margin in inches. Defaults to 1cm (~0.4 inches).
+    * `bottom` number (optional) - Bottom margin in inches. Defaults to 1cm (~0.4 inches).
+    * `left` number (optional) - Left margin in inches. Defaults to 1cm (~0.4 inches).
+    * `right` number (optional) - Right margin in inches. Defaults to 1cm (~0.4 inches).
+  * `pageRanges` string (optional) - Paper ranges to print, e.g., '1-5, 8, 11-13'. Defaults to the empty string, which means print all pages.
+  * `headerTemplate` string (optional) - HTML template for the print header. Should be valid HTML markup with following classes used to inject printing values into them: `date` (formatted print date), `title` (document title), `url` (document location), `pageNumber` (current page number) and `totalPages` (total pages in the document). For example, `<span class=title></span>` would generate span containing the title.
+  * `footerTemplate` string (optional) - HTML template for the print footer. Should use the same format as the `headerTemplate`.
+  * `preferCSSPageSize` boolean (optional) - Whether or not to prefer page size as defined by css. Defaults to false, in which case the content will be scaled to fit the paper size.
 
 Returns `Promise<Buffer>` - Resolves with the generated PDF data.
 
-Prints window's web page as PDF with Chromium's preview printing custom
-settings.
+Prints the window's web page as PDF.
 
 The `landscape` will be ignored if `@page` CSS at-rule is used in the web page.
 
-By default, an empty `options` will be regarded as:
-
-```javascript
-{
-  marginsType: 0,
-  printBackground: false,
-  printSelectionOnly: false,
-  landscape: false,
-  pageSize: 'A4',
-  scaleFactor: 100
-}
-```
-
-Use `page-break-before: always;` CSS style to force to print to a new page.
-
 An example of `webContents.printToPDF`:
 
 ```javascript
@@ -1504,7 +1489,7 @@ const fs = require('fs')
 const path = require('path')
 const os = require('os')
 
-const win = new BrowserWindow({ width: 800, height: 600 })
+const win = new BrowserWindow()
 win.loadURL('http://github.com')
 
 win.webContents.on('did-finish-load', () => {
@@ -1521,6 +1506,8 @@ win.webContents.on('did-finish-load', () => {
 })
 ```
 
+See [Page.printToPdf](https://chromedevtools.github.io/devtools-protocol/tot/Page/#method-printToPDF) for more information.
+
 #### `contents.addWorkSpace(path)`
 
 * `path` string

docs/api/webview-tag.md

@@ -565,21 +565,21 @@ Prints `webview`'s web page. Same as `webContents.print([options])`.
 ### `<webview>.printToPDF(options)`
 
 * `options` Object
-  * `headerFooter` Record<string, string> (optional) - the header and footer for the PDF.
-    * `title` string - The title for the PDF header.
-    * `url` string - the url for the PDF footer.
-  * `landscape` boolean (optional) - `true` for landscape, `false` for portrait.
-  * `marginsType` Integer (optional) - Specifies the type of margins to use. Uses 0 for
-    default margin, 1 for no margin, and 2 for minimum margin.
-    and `width` in microns.
-  * `scaleFactor` number (optional) - The scale factor of the web page. Can range from 0 to 100.
-  * `pageRanges` Record<string, number> (optional) - The page range to print. On macOS, only the first range is honored.
-    * `from` number - Index of the first page to print (0-based).
-    * `to` number - Index of the last page to print (inclusive) (0-based).
-  * `pageSize` string | Size (optional) - Specify page size of the generated PDF. Can be `A3`,
-  `A4`, `A5`, `Legal`, `Letter`, `Tabloid` or an Object containing `height`
-  * `printBackground` boolean (optional) - Whether to print CSS backgrounds.
-  * `printSelectionOnly` boolean (optional) - Whether to print selection only.
+  * `landscape` boolean (optional) - Paper orientation.`true` for landscape, `false` for portrait. Defaults to false.
+  * `displayHeaderFooter` boolean (optional) - Whether to display header and footer. Defaults to false.
+  * `printBackground` boolean (optional) - Whether to print background graphics. Defaults to false.
+  * `scale` number(optional)  - Scale of the webpage rendering. Defaults to 1.
+  * `pageSize` string | Size (optional) - Specify page size of the generated PDF. Can be `A0`, `A1`, `A2`, `A3`,
+  `A4`, `A5`, `A6`, `Legal`, `Letter`, `Tabloid`, `Ledger`, or an Object containing `height` and `width` in inches. Defaults to `Letter`.
+  * `margins` Object (optional)
+    * `top` number (optional) - Top margin in inches. Defaults to 1cm (~0.4 inches).
+    * `bottom` number (optional) - Bottom margin in inches. Defaults to 1cm (~0.4 inches).
+    * `left` number (optional) - Left margin in inches. Defaults to 1cm (~0.4 inches).
+    * `right` number (optional) - Right margin in inches. Defaults to 1cm (~0.4 inches).
+  * `pageRanges` string (optional) - Paper ranges to print, e.g., '1-5, 8, 11-13'. Defaults to the empty string, which means print all pages.
+  * `headerTemplate` string (optional) - HTML template for the print header. Should be valid HTML markup with following classes used to inject printing values into them: `date` (formatted print date), `title` (document title), `url` (document location), `pageNumber` (current page number) and `totalPages` (total pages in the document). For example, `<span class=title></span>` would generate span containing the title.
+  * `footerTemplate` string (optional) - HTML template for the print footer. Should use the same format as the `headerTemplate`.
+  * `preferCSSPageSize` boolean (optional) - Whether or not to prefer page size as defined by css. Defaults to false, in which case the content will be scaled to fit the paper size.
 
 Returns `Promise<Uint8Array>` - Resolves with the generated PDF data.
 

docs/breaking-changes.md

@@ -14,6 +14,61 @@ This document uses the following convention to categorize breaking changes:
 
 ## Planned Breaking API Changes (20.0)
 
+### API Changed: `webContents.printToPDF()`
+
+`webContents.printToPDF()` has been modified to conform to [`Page.printToPDF`](https://chromedevtools.github.io/devtools-protocol/tot/Page/#method-printToPDF) in the Chrome DevTools Protocol. This has been changes in order to
+address changes upstream that made our previous implementation untenable and rife with bugs.
+
+**Arguments Changed**
+
+* `pageRanges`
+
+**Arguments Removed**
+
+* `printSelectionOnly`
+* `marginsType`
+* `headerFooter`
+* `scaleFactor`
+
+**Arguments Added**
+
+* `headerTemplate`
+* `footerTemplate`
+* `displayHeaderFooter`
+* `margins`
+* `scale`
+* `preferCSSPageSize`
+
+```js
+// Main process
+const { webContents } = require('electron')
+
+webContents.printToPDF({
+  landscape: true,
+  displayHeaderFooter: true,
+  printBackground: true,
+  scale: 2,
+  pageSize: 'Ledger',
+  margins: {
+    top: 2,
+    bottom: 2,
+    left: 2,
+    right: 2
+  },
+  pageRanges: '1-5, 8, 11-13',
+  headerTemplate: '<h1>Title</h1>',
+  footerTemplate: '<div><span class="pageNumber"></span></div>',
+  preferCSSPageSize: true
+}).then(data => {
+  fs.writeFile(pdfPath, data, (error) => {
+    if (error) throw error
+    console.log(`Wrote PDF successfully to ${pdfPath}`)
+  })
+}).catch(error => {
+  console.log(`Failed to write PDF to ${pdfPath}: `, error)
+})
+```
+
 ### Default Changed: renderers without `nodeIntegration: true` are sandboxed by default
 
 Previously, renderers that specified a preload script defaulted to being