Consolidate the roll-printing sample with the regular sample

There is now a checkbox on the main UI to select roll printers or all
printers.  For roll printing, this sample now demonstrates how to check
if the printer is capable of roll printing, if the printer is capable of
trimming the paper after printing, and how the media length can be a
variable value.

api-samples/printing/README.md

@@ -8,6 +8,8 @@ The `chrome.printing` namespace only works on ChromeOS. The sample demonstrates
 
 Calling `submitJob()` triggers a dialog box asking the user to confirm printing. Use the [`PrintingAPIExtensionsAllowlist`](https://chromeenterprise.google/policies/#PrintingAPIExtensionsAllowlist") policy to bypass confirmation.
 
+If the `'Roll Printers` checkbox is selected, only printers capable of roll printing will appear in the table.  In this case, a separate test file is printed and the height of the media can be variable.
+
 ## Implementation Notes
 
 Before Chrome 120, `submitJob()` function throws an error when returning a promise.

api-samples/printing/printers.html

@@ -29,6 +29,8 @@ <h2>Print Job:</h2>
 
     <h2>Printers:</h2>
     <div id="printers">
+      <input type='checkbox' id='rollPrinters' name='rollPrinters'>
+      <label for='rollPrinters'>Roll Printers</label>
       <table id="printersTable">
         <thead>
           <tr>
@@ -41,9 +43,11 @@ <h2>Printers:</h2>
             <th>Default</th>
             <th>Recently used</th>
             <th>Capabilities</th>
+            <th>Supports trim</th>
             <th>Status</th>
           </tr>
         </thead>
+        <tbody id="tbody"/>
       </table>
     </div>
   </body>

api-samples/printing/printers.js

@@ -2,7 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-function onPrintButtonClicked(printerId, dpi) {
+let listOfPrinters = [];
+
+function rollPrintingEnabled() {
+  return document.getElementById('rollPrinters').checked;
+}
+
+function onPrintButtonClicked(printerId, dpi, performTrim) {
   let ticket = {
     version: '1.0',
     print: {
@@ -14,16 +20,34 @@ function onPrintButtonClicked(printerId, dpi) {
         horizontal_dpi: dpi.horizontal_dpi,
         vertical_dpi: dpi.vertical_dpi
       },
-      media_size: {
-        width_microns: 210000,
-        height_microns: 297000,
-        vendor_id: 'iso_a4_210x297mm'
-      },
       collate: { collate: false }
     }
   };
 
-  fetch('test.pdf')
+  if (rollPrintingEnabled()) {
+    filename = 'test-rollprinting.pdf';
+    ticket.print.media_size = {
+      width_microns: 72320,
+      // Note that this value needs to be between min_height_microns and
+      // max_height_microns.  Usually this matches the height of the document
+      // being printed.
+      height_microns: 110000
+    };
+    // This only makese sense to specify if the printer supports the trim
+    // option.
+    if (performTrim) {
+      ticket.print.vendor_ticket_item = [{id: 'finishings', value: 'trim'}];
+    }
+  } else {
+    filename = 'test.pdf';
+    ticket.print.media_size = {
+      width_microns: 210000,
+      height_microns: 297000,
+      vendor_id: 'iso_a4_210x297mm'
+    };
+  }
+
+  fetch(filename)
     .then((response) => response.arrayBuffer())
     .then((arrayBuffer) => {
       const request = {
@@ -73,48 +97,67 @@ function addCell(parent) {
   return newCell;
 }
 
+function supportsRollPrinting(printerInfo) {
+  // If any of the media size optionis support continuous feed, return true.
+  const newOptions = printerInfo.capabilities.printer.media_size.option.filter(
+      (option) => option.is_continuous_feed);
+  if (newOptions.length > 0) {
+    return true;
+  }
+  return false;
+}
+
 function createPrintersTable() {
-  chrome.printing.getPrinters().then((printers) => {
-    const tbody = document.createElement('tbody');
-    printers.forEach((printer) => {
-      chrome.printing.getPrinterInfo(printer.id).then((printerInfo) => {
-        const columnValues = [
-          printer.id,
-          printer.name,
-          printer.description,
-          printer.uri,
-          printer.source,
-          printer.isDefault,
-          printer.recentlyUsedRank,
-          JSON.stringify(printerInfo.capabilities),
-          printerInfo.status
-        ];
-
-        let tr = document.createElement('tr');
-        const printTd = document.createElement('td');
-        printTd.appendChild(
+  // Reset this so the table can be rebuilt with either all printers or just
+  // printers capable of roll printing.
+  let tbody = document.getElementById('tbody');
+  while (tbody.firstChild) {
+    tbody.removeChild(tbody.firstChild);
+  }
+
+  listOfPrinters.forEach((printer) => {
+    if (!rollPrintingEnabled() || supportsRollPrinting(printer.info)) {
+      // The printer needs to support this specific vendor capability if the
+      // print job ticket is going to specify the trim option.
+      const supportsTrim =
+            printer.info.capabilities.printer.vendor_capability.some(
+                (capability) => capability.display_name == "finishings/11");
+      const columnValues = [
+        printer.data.id,
+        printer.data.name,
+        printer.data.description,
+        printer.data.uri,
+        printer.data.source,
+        printer.data.isDefault,
+        printer.data.recentlyUsedRank,
+        JSON.stringify(printer.info.capabilities),
+        supportsTrim,
+        printer.info.status
+      ];
+
+      let tr = document.createElement('tr');
+      const printTd = document.createElement('td');
+      printTd.appendChild(
           createButton('Print', () => {
             onPrintButtonClicked(
-              printer.id,
-              printerInfo.capabilities.printer.dpi.option[0]
+                printer.data.id,
+                printer.info.capabilities.printer.dpi.option[0],
+                supportsTrim
             );
           })
-        );
+      );
 
-        tr.appendChild(printTd);
+      tr.appendChild(printTd);
 
-        for (const columnValue of columnValues) {
-          const td = document.createElement('td');
-          td.appendChild(document.createTextNode(columnValue));
-          td.setAttribute('align', 'center');
-          tr.appendChild(td);
-        }
+      for (const columnValue of columnValues) {
+        const td = document.createElement('td');
+        td.appendChild(document.createTextNode(columnValue));
+        td.setAttribute('align', 'center');
+        tr.appendChild(td);
+      }
 
-        tbody.appendChild(tr);
-      });
-    });
-    const table = document.getElementById('printersTable');
-    table.appendChild(tbody);
+      tbody.appendChild(tr);
+    }
   });
 
   chrome.printing.onJobStatusChanged.addListener((jobId, status) => {
@@ -149,5 +192,17 @@ function createPrintersTable() {
 }
 
 document.addEventListener('DOMContentLoaded', () => {
-  createPrintersTable();
+  chrome.printing.getPrinters().then((printers) => {
+    printers.forEach((printer) => {
+      chrome.printing.getPrinterInfo(printer.id).then((printerInfo) => {
+        listOfPrinters.push({data: printer, info: printerInfo});
+        createPrintersTable();
+      });
+    });
+  });
+
+  let checkbox = document.getElementById('rollPrinters')
+  checkbox.addEventListener('change', function() {
+    createPrintersTable();
+  });
 });