Bug 1651117 part 1: Add nsIPrinter supportsColor attribute and Windows implementation. r=jwatt

Differential Revision: https://phabricator.services.mozilla.com/D85032

layout/base/tests/chrome/test_get_printer_basic_attributes.html

@@ -17,6 +17,7 @@ function run() {
     printerList.printers.forEach(printer => {
       info(`Listing basic attributes for ${printer.name}:`);
       info(`* supportsDuplex: ${printer.supportsDuplex}`);
+      info(`* supportsColor: ${printer.supportsColor}`);
     })
 
     ok(true, "Retrieved printer basic attributes successfully.");

widget/nsIPrinter.idl

@@ -23,4 +23,9 @@ interface nsIPrinter : nsISupports
    * Whether this printer supports duplex printing.
    */
   readonly attribute boolean supportsDuplex;
+
+  /**
+   * Whether this printer supports color printing.
+   */
+  readonly attribute boolean supportsColor;
 };

widget/nsPrinter.cpp

@@ -32,3 +32,11 @@ nsPrinter::GetSupportsDuplex(bool* aSupportsDuplex) {
   *aSupportsDuplex = mSupportsDuplex;
   return NS_OK;
 }
+
+NS_IMETHODIMP
+nsPrinter::GetSupportsColor(bool* aSupportsColor) {
+  MOZ_ASSERT(aSupportsColor);
+  // Dummy implementation waiting platform specific one.
+  *aSupportsColor = false;
+  return NS_OK;
+}

widget/nsPrinterCUPS.cpp

@@ -48,6 +48,14 @@ nsPrinterCUPS::GetSupportsDuplex(bool* aSupportsDuplex) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsPrinterCUPS::GetSupportsColor(bool* aSupportsColor) {
+  MOZ_ASSERT(aSupportsColor);
+  // Dummy implementation waiting platform specific one.
+  *aSupportsColor = false;
+  return NS_OK;
+}
+
 bool nsPrinterCUPS::Supports(const char* option, const char* value) const {
   MOZ_ASSERT(mPrinterInfo);
   return mShim.mCupsCheckDestSupported(CUPS_HTTP_DEFAULT, mPrinter,

widget/windows/nsPrinterWin.cpp

@@ -134,3 +134,18 @@ nsPrinterWin::GetSupportsDuplex(bool* aSupportsDuplex) {
   *aSupportsDuplex = mSupportsDuplex.value();
   return NS_OK;
 }
+
+NS_IMETHODIMP
+nsPrinterWin::GetSupportsColor(bool* aSupportsColor) {
+  MOZ_ASSERT(aSupportsColor);
+
+  if (mSupportsColor.isNothing()) {
+    // Note: this is a blocking call, which could be slow.
+    mSupportsColor =
+        Some(::DeviceCapabilitiesW(mName.get(), nullptr, DC_COLORDEVICE,
+                                   nullptr, nullptr) == 1);
+  }
+
+  *aSupportsColor = mSupportsColor.value();
+  return NS_OK;
+}

widget/windows/nsPrinterWin.h

@@ -28,6 +28,7 @@ class nsPrinterWin final : public nsIPrinter {
   nsString mName;
   nsTArray<RefPtr<nsIPaper>> mPaperList;
   Maybe<bool> mSupportsDuplex;
+  Maybe<bool> mSupportsColor;
 };
 
 #endif  // nsPrinterWin_h_