Bug 1667486 part 2 - Use our own localization for nsPrinterCUPS paper sizes when possible r=emilio

This should be able to avoid creating a printer-specific HTTP connection in
nsPrinterCUPS::DefaultSettings when the paper size is a PWG-recognized size.

The current maximum error when comparing paper sizes is 4 points. This may need
to be revised later.

Differential Revision: https://phabricator.services.mozilla.com/D91497

widget/nsPrinterBase.cpp

@@ -15,6 +15,14 @@ using namespace mozilla;
 using mozilla::dom::Promise;
 using mozilla::gfx::MarginDouble;
 
+// The maximum error when considering a paper size equal, in points.
+// There is some variance in the actual sizes returned by printer drivers and
+// print servers for paper sizes. This is a best-guess based on initial
+// telemetry which should catch most near-miss dimensions. This should let us
+// get consistent paper size names even when the size isn't quite exactly the
+// correct size.
+static constexpr double kPaperSizePointsEpsilon = 4.0;
+
 void nsPrinterBase::CachePrintSettingsInitializer(
     const PrintSettingsInitializer& aInitializer) {
   if (mPrintSettingsInitializer.isNothing()) {
@@ -166,5 +174,20 @@ NS_INTERFACE_MAP_END
 NS_IMPL_CYCLE_COLLECTING_ADDREF(nsPrinterBase)
 NS_IMPL_CYCLE_COLLECTING_RELEASE(nsPrinterBase)
 
-nsPrinterBase::nsPrinterBase() = default;
+nsPrinterBase::nsPrinterBase(const CommonPaperInfoArray* aPaperInfoArray)
+    : mCommonPaperInfo(aPaperInfoArray) {
+  MOZ_DIAGNOSTIC_ASSERT(aPaperInfoArray, "Localized paper info was null");
+}
 nsPrinterBase::~nsPrinterBase() = default;
+
+const PaperInfo* nsPrinterBase::FindCommonPaperSize(
+    const gfx::SizeDouble& aSize) const {
+  for (const PaperInfo& paper : *mCommonPaperInfo) {
+    if (std::abs(paper.mSize.width - aSize.width) <= kPaperSizePointsEpsilon &&
+        std::abs(paper.mSize.height - aSize.height) <=
+            kPaperSizePointsEpsilon) {
+      return &paper;
+    }
+  }
+  return nullptr;
+}

widget/nsPrinterBase.h

@@ -41,6 +41,9 @@ class nsPrinterBase : public nsIPrinter {
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_CLASS(nsPrinterBase)
 
+  // We require the paper info array
+  nsPrinterBase() = delete;
+
   // No copy or move, we're an identity.
   nsPrinterBase(const nsPrinterBase&) = delete;
   nsPrinterBase(nsPrinterBase&&) = delete;
@@ -84,7 +87,7 @@ class nsPrinterBase : public nsIPrinter {
   Maybe<PrintSettingsInitializer> mPrintSettingsInitializer;
 
  protected:
-  nsPrinterBase();
+  nsPrinterBase(const mozilla::CommonPaperInfoArray* aPaperInfoArray);
   virtual ~nsPrinterBase();
 
   // Implementation-specific methods. These must not make assumptions about
@@ -96,11 +99,17 @@ class nsPrinterBase : public nsIPrinter {
   virtual bool SupportsCollation() const = 0;
   virtual nsTArray<mozilla::PaperInfo> PaperList() const = 0;
   virtual MarginDouble GetMarginsForPaper(nsString aPaperId) const = 0;
+  // Searches our built-in list of commonly used PWG paper sizes for a matching,
+  // localized PaperInfo. Returns null if there is no matching size.
+  const mozilla::PaperInfo* FindCommonPaperSize(
+      const mozilla::gfx::SizeDouble& aSize) const;
 
  private:
   mozilla::EnumeratedArray<AsyncAttribute, AsyncAttribute::Last,
                            RefPtr<Promise>>
       mAsyncAttributePromises;
+  // List of built-in, commonly used paper sizes.
+  const RefPtr<const mozilla::CommonPaperInfoArray> mCommonPaperInfo;
 };
 
 #endif

widget/nsPrinterCUPS.cpp

@@ -18,13 +18,14 @@ using namespace mozilla;
 static constexpr Array<const char* const, 1> requestedAttributes{
     "cups-version"};
 
-static PaperInfo MakePaperInfo(const char* aName, const cups_size_t& aMedia) {
-  const double kPointsPerHundredthMillimeter = 72.0 / 2540.0;
-  // XXX Do we actually have the guarantee that these are utf-8?
+static constexpr double kPointsPerHundredthMillimeter = 72.0 / 2540.0;
+
+static PaperInfo MakePaperInfo(const nsAString& aName,
+                               const cups_size_t& aMedia) {
+  // XXX Do we actually have the guarantee that this is utf-8?
   NS_ConvertUTF8toUTF16 paperId(aMedia.media);  // internal paper name/ID
-  NS_ConvertUTF8toUTF16 paperName(aName);       // localized human-friendly name
   return PaperInfo(
-      paperId, paperName,
+      paperId, aName,
       {aMedia.width * kPointsPerHundredthMillimeter,
        aMedia.length * kPointsPerHundredthMillimeter},
       Some(gfx::MarginDouble{aMedia.top * kPointsPerHundredthMillimeter,
@@ -123,7 +124,18 @@ PrintSettingsInitializer nsPrinterCUPS::DefaultSettings() const {
     };
   }
 
-  const char* localizedName = nullptr;
+  // Check if this is a localized fallback paper size, in which case we can
+  // avoid using the CUPS localization methods.
+  const gfx::SizeDouble sizeDouble{
+      media.width * kPointsPerHundredthMillimeter,
+      media.length * kPointsPerHundredthMillimeter};
+  if (const PaperInfo* const paperInfo = FindCommonPaperSize(sizeDouble)) {
+    return PrintSettingsInitializer{
+        std::move(printerName),
+        MakePaperInfo(paperInfo->mName, media),
+        SupportsColor(),
+    };
+  }
 
   // blocking call
   http_t* connection = mShim.cupsConnectDest(mPrinter, CUPS_DEST_FLAGS_NONE,
@@ -134,8 +146,11 @@ PrintSettingsInitializer nsPrinterCUPS::DefaultSettings() const {
                                              /* callback */ nullptr,
                                              /* user_data */ nullptr);
 
+  // XXX Do we actually have the guarantee that this is utf-8?
+  NS_ConvertUTF8toUTF16 localizedName{
+      connection ? LocalizeMediaName(*connection, media) : ""};
+
   if (connection) {
-    localizedName = LocalizeMediaName(*connection, media);
     mShim.httpClose(connection);
   }
 
@@ -281,18 +296,28 @@ nsTArray<PaperInfo> nsPrinterCUPS::PaperList() const {
   nsTArray<PaperInfo> paperList;
   nsTHashtable<nsCharPtrHashKey> paperSet(std::max(paperCount, 0));
 
+  paperList.SetCapacity(paperCount);
   for (int i = 0; i < paperCount; ++i) {
     cups_size_t media;
-    int getInfoSucceeded = mShim.cupsGetDestMediaByIndex(
+    const int getInfoSucceeded = mShim.cupsGetDestMediaByIndex(
         connection, mPrinter, printerInfo, i, CUPS_MEDIA_FLAGS_DEFAULT, &media);
 
     if (!getInfoSucceeded || !paperSet.EnsureInserted(media.media)) {
       continue;
     }
-
-    const char* mediaName =
-        connection ? LocalizeMediaName(*connection, media) : media.media;
-    paperList.AppendElement(MakePaperInfo(mediaName, media));
+    // Check if this is a PWG paper size, in which case we can avoid using the
+    // CUPS localization methods.
+    const gfx::SizeDouble sizeDouble{
+        media.width * kPointsPerHundredthMillimeter,
+        media.length * kPointsPerHundredthMillimeter};
+    if (const PaperInfo* const paperInfo = FindCommonPaperSize(sizeDouble)) {
+      paperList.AppendElement(MakePaperInfo(paperInfo->mName, media));
+    } else {
+      const char* const mediaName =
+          connection ? LocalizeMediaName(*connection, media) : media.media;
+      paperList.AppendElement(
+          MakePaperInfo(NS_ConvertUTF8toUTF16(mediaName), media));
+    }
   }
 
   if (connection) {

widget/nsPrinterCUPS.h

@@ -36,9 +36,11 @@ class nsPrinterCUPS final : public nsPrinterBase {
 
   nsPrinterCUPS() = delete;
 
-  nsPrinterCUPS(const nsCUPSShim& aShim, nsString aDisplayName,
+  nsPrinterCUPS(const mozilla::CommonPaperInfoArray* aArray,
+                const nsCUPSShim& aShim, nsString aDisplayName,
                 cups_dest_t* aPrinter)
-      : mShim(aShim),
+      : nsPrinterBase(aArray),
+        mShim(aShim),
         mDisplayName(std::move(aDisplayName)),
         mPrinter(aPrinter),
         mPrinterInfoMutex("nsPrinterCUPS::mPrinterInfoMutex") {}

widget/nsPrinterListBase.cpp

@@ -53,6 +53,7 @@ void ResolveOrReject(dom::Promise& aPromise, nsPrinterListBase& aList,
 
 NS_IMETHODIMP nsPrinterListBase::GetPrinters(JSContext* aCx,
                                              Promise** aResult) {
+  EnsureCommonPaperInfo(aCx);
   return mozilla::AsyncPromiseAttributeGetter(*this, mPrintersPromise, aCx,
                                               aResult, "Printers"_ns,
                                               &nsPrinterListBase::Printers);
@@ -61,6 +62,7 @@ NS_IMETHODIMP nsPrinterListBase::GetPrinters(JSContext* aCx,
 NS_IMETHODIMP nsPrinterListBase::GetPrinterByName(const nsAString& aPrinterName,
                                                   JSContext* aCx,
                                                   Promise** aResult) {
+  EnsureCommonPaperInfo(aCx);
   return PrintBackgroundTaskPromise(*this, aCx, aResult, "PrinterByName"_ns,
                                     &nsPrinterListBase::PrinterByName,
                                     nsString{aPrinterName});
@@ -68,6 +70,7 @@ NS_IMETHODIMP nsPrinterListBase::GetPrinterByName(const nsAString& aPrinterName,
 
 NS_IMETHODIMP nsPrinterListBase::GetPrinterBySystemName(
     const nsAString& aPrinterName, JSContext* aCx, Promise** aResult) {
+  EnsureCommonPaperInfo(aCx);
   return PrintBackgroundTaskPromise(
       *this, aCx, aResult, "PrinterBySystemName"_ns,
       &nsPrinterListBase::PrinterBySystemName, nsString{aPrinterName});
@@ -75,6 +78,7 @@ NS_IMETHODIMP nsPrinterListBase::GetPrinterBySystemName(
 
 NS_IMETHODIMP nsPrinterListBase::GetNamedOrDefaultPrinter(
     const nsAString& aPrinterName, JSContext* aCx, Promise** aResult) {
+  EnsureCommonPaperInfo(aCx);
   return PrintBackgroundTaskPromise(
       *this, aCx, aResult, "NamedOrDefaultPrinter"_ns,
       &nsPrinterListBase::NamedOrDefaultPrinter, nsString{aPrinterName});

widget/nsPrinterListCUPS.cpp

@@ -108,7 +108,7 @@ nsTArray<PrinterInfo> nsPrinterListCUPS::Printers() const {
 
 RefPtr<nsIPrinter> nsPrinterListCUPS::CreatePrinter(PrinterInfo aInfo) const {
   return mozilla::MakeRefPtr<nsPrinterCUPS>(
-      sCupsShim, std::move(aInfo.mName),
+      mCommonPaperInfo, sCupsShim, std::move(aInfo.mName),
       static_cast<cups_dest_t*>(aInfo.mCupsHandle));
 }
 

widget/windows/nsDeviceContextSpecWin.cpp

@@ -586,7 +586,7 @@ Maybe<nsPrinterListBase::PrinterInfo> nsPrinterListWin::PrinterBySystemName(
 }
 
 RefPtr<nsIPrinter> nsPrinterListWin::CreatePrinter(PrinterInfo aInfo) const {
-  return nsPrinterWin::Create(std::move(aInfo.mName));
+  return nsPrinterWin::Create(mCommonPaperInfo, std::move(aInfo.mName));
 }
 
 nsresult nsPrinterListWin::SystemDefaultPrinterName(nsAString& aName) const {

widget/windows/nsPrinterWin.cpp

@@ -22,13 +22,16 @@ using namespace mozilla::widget;
 static const double kPointsPerTenthMM = 72.0 / 254.0;
 static const double kPointsPerInch = 72.0;
 
-nsPrinterWin::nsPrinterWin(const nsAString& aName)
-    : mName(aName),
+nsPrinterWin::nsPrinterWin(const CommonPaperInfoArray* aArray,
+                           const nsAString& aName)
+    : nsPrinterBase(aArray),
+      mName(aName),
       mDefaultDevmodeWStorage("nsPrinterWin::mDefaultDevmodeWStorage") {}
 
 // static
-already_AddRefed<nsPrinterWin> nsPrinterWin::Create(const nsAString& aName) {
-  return do_AddRef(new nsPrinterWin(aName));
+already_AddRefed<nsPrinterWin> nsPrinterWin::Create(
+    const CommonPaperInfoArray* aArray, const nsAString& aName) {
+  return do_AddRef(new nsPrinterWin(aArray, aName));
 }
 
 nsTArray<uint8_t> nsPrinterWin::CopyDefaultDevmodeW() const {

widget/windows/nsPrinterWin.h

@@ -23,10 +23,13 @@ class nsPrinterWin final : public nsPrinterBase {
   MarginDouble GetMarginsForPaper(nsString aPaperId) const final;
 
   nsPrinterWin() = delete;
-  static already_AddRefed<nsPrinterWin> Create(const nsAString& aName);
+  static already_AddRefed<nsPrinterWin> Create(
+      const mozilla::CommonPaperInfoArray* aPaperInfoArray,
+      const nsAString& aName);
 
  private:
-  explicit nsPrinterWin(const nsAString& aName);
+  nsPrinterWin(const mozilla::CommonPaperInfoArray* aPaperInfoArray,
+               const nsAString& aName);
   ~nsPrinterWin() = default;
 
   nsTArray<uint8_t> CopyDefaultDevmodeW() const;