Eliminate PS printing edge cases

printing/print_settings_initializer_win.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "printing/print_settings_initializer_win.h"
 
 #include <windows.h>
 
 #include "printing/print_settings.h"
 
 namespace printing {
 
 namespace {
 
 bool HasEscapeSupprt(HDC hdc, DWORD escape) {

[Lei Zhang, 2017/02/25 09:09:35]

Looks like we didn't have the $250 and couldn't buy a vowel here.

[rbpotter, 2017/02/27 16:40:50]

Done.

   const char* ptr = reinterpret_cast<const char*>(&escape);
   return ExtEscape(hdc, QUERYESCSUPPORT, sizeof(escape), ptr, 0, nullptr) > 0;
 }
 
 bool IsTechnology(HDC hdc, const char* technology) {
   if (::GetDeviceCaps(hdc, TECHNOLOGY) != DT_RASPRINTER)
     return false;
 
-  // If postscript, try to query Postscript Identify and then set to
-  // postscript mode before calling any more ExtEscape functions. Otherwise,
-  // PSLEVEL query will not work.
-  if (strcmp(technology, "PostScript") == 0 &&
-      HasEscapeSupprt(hdc, POSTSCRIPT_IDENTIFY)) {
-    DWORD mode = PSIDENT_PSCENTRIC;
-    const char* ptr = reinterpret_cast<const char*>(&mode);
-    ExtEscape(hdc, POSTSCRIPT_IDENTIFY, sizeof(DWORD), ptr, 0, nullptr);
-    return true;
-  }
-
   if (!HasEscapeSupprt(hdc, GETTECHNOLOGY))
     return false;
 
   char buf[256];
   memset(buf, 0, sizeof(buf));
   if (ExtEscape(hdc, GETTECHNOLOGY, 0, nullptr, sizeof(buf) - 1, buf) <= 0)
     return false;
   return strcmp(buf, technology) == 0;
 }
 
+bool SetPrinterToGdiMode(HDC hdc) {
+  // Try to set to GDI centric mode
+  DWORD mode = PSIDENT_GDICENTRIC;
+  const char* ptr = reinterpret_cast<const char*>(&mode);
+  int ret = ExtEscape(hdc, POSTSCRIPT_IDENTIFY, sizeof(DWORD), ptr, 0, nullptr);
+  return ret > 0;
+}
+
+int GetPrinterPostScriptLevel(HDC hdc) {
+  constexpr int param = FEATURESETTING_PSLEVEL;
+  const char* param_char_ptr = reinterpret_cast<const char*>(&param);
+  int param_out = 0;
+  char* param_out_char_ptr = reinterpret_cast<char*>(&param_out);
+  if (ExtEscape(hdc, GET_PS_FEATURESETTING, sizeof(param), param_char_ptr,
+                sizeof(param_out), param_out_char_ptr) > 0) {
+    return param_out;
+  }
+  return -1;

[Lei Zhang, 2017/02/25 09:09:35]

0 here as well?

[rbpotter, 2017/02/27 16:40:50]

Done.

+}
+
 bool IsPrinterPostScript(HDC hdc, int* level) {
   static constexpr char kPostScriptDriver[] = "PostScript";
-  if (!IsTechnology(hdc, kPostScriptDriver)) {
+  // Try to set to Gdi mode so that language level detection works (not

[Lei Zhang, 2017/02/25 09:09:35]

s/Gdi/GDI/

[rbpotter, 2017/02/27 16:40:50]

Done.

+  // supported in compatability mode). Use GDI mode instead of PS mode so that
+  // if level detection fails we can fall back to normal printing.
+  // Note: This has to occur before other escape functions are called. Also, if
+  // the printer supports POSTSCRIPT_IDENTIFY, we know it has a postscript
+  // driver.
+  if (HasEscapeSupprt(hdc, POSTSCRIPT_IDENTIFY)) {
+    SetPrinterToGdiMode(hdc);

[Lei Zhang, 2017/02/25 09:09:35]

This patch set no longer checks the return value. Does that mean its return type
can be void?

[rbpotter, 2017/02/27 16:40:50]

Yes- don't need to check since GDI mode doesn't cause problems for normal
printing. Done.

+  } else if (!IsTechnology(hdc, kPostScriptDriver)) {
+    // Doesn't support POSTSCRIPT_IDENTIFY and doesn't look like PostScript.
+    return false;
+  } else if (!HasEscapeSupprt(hdc, POSTSCRIPT_PASSTHROUGH) ||
+             !HasEscapeSupprt(hdc, POSTSCRIPT_DATA)) {
+    // Can't change to GDI mode and doesn't have compatibility mode functions
     return false;
   }
 
-  // Query the PS Level if possible.
-  if (HasEscapeSupprt(hdc, GET_PS_FEATURESETTING)) {
-    constexpr int param = FEATURESETTING_PSLEVEL;
-    const char* param_char_ptr = reinterpret_cast<const char*>(&param);
-    int param_out = -1;
-    char* param_out_char_ptr = reinterpret_cast<char*>(&param_out);
-    if (ExtEscape(hdc, GET_PS_FEATURESETTING, sizeof(param), param_char_ptr,
-                  sizeof(param_out), param_out_char_ptr) > 0) {
-      if (param_out < 2 || param_out > 3)
-        return false;
-
-      *level = param_out;
-      return true;
-    }
-  }
-
-  // If it looks like a PS printer.
-  if (HasEscapeSupprt(hdc, POSTSCRIPT_PASSTHROUGH) &&
-      HasEscapeSupprt(hdc, POSTSCRIPT_DATA)) {
+  if (!HasEscapeSupprt(hdc, GET_PS_FEATURESETTING)) {

[Lei Zhang, 2017/02/25 09:09:35]

If a printer does not support POSTSCRIPT_IDENTIFY, we can still reach here by
passing the two else-if checks. However, in that case we are still in
compatibility mode and this block will always execute. Can we structure the
logic as follows?

if (!HasEscapeSupport(hdc, POSTSCRIPT_IDENTIFY)) {
  if (!IsTechnology(hdc, kPostScriptDriver))
    return false;
  if (!HasEscapeSupport(hdc, POSTSCRIPT_PASSTHROUGH) ||
      !HasEscapeSupport(hdc, POSTSCRIPT_DATA)) {
    return false;
  }
  *level = 2;
  return true;
}

SetPrinterToGdiMode(hdc);
if (!HasEscapeSupport(hdc, GET_PS_FEATURESETTING)) {
  *level = 2;
  return true;
}

*level = GetPrinterPostScriptLevel(hdc);
return *level == 2 || *level == 3;

[rbpotter, 2017/02/27 16:40:50]

Done.

+    // Can't query the level, use level 2 to be safe
     *level = 2;
     return true;
   }
-
-  return false;
+  *level = GetPrinterPostScriptLevel(hdc);
+  if (*level < 2 || *level > 3) {
+    // Invalid or insufficient postscript language level.
+    return false;
+  }
+  return true;
 }
 
 bool IsPrinterXPS(HDC hdc) {
   static constexpr char kXPSDriver[] =
       "http://schemas.microsoft.com/xps/2005/06";
   return IsTechnology(hdc, kXPSDriver);
 }
 
 }  // namespace
 
@@ skipping 57 matching lines @@
     return;
   }
   if (IsPrinterXPS(hdc)) {
     print_settings->set_printer_type(PrintSettings::PrinterType::TYPE_XPS);
     return;
   }
   print_settings->set_printer_type(PrintSettings::PrinterType::TYPE_NONE);
 }
 
 }  // namespace printing