SkXPS: clean up SkConstexprMath

src/xps/SkXPSDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTypes.h"
 #if defined(SK_BUILD_FOR_WIN32)
 
 #ifndef UNICODE
 #define UNICODE
 #endif
 #ifndef _UNICODE
 #define _UNICODE
 #endif
 #include <ObjBase.h>
 #include <XpsObjectModel.h>
 #include <T2EmbApi.h>
 #include <FontSub.h>
+#include <limits>
 
 #include "SkColor.h"
-#include "SkConstexprMath.h"
 #include "SkData.h"
 #include "SkDraw.h"
 #include "SkEndian.h"
 #include "SkFindAndPlaceGlyph.h"
 #include "SkGeometry.h"
 #include "SkGlyphCache.h"
 #include "SkHRESULT.h"
 #include "SkImageEncoder.h"
 #include "SkIStream.h"
 #include "SkMaskFilter.h"
@@ skipping 149 matching lines @@
     this->fCurrentUnitsPerMeter = unitsPerMeter;
     this->fCurrentPixelsPerMeter = pixelsPerMeter;
 
     this->fCurrentXpsCanvas.reset();
     HRBM(this->fXpsFactory->CreateCanvas(&this->fCurrentXpsCanvas),
          "Could not create base canvas.");
 
     return true;
 }
 
+template <typename T> static constexpr size_t sk_digits_in() {
+    return static_cast<size_t>(std::numeric_limits<T>::digits10 + 1);
+}
+
 HRESULT SkXPSDevice::createXpsThumbnail(IXpsOMPage* page,
                                         const unsigned int pageNum,
                                         IXpsOMImageResource** image) {
     SkTScopedComPtr<IXpsOMThumbnailGenerator> thumbnailGenerator;
     HRM(CoCreateInstance(
             CLSID_XpsOMThumbnailGenerator,
             nullptr,
             CLSCTX_INPROC_SERVER,
             IID_PPV_ARGS(&thumbnailGenerator)),
         "Could not create thumbnail generator.");
 
     SkTScopedComPtr<IOpcPartUri> partUri;
-    static const size_t size = SkTUMax<
-        SK_ARRAY_COUNT(L"/Documents/1/Metadata/.png") + SK_DIGITS_IN(pageNum),
-        SK_ARRAY_COUNT(L"/Metadata/" L_GUID_ID L".png")
-    >::value;
+    constexpr size_t size = SkTMax(

[bungeman-skia, 2016/05/31 18:07:17]

I've gone back and forth now trying to figure out when to use 'static constexpr'
and when to use just 'constexpr' for function locals. In this case it shouldn't
make a (practical) difference, so we can leave it as is (it probably would make
a difference if we needed to take the address of 'size').

+            SK_ARRAY_COUNT(L"/Documents/1/Metadata/.png") + sk_digits_in<decltype(pageNum)>(),
+            SK_ARRAY_COUNT(L"/Metadata/" L_GUID_ID L".png"));
     wchar_t buffer[size];
     if (pageNum > 0) {
         swprintf_s(buffer, size, L"/Documents/1/Metadata/%u.png", pageNum);
     } else {
         wchar_t id[GUID_ID_LEN];
         HR(this->createId(id, GUID_ID_LEN));
         swprintf_s(buffer, size, L"/Metadata/%s.png", id);
     }
     HRM(this->fXpsFactory->CreatePartUri(buffer, &partUri),
         "Could not create thumbnail part uri.");
 
     HRM(thumbnailGenerator->GenerateThumbnail(page,
                                               XPS_IMAGE_TYPE_PNG,
                                               XPS_THUMBNAIL_SIZE_LARGE,
                                               partUri.get(),
                                               image),
         "Could not generate thumbnail.");
 
     return S_OK;
 }
 
 HRESULT SkXPSDevice::createXpsPage(const XPS_SIZE& pageSize,
                                    IXpsOMPage** page) {
-    static const size_t size = SK_ARRAY_COUNT(L"/Documents/1/Pages/.fpage")
-                             + SK_DIGITS_IN(fCurrentPage);
+    constexpr size_t size =
+        SK_ARRAY_COUNT(L"/Documents/1/Pages/.fpage")
+        + sk_digits_in<decltype(fCurrentPage)>();
     wchar_t buffer[size];
     swprintf_s(buffer, size, L"/Documents/1/Pages/%u.fpage",
                              this->fCurrentPage);
     SkTScopedComPtr<IOpcPartUri> partUri;
     HRM(this->fXpsFactory->CreatePartUri(buffer, &partUri),
         "Could not create page part uri.");
 
     //If the language is unknown, use "und" (XPS Spec 2.3.5.1).
     HRM(this->fXpsFactory->CreatePage(&pageSize,
                                       L"und",
@@ skipping 2027 matching lines @@
         //SkXPSDevice* dev = new SkXPSDevice(this);
         //SkSize s = SkSize::Make(width, height);
         //dev->BeginCanvas(s, s, SkMatrix::I());
         //return dev;
     }
 #endif
     return new SkXPSDevice(this->fXpsFactory.get());
 }
 
 #endif//defined(SK_BUILD_FOR_WIN32)