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 161 matching lines @@
                                         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<size_t>(

[bungeman-skia, 2016/05/23 18:12:38]

Both parameters are size_t now, so it shouldn't need to be specified here.

[hal.canary, 2016/05/28 17:05:54]

Done.

+            SK_ARRAY_COUNT(L"/Documents/1/Metadata/.png")
+            + static_cast<size_t>(std::numeric_limits<unsigned>::digits10 + 1),

[bungeman-skia, 2016/05/23 18:12:38]

It's rather annoying that this indentation kinda hides where the two parameters
are. Maybe it makes sense to create a file local

template <typename T> static constexpr size_t sk_digits_in(T) {
    return static_cast<size_t>(std::numeric_limits<T>::digits10 + 1);
}

so that each parameter fits on one line (and also indicates intent). This also
fixes the issue where in the new code 'unsigned' (a manual inlining of
'decltype(pageNum)') is being used instead of 'pageNum'. 

[hal.canary, 2016/05/28 17:05:54]

Done.

+            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")
+        + static_cast<size_t>(std::numeric_limits<unsigned>::digits10 + 1);
     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)