Fix threading issue in DirectWrite port initialization.

src/ports/SkFontHost_win_dw.cpp

Index: src/ports/SkFontHost_win_dw.cpp
===================================================================
--- src/ports/SkFontHost_win_dw.cpp	(revision 12568)
+++ src/ports/SkFontHost_win_dw.cpp	(working copy)
@@ -21,6 +21,7 @@
 #include "SkGlyph.h"
 #include "SkHRESULT.h"
 #include "SkMaskGamma.h"
+#include "SkOnce.h"
 #include "SkOTTable_head.h"
 #include "SkOTTable_hhea.h"
 #include "SkOTTable_OS_2.h"
@@ -44,6 +45,7 @@
 /** Prefer to use this type to prevent template proliferation. */
 typedef SkAutoSTMalloc<16, WCHAR> SkSMallocWCHAR;
 
+/** Converts a utf8 string to a WCHAR string. */
 static HRESULT cstring_to_wchar(const char* skname, SkSMallocWCHAR* name) {
     int wlen = MultiByteToWideChar(CP_UTF8, 0, skname, -1, NULL, 0);
     if (0 == wlen) {
@@ -58,6 +60,7 @@
     return S_OK;
 }
 
+/** Converts a WCHAR string to a utf8 string. */
 static HRESULT wchar_to_skstring(WCHAR* name, SkString* skname) {
     int len = WideCharToMultiByte(CP_UTF8, 0, name, -1, NULL, 0, NULL, NULL);
     if (0 == len) {
@@ -74,6 +77,37 @@
 
 ///////////////////////////////////////////////////////////////////////////////
 
+static void create_dwrite_factory(IDWriteFactory** factory) {
+    typedef decltype(DWriteCreateFactory)* DWriteCreateFactoryProc;
+    DWriteCreateFactoryProc dWriteCreateFactoryProc =
+        reinterpret_cast<DWriteCreateFactoryProc>(
+            GetProcAddress(LoadLibraryW(L"dwrite.dll"), "DWriteCreateFactory")
+        )
+    ;

[caryclark, 2013/12/09 18:45:50]

I know this is old code, but I find the indention very strange. Do we do this in
other places in Skia?

[bungeman-skia, 2013/12/09 18:57:51]

Probably not. I think the idea was to put the closer of multi-line expressions
at the same indentation as the opener. It just makes the expressions look like
blocks. Modified now that we have more space and we can get away with fewer
indentation levels.

+    if (!dWriteCreateFactoryProc) {
+        HRESULT hr = HRESULT_FROM_WIN32(GetLastError());
+        if (!IS_ERROR(hr)) {
+            hr = ERROR_PROC_NOT_FOUND;
+        }
+        HRVM(hr, "Could not get DWriteCreateFactory proc.");
+    }
+
+    HRVM(dWriteCreateFactoryProc(DWRITE_FACTORY_TYPE_SHARED,
+                                __uuidof(IDWriteFactory),
+                                reinterpret_cast<IUnknown**>(&factory)),
+         "Could not create DirectWrite factory.");

[caryclark, 2013/12/09 18:45:50]

More unusual indention

[bungeman-skia, 2013/12/09 18:57:51]

Not sure this is that unusual, the HRVM macro takes two arguments, an expression
and a string. The string here is just the second argument, so it lines up with
the first argument.

+}
+
+static IDWriteFactory* get_dwrite_factory() {
+    static IDWriteFactory* gDWriteFactory = NULL;
+    SK_DECLARE_STATIC_ONCE(once);
+    SkOnce(&once, create_dwrite_factory, &gDWriteFactory);
+
+    return gDWriteFactory;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 class StreamFontFileLoader;
 
 class SkFontMgr_DirectWrite : public SkFontMgr {
@@ -173,40 +207,9 @@
     SkTDArray<uint8_t> fBits;
 };
 
-static HRESULT get_dwrite_factory(IDWriteFactory** factory) {
-    static IDWriteFactory* gDWriteFactory = NULL;
-
-    if (gDWriteFactory != NULL) {
-        *factory = gDWriteFactory;
-        return S_OK;
-    }
-
-    typedef decltype(DWriteCreateFactory)* DWriteCreateFactoryProc;
-    DWriteCreateFactoryProc dWriteCreateFactoryProc =
-        reinterpret_cast<DWriteCreateFactoryProc>(
-            GetProcAddress(LoadLibraryW(L"dwrite.dll"), "DWriteCreateFactory")
-        )
-    ;
-    if (!dWriteCreateFactoryProc) {
-        HRESULT hr = HRESULT_FROM_WIN32(GetLastError());
-        if (!IS_ERROR(hr)) {
-            hr = ERROR_PROC_NOT_FOUND;
-        }
-        return hr;
-    }
-
-    HRM(dWriteCreateFactoryProc(DWRITE_FACTORY_TYPE_SHARED,
-                                __uuidof(IDWriteFactory),
-                                reinterpret_cast<IUnknown**>(&gDWriteFactory)),
-        "Could not create DirectWrite factory.");
-
-    *factory = gDWriteFactory;
-    return S_OK;
-}
-
 const void* DWriteOffscreen::draw(const SkGlyph& glyph, bool isBW) {
-    IDWriteFactory* factory;
-    HRNM(get_dwrite_factory(&factory), "Could not get factory.");
+    IDWriteFactory* factory = get_dwrite_factory();
+    SkASSERT(factory != NULL);
 
     if (fWidth < glyph.fWidth || fHeight < glyph.fHeight) {
         fWidth = SkMax32(fWidth, glyph.fWidth);
@@ -553,8 +556,8 @@
     ~DWriteFontTypeface() {
         if (fDWriteFontCollectionLoader.get() == NULL) return;
 
-        IDWriteFactory* factory;
-        HRVM(get_dwrite_factory(&factory), "Could not get factory.");
+        IDWriteFactory* factory = get_dwrite_factory();
+        SkASSERT(factory != NULL);
         HRV(factory->UnregisterFontCollectionLoader(fDWriteFontCollectionLoader.get()));
         HRV(factory->UnregisterFontFileLoader(fDWriteFontFileLoader.get()));
     }
@@ -806,8 +809,8 @@
     run.isSideways = FALSE;
     run.glyphOffsets = &offset;
 
-    IDWriteFactory* factory;
-    HRVM(get_dwrite_factory(&factory), "Could not get factory.");
+    IDWriteFactory* factory = get_dwrite_factory();
+    SkASSERT(factory != NULL);
 
     const bool isBW = SkMask::kBW_Format == fRec.fMaskFormat;
     DWRITE_RENDERING_MODE renderingMode;
@@ -1272,8 +1275,10 @@
 };
 
 static SkTypeface* create_from_stream(SkStream* stream, int ttcIndex) {
-    IDWriteFactory* factory;
-    HRN(get_dwrite_factory(&factory));
+    IDWriteFactory* factory = get_dwrite_factory();
+    if (NULL == factory) {
+        return NULL;
+    }
 
     SkTScopedComPtr<StreamFontFileLoader> fontFileLoader;
     HRN(StreamFontFileLoader::Create(stream, &fontFileLoader));
@@ -1373,8 +1378,8 @@
     rec->setHinting(h);
 
 #if SK_FONT_HOST_USE_SYSTEM_SETTINGS
-    IDWriteFactory* factory;
-    if (SUCCEEDED(get_dwrite_factory(&factory))) {
+    IDWriteFactory* factory = get_dwrite_factory();
+    if (factory != NULL) {
         SkTScopedComPtr<IDWriteRenderingParams> defaultRenderingParams;
         if (SUCCEEDED(factory->CreateRenderingParams(&defaultRenderingParams))) {
             float gamma = defaultRenderingParams->GetGamma();
@@ -1880,8 +1885,10 @@
 }
 
 SkFontMgr* SkFontMgr_New_DirectWrite() {
-    IDWriteFactory* factory;
-    HRNM(get_dwrite_factory(&factory), "Could not get factory.");
+    IDWriteFactory* factory = get_dwrite_factory();
+    if (NULL == factory) {
+        return NULL;
+    }
 
     SkTScopedComPtr<IDWriteFontCollection> sysFontCollection;
     HRNM(factory->GetSystemFontCollection(&sysFontCollection, FALSE),