src/utils/win/SkDWrite.cpp

/*
 * Copyright 2014 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkDWrite.h"
#include "SkHRESULT.h"
#include "SkOnce.h"
#include "SkString.h"

#include <dwrite.h>

static IDWriteFactory* gDWriteFactory = NULL;

static void release_dwrite_factory() {
    if (gDWriteFactory) {
        gDWriteFactory->Release();
    }
}

static void create_dwrite_factory(IDWriteFactory** factory) {
    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;
        }
        HRVM(hr, "Could not get DWriteCreateFactory proc.");
    }

    HRVM(dWriteCreateFactoryProc(DWRITE_FACTORY_TYPE_SHARED,
                                 __uuidof(IDWriteFactory),
                                 reinterpret_cast<IUnknown**>(factory)),
         "Could not create DirectWrite factory.");
    atexit(release_dwrite_factory);
}


IDWriteFactory* sk_get_dwrite_factory() {
    SK_DECLARE_STATIC_ONCE(once);
    SkOnce(&once, create_dwrite_factory, &gDWriteFactory);

    return gDWriteFactory;
}

////////////////////////////////////////////////////////////////////////////////
// String conversion

/** Converts a utf8 string to a WCHAR string. */
HRESULT sk_cstring_to_wchar(const char* skname, SkSMallocWCHAR* name) {
    int wlen = MultiByteToWideChar(CP_UTF8, 0, skname, -1, NULL, 0);
    if (0 == wlen) {
        HRM(HRESULT_FROM_WIN32(GetLastError()),
            "Could not get length for wchar to utf-8 conversion.");
    }
    name->reset(wlen);
    wlen = MultiByteToWideChar(CP_UTF8, 0, skname, -1, name->get(), wlen);
    if (0 == wlen) {
        HRM(HRESULT_FROM_WIN32(GetLastError()), "Could not convert wchar to utf-8.");
    }
    return S_OK;
}

/** Converts a WCHAR string to a utf8 string. */
HRESULT sk_wchar_to_skstring(WCHAR* name, SkString* skname) {
    int len = WideCharToMultiByte(CP_UTF8, 0, name, -1, NULL, 0, NULL, NULL);
    if (0 == len) {
        HRM(HRESULT_FROM_WIN32(GetLastError()),
            "Could not get length for utf-8 to wchar conversion.");
    }
    skname->resize(len - 1);

    // TODO: remove after https://code.google.com/p/skia/issues/detail?id=1989 is fixed.
    // If we resize to 0 then the skname points to gEmptyRec (the unique empty SkString::Rec).
    // gEmptyRec is static const and on Windows this means the value is in a read only page.
    // Writing to it in the following call to WideCharToMultiByte will cause an access violation.
    if (1 == len) {
        return S_OK;
    }

    len = WideCharToMultiByte(CP_UTF8, 0, name, -1, skname->writable_str(), len, NULL, NULL);
    if (0 == len) {
        HRM(HRESULT_FROM_WIN32(GetLastError()), "Could not convert utf-8 to wchar.");
    }
    return S_OK;
}

////////////////////////////////////////////////////////////////////////////////
// Locale

void sk_get_locale_string(IDWriteLocalizedStrings* names, const WCHAR* preferedLocale,
                          SkString* skname) {
    UINT32 nameIndex = 0;
    if (preferedLocale) {
        // Ignore any errors and continue with index 0 if there is a problem.
        BOOL nameExists;
        names->FindLocaleName(preferedLocale, &nameIndex, &nameExists);
        if (!nameExists) {
            nameIndex = 0;
        }
    }

    UINT32 nameLength;
    HRVM(names->GetStringLength(nameIndex, &nameLength), "Could not get name length.");
    nameLength += 1;

    SkSMallocWCHAR name(nameLength);
    HRVM(names->GetString(nameIndex, name.get(), nameLength), "Could not get string.");

    HRV(sk_wchar_to_skstring(name.get(), skname));
}

HRESULT SkGetGetUserDefaultLocaleNameProc(SkGetUserDefaultLocaleNameProc* proc) {
    *proc = reinterpret_cast<SkGetUserDefaultLocaleNameProc>(
        GetProcAddress(LoadLibraryW(L"Kernel32.dll"), "GetUserDefaultLocaleName")
    );
    if (!*proc) {
        HRESULT hr = HRESULT_FROM_WIN32(GetLastError());
        if (!IS_ERROR(hr)) {
            hr = ERROR_PROC_NOT_FOUND;
        }
        return hr;
    }
    return S_OK;
}