HRESULT DWriteCreateResources(HDC hdc, wchar_t *text, HFONT hfont)
{
HRESULT hr = S_OK;
// If the DirectWrite factory doesn't exist, create the resources,
// only create these resources once.
if (!g_pDWriteFactory)
{
HWND hwnd;
RECT r;
// DirectWrite variables.
IDWriteFontFamily* pFontFamily = NULL;
IDWriteFont* pFont = NULL;
IDWriteLocalizedStrings* pFamilyNames = NULL;
// Logical (GDI) font.
LOGFONT lf = {};
UINT32 length = 0;
UINT32 index = 0;
float fontSize = 0;
// length of the string
UINT32 textLength = 0;
wchar_t *name = NULL;
// Get a handle to the DC and the window rect.
hwnd = WindowFromDC(hdc);
GetClientRect(hwnd, &r);
// Calculate the string length.
textLength = UINT32(wcslen(text));
// Create the DirectWrite factory.
hr = DWriteCreateFactory(
DWRITE_FACTORY_TYPE_SHARED,
__uuidof(IDWriteFactory),
reinterpret_cast<IUnknown**>(&g_pDWriteFactory)
);
// Create a GDI interop interface.
if (SUCCEEDED(hr))
{
hr = g_pDWriteFactory->GetGdiInterop(&g_pGdiInterop);
}
if (SUCCEEDED(hr))
{
// Get a logical font from the font handle.
GetObject(hfont, sizeof(LOGFONT), &lf);
}
// Convert to a DirectWrite font.
if (SUCCEEDED(hr))
{
hr = g_pGdiInterop->CreateFontFromLOGFONT(&lf, &pFont);
}
// Get the font family.
if (SUCCEEDED(hr))
{
hr = pFont->GetFontFamily(&pFontFamily);
}
// Get a list of localized family names.
if (SUCCEEDED(hr))
{
hr = pFontFamily->GetFamilyNames(&pFamilyNames);
}
// Select the first locale. This is OK, because we are not displaying the family name.
index = 0;
// Get the length of the family name.
if (SUCCEEDED(hr))
{
hr = pFamilyNames->GetStringLength(index, &length);
}
if (SUCCEEDED(hr))
{
// Allocate a new string.
name = new (std::nothrow) wchar_t[length+1];
if (name == NULL)
{
hr = E_OUTOFMEMORY;
}
}
// Get the actual family name.
if (SUCCEEDED(hr))
{
hr = pFamilyNames->GetString(index, name, length+1);
}
if (SUCCEEDED(hr))
{
// Calculate the font size.
fontSize = (float) -MulDiv(lf.lfHeight, 96, GetDeviceCaps(hdc, LOGPIXELSY));
}
// Create a text format using the converted font information.
if (SUCCEEDED(hr))
{
hr = g_pDWriteFactory->CreateTextFormat(
name, // Font family name.
NULL,
pFont->GetWeight(),
pFont->GetStyle(),
pFont->GetStretch(),
fontSize,
L"en-us",
&g_pTextFormat
);
}
// Create a text layout.
if (SUCCEEDED(hr))
{
hr = g_pDWriteFactory->CreateTextLayout(
text,
textLength,
g_pTextFormat,
1024.0f,
480.0f,
&g_pTextLayout
);
}
// Underline and strikethrough are part of a LOGFONT structure, but are not
// part of a DWrite font object so we must set them using the text layout.
if(lf.lfUnderline)
{
DWRITE_TEXT_RANGE textRange = {0, textLength};
g_pTextLayout->SetUnderline(true, textRange);
}
if(lf.lfStrikeOut)
{
DWRITE_TEXT_RANGE textRange = {0, textLength};
g_pTextLayout->SetStrikethrough(true, textRange);
}
// Create a bitmap render target for our custom renderer.
if (SUCCEEDED(hr))
{
hr = g_pGdiInterop->CreateBitmapRenderTarget(hdc, r.right, r.bottom, &g_pBitmapRenderTarget);
}
// Create default rendering params for our custom renderer.
if (SUCCEEDED(hr))
{
hr = g_pDWriteFactory->CreateRenderingParams(&g_pRenderingParams);
}
if (SUCCEEDED(hr))
{
// Initialize the custom renderer class.
g_pGdiTextRenderer = new (std::nothrow) GdiTextRenderer(g_pBitmapRenderTarget, g_pRenderingParams);
}
// Clean up local interfaces.
SafeRelease(&pFontFamily);
SafeRelease(&pFont);
SafeRelease(&pFamilyNames);
}
return hr;
}
HRESULT
DWriteContext::SetLOGFONT(const LOGFONTW &logFont, float fontSize)
{
// Most of this function is copy from: http://msdn.microsoft.com/en-us/library/windows/desktop/dd941783(v=vs.85).aspx
HRESULT hr = S_OK;
IDWriteFont *font = NULL;
IDWriteFontFamily *fontFamily = NULL;
IDWriteLocalizedStrings *localizedFamilyNames = NULL;
if (SUCCEEDED(hr))
{
hr = mGdiInterop->CreateFontFromLOGFONT(&logFont, &font);
}
// Get the font family to which this font belongs.
if (SUCCEEDED(hr))
{
hr = font->GetFontFamily(&fontFamily);
}
// Get the family names. This returns an object that encapsulates one or
// more names with the same meaning but in different languages.
if (SUCCEEDED(hr))
{
hr = fontFamily->GetFamilyNames(&localizedFamilyNames);
}
// Get the family name at index zero. If we were going to display the name
// we'd want to try to find one that matched the use locale, but for
// purposes of creating a text format object any language will do.
wchar_t familyName[100];
if (SUCCEEDED(hr))
{
hr = localizedFamilyNames->GetString(0, familyName,
ARRAYSIZE(familyName));
}
if (SUCCEEDED(hr))
{
// If no font size was passed in use the lfHeight of the LOGFONT.
if (fontSize == 0)
{
// Convert from pixels to DIPs.
fontSize = PixelsToDipsY(logFont.lfHeight);
if (fontSize < 0)
{
// Negative lfHeight represents the size of the em unit.
fontSize = -fontSize;
}
else
{
// Positive lfHeight represents the cell height (ascent +
// descent).
DWRITE_FONT_METRICS fontMetrics;
font->GetMetrics(&fontMetrics);
// Convert the cell height (ascent + descent) from design units
// to ems.
float cellHeight = static_cast<float>(
fontMetrics.ascent + fontMetrics.descent)
/ fontMetrics.designUnitsPerEm;
// Divide the font size by the cell height to get the font em
// size.
fontSize /= cellHeight;
}
}
}
// The text format includes a locale name. Ideally, this would be the
// language of the text, which may or may not be the same as the primary
// language of the user. However, for our purposes the user locale will do.
wchar_t localeName[LOCALE_NAME_MAX_LENGTH];
if (SUCCEEDED(hr))
{
if (GetUserDefaultLocaleName(localeName, LOCALE_NAME_MAX_LENGTH) == 0)
hr = HRESULT_FROM_WIN32(GetLastError());
}
if (SUCCEEDED(hr))
{
// Create the text format object.
hr = mDWriteFactory->CreateTextFormat(
familyName,
NULL, // no custom font collection
font->GetWeight(),
font->GetStyle(),
font->GetStretch(),
fontSize,
localeName,
&mTextFormat);
}
if (SUCCEEDED(hr))
{
mFontWeight = static_cast<DWRITE_FONT_WEIGHT>(logFont.lfWeight);
mFontStyle = logFont.lfItalic ? DWRITE_FONT_STYLE_ITALIC
: DWRITE_FONT_STYLE_NORMAL;
}
SafeRelease(&localizedFamilyNames);
SafeRelease(&fontFamily);
SafeRelease(&font);
return hr;
}