bool CDirectWriteRenderer::GetFontMetrics(CDirectWriteFont &Font, FontMetrics *pMetrics)
{
if (pMetrics == nullptr)
return false;
if (m_pRenderTarget == nullptr)
return false;
HRESULT hr = E_UNEXPECTED;
IDWriteTextFormat *pTextFormat = Font.GetTextFormat();
if (pTextFormat != nullptr) {
IDWriteFontCollection *pFontCollection;
hr = pTextFormat->GetFontCollection(&pFontCollection);
if (SUCCEEDED(hr)) {
WCHAR szName[256];
hr = pTextFormat->GetFontFamilyName(szName, lengthof(szName));
if (SUCCEEDED(hr)) {
UINT32 Index;
BOOL fExists;
hr = pFontCollection->FindFamilyName(szName, &Index, &fExists);
if (SUCCEEDED(hr)) {
IDWriteFontFamily *pFontFamily;
hr = pFontCollection->GetFontFamily(Index, &pFontFamily);
if (SUCCEEDED(hr)) {
IDWriteFont *pFont;
hr = pFontFamily->GetFirstMatchingFont(
pTextFormat->GetFontWeight(),
pTextFormat->GetFontStretch(),
pTextFormat->GetFontStyle(),
&pFont);
if (SUCCEEDED(hr)) {
DWRITE_FONT_METRICS Metrics;
pFont->GetMetrics(&Metrics);
const float Ratio = pTextFormat->GetFontSize() / static_cast<float>(Metrics.designUnitsPerEm);
pMetrics->Ascent = Metrics.ascent * Ratio;
pMetrics->Descent = Metrics.descent * Ratio;
pMetrics->LineGap = Metrics.lineGap * Ratio;
pFont->Release();
}
pFontFamily->Release();
}
}
}
}
pFontCollection->Release();
}
return SUCCEEDED(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;
}