Gfx: Make AccurateText=0 more consistent with GDI+ for D2D

The height is now based on a formula that should be exactly equal to that provided by GDI+. The padding should now be equal on the left and right sides now. There may be some discrepancies in overall width, but it should always be reasonably to close to GDI+.

In addition, this makes D2D behavior match GDI+ when a newline character is the last character of the text.

Common/Gfx/TextFormatD2D.cpp

@@ -22,7 +22,9 @@
 
 namespace Gfx {
 
-TextFormatD2D::TextFormatD2D()
+TextFormatD2D::TextFormatD2D() :
+	m_ExtraHeight(),
+	m_LineGap()
 {
 }
 
@@ -37,7 +39,8 @@ void TextFormatD2D::Dispose()
 	m_InlineEllipsis.Reset();
 }
 
-void TextFormatD2D::CreateLayout(const WCHAR* str, UINT strLen, float maxW, float maxH)
+void TextFormatD2D::CreateLayout(
+	const WCHAR* str, UINT strLen, float maxW, float maxH, bool gdiEmulation)
 {
 	bool strChanged = false;
 	if (strLen != m_LastString.length() ||
@@ -63,6 +66,17 @@ void TextFormatD2D::CreateLayout(const WCHAR* str, UINT strLen, float maxW, floa
 	{
 		CanvasD2D::c_DWFactory->CreateTextLayout(
 			str, strLen, m_TextFormat.Get(), maxW, maxH, m_TextLayout.ReleaseAndGetAddressOf());
+
+		if (gdiEmulation && m_TextLayout)
+		{
+			Microsoft::WRL::ComPtr<IDWriteTextLayout1> textLayout1;
+			m_TextLayout.As(&textLayout1);
+
+			const float xOffset = m_TextFormat->GetFontSize() / 6.0f;
+			const float emOffset = xOffset / 24.0f;
+			const DWRITE_TEXT_RANGE range = {0, strLen};
+			textLayout1->SetCharacterSpacing(emOffset, emOffset, 0.0f, range);
+		}
 	}
 }
 
@@ -80,6 +94,7 @@ void TextFormatD2D::SetProperties(
 	DWRITE_FONT_STYLE dwriteFontStyle =
 		italic ? DWRITE_FONT_STYLE_ITALIC : DWRITE_FONT_STYLE_NORMAL;
 	DWRITE_FONT_STRETCH dwriteFontStretch = DWRITE_FONT_STRETCH_NORMAL;
+	const float dwriteFontSize = size * (4.0f / 3.0f);
 
 	// |fontFamily| uses the GDI/GDI+ font naming convention so try to create DirectWrite font
 	// using the GDI family name and then create a text format using the DirectWrite family name
@@ -95,7 +110,7 @@ void TextFormatD2D::SetProperties(
 			dwriteFontWeight,
 			dwriteFontStyle,
 			dwriteFontStretch,
-			size * (4.0f / 3.0f),
+			dwriteFontSize,
 			L"",
 			&m_TextFormat);
 	}
@@ -135,7 +150,7 @@ void TextFormatD2D::SetProperties(
 			dwriteFontWeight,
 			dwriteFontStyle,
 			dwriteFontStretch,
-			size * (4.0f / 3.0f),
+			dwriteFontSize,
 			L"",
 			&m_TextFormat);
 	}
@@ -144,6 +159,36 @@ void TextFormatD2D::SetProperties(
 	{
 		SetHorizontalAlignment(GetHorizontalAlignment());
 		SetVerticalAlignment(GetVerticalAlignment());
+
+		// TODO: Clean this up and check for errors.
+		Microsoft::WRL::ComPtr<IDWriteFontCollection> collection;
+		m_TextFormat->GetFontCollection(collection.GetAddressOf());
+
+		UINT32 familyNameIndex;
+		BOOL exists;
+		collection->FindFamilyName(dwriteFamilyName, &familyNameIndex, &exists); 
+
+		Microsoft::WRL::ComPtr<IDWriteFontFamily> fontFamily;
+		collection->GetFontFamily(familyNameIndex, fontFamily.GetAddressOf());
+
+		Microsoft::WRL::ComPtr<IDWriteFont> font;
+		fontFamily->GetFirstMatchingFont(
+			m_TextFormat->GetFontWeight(),
+			m_TextFormat->GetFontStretch(),
+			m_TextFormat->GetFontStyle(),
+			font.GetAddressOf());
+
+		DWRITE_FONT_METRICS fmetrics;
+		font->GetMetrics(&fmetrics);
+
+		// GDI+ compatibility: GDI+ adds extra padding below the string when |m_AccurateText| is
+		// |false|. The bottom padding seems to be based on the font metrics so we can calculate it
+		// once and keep using it regardless of the actual string. In some cases, GDI+ also adds
+		// the line gap to the overall height so we will store it as well.
+		const float pixelsPerDesignUnit =  dwriteFontSize / (float)fmetrics.designUnitsPerEm;
+		m_ExtraHeight =
+			(((float)fmetrics.designUnitsPerEm / 8.0f) - fmetrics.lineGap) * pixelsPerDesignUnit;
+		m_LineGap = fmetrics.lineGap * pixelsPerDesignUnit;
 	}
 	else
 	{
@@ -151,6 +196,71 @@ void TextFormatD2D::SetProperties(
 	}
 }
 
+DWRITE_TEXT_METRICS TextFormatD2D::GetMetrics(
+	const WCHAR* str, UINT strLen, bool gdiEmulation, float maxWidth)
+{
+	// GDI+ compatibility: If the last character is a newline, GDI+ measurements seem to ignore it.
+	bool strippedLastNewLine = false;
+	if (str[strLen - 1] == L'\n')
+	{
+		strippedLastNewLine = true;
+		--strLen;
+
+		if (str[strLen - 1] == L'\r')
+		{
+			--strLen;
+		}
+	}
+
+	DWRITE_TEXT_METRICS metrics = {0};
+	Microsoft::WRL::ComPtr<IDWriteTextLayout> textLayout;
+	HRESULT hr = CanvasD2D::c_DWFactory->CreateTextLayout(
+		str,
+		strLen,
+		m_TextFormat.Get(),
+		maxWidth,
+		10000,
+		textLayout.GetAddressOf());
+	if (SUCCEEDED(hr))
+	{
+		const float xOffset = m_TextFormat->GetFontSize() / 6.0f;
+		if (gdiEmulation)
+		{
+			Microsoft::WRL::ComPtr<IDWriteTextLayout1> textLayout1;
+			textLayout.As(&textLayout1);
+
+			const float emOffset = xOffset / 24.0f;
+			const DWRITE_TEXT_RANGE range = {0, strLen};
+			textLayout1->SetCharacterSpacing(emOffset, emOffset, 0.0f, range);
+		}
+
+		textLayout->GetMetrics(&metrics);
+		if (metrics.width > 0.0f)
+		{
+			if (gdiEmulation)
+			{
+				metrics.width += xOffset * 2;
+				metrics.height += m_ExtraHeight;
+
+				// GDI+ compatibility: If the string contains a newline (even if it is the
+				// stripped last character), GDI+ adds the line gap to the overall height.
+				if (strippedLastNewLine || wmemchr(str, L'\n', strLen) != nullptr)
+				{
+					metrics.height += m_LineGap;
+				}
+			}
+		}
+		else
+		{
+			// GDI+ compatibility: Get rid of the height that DirectWrite assigns to zero-width
+			// strings.
+			metrics.height = 0.0f;
+		}
+	}
+
+	return metrics;
+}
+
 void TextFormatD2D::SetTrimming(bool trim)
 {
 	IDWriteInlineObject* inlineObject = nullptr;