// This method takes an attributed string and outputs a GlyphLayout data
// structure that contains the glyph number and location of each inidividual glyph
void getGlyphLayout (const AttributedString& text, GlyphLayout& glyphLayout)
{
// For now we are creating the DirectWrite Factory, System Font Collection,
// D2D Factory and GDI Render target every time we layout text.
// This is inefficient and we may be loading and unloading libraries each layout.
// These four things should be created once at application startup and be destroyed
// when the application exits. I'm not sure where the best place to do this so
// for now I will just use the inefficient method.
IDWriteFactory* dwFactory = nullptr;
HRESULT hr = DWriteCreateFactory (DWRITE_FACTORY_TYPE_SHARED, __uuidof(IDWriteFactory),
reinterpret_cast<IUnknown**>(&dwFactory));
IDWriteFontCollection* dwFontCollection = nullptr;
hr = dwFactory->GetSystemFontCollection (&dwFontCollection);
// To add color to text, we need to create a D2D render target
// Since we are not actually rendering to a D2D context we create a temporary GDI render target
ID2D1Factory *d2dFactory = nullptr;
hr = D2D1CreateFactory (D2D1_FACTORY_TYPE_SINGLE_THREADED, &d2dFactory);
D2D1_RENDER_TARGET_PROPERTIES d2dRTProp = D2D1::RenderTargetProperties(
D2D1_RENDER_TARGET_TYPE_SOFTWARE,
D2D1::PixelFormat(
DXGI_FORMAT_B8G8R8A8_UNORM,
D2D1_ALPHA_MODE_IGNORE),
0,
0,
D2D1_RENDER_TARGET_USAGE_GDI_COMPATIBLE,
D2D1_FEATURE_LEVEL_DEFAULT
);
ID2D1DCRenderTarget* d2dDCRT = nullptr;
hr = d2dFactory->CreateDCRenderTarget (&d2dRTProp, &d2dDCRT);
// Initially we set the paragraph up with a default font and then apply the attributed string ranges later
Font defaultFont;
const float defaultFontHeightToEmSizeFactor = getFontHeightToEmSizeFactor (defaultFont, *dwFontCollection);
// We should probably be detecting the locale instead of hard coding it to en-us
String localeName("en-us");
// We multiply the font height by the size factor so we layout text at the correct size
IDWriteTextFormat* dwTextFormat = nullptr;
hr = dwFactory->CreateTextFormat (
defaultFont.getTypefaceName().toWideCharPointer(),
dwFontCollection,
DWRITE_FONT_WEIGHT_REGULAR,
DWRITE_FONT_STYLE_NORMAL,
DWRITE_FONT_STRETCH_NORMAL,
defaultFont.getHeight() * defaultFontHeightToEmSizeFactor,
localeName.toWideCharPointer(),
&dwTextFormat
);
// Paragraph Attributes
// Set Paragraph Alignment
if (text.getTextAlignment() == AttributedString::left)
dwTextFormat->SetTextAlignment (DWRITE_TEXT_ALIGNMENT_LEADING);
if (text.getTextAlignment() == AttributedString::right)
dwTextFormat->SetTextAlignment (DWRITE_TEXT_ALIGNMENT_TRAILING);
if (text.getTextAlignment() == AttributedString::center)
dwTextFormat->SetTextAlignment (DWRITE_TEXT_ALIGNMENT_CENTER);
// DirectWrite cannot justify text, default to left alignment
if (text.getTextAlignment() == AttributedString::justified)
dwTextFormat->SetTextAlignment (DWRITE_TEXT_ALIGNMENT_LEADING);
// Set Word Wrap
if (text.getWordWrap() == AttributedString::none)
dwTextFormat->SetWordWrapping (DWRITE_WORD_WRAPPING_NO_WRAP);
if (text.getWordWrap() == AttributedString::byWord)
dwTextFormat->SetWordWrapping (DWRITE_WORD_WRAPPING_WRAP);
// DirectWrite does not support wrapping by character, default to wrapping by word
if (text.getWordWrap() == AttributedString::byChar)
dwTextFormat->SetWordWrapping (DWRITE_WORD_WRAPPING_WRAP);
// DirectWrite does not automatically set reading direction
// This must be set correctly and manually when using RTL Scripts (Hebrew, Arabic)
if (text.getReadingDirection() == AttributedString::rightToLeft)
dwTextFormat->SetReadingDirection (DWRITE_READING_DIRECTION_RIGHT_TO_LEFT);
IDWriteTextLayout* dwTextLayout = nullptr;
hr = dwFactory->CreateTextLayout (
text.getText().toWideCharPointer(),
text.getText().length(),
dwTextFormat,
glyphLayout.getWidth(),
glyphLayout.getHeight(),
&dwTextLayout
);
// Character Attributes
int numCharacterAttributes = text.getCharAttributesSize();
for (int i = 0; i < numCharacterAttributes; ++i)
{
Attr* attr = text.getCharAttribute (i);
// Character Range Error Checking
if (attr->range.getStart() > text.getText().length()) continue;
if (attr->range.getEnd() > text.getText().length()) attr->range.setEnd (text.getText().length());
if (attr->attribute == Attr::font)
{
AttrFont* attrFont = static_cast<AttrFont*>(attr);
DWRITE_TEXT_RANGE dwRange;
dwRange.startPosition = attrFont->range.getStart();
dwRange.length = attrFont->range.getLength();
dwTextLayout->SetFontFamilyName (attrFont->font.getTypefaceName().toWideCharPointer(), dwRange);
// We multiply the font height by the size factor so we layout text at the correct size
const float fontHeightToEmSizeFactor = getFontHeightToEmSizeFactor (attrFont->font, *dwFontCollection);
dwTextLayout->SetFontSize (attrFont->font.getHeight() * fontHeightToEmSizeFactor, dwRange);
}
if (attr->attribute == Attr::foregroundColour)
{
AttrColour* attrColour = static_cast<AttrColour*>(attr);
DWRITE_TEXT_RANGE dwRange;
dwRange.startPosition = attrColour->range.getStart();
dwRange.length = attrColour->range.getLength();
ID2D1SolidColorBrush* d2dBrush = nullptr;
d2dDCRT->CreateSolidColorBrush (D2D1::ColorF (D2D1::ColorF(attrColour->colour.getFloatRed(),
attrColour->colour.getFloatGreen(), attrColour->colour.getFloatBlue(),
attrColour->colour.getFloatAlpha())), &d2dBrush);
// We need to call SetDrawingEffect with a legimate brush to get DirectWrite to break text based on colours
dwTextLayout->SetDrawingEffect (d2dBrush, dwRange);
safeRelease (&d2dBrush);
}
}
UINT32 actualLineCount = 0;
hr = dwTextLayout->GetLineMetrics (nullptr, 0, &actualLineCount);
// Preallocate GlyphLayout Line Array
glyphLayout.setNumLines (actualLineCount);
HeapBlock <DWRITE_LINE_METRICS> dwLineMetrics (actualLineCount);
hr = dwTextLayout->GetLineMetrics (dwLineMetrics, actualLineCount, &actualLineCount);
int location = 0;
// Create GlyphLine structures for each line in the layout
for (UINT32 i = 0; i < actualLineCount; ++i)
{
// Get string range
Range<int> lineStringRange (location, (int) location + dwLineMetrics[i].length);
location = dwLineMetrics[i].length;
GlyphLine* glyphLine = new GlyphLine();
glyphLine->setStringRange (lineStringRange);
glyphLayout.addGlyphLine (glyphLine);
}
// To copy glyph data from DirectWrite into our own data structures we must create our
// own CustomTextRenderer. Instead of passing the draw method an actual graphics context,
// we pass it the GlyphLayout object that needs to be filled with glyphs.
CustomDirectWriteTextRenderer* textRenderer = nullptr;
textRenderer = new CustomDirectWriteTextRenderer();
hr = dwTextLayout->Draw (
&glyphLayout,
textRenderer,
glyphLayout.getX(),
glyphLayout.getY()
);
safeRelease (&textRenderer);
safeRelease (&dwTextLayout);
safeRelease (&dwTextFormat);
safeRelease (&d2dDCRT);
safeRelease (&d2dFactory);
safeRelease (&dwFontCollection);
safeRelease (&dwFactory);
}
void setTextFormatProperties (const AttributedString& text, IDWriteTextFormat& format)
{
DWRITE_TEXT_ALIGNMENT alignment = DWRITE_TEXT_ALIGNMENT_LEADING;
DWRITE_WORD_WRAPPING wrapType = DWRITE_WORD_WRAPPING_WRAP;
switch (text.getJustification().getOnlyHorizontalFlags())
{
case Justification::left: break;
case Justification::right: alignment = DWRITE_TEXT_ALIGNMENT_TRAILING; break;
case Justification::horizontallyCentred: alignment = DWRITE_TEXT_ALIGNMENT_CENTER; break;
case Justification::horizontallyJustified: break; // DirectWrite cannot justify text, default to left alignment
default: jassertfalse; break; // Illegal justification flags
}
switch (text.getWordWrap())
{
case AttributedString::none: wrapType = DWRITE_WORD_WRAPPING_NO_WRAP; break;
case AttributedString::byWord: break;
case AttributedString::byChar: break; // DirectWrite doesn't support wrapping by character, default to word-wrap
default: jassertfalse; break; // Illegal flags!
}
// DirectWrite does not automatically set reading direction
// This must be set correctly and manually when using RTL Scripts (Hebrew, Arabic)
if (text.getReadingDirection() == AttributedString::rightToLeft)
{
format.SetReadingDirection (DWRITE_READING_DIRECTION_RIGHT_TO_LEFT);
switch (text.getJustification().getOnlyHorizontalFlags())
{
case Justification::left: alignment = DWRITE_TEXT_ALIGNMENT_TRAILING; break;
case Justification::right: alignment = DWRITE_TEXT_ALIGNMENT_LEADING; break;
default: break;
}
}
format.SetTextAlignment (alignment);
format.SetWordWrapping (wrapType);
}