C++ IDWriteTextLayout::GetLineMetrics方法代码示例

//.........这里部分代码省略.........
            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);
    }