Add baseline-shift support #202

source/graphics.h

@@ -388,7 +388,7 @@ class PathIterator {
 
 private:
     const plutovg_path_element_t* m_elements;
-    int m_size;
+    const int m_size;
     int m_index;
 };
 

source/svglayoutstate.cpp

@@ -118,6 +118,17 @@ static Length parseLength(const std::string_view& input, LengthNegativeMode mode
     return value;
 }
 
+static BaselineShift parseBaselineShift(const std::string_view& input)
+{
+    if(input.compare("baseline") == 0)
+        return BaselineShift::Type::Baseline;
+    if(input.compare("sub") == 0)
+        return BaselineShift::Type::Sub;
+    if(input.compare("super") == 0)
+        return BaselineShift::Type::Super;
+    return parseLength(input, LengthNegativeMode::Allow, Length(0.f, LengthUnits::None));
+}
+
 static LengthList parseDashArray(std::string_view input)
 {
     if(input.compare("none") == 0)
@@ -364,6 +375,9 @@ SVGLayoutState::SVGLayoutState(const SVGLayoutState& parent, const SVGElement* e
         case PropertyID::Font_Size:
             m_font_size = parseFontSize(input, this);
             break;
+        case PropertyID::Baseline_Shift:
+            m_baseline_shit = parseBaselineShift(input);
+            break;
         case PropertyID::Stroke_Width:
             m_stroke_width = parseLength(input, LengthNegativeMode::Forbid, Length(1.f, LengthUnits::None));
             break;

source/svglayoutstate.h

@@ -26,6 +26,7 @@ class SVGLayoutState {
     float stroke_miterlimit() const { return m_stroke_miterlimit; }
     float font_size() const { return m_font_size; }
 
+    const BaselineShift& baseline_shit() const { return m_baseline_shit; }
     const Length& stroke_width() const { return m_stroke_width; }
     const Length& stroke_dashoffset() const { return m_stroke_dashoffset; }
     const LengthList& stroke_dasharray() const { return m_stroke_dasharray; }
@@ -74,6 +75,7 @@ class SVGLayoutState {
     float m_stroke_miterlimit = 4.f;
     float m_font_size = 12.f;
 
+    BaselineShift m_baseline_shit;
     Length m_stroke_width{1.f, LengthUnits::None};
     Length m_stroke_dashoffset{0.f, LengthUnits::None};
     LengthList m_stroke_dasharray;

source/svgproperty.cpp

@@ -71,6 +71,7 @@ PropertyID csspropertyid(const std::string_view& name)
         std::string_view name;
         PropertyID value;
     } table[] = {
+        {"baseline-shift", PropertyID::Baseline_Shift},
         {"clip-path", PropertyID::Clip_Path},
         {"clip-rule", PropertyID::Clip_Rule},
         {"color", PropertyID::Color},
@@ -240,8 +241,8 @@ bool Length::parse(std::string_view input, LengthNegativeMode mode)
             m_value = value * dpi / 72.f;
         else
             return false;
-        input.remove_prefix(1);
         m_units = LengthUnits::Px;
+        input.remove_prefix(1);
         break;
     case 'i':
         input.remove_prefix(1);

source/svgproperty.h

@@ -9,6 +9,7 @@ namespace lunasvg {
 
 enum class PropertyID : uint8_t {
     Unknown = 0,
+    Baseline_Shift,
     Class,
     ClipPathUnits,
     Clip_Path,
@@ -327,6 +328,27 @@ class SVGLengthList final : public SVGProperty {
     LengthList m_values;
 };
 
+class BaselineShift {
+public:
+    enum class Type {
+        Baseline,
+        Sub,
+        Super,
+        Length
+    };
+
+    BaselineShift() = default;
+    BaselineShift(Type type) : m_type(type) {}
+    BaselineShift(const Length& length) : m_type(Type::Length), m_length(length) {}
+
+    Type type() const { return m_type; }
+    const Length& length() const { return m_length; }
+
+private:
+    Type m_type{Type::Baseline};
+    Length m_length;
+};
+
 class SVGNumber : public SVGProperty {
 public:
     SVGNumber(PropertyID id, float value)

source/svgtextelement.cpp

@@ -8,7 +8,26 @@ namespace lunasvg {
 
 static float calculateBaselineOffset(const SVGTextPositioningElement* element)
 {
-    return 0.f;
+    const auto& baselineShift = element->baseline_shit();
+    if(baselineShift.type() == BaselineShift::Type::Baseline) {
+        return 0.f;
+    }
+
+    const auto& font = element->font();
+    if(baselineShift.type() == BaselineShift::Type::Sub)
+        return -font.height() / 2.f;
+    if(baselineShift.type() == BaselineShift::Type::Super) {
+        return font.height() / 2.f;
+    }
+
+    const auto& length = baselineShift.length();
+    if(length.units() == LengthUnits::Percent)
+        return length.value() * font.size() / 100.f;
+    if(length.units() == LengthUnits::Ex)
+        return length.value() * font.size() / 2.f;
+    if(length.units() == LengthUnits::Em)
+        return length.value() * font.size();
+    return length.value();
 }
 
 static bool needsTextAnchorAdjustment(const SVGTextPositioningElement* element)
@@ -281,6 +300,7 @@ void SVGTextPositioningElement::layoutElement(const SVGLayoutState& state)
     m_font = state.font();
     m_fill = getPaintServer(state.fill(), state.fill_opacity());
     m_stroke = getPaintServer(state.stroke(), state.stroke_opacity());
+    m_baseline_shit = state.baseline_shit();
     SVGGraphicsElement::layoutElement(state);
 
     LengthContext lengthContext(this);

source/svgtextelement.h

@@ -80,6 +80,7 @@ class SVGTextPositioningElement : public SVGGraphicsElement {
     const Font& font() const { return m_font; }
     const SVGPaintServer& fill() const { return m_fill; }
     const SVGPaintServer& stroke() const { return m_stroke; }
+    const BaselineShift& baseline_shit() const { return m_baseline_shit; }
 
     float stroke_width() const { return m_stroke_width; }
     TextAnchor text_anchor() const { return m_text_anchor; }
@@ -98,6 +99,7 @@ class SVGTextPositioningElement : public SVGGraphicsElement {
     Font m_font;
     SVGPaintServer m_fill;
     SVGPaintServer m_stroke;
+    BaselineShift m_baseline_shit;
 
     float m_stroke_width = 1.f;
     TextAnchor m_text_anchor = TextAnchor::Start;