Fix text-anchor subtree advance/extent calculation for letter-spacing

Related to
https://github.com/react-native-community/react-native-svg/issues/570

android/src/main/java/com/horcrux/svg/GlyphContext.java

@@ -19,7 +19,7 @@ import javax.annotation.Nullable;
 class GlyphContext {
 
     // Current stack (one per node push/pop)
-    private final ArrayList<FontData> mFontContext = new ArrayList<>();
+    final ArrayList<FontData> mFontContext = new ArrayList<>();
 
     // Unique input attribute lists (only added if node sets a value)
     private final ArrayList<SVGLength[]> mXsContext = new ArrayList<>();

android/src/main/java/com/horcrux/svg/TSpanView.java

@@ -146,6 +146,7 @@ class TSpanView extends TextView {
                 String disableDiscretionaryLigatures = "'liga' 0, 'clig' 0, 'dlig' 0, 'hlig' 0, 'cala' 0, ";
                 paint.setFontFeatureSettings(defaultFeatures + disableDiscretionaryLigatures + font.fontFeatureSettings);
             }
+            paint.setLetterSpacing((float)(letterSpacing / (font.fontSize * mScale)));
         }
 
         return paint.measureText(line);
@@ -610,7 +611,7 @@ class TSpanView extends TextView {
                     // this will just retrieve the bounding rect for 'x'
                     paint.getTextBounds("x", 0, 1, bounds);
                     int xHeight = bounds.height();
-                    baselineShift = xHeight / 2;
+                    baselineShift = xHeight / 2.0;
                     break;
 
                 case central:
@@ -738,7 +739,6 @@ class TSpanView extends TextView {
         final Matrix end = new Matrix();
 
         final float[] startPointMatrixData = new float[9];
-        final float[] midPointMatrixData = new float[9];
         final float[] endPointMatrixData = new float[9];
 
         emoji.clear();
@@ -1008,6 +1008,9 @@ class TSpanView extends TextView {
         paint.setTypeface(typeface);
         paint.setTextSize((float) fontSize);
         paint.setTextAlign(Paint.Align.LEFT);
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            paint.setLetterSpacing(0);
+        }
 
         // Do these have any effect for anyone? Not for me (@msand) at least.
         // paint.setUnderlineText(underlineText);

android/src/main/java/com/horcrux/svg/TextView.java

@@ -213,23 +213,17 @@ class TextView extends GroupView {
 
     TextView getTextAnchorRoot() {
         GlyphContext gc = getTextRootGlyphContext();
-        FontData font = gc.getFont();
-        TextProperties.TextAnchor textAnchor = font.textAnchor;
-        if (textAnchor == TextProperties.TextAnchor.start) {
-            return this;
-        }
+        ArrayList<FontData> font = gc.mFontContext;
+        TextView node = this;
         ViewParent parent = this.getParent();
-        if (parent instanceof TextView) {
-            TextView parentText = (TextView)parent;
-            GlyphContext parentGc = parentText.getGlyphContext();
-            FontData parentFont = parentGc.getFont();
-            if (parentFont.textAnchor == TextProperties.TextAnchor.start) {
-                return this;
-            } else {
-                return parentText.getTextAnchorRoot();
+        for (int i = font.size() - 1; i >= 0; i--) {
+            if (!(parent instanceof TextView) || font.get(i).textAnchor == TextProperties.TextAnchor.start) {
+                return node;
             }
+            node = (TextView) parent;
+            parent = node.getParent();
         }
-        return this;
+        return node;
     }
 
     double getSubtreeTextChunksTotalAdvance(Paint paint) {
@@ -240,7 +234,7 @@ class TextView extends GroupView {
         for (int i = 0; i < getChildCount(); i++) {
             View child = getChildAt(i);
             if (child instanceof TextView) {
-                TextView text = (TextView)child;
+                TextView text = (TextView) child;
                 advance += text.getSubtreeTextChunksTotalAdvance(paint);
             }
         }

ios/Text/RNSVGTSpan.m

@@ -121,7 +121,7 @@ static CGFloat RNSVGTSpan_radToDeg = 180 / (CGFloat)M_PI;
     RNSVGFontData* font = [gc getFont];
 
     CGFloat letterSpacing = font->letterSpacing;
-    bool autoKerning = !font->manualKerning;
+    CGFloat kerning = font->kerning;
 
     bool allowOptionalLigatures = letterSpacing == 0 && font->fontVariantLigatures == RNSVGFontVariantLigaturesNormal;
 
@@ -133,19 +133,18 @@ static CGFloat RNSVGTSpan_radToDeg = 180 / (CGFloat)M_PI;
     if (fontRef != nil) {
         attrs[NSFontAttributeName] = (__bridge id)fontRef;
     }
-    if (!autoKerning) {
-        NSNumber *noAutoKern = [NSNumber numberWithFloat:0.0f];
+    float kern = (float)(letterSpacing + kerning);
+    NSNumber *kernAttr = [NSNumber numberWithFloat:kern];
 
 #if DTCORETEXT_SUPPORT_NS_ATTRIBUTES
-        if (___useiOS6Attributes)
-        {
-            [attrs setObject:noAutoKern forKey:NSKernAttributeName];
-        }
-        else
+    if (___useiOS6Attributes)
+    {
+        [attrs setObject:kernAttr forKey:NSKernAttributeName];
+    }
+    else
 #endif
-        {
-            [attrs setObject:noAutoKern forKey:(id)kCTKernAttributeName];
-        }
+    {
+        [attrs setObject:kernAttr forKey:(id)kCTKernAttributeName];
     }
 
     attributes = (__bridge CFDictionaryRef)attrs;