Improve text subtree advance calculation caching

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

@@ -108,6 +108,9 @@ class TSpanView extends TextView {
     }
 
     double getSubtreeTextChunksTotalAdvance(Paint paint) {
+        if (!Double.isNaN(cachedAdvance)) {
+            return cachedAdvance;
+        }
         double advance = 0;
 
         if (mContent == null) {
@@ -118,6 +121,7 @@ class TSpanView extends TextView {
                     advance += text.getSubtreeTextChunksTotalAdvance(paint);
                 }
             }
+            cachedAdvance = advance;
             return advance;
         }
 
@@ -125,6 +129,7 @@ class TSpanView extends TextView {
         final int length = line.length();
 
         if (length == 0) {
+            cachedAdvance = 0;
             return advance;
         }
 
@@ -149,7 +154,8 @@ class TSpanView extends TextView {
             paint.setLetterSpacing((float)(letterSpacing / (font.fontSize * mScale)));
         }
 
-        return paint.measureText(line);
+        cachedAdvance = paint.measureText(line);
+        return cachedAdvance;
     }
 
     @SuppressWarnings("ConstantConditions")

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

@@ -50,11 +50,15 @@ class TextView extends GroupView {
         if (mPath == null) {
             return;
         }
-        cachedAdvance = Double.NaN;
         super.invalidate();
         clearChildCache();
     }
 
+    void clearCache() {
+        cachedAdvance = Double.NaN;
+        super.clearCache();
+    }
+
     @ReactProp(name = "textLength")
     public void setTextLength(Dynamic length) {
         mTextLength = SVGLength.from(length);

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

@@ -101,7 +101,7 @@ abstract public class VirtualView extends ReactViewGroup {
         super.invalidate();
     }
 
-    private void clearCache() {
+    void clearCache() {
         canvasDiagonal = -1;
         canvasHeight = -1;
         canvasWidth = -1;

ios/RNSVGNode.h

@@ -118,4 +118,6 @@ extern CGFloat const RNSVG_DEFAULT_FONT_SIZE;
 
 - (void)clearChildCache;
 
+- (void)clearPath;
+
 @end

ios/Text/RNSVGTSpan.m

@@ -25,6 +25,7 @@ static CGFloat RNSVGTSpan_radToDeg = 180 / (CGFloat)M_PI;
     BOOL isClosed;
     NSMutableArray *emoji;
     NSMutableArray *emojiTransform;
+    CGFloat cachedAdvance;
 }
 
 - (id)init
@@ -41,6 +42,12 @@ static CGFloat RNSVGTSpan_radToDeg = 180 / (CGFloat)M_PI;
     return self;
 }
 
+- (void)clearPath
+{
+    [super clearPath];
+    cachedAdvance = NAN;
+}
+
 - (void)setContent:(NSString *)content
 {
     if ([content isEqualToString:_content]) {
@@ -102,6 +109,9 @@ static CGFloat RNSVGTSpan_radToDeg = 180 / (CGFloat)M_PI;
 
 - (CGFloat)getSubtreeTextChunksTotalAdvance
 {
+    if (!isnan(cachedAdvance)) {
+        return cachedAdvance;
+    }
     CGFloat advance = 0;
 
     NSString *str = self.content;
@@ -112,6 +122,7 @@ static CGFloat RNSVGTSpan_radToDeg = 180 / (CGFloat)M_PI;
                 advance += [text getSubtreeTextChunksTotalAdvance];
             }
         }
+        cachedAdvance = advance;
         return advance;
     }
 
@@ -155,6 +166,7 @@ static CGFloat RNSVGTSpan_radToDeg = 180 / (CGFloat)M_PI;
 
     CGRect textBounds = CTLineGetBoundsWithOptions(line, 0);
     CGFloat textMeasure = CGRectGetWidth(textBounds);
+    cachedAdvance = textMeasure;
     return textMeasure;
 }
 

ios/Text/RNSVGText.m

@@ -26,11 +26,16 @@
     if (self.dirty || self.merging) {
         return;
     }
-    cachedAdvance = NAN;
     [super invalidate];
     [self clearChildCache];
 }
 
+- (void)clearPath
+{
+    [super clearPath];
+    cachedAdvance = NAN;
+}
+
 - (void)setTextLength:(RNSVGLength *)textLength
 {
     if ([textLength isEqualTo:_textLength]) {