first step of TSpan

ios/Text/RNSVGTSpan.h

@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) 2015-present, Horcrux.
+ * All rights reserved.
+ *
+ * This source code is licensed under the MIT-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <Foundation/Foundation.h>
+#import "RNSVGPath.h"
+#import "RNSVGTextFrame.h"
+
+@interface RNSVGText : RNSVGPath
+
+@property (nonatomic, assign) CTTextAlignment alignment;
+@property (nonatomic, assign) RNSVGTextFrame textFrame;
+@property (nonatomic, assign) NSString
+
+@end

ios/Text/RNSVGTSpan.m

@@ -0,0 +1,136 @@
+/**
+ * Copyright (c) 2015-present, Horcrux.
+ * All rights reserved.
+ *
+ * This source code is licensed under the MIT-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import "RNSVGText.h"
+#import "RNSVGBezierPath.h"
+#import <CoreText/CoreText.h>
+
+@implementation RNSVGText
+
+static void RNSVGFreeTextFrame(RNSVGTextFrame frame)
+{
+    if (frame.count) {
+        // We must release each line before freeing up this struct
+        for (int i = 0; i < frame.count; i++) {
+            CFRelease(frame.lines[i]);
+        }
+        free(frame.lines);
+        free(frame.widths);
+    }
+}
+
+- (void)setAlignment:(CTTextAlignment)alignment
+{
+    [self invalidate];
+    _alignment = alignment;
+}
+
+- (void)setTextFrame:(RNSVGTextFrame)textFrame
+{
+    RNSVGFreeTextFrame(_textFrame);
+    [self invalidate];
+    _textFrame = textFrame;
+}
+
+- (void)setPath:(NSArray *)path
+{
+    if (path == _path) {
+        return;
+    }
+    [self invalidate];
+    _path = path;
+}
+
+- (void)dealloc
+{
+    RNSVGFreeTextFrame(_textFrame);
+}
+
+- (CGPathRef)getPath:(CGContextRef)context
+{
+    CGMutablePathRef path = CGPathCreateMutable();
+    RNSVGTextFrame frame = self.textFrame;
+    for (int i = 0; i < frame.count; i++) {
+        CGFloat shift;
+        CGFloat width = frame.widths[i];
+        switch (self.alignment) {
+            case kCTTextAlignmentRight:
+                shift = width;
+                break;
+            case kCTTextAlignmentCenter:
+                shift = width / 2;
+                break;
+            default:
+                shift = 0;
+                break;
+        }
+        // We should consider snapping this shift to device pixels to improve rendering quality
+        // when a line has subpixel width.
+        CGAffineTransform offset = CGAffineTransformMakeTranslation(-shift, frame.baseLine + frame.lineHeight * i + (self.path ? -frame.lineHeight : 0));
+        
+        CGMutablePathRef line = [self setLinePath:frame.lines[i]];
+        CGPathAddPath(path, &offset, line);
+        CGPathRelease(line);
+    }
+    
+    return (CGPathRef)CFAutorelease(path);
+}
+
+- (CGMutablePathRef)setLinePath:(CTLineRef)line
+{
+    CGAffineTransform upsideDown = CGAffineTransformMakeScale(1.0, -1.0);
+    CGMutablePathRef path = CGPathCreateMutable();
+    
+    CFArrayRef glyphRuns = CTLineGetGlyphRuns(line);
+    CTRunRef run = CFArrayGetValueAtIndex(glyphRuns, 0);
+    
+    CFIndex runGlyphCount = CTRunGetGlyphCount(run);
+    CGPoint positions[runGlyphCount];
+    CGGlyph glyphs[runGlyphCount];
+    
+    // Grab the glyphs, positions, and font
+    CTRunGetPositions(run, CFRangeMake(0, 0), positions);
+    CTRunGetGlyphs(run, CFRangeMake(0, 0), glyphs);
+    CFDictionaryRef attributes = CTRunGetAttributes(run);
+    
+    CTFontRef runFont = CFDictionaryGetValue(attributes, kCTFontAttributeName);
+    
+    RNSVGBezierPath *bezierPath = [[RNSVGBezierPath alloc] initWithBezierCurves:self.path];
+    
+    for(CFIndex i = 0; i < runGlyphCount; ++i) {
+        CGPathRef letter = CTFontCreatePathForGlyph(runFont, glyphs[i], nil);
+        CGPoint point = positions[i];
+        
+        if (letter) {
+            CGAffineTransform transform;
+            
+            // draw glyphs along path
+            if (self.path) {
+                transform = [bezierPath transformAtDistance:point.x];
+                
+                // break loop if line reaches the end of the Path.
+                if (!transform.a || !transform.d) {
+                    CGPathRelease(letter);
+                    break;
+                }
+                transform = CGAffineTransformScale(transform, 1.0, -1.0);
+            } else {
+                transform = CGAffineTransformTranslate(upsideDown, point.x, point.y);
+            }
+            
+            
+            CGPathAddPath(path, &transform, letter);
+        }
+        
+        CGPathRelease(letter);
+    }
+    
+    return path;
+}
+
+@end