feat: improve marker rendering

Author: msand

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

@@ -132,14 +132,15 @@ void renderMarker(Canvas canvas, Paint paint, float opacity, RNSVGMarkerPosition
 
         Point origin = position.origin;
         Matrix transform = new Matrix();
-        transform.setTranslate((float)origin.x, (float)origin.y);
+        transform.setTranslate((float)origin.x * mScale, (float)origin.y * mScale);
 
         double markerAngle = "auto".equals(mOrient) ? -1 : Double.parseDouble(mOrient);
-        transform.postRotate((float)(markerAngle == -1 ? position.angle : markerAngle));
+        float degrees = 180 + (float) (markerAngle == -1 ? position.angle : markerAngle);
+        transform.preRotate(degrees);
 
         boolean useStrokeWidth = "strokeWidth".equals(mMarkerUnits);
         if (useStrokeWidth) {
-            transform.postScale(strokeWidth, strokeWidth);
+            transform.preScale(strokeWidth, strokeWidth);
         }
 
         canvas.concat(transform);

ios/Elements/RNSVGMarker.m

@@ -150,6 +150,12 @@ - (void)setMeetOrSlice:(RNSVGVBMOS)meetOrSlice
     _meetOrSlice = meetOrSlice;
 }
 
+static CGFloat RNSVG_degToRad = (CGFloat)M_PI / 180;
+
+double deg2rad(CGFloat deg) {
+    return deg * RNSVG_degToRad;
+}
+
 - (void)renderMarker:(CGContextRef)context rect:(CGRect)rect position:(RNSVGMarkerPosition*)position strokeWidth:(CGFloat)strokeWidth
 {
     CGContextSaveGState(context);
@@ -158,7 +164,9 @@ - (void)renderMarker:(CGContextRef)context rect:(CGRect)rect position:(RNSVGMark
     CGAffineTransform transform = CGAffineTransformMakeTranslation(origin.x, origin.y);
 
     float markerAngle = [@"auto" isEqualToString:_orient] ? -1 : [_orient doubleValue];
-    transform = CGAffineTransformRotate(transform, markerAngle == -1 ? [position angle] : markerAngle);
+    float angle = 180 + (markerAngle == -1 ? [position angle] : markerAngle);
+    float rad = deg2rad(angle);
+    transform = CGAffineTransformRotate(transform, rad);
 
     bool useStrokeWidth = [@"strokeWidth" isEqualToString:_markerUnits];
     if (useStrokeWidth) {

ios/Utils/RNSVGMarkerPosition.h

@@ -8,7 +8,7 @@ typedef enum RNSVGMarkerType {
     kEndMarker
 } RNSVGMarkerType;
 
-#define RNSVGNULLPOINT CGRectNull.origin
+#define RNSVGZEROPOINT CGRectZero.origin
 
 @interface RNSVGMarkerPosition : NSObject
 

ios/Utils/RNSVGMarkerPosition.m

@@ -8,7 +8,7 @@ - (instancetype) init
     if (self)
     {
         _type = kStartMarker;
-        _origin = RNSVGNULLPOINT;
+        _origin = RNSVGZEROPOINT;
         _angle = 0;
     }
     return self;
@@ -25,8 +25,8 @@ + (instancetype) markerPosition:(RNSVGMarkerType)type origin:(CGPoint)origin ang
 + (NSArray<RNSVGMarkerPosition*>*) fromCGPath:(CGPathRef)path {
     positions_ = [[NSMutableArray alloc] init];
     element_index_ = 0;
-    origin_ = RNSVGNULLPOINT;
-    subpath_start_ = RNSVGNULLPOINT;
+    origin_ = RNSVGZEROPOINT;
+    subpath_start_ = RNSVGZEROPOINT;
     CGPathApply(path, (__bridge void *)positions_, UpdateFromPathElement);
     PathIsDone();
     return positions_;