fix: #179 Same watermark image is behaving differently on ANDROID and…

… IOS when use given position enum

fix #179 Same watermark image is behaving differently on ANDROID and IOS when use given position enum

ios/RCTImageMarker/ImageMarker.swift

@@ -273,7 +273,7 @@ public final class ImageMarker: NSObject, RCTBridgeModule {
 
     func markImage(with image: UIImage, waterImages: [UIImage], options: MarkImageOptions) -> UIImage? {
 
-        var bg = image;
+        let bg = image;
         let w = bg.size.width
         let h = bg.size.height
         UIGraphicsBeginImageContextWithOptions(bg.size, false, options.backgroundImage.scale)
@@ -323,39 +323,43 @@ public final class ImageMarker: NSObject, RCTBridgeModule {
                     case .topLeft:
                         rect = CGRect(origin: CGPoint(x: 20, y: 20), size: size)
                     case .topCenter:
-                        rect = CGRect(origin: CGPoint(x: (w - size.width) / 2, y: 20), size: size)
+                        rect = CGRect(origin: CGPoint(x: (w - ww) / 2, y: 20), size: size)
                     case .topRight:
-                        rect = CGRect(origin: CGPoint(x: w - size.width - 20, y: 20), size: size)
+                        rect = CGRect(origin: CGPoint(x: w - ww - 20, y: 20), size: size)
                     case .bottomLeft:
-                        rect = CGRect(origin: CGPoint(x: 20, y: h - size.height - 20), size: size)
+                        rect = CGRect(origin: CGPoint(x: 20, y: h - wh - 20), size: size)
                     case .bottomCenter:
-                        rect = CGRect(origin: CGPoint(x: (w - size.width) / 2, y: h - size.height - 20), size: size)
+                        rect = CGRect(origin: CGPoint(x: (w - ww) / 2, y: h - wh - 20), size: size)
                     case .bottomRight:
-                        rect = CGRect(origin: CGPoint(x: w - size.width - 20, y: h - size.height - 20), size: size)
+                        rect = CGRect(origin: CGPoint(x: w - ww - 20, y: h - wh - 20), size: size)
                     case .center:
-                        rect = CGRect(origin: CGPoint(x: (w - size.width) / 2, y: (h - size.height) / 2), size: size)
+                        rect = CGRect(origin: CGPoint(x: (w - ww) / 2, y: (h - wh) / 2), size: size)
                     default:
                         rect = CGRect(origin: CGPoint(x: 20, y: 20), size: size)
                     }
             } else {
-                rect = CGRect(x: Utils.parseSpreadValue(v: watermarkOptions.X, relativeTo: w) ?? 20, y: Utils.parseSpreadValue(v: watermarkOptions.Y, relativeTo: h) ?? 20, width: CGFloat(ww), height: CGFloat(wh))
+                rect = CGRect(x: Utils.parseSpreadValue(v: watermarkOptions.X, relativeTo: w) ?? 20, y: Utils.parseSpreadValue(v: watermarkOptions.Y, relativeTo: h) ?? 20, width: diagonal, height: diagonal)
             }
 
             UIGraphicsBeginImageContextWithOptions(CGSize(width: diagonal, height: diagonal), false, 1)
             let markerContext = UIGraphicsGetCurrentContext()
+            markerContext?.setFillColor(UIColor.red.cgColor)
+            markerContext?.fill(rect)
             markerContext?.saveGState()
-
+            
             if watermarkOptions.imageOption.alpha != 1.0 {
                 markerContext?.beginTransparencyLayer(auxiliaryInfo: nil)
                 markerContext?.setAlpha(watermarkOptions.imageOption.alpha)
                 markerContext?.setBlendMode(.multiply)
                 let markerImage = markerImg.rotatedImageWithTransform(watermarkOptions.imageOption.rotate)
-                markerContext?.draw(markerImage.cgImage!, in: CGRect(origin: .zero, size: CGSize(width: diagonal, height: diagonal)))
+                let originPoint = CGPoint(x: 0, y: rect.height - markerImage.size.height)
+                markerContext?.draw(markerImage.cgImage!, in: CGRect(origin: originPoint, size: CGSize(width: markerImage.size.width, height: markerImage.size.height)))
                 markerContext?.endTransparencyLayer()
 
             } else {
                 let markerImage = markerImg.rotatedImageWithTransform(watermarkOptions.imageOption.rotate)
-                markerContext?.draw(markerImage.cgImage!, in: CGRect(origin: .zero, size: CGSize(width: diagonal, height: diagonal)))
+                let originPoint = CGPoint(x: 0, y: rect.height - markerImage.size.height)
+                markerContext?.draw(markerImage.cgImage!, in: CGRect(origin: originPoint, size: CGSize(width: markerImage.size.width, height: markerImage.size.height)))
             }
             markerContext?.restoreGState()