Better fix for the local image working with preload

Examples/AdvancedEffects/src/Transition.js

@@ -6,6 +6,7 @@ class Transition extends React.Component {
     const { width, height, shader, progress, from, to, uniforms } = this.props;
     const scale = React.PixelRatio.get();
     return <GL.View
+      preload
       shader={shader}
       width={width}
       height={height}

Examples/AdvancedEffects/src/Vignette.js

@@ -56,6 +56,7 @@ class Vignette extends React.Component {
     const { width, height, time, source } = this.props;
     const { finger } = this.state;
     return <GL.View
+      preload
       onStartShouldSetResponder={() => true}
       onMoveShouldSetResponder={() => true}
       onResponderMove={this.onResponderMove}

RNGL/GLImage.m

@@ -79,9 +79,10 @@ RCT_NOT_IMPLEMENTED(-init)
     // Load the image (without resizing it)
     
     if (![_src hasPrefix:@"http://"] && ![_src hasPrefix:@"https://"]) {
-      // N.B: in this case we don't trigger onload because image is already loaded.
-      // this behavior is specific to GLCanvas needs
       self.image = [UIImage imageNamed:_src];
+      dispatch_async(dispatch_get_main_queue(), ^{
+        if (_onload) _onload();
+      });
     } else {
       _loading = [_bridge.imageLoader loadImageWithTag:_src
                                        size:CGSizeZero