Image operations: update existing preview in new arrives

There was a bug:
1. insert very big image
2. rotate and quickly after that rotate again but hold
   mouse click so you will still see the preview
result: before patch preview was disappearing
        after patch preview is updated

Signed-off-by: Szymon Kłos <szymon.klos@collabora.com>
Change-Id: Ieb343a371816fe14e4c65f862abf1e55bf36de1b

browser/src/layer/tile/CanvasTileLayer.js

@@ -1967,8 +1967,11 @@ L.CanvasTileLayer = L.Layer.extend({
 			if (extraInfo.id) {
 				this._map._cacheSVG[extraInfo.id] = textMsg;
 			}
+			var wasVisibleSVG = this._graphicMarker._hasVisibleEmbeddedSVG();
 			this._graphicMarker.removeEmbeddedSVG();
 			this._graphicMarker.addEmbeddedSVG(textMsg);
+			if (wasVisibleSVG)
+				this._graphicMarker._showEmbeddedSVG();
 		}
 	},
 

browser/src/layer/vector/SVGGroup.js

@@ -254,6 +254,16 @@ L.SVGGroup = L.Layer.extend({
 		});
 	},
 
+	_hasVisibleEmbeddedSVG: function () {
+		var result = false;
+		this._forEachSVGNode(function (svgNode) {
+			if (svgNode.getAttribute('opacity') !== 0)
+				result = true;
+		});
+
+		return result;
+	},
+
 	_transform: function(matrix) {
 		if (this._renderer) {
 			if (matrix) {