add width to css for FloatImage (#1570)

* add width to css for FloatImage

Allows for setting relative size of an image without changing default behavior,  fixes #1001 imo...

* forgot to declare in __init__

ok, my bad that was extremely careless... I hope it passes this time

* added style test template update

asserts a 20% image width

Author: beautah

folium/plugins/float_image.py

@@ -12,6 +12,7 @@ class FloatImage(MacroElement):
                         position:absolute;
                         bottom:{{this.bottom}}%;
                         left:{{this.left}}%;
+                        width:{{this.width}}%;
                         }
                 </style>
             {% endmacro %}
@@ -24,9 +25,10 @@ class FloatImage(MacroElement):
             {% endmacro %}
             """)
 
-    def __init__(self, image, bottom=75, left=75):
+    def __init__(self, image, bottom=75, left=75, width=100):
         super(FloatImage, self).__init__()
         self._name = 'FloatImage'
         self.image = image
         self.bottom = bottom
         self.left = left
+        self.width = width

tests/plugins/test_float_image.py

@@ -13,7 +13,7 @@
 def test_float_image():
     m = folium.Map([45., 3.], zoom_start=4)
     url = 'https://raw.githubusercontent.com/SECOORA/static_assets/master/maps/img/rose.png'
-    szt = plugins.FloatImage(url, bottom=60, left=70)
+    szt = plugins.FloatImage(url, bottom=60, left=70, width=20)
     m.add_child(szt)
     m._repr_html_()
 
@@ -35,6 +35,7 @@ def test_float_image():
                 position:absolute;
                 bottom:60%;
                 left:70%;
+                width:20%;
                 }
         </style>
     """)