#!/usr/bin/env python
# coding: utf-8

# In[1]:


import os
import folium

print(folium.__version__)


# # How to use ImageOverlay

# It may happen that you want to draw an image on you map. Here are example on how to do that.

# ## In importing a PNG
# 
# If you have a static image file on your disk, you can simply draw it on the map in doing:

# In[2]:


Mercator_projection_SW = os.path.join('data', 'Mercator_projection_SW.png')


# In[3]:


from folium import plugins


m = folium.Map([37, 0], zoom_start=1, tiles='stamentoner')

plugins.ImageOverlay(
    image=open(Mercator_projection_SW, 'br'),
    bounds=[[-82, -180], [82, 180]],
    opacity=0.8,
).add_to(m)

folium.LayerControl().add_to(m)

m.save(os.path.join('results', 'ImageOverlay_0.html'))

m


# A few remarks:
# 
# * Note that your image has to be in Mercator projection format.
# 
#   The image we've used is based on https://en.wikipedia.org/wiki/File:Mercator_projection_SW.jpg ; that you can find in wikipedia's article on Mercator Projection (https://en.wikipedia.org/wiki/Mercator_projection).
# 
# 
# * In python 3, be careful to mention explictely the `read mode` of the file (`open(..., 'rb')`). You'll get an error otherwise. 
# 
# You can also provide simply a file name. In this case, the image will not be embedded in folium's output : you'll need to keep it on your server when your map will be deployed.

# In[4]:


Mercator_projection_SW


# In[5]:


import shutil
shutil.copyfile(Mercator_projection_SW, os.path.join('results', 'merc.png'))

m = folium.Map([37, 0], zoom_start=1, tiles='stamentoner')

plugins.ImageOverlay(
    image='merc.png',
    bounds=[[-82, -180], [82, 180]],
    opacity=0.8,
).add_to(m)

folium.LayerControl().add_to(m)


m.save(os.path.join('results', 'ImageOverlay_1.html'))

m


# ## In importing a JPG

# This works exactly the same way if you want to put a JPG intead of a PNG.

# In[6]:


Mercator_projection_SW = os.path.join('data', 'Mercator_projection_SW.jpg')

m = folium.Map([37, 0], zoom_start=1, tiles='stamentoner')

plugins.ImageOverlay(
    image=open(Mercator_projection_SW, 'br'),
    bounds=[[-82, -180], [82, 180]],
    opacity=0.8,
).add_to(m)

folium.LayerControl().add_to(m)

m.save(os.path.join('results', 'ImageOverlay_2.html'))

m


# ## In creating an image with numpy

# Now you may wish to create your own image, based on another python computation.
# For this, you'll need to have numpy installed on your machine.

# Let's creater an image to draw a rectangle in the bounds [[0, -60], [60, 60]]

# In[7]:


import numpy as np

image = np.zeros((61, 61))
image[0, :] = 1.0
image[60, :] = 1.0
image[:, 0] = 1.0
image[:, 60] = 1.0


# We can draw it on the map in using:

# In[8]:


m = folium.Map([37, 0], zoom_start=3)

plugins.ImageOverlay(
    image=image,
    bounds=[[0, -60], [60, 60]],
    colormap=lambda x: (1, 0, 0, x),
).add_to(m)

m


# Note that you need to provide a colormap of the form `lambda x: (R,G,B,A)` where `R,G,B,A` are floats between 0 and 1.

# Now, let's try to add a line at latitude 45°, and add a polyline to verify it's well rendered.  We'll need to specify `origin='lower` to inform folium that the first lines of the array are to be plotted at the bottom of the image (see `numpy.imshow`, it's the same principle).

# In[9]:


image[45, :] = 1.0


m = folium.Map([37, 0], zoom_start=3)

plugins.ImageOverlay(
    image=image,
    bounds=[[0, -60], [60, 60]],
    colormap=lambda x: (1, 0, 0, x),
    origin='lower',
).add_to(m)

folium.PolyLine([[45, -60], [45, 60]]).add_to(m)

m.save(os.path.join('results', 'ImageOverlay_3.html'))

m


# But even with `origin='lower'`, the red line is not at the good latitude. This is due to Mercator projection used in Leaflet (and most other map systems).
# 
# You can read wikipedia's article on Mercator Projection (https://en.wikipedia.org/wiki/Mercator_projection), or simply let folium do the job, in precising that you want the mercator stuff to be handled.

# In[10]:


m = folium.Map([37, 0], zoom_start=3)

folium.PolyLine([[45, -60], [45, 60]]).add_to(m)

plugins.ImageOverlay(
    image=image,
    bounds=[[0, -60], [60, 60]],
    origin='lower',
    colormap=lambda x: (1, 0, 0, x),
    mercator_project=True,
).add_to(m)

m.save(os.path.join('results', 'ImageOverlay_4.html'))

m


# This time, the lines are properly positionned (at the precision of the array).