def add_offsetboxes(ax, size=10, margin=.1, color='black'):
    """
    Surround ax with OffsetBoxes
    """
    m, mp = margin, 1+margin
    anchor_points = [(-m, -m), (-m, .5), (-m, mp),
                     (mp, .5), (.5, mp), (mp, mp),
                     (.5, -m), (mp, -m), (.5, -m)]
    for point in anchor_points:
        da = DrawingArea(size, size)
        background = Rectangle((0, 0), width=size,
                               height=size,
                               facecolor=color,
                               edgecolor='None',
                               linewidth=0,
                               antialiased=False)
        da.add_artist(background)

        anchored_box = AnchoredOffsetbox(
            loc='center',
            child=da,
            pad=0.,
            frameon=False,
            bbox_to_anchor=point,
            bbox_transform=ax.transAxes,
            borderpad=0.)
        ax.add_artist(anchored_box)
    return anchored_box 

def add_segmented_colorbar(da, colors, direction):
    """
    Add 'non-rastered' colorbar to DrawingArea
    """
    nbreak = len(colors)
    if direction == 'vertical':
        linewidth = da.height/nbreak
        verts = [None] * nbreak
        x1, x2 = 0, da.width
        for i, color in enumerate(colors):
            y1 = i * linewidth
            y2 = y1 + linewidth
            verts[i] = ((x1, y1), (x1, y2), (x2, y2), (x2, y1))
    else:
        linewidth = da.width/nbreak
        verts = [None] * nbreak
        y1, y2 = 0, da.height
        for i, color in enumerate(colors):
            x1 = i * linewidth
            x2 = x1 + linewidth
            verts[i] = ((x1, y1), (x1, y2), (x2, y2), (x2, y1))

    coll = mcoll.PolyCollection(verts,
                                facecolors=colors,
                                linewidth=0,
                                antialiased=False)
    da.add_artist(coll) 

def add_offsetboxes(ax, size=10, margin=.1, color='black'):
    """
    Surround ax with OffsetBoxes
    """
    m, mp = margin, 1+margin
    anchor_points = [(-m, -m), (-m, .5), (-m, mp),
                     (mp, .5), (.5, mp), (mp, mp),
                     (.5, -m), (mp, -m), (.5, -m)]
    for point in anchor_points:
        da = DrawingArea(size, size)
        background = Rectangle((0, 0), width=size,
                               height=size,
                               facecolor=color,
                               edgecolor='None',
                               linewidth=0,
                               antialiased=False)
        da.add_artist(background)

        anchored_box = AnchoredOffsetbox(
            loc='center',
            child=da,
            pad=0.,
            frameon=False,
            bbox_to_anchor=point,
            bbox_transform=ax.transAxes,
            borderpad=0.)
        ax.add_artist(anchored_box)
    return anchored_box 

def add_offsetboxes(ax, size=10, margin=.1, color='black'):
    """
    Surround ax with OffsetBoxes
    """
    m, mp = margin, 1+margin
    anchor_points = [(-m, -m), (-m, .5), (-m, mp),
                     (mp, .5), (.5, mp), (mp, mp),
                     (.5, -m), (mp, -m), (.5, -m)]
    for point in anchor_points:
        da = DrawingArea(size, size)
        background = Rectangle((0, 0), width=size,
                               height=size,
                               facecolor=color,
                               edgecolor='None',
                               linewidth=0,
                               antialiased=False)
        da.add_artist(background)

        anchored_box = AnchoredOffsetbox(
            loc=10,
            child=da,
            pad=0.,
            frameon=False,
            bbox_to_anchor=point,
            bbox_transform=ax.transAxes,
            borderpad=0.)
        ax.add_artist(anchored_box)
    return anchored_box 

def add_interpolated_colorbar(da, colors, direction):
    """
    Add 'rastered' colorbar to DrawingArea
    """
    # Special case that arises due to not so useful
    # aesthetic mapping.
    if len(colors) == 1:
        colors = [colors[0], colors[0]]

    # Number of horizontal egdes(breaks) in the grid
    # No need to create more nbreak than colors, provided
    # no. of colors = no. of breaks = no. of cmap colors
    # the shading does a perfect interpolation
    nbreak = len(colors)

    if direction == 'vertical':
        mesh_width = 1
        mesh_height = nbreak-1
        linewidth = da.height/mesh_height
        # Construct rectangular meshgrid
        # The values(Z) at each vertex are just the
        # normalized (onto [0, 1]) vertical distance
        x = np.array([0, da.width])
        y = np.arange(0, nbreak) * linewidth
        X, Y = np.meshgrid(x, y)
        Z = Y/y.max()
    else:
        mesh_width = nbreak-1
        mesh_height = 1
        linewidth = da.width/mesh_width
        x = np.arange(0, nbreak) * linewidth
        y = np.array([0, da.height])
        X, Y = np.meshgrid(x, y)
        Z = X/x.max()

    # As a 2D coordinates array
    coordinates = np.zeros(
        ((mesh_width+1)*(mesh_height+1), 2),
        dtype=float)
    coordinates[:, 0] = X.ravel()
    coordinates[:, 1] = Y.ravel()

    cmap = ListedColormap(colors)
    coll = mcoll.QuadMesh(mesh_width, mesh_height,
                          coordinates,
                          antialiased=False,
                          shading='gouraud',
                          linewidth=0,
                          cmap=cmap,
                          array=Z.ravel())
    da.add_artist(coll)