Update graphs controllers and views.

controllers/graphs.py

@@ -2,12 +2,10 @@
 
 """
 import base64
-import matplotlib
-matplotlib.use("Agg")
-import matplotlib.pyplot as plt
-import os
+import io
 
 
+from matplotlib.figure import Figure
 from gluon import current
 from gluon.storage import Storage
 from graph_tools import (FROM_TO,
@@ -17,10 +15,6 @@ from graph_tools import (FROM_TO,
                          savefig,
                          stackchart)
 from model_selector import YEAR_SUBMIT
-from uuid import uuid4
-
-
-mplstyle()
 
 
 def dashboard():
@@ -43,8 +37,10 @@ def dashboard():
     selector.Graph_selectorYear_start = ""
     selector.Graph_selectorYear_end = ""
 
-    # figure layout
-    fig, (ax1, ax2) = plt.subplots(nrows=1, ncols=2, sharey=True)
+    # figure layout and style
+    mplstyle()
+    fig = Figure()
+    ax1, ax2 = fig.subplots(nrows=1, ncols=2, sharey=True)
 
     # the number of publications per year except for the current year
     # the starting value is defined in the preferences of the application
@@ -77,8 +73,12 @@ def dashboard():
     linechart(db, selector, target=ax2, title=title)
 
     # delegate the rendering to the view
+    buf = io.BytesIO()
+    fig.savefig(buf, format="svg")
+    data = base64.b64encode(buf.getbuffer()).decode("ascii")
+
     response.view = "graphs/index.html"
-    return dict(data=savefig(fig, "svg"))
+    return dict(data=data)
 
 
 def publications_versus_time():
@@ -91,19 +91,24 @@ def publications_versus_time():
     graph = db.graphs[selector.Graph_selectorId_graphs]
     axis = graph.stack_axis
 
-    # instantiate the graph
-    ax = (stackchart(db, selector) if axis else linechart(db, selector))
-    fig = ax.get_figure()
+    # figure and style
+    mplstyle()
+    fig = Figure()
+    ax = fig.subplots(nrows=1, ncols=1)
+
+    # create the plot
+    if axis:
+        stackchart(db, selector, target=ax)
+    else:
+        linechart(db, selector, target=ax)
 
     # delegate the rendering to the view
     extension = request.extension
     fmt = ("svg" if extension == "html" else extension)
 
-    # base64 string encoding
-    data = savefig(fig, fmt)
-    if fmt in ("pdf", "png"):
-        data = base64.b64encode(data)
-        data = data.decode("ascii")
+    buf = io.BytesIO()
+    fig.savefig(buf, format=fmt)
+    data = base64.b64encode(buf.getbuffer()).decode("ascii")
 
     response.view = "graphs/index.%s" % extension
     return dict(data=data)

views/graphs/index.html

@@ -11,7 +11,7 @@
     data = urllib.parse.quote(data)
 
 }}
-<img src="data:image/svg+xml;utf8,{{=data}}" height=400></img>
+<img src="data:image/svg+xml;base64,{{=data}}" height=400></img>
 {{
     from datetime import datetime