Speed up performance with caching and low vs high res options

Author: bprobert97

app.py

@@ -51,7 +51,6 @@
 # Streamlit App
 # ───────────────────────────────────────────────
 st.set_page_config(page_title="Glasgow Starplot Viewer", page_icon="🌌")
-
 st.title("🌌 Glasgow Starplot Viewer")
 
 # Sidebar: controls
@@ -60,27 +59,40 @@
 obs_time = st.sidebar.time_input("Time", value=datetime.now().time())
 mag_limit = st.sidebar.slider("Magnitude Limit", 1, 8, 5)
 
-# Session state to persist chart path
+# Extra option: fast vs HD
+quality = st.sidebar.radio("Quality", ["Fast (preview)", "HD (slower)"])
+resolution = 1200 if quality == "Fast (preview)" else 2400
+
+# Session state
 if "chart_bytes" not in st.session_state:
     st.session_state.chart_bytes = None
 
+
+# ───────────────────────────────────────────────
+# Cached chart generator
+# ───────────────────────────────────────────────
+@st.cache_data
+def generate_chart(plot_type, dt, mag_limit, resolution):
+    if plot_type == "Horizon":
+        return make_horizon_plot(dt=dt, mag_limit=mag_limit, resolution=resolution)
+    else:
+        return make_zenith_plot(dt=dt, mag_limit=mag_limit, resolution=resolution)
+
+
 # ───────────────────────────────────────────────
 # Generate chart button
 # ───────────────────────────────────────────────
-# Generate chart
 if st.sidebar.button("Generate Chart"):
     tz = ZoneInfo("Europe/London")
     dt = datetime.combine(obs_date, obs_time).replace(tzinfo=tz)
 
     with st.spinner("Generating chart, please wait..."):
-        if plot_type == "Horizon":
-            img_bytes = make_horizon_plot(dt=dt, mag_limit=mag_limit)
-        else:
-            img_bytes = make_zenith_plot(dt=dt, mag_limit=mag_limit)
+        img_bytes = generate_chart(plot_type, dt, mag_limit, resolution)
 
     st.session_state.chart_bytes = img_bytes
     st.success("✅ Chart generated!")
 
+
 # ───────────────────────────────────────────────
 # Display chart + download button
 # ───────────────────────────────────────────────

scripts/glasgow_horizon.py

@@ -31,7 +31,8 @@
 
 def make_horizon_plot(
     dt: Optional[datetime] = None,
-    mag_limit: int = 5) -> bytes:
+    mag_limit: int = 5,
+    resolution: int = 1600) -> bytes:
     """
     Generate a horizon star plot.
 
@@ -40,6 +41,7 @@ def make_horizon_plot(
     the star plot
     - mag_limit: The magitude limit for stars displayed on
     the star plot.
+    - resolution: image resolution
 
     Returns: The image in bytes
     """
@@ -69,7 +71,7 @@ def make_horizon_plot(
         azimuth=(135, 225),
         observer=observer,
         style=style,
-        resolution=1600,  # reduce size for faster rendering
+        resolution=resolution,
         scale=0.9,
     )
 

scripts/glasgow_zenith.py

@@ -31,7 +31,8 @@
 
 def make_zenith_plot(
     dt: Optional[datetime] = None,
-    mag_limit: int = 5) -> bytes:
+    mag_limit: int = 5,
+    resolution: int = 1600) -> bytes:
     """
     Generate a zenith star plot.
 
@@ -40,6 +41,7 @@ def make_zenith_plot(
     the star plot
     - mag_limit: The magitude limit for stars displayed on
     the star plot.
+    - resolution: image resolution
 
     Returns: The image in bytes
     """
@@ -65,7 +67,7 @@ def make_zenith_plot(
     # Create Zenith plot
     p = ZenithPlot(
         observer=observer,
-        resolution=1600,  # smaller for faster rendering
+        resolution=resolution,
         scale=0.9,
         style=style
     )