Breaking down chart drawing methods as suggested by Sandor.

MyTracks/src/com/google/android/apps/mytracks/ChartView.java

@@ -510,36 +510,77 @@ public class ChartView extends View {
   @Override
   protected void onDraw(Canvas c) {
     synchronized (data) {
-      if (w != c.getWidth() || h != c.getHeight()) {
+      updateEffectiveDimensionsIfChanged(c);
-        // Dimensions have changed (for example due to orientation change).
+
-        w = c.getWidth();
+      // Keep original state.
-        h = c.getHeight();
-        effectiveWidth = Math.max(0, w - leftBorder - RIGHT_BORDER);
-        effectiveHeight = Math.max(0, h - topBorder - bottomBorder);
-        setUpPath();
-      }
       c.save();
+
       c.drawColor(Color.WHITE);
-      if (data.size() < 1) {
+
+      if (data.isEmpty()) {
+        // No data, draw only axes
         drawXAxis(c);
         drawYAxis(c);
         c.restore();
         return;
       }
 
+      // Clip to graph drawing space
       c.save();
+      clipToGraphSpace(c);
+
+      // Draw the grid and the data on it.
+      drawGrid(c);
+      drawDataSeries(c);
+      drawWaypoints(c);
+
+      // Go back to full canvas drawing.
+      c.restore();
+
+      // Draw the axes and their labels.
+      drawAxesAndLabels(c);
+
+      // Go back to original state.
+      c.restore();
+
+      // Draw the pointer
+      if (showPointer) {
+        drawPointer(c);
+      }
+    }
+  }
+
+  private void clipToGraphSpace(Canvas c) {
     c.clipRect(leftBorder + 1 + getScrollX(), topBorder + 1,
         w - RIGHT_BORDER + getScrollX() - 1, h - bottomBorder - 1);
+  }
 
-      drawGrid(c);
+  private void drawAxesAndLabels(Canvas c) {
+    // Draw the axis and labels.
+    drawXLabels(c);
+    drawXAxis(c);
+    drawSeriesTitles(c);
 
-      // Draw the data series.
+    c.translate(getScrollX(), 0);
+    drawYAxis(c);
+    float density = getContext().getResources().getDisplayMetrics().density;
+    final int spacer = (int) (5 * density);
+    int x = leftBorder - spacer;
     for (ChartValueSeries cvs : series) {
       if (cvs.isEnabled() && cvs.hasData()) {
-          cvs.drawPath(c);
+        x -= drawYLabels(cvs, c, x) + spacer;
+      }
     }
   }
 
+  private void drawPointer(Canvas c) {
+    c.translate(getX(maxX) - pointer.getIntrinsicWidth() / 2,
+                getY(series[0], data.get(data.size() - 1)[1])
+                - pointer.getIntrinsicHeight() / 2 - 12);
+    pointer.draw(c);
+  }
+
+  private void drawWaypoints(Canvas c) {
     // Draw the waypoints.
     for (int i = 1; i < waypoints.size(); i++) {
       final Waypoint waypoint = waypoints.get(i);
@@ -558,30 +599,13 @@ public class ChartView extends View {
       }
       c.restore();
     }
+  }
 
-      c.restore();
+  private void drawDataSeries(Canvas c) {
-
+    // Draw the data series.
-      // Draw the axis and labels.
-      drawXLabels(c);
-      drawXAxis(c);
-      drawSeriesTitles(c);
-
-      c.translate(getScrollX(), 0);
-      drawYAxis(c);
-      float density = getContext().getResources().getDisplayMetrics().density;
-      final int spacer = (int) (5 * density);
-      int x = leftBorder - spacer;
     for (ChartValueSeries cvs : series) {
       if (cvs.isEnabled() && cvs.hasData()) {
-          x -= drawYLabels(cvs, c, x) + spacer;
+        cvs.drawPath(c);
-        }
-      }
-      c.restore();
-      if (showPointer && !data.isEmpty()) {
-        c.translate(getX(maxX) - pointer.getIntrinsicWidth() / 2,
-                    getY(series[0], data.get(data.size() - 1)[1])
-                    - pointer.getIntrinsicHeight() / 2 - 12);
-        pointer.draw(c);
       }
     }
   }
@@ -603,7 +627,7 @@ public class ChartView extends View {
   }
 
   /**
-   * Sets up the path that is used to draw the histogram in onDraw(). The path
+   * Sets up the path that is used to draw the chart in onDraw(). The path
    * needs to be updated any time after the data or histogram dimensions change.
    */
   private void setUpPath() {
@@ -611,10 +635,16 @@ public class ChartView extends View {
       for (ChartValueSeries cvs : series) {
         cvs.getPath().reset();
       }
-      if (data.isEmpty()) {
+
-        return;
+      if (!data.isEmpty()) {
+        drawPath();
+        closePath();
+      }
+    }
   }
 
+  /** Actually draws the data points as a path. */
+  private void drawPath() {
     // All of the data points to the respective series.
     // TODO: Come up with a better sampling than Math.max(1, (maxZoomLevel - zoomLevel + 1) / 2);
     int sampling = 1;
@@ -633,7 +663,10 @@ public class ChartView extends View {
         }
       }
     }
+  }
 
+  /** Closes the drawn path so it looks like a solid graph. */
+  private void closePath() {
     // Close the path.
     int yCorner = topBorder + effectiveHeight;
     int xCorner = getX(data.get(0)[0]);
@@ -652,7 +685,6 @@ public class ChartView extends View {
       }
     }
   }
-  }
 
   /**
    * Find the index of the first point which has a series populated.
@@ -691,10 +723,24 @@ public class ChartView extends View {
     float density = getContext().getResources().getDisplayMetrics().density;
     maxLength = Math.max(maxLength, 1);
     leftBorder = (int) (density * (4 + 8 * maxLength));
-    effectiveWidth = w - leftBorder - RIGHT_BORDER;
     bottomBorder = (int) (density * BOTTOM_BORDER);
     topBorder = (int) (density * TOP_BORDER);
-    effectiveHeight = h - topBorder - bottomBorder;
+    updateEffectiveDimensions();
+  }
+
+  private void updateEffectiveDimensions() {
+    effectiveWidth = Math.max(0, w - leftBorder - RIGHT_BORDER);
+    effectiveHeight = Math.max(0, h - topBorder - bottomBorder);
+  }
+
+  private void updateEffectiveDimensionsIfChanged(Canvas c) {
+    if (w != c.getWidth() || h != c.getHeight()) {
+      // Dimensions have changed (for example due to orientation change).
+      w = c.getWidth();
+      h = c.getHeight();
+      updateEffectiveDimensions();
+      setUpPath();
+    }
   }
 
   private int getX(double distance) {
@@ -795,10 +841,6 @@ public class ChartView extends View {
   }
 
   private void drawGrid(Canvas c) {
-    if (data.isEmpty()) {
-      return;
-    }
-
     float rightEdge = getX(maxX);
     for (int i = 1; i < MAX_INTERVALS; ++i) {
       int y = i * effectiveHeight / MAX_INTERVALS + topBorder;