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+# Pie Charts
+Like all other primary chart and graph classes in Androidplot, `PieChart` is simply a composition
+of widgets along with convenience methods.  The real work is actually done by `PieWidget`.
+
+![image](images/screens/pie_horiz.png)
+
+# Basic Usage
+Pie charts are composed of one or more values called Segments which combines a vaue and a label:
+
+```java
+Segment segment = new Segment("my segment", 10);
+```
+
+Displaying a `Segment` to a pie chart also requires a `SegmentFormatter`.  `SegmentFormatter` is what defines
+the visual characteristics of the associated `Segment`; color, border thickness, 
+segment offset, label text style (if any) etc.  The below code instantiates a new `SegmentFormatter`
+with a segment color of red:
+
+```java
+SegmentFormatter formatter = new SegmentFormatter(Color.RED);
+```
+
+Finally, the `Segment` must be added to the pie chart along with it's `SegmentFormatter`:
+
+```java
+pie.addSegment(segment, formatter);
+```
+
+# Donut Size
+By default, `PieChart` draws it's self as a ring.  The amount of empty space in the middle of
+the pie is called the `donutSize`.  Setting a `donutSize` of 0 causes the `PieChart` to draw it's 
+self as a full circle.
+
+![image](images/pie_donut_size.png)
+
+Setting `donutSize` programmatically:
+
+```java
+// draw pie with an empty inner space radius equal to 50% of the pie's radius.
+pieRenderer.setDonutSize(0.5, PieRenderer.DonutMode.PERCENT);
+
+// donut size may also be expressed in pixels:
+pieRenderer.setDonutSize(PixelUtils.dpToPix(30), PieRenderer.DonutMode.PIXELS);
+```
+
+# Segment Orientation
+Each `Segment` is drawn in the order it was added to the `PieChart` clockwise from `startDegs` 
+which by default is 0.
+
+![image](images/pie_orientation.png)
+
+Using the image above, to move Segment0 to the Northeast quadrant
+of the pie (currently occupied by Segment3) `startDeg` should be set to 90:
+
+```java
+pie.getRenderer(PieRenderer.class).setStartDegs(90);
+```
+# Extent
+The `extentDegs` value determines the number of degrees running clockwise from `startDegs` that 
+represent 100% of the pie chart.  The formal description is a little obtuse but is easy to understand 
+through example.  You could for instance use `extentDegs` in conjunction with `startDegs` to represent 
+the full pie as a gauge:
+
+```java
+// start the first segment at 5 degrees;
+pie.getRenderer(PieRenderer.class).setStartDegs(165);
+pie.getRenderer(PieRenderer.class).setExtentDegs(150);
+```
+Which produces a pie chart profile like this:
+
+![image](images/pie_extent.png)
+
+# SegmentFormatter
+As mentioned above, `SegmentFormatter` defines how a `Segment` is visually represented in a `PieChart`.
+In addition to basic color / border line styling params, there are several parameters available
+to visually distinguish a segment:
+
+## Offset
+Value in pixels used to "shift" the position of the segment outward relative to the center of the `PieChart`.
+The visual effect is equivalent to cutting up a pie and dragging one piece out and away from the rest of the pie:
+
+![image](images/pie_offset.png)
+
+## RadialInset
+Value in degrees used to shrink the radial edges of the segment inward.  The visual effect is equivalent
+to shaving the edges off of a slice of pie, resulting in a narrower slice of pie:
+
+![image](images/pie_radial_inset.png)
+
+## InnerInset
+Value in pixels used to shrink the inner section of the pie.  The visual effect is equivalent to
+cutting the tip off of a slice of pie:
+
+![image](images/pie_inner_inset.png)
+
+## OuterInset
+Value in pixels used to shrink the outer edge of the pie.  The visual effect is equivalent to evenly
+shaving the crust off of a slice of pie:
+
+![image](images/pie_outer_inset.png)
+
+See the DemoApp's 
+[pie chart example source](../demoapp/src/main/java/com/androidplot/demos/SimplePieChartActivity.java) for a comprehensive usage example.
+