Labeling Wedges of a Pie Chart

Pie wedge labels display the data value and percentage of the total by default. A variety of other choices are available. The trick is to set the label style for each data item. In the loop in which the data are added to the graph, set the annotations and the desired label style. For example,

 

m_Graph.GetGroup(g)->GetIndex(x)->GetStyle()-> SetLabelStyle(CX_LABEL_TEXT);

The various label style choices are described below:

Label styles

Wedge label style

Description

CX_LABEL_NONE

  

CX_LABEL_AUTOMATIC

Dynamic labels uses an appropriate label style from one of the label styles below.

CX_LABEL_VALUE

Data value

CX_LABEL_PERCENT

Data value as % of total

CX_LABEL_TEXT

Data object’s annotation

CX_LABEL_VALUE_PERCENT

Combination of above

CX_LABEL_TEXT_VALUE

 

CX_LABEL_TEXT_PERCENT

 

CX_LABEL_TEXT_VALUE_PERCENT

 

To explode a pie wedge from the pie:

  • Call SetHighlight() on the style member of the data object:

    m_Graph.GetSafeData(index,group)->GetStyle()-> SetHighlight(CX_HIGHLIGHT_MEDIUM);

  • The highlight styles explode the wedge from the pie. CX_HIGHLIGHT_SMALL, CX_HIGHLIGHT_MEDIUM or CX_HIGHLIGHT_AUTOMATIC, and CX_HIGHLIGHT_LARGE displace the wedge by 15%, 20%, and 30% of the pie’s radius, respectively.

 

To place wedge labels inside of pie (instead of surrounding it), call SetObjectInsideView(TRUE) on the display’s style.

 

pDisplay->GetStyle()->SetObjectInsideView(TRUE);

To hide the labels of small wedges, specify a size limit using SetUseMaxScale(TRUE) and SetMinRangeX(). Data values (wedges) smaller than this limit are not labeled. The limit can be an absolute value or a percentage of the total of values in the pie. Negative values between 0 and -100 are interpreted as percentages.

 

pS->SetUseMaxScale(TRUE);

pD->SetMinRangeX(600.); // don't label wedges less than 600

or

 

pD->SetMinRangeX(-10.); // don't label wedges that are less than

// 10% of total