Please see the Wikipedia page on tree maps for more information on tree maps in general.
By design, tree maps only display values of leaf nodes. Branch nodes are only expressed in the way the leaf nodes are nested. For non-leaf nodes which have significant inherent values, JProfiler constructs synthetic child nodes. In the diagram below, you can see that node A has an inherent value of 20% so that its child nodes have a sum of 80%. To show the 20% inherent value of A in the tree map, a synthetic child node A' with a total value of 20% is created. It is a leaf node and a sibling node of B1 and B2. A' will be shown as a colored rectangle in the tree map while A is only used for determining the geometric arrangement of its child nodes B1, B2 and A'.
The tree map is shown up to a maximum nesting depth of 25 levels. The depth of the particular leaf in the tree map is encoded in its color. The color scale blends blue into yellow, where blue indicates a smaller and yellow a larger depth. The scale is always relative to all currently displayed nodes. For example, if you zoom into a particular area of the tree map, the scale will be re-adjusted so that that the depth of the parent node corresponds to blue. Below the tree map, a legend presents all possible colors as well as the displayed maximum and minimum depths.
Double-clicking on any colored rectangle in the tree map will zoom to the parent node unless the node is
already a top-level node. There are tool bar actions for for
zooming in and
zooming out, as well as as context actions for
showing the actual root of the associated tree.
In order to explore the hierarchical environment of a particular leaf in the tree map, there is a context action "Show In Tree", that switches to the tree view mode and selects the same node there.