When using Style to format a drawing it is a really bad idea to use the same color for objects that is used for the background color. It can also be a bad idea to use transparent color. This topic illustrates why.
Consider the map seen above, which includes a drawing called Regions that shows French regions as areas. The drawing appears to be missing some regions.
A second drawing called Roads shows a selection of roads in France as lines. We double-click the Roads layer tab to turn on that layer for display.
Next we will drag the Roads tab to the right of the Regions tab, to move the Roads layer below the Regions layer.
The effect is perplexing, as roads are seen in some places where there appear to be no regions but they are not seen in others.
If we click on the Regions tab to make the Regions drawing the active layer and then click on the Style pane, we can see what is going on.
In the Style pane we click on the Fill Color button for areas to see the thematic format it uses. The palette shows that some regions are colored using white color while others are colored using transparent (the hatch pattern) color.
In both cases, the regions will be invisible against a white background. The regions which are transparent will allow roads in a layer below them to be seen while those regions which are white will be opaque and will not allow the roads below them to be seen.
In the above illustration we have used the Layers pane to specify a light beige background for the map. We have also included a drawing layer called Pattern that contains a square area which is formatted using an area style that is a diagonal hatch pattern. The beige background and the hatch pattern help us see where the white regions are located and where the transparent regions are located, as shown by their white borders.
As bad an idea as it may be to color objects in a drawing using the same color as the background, at least we can see such objects by changing the background color. Usually it is an even worse idea to color objects using transparent color because they cannot be seen at all even if we change the background color. We can only infer they are there by ctrl-clicking on them to select them as seen in the illustration above. When objects are selected in a drawing they are colored in red selection color that overrides transparent color formatting.
Nonetheless there are sensible uses for transparent color in formatting. For example, the hatched pattern square used in the Pattern layer above has transparent fill color but a dark brown foreground color. The combination of the two with the hatch pattern prevents the square from being completely invisible.
Historical regions - The illustrations in this topic use data from the US government, which show the regions of France as they were before 1 January 2016, when regions in France were reduced from 22 to 13.
User Interface Basics
Example: Format a Drawing using the Style Pane - In this example we provide a first, step by step look at how to format areas in a drawing using the Style pane. We can specify the same formatting for all areas or use a field to automatically set formatting, a process usually known as thematic formatting.
Example: Format the Size of City Points by Population - A common GIS task is to format the size of points in a drawing based on some value. For example, the size of points that represent cities might be formatted based on the value of the city's population, with cities that have larger populations being marked by larger point icons. This is an example of thematic formatting and is easy to do using the Style pane.
Example: Add, Delete and Edit Thematic Formatting Intervals - This topic provides a step by step example of adding, deleting and editing intervals in the Style pane that are used for thematic formatting.
Example: Style Properties in the mfd_meta Table - Style properties for drawings such as colors for areas are stored in human readable JSON values as properties in the mfd_meta system table. This example shows how we can copy formatting from one drawing to another by simply copying values between records in the mfd_meta table.
Example: Formatting Tricks - The visualization capabilities of Manifold using Style can be exploited to provide many visual effects. This topic provides some examples of how to use Style in unexpected ways to create a range of more elaborate effects.