Layer Restrictions

images\btn_layer_restrict.gif The Restrictions button in the layers pane displays and sets layer restrictions. Layer restrictions may also be set by right clicking on a layer tab in a map window and choosing Restrictions.


Each layer within a map may be specified to be clickable, editable, selectable or snapable (in any combination) with mouse commands. Each layer has four restriction options:


·      Enable mouse clicks

·      Enable mouse editing

·      Enable mouse selection

·      Enable mouse snaps


By default, all four options are enabled so objects in layers by default may be clicked, edited, selected or snapped.




The layers pane shows edit restrictions with a no marking each restriction. The "yes" implied by default is not shown for greater legibility. For example, in the above illustration the Cities layer is clickable and snappable but not editable or selectable. Double-click into any restriction setting in the layers pane to toggle it between no and the default yes setting.




If we were to right click on the Cities layer tab in the map and choose Restrictions the Layer Restrictions dialog would show restrictions status for that layer. In this dialog a check mark enables the function and no check mark removes the function. For example un-checking the Enable mouse edits box will prevent a CTRL-ALT click on an object in that layer from selecting it for editing.


Layer restrictions are used to show layers in maps while preventing some layers from participating in mouse commands. This makes it easier to edit desired layers in complex maps. Another use for layer restrictions is in Manifold IMS to restrict the action of hyperlinks or the Info tool to a limited set of layers.


Layer restrictions operate only with mouse commands. Keyboard and menu commands are not limited by layer restrictions, and smart mouse selection does not observe layer restrictions. For example, if a layer has had the Enable mouse selection checkbox un-checked none of the mouse selection commands will select objects in that layer. However, using CTRL-A or Edit - Select All will select all objects in that layer, the query toolbar will select objects in that layer and queries will select objects in that layer.


Copying Restrictions to All Layers


A CTRL-double click (that is, double-clicking while holding down the CTRL key) onto a restriction for one layer in the layers pane will copy that restriction to all layers. For example, suppose we have many layers in a project but we only want one layer, called Roads, to be editable. We can set the Editable restriction in the Roads layer to no and then CTRL-double click to set the Editable restriction to no for all layers. We can then click off the Editable restriction in the Roads layer so that it is the one layer that is editable while all the others are not editable.




We should keep in mind the interplay between user interface dynamics, layer structure and layer restrictions. When computing the effects of clicks and layer restrictions, Manifold first determines the clicked object and then checks if the click should be processed or not.


Let's consider an example case of a map with three layers. The upper layer has a single point formatted as a green circle, the middle layer has an area and the lower layer has a point formatted as a green square.




Seen in the map view, we see the round point above the area, shown with a hatching area style with transparent color in background, so that anything below the area shows through the "mesh." The square point is below the area.




If we could see the layers in the map in three dimensions, they would be stacked as above. Suppose the points are in layers with no restrictions, but the area is in a layer that is restricted and does not allow clicks.




In that case we could click on the round point but we could not click on the square point. Because the (restricted) area is above the square point, if we tried to click on the square point we could not do so because any clicks in that vicinity would be judged as clicks on the area that covers the square point.




Suppose the square point was in a layer above the area. Even in this case it would be difficult to click on the square point because anytime we click near the square point but not right on the center of the square point Manifold will judge the click to be onto the area. Since the area is within a restricted layer the click would not be processed.


Note that the size of the icon used for a point style does not determine the clickable region around that point. One must click on the center of the point to select it.


See Also



Editing with Snap

Edit - Snap To