Scale information for drawing annotations

#Annotations are used to add helpful information to two dimensional (2D) and three dimensional (3D) computer aided design drawings. Examples of annotations include text labels and hatch patterns. A view is a rectangle or other planar shape that a drawing, or portion thereof, is projected onto and in turn viewed by a user on a display device. A view is of a model space or a paper space (e.g., a preview of a printed drawing plan), and has a scale associated with it that specifies a ratio of units, such as drawing units to paper units. Objects in a drawing are given sizes in terms of units (e.g., inches, feet, centimeters) and appear in the correct proportions depending on a view's scale and space. For example, if a view scale is 1″ drawing units to ¼″ paper units, a drawing will be rendered as though every inch was a quarter inch in a paper space view. Typically, an annotation is created for a specific view scale. In order for the annotation to appear in the correct proportion at other scales, a version of the annotation needs to be created for each view scale that is desired. This is cumbersome since creating more than one version of an annotation is time consuming, prone to errors, and requires that a change to an annotation be propagated to each version.

#In general, one or more aspects of the subject matter described in this specification can be embodied in one or more methods that include identifying a drawing scale for a graphical view of a drawing, the scale specifying a ratio of two units. One or more annotations associated with the view that support the scale are selected, each of the selected annotations associated with context for the scale, the context specifying one or more of: the annotation's position in the view, the annotation's size in the view, the annotation's style in the view, or the annotation's rotation in the view. A graphical representation of each of the selected annotations is added to the view according to the scale and each annotation's respective context. Any annotation that does not support the scale is removed from the view. Other implementations of this aspect include corresponding systems, apparatus, and computer program products.

#These and other implementations can optionally include one or more of the following features. The two units can be paper units and drawing units. The annotation can be one or more of: text, a hatch pattern, a dimension, a leader, a block or a block attribute.

#FIGS. 1A and 1B illustrate example annotations shown in views having different scales.

#FIG. 2 is a flowchart of a method for updating a graphical view of a drawing.

#FIG. 3A is an illustration of a data store that includes scale information.

#Like reference numbers and designations in the various drawings indicate like elements.

#FIGS. 1A and 1B illustrate example annotations shown in views having different scales. An annotation (also known as an annotative entity) is an explanatory item on a drawing, which can be used to label or describe other, non-annotative drawing objects. Annotations can be of several types. For example, annotations can be text, hatch patterns (e.g., shading consisting of multiple crossing lines), dimensions (e.g., a measure of spatial extent, such as a width or height), leaders (e.g., explanatory text with an arrow pointing to the object being described), blocks (e.g., an object, such as a door, which is defined once and referenced multiple times in a drawing) and block attributes (e.g., an attribute of a block, such as a door number, which distinguishes one door block reference from another).

#A view 100 in FIG. 1A has a scale of “1:1” (the “1:1” can be read as “one to one”). A scale specifies a ratio between two units. For example, a scale of “1:1” can specify a ratio of one paper unit to one drawing unit. A paper unit can be used to specify the size of a drawing item (such as an annotation) as it appears on paper. A drawing unit can be used to specify the size of an item in model space (e.g., a physical size). A view 102 in FIG. 1B has a scale of “1:2”, which specifies a ratio of one paper unit to two drawing units.