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3.1 Diagram Editor

See also the Menu Reference, Section 7.6.

The Diagram Editor is a tool for creating, managing and maintaining graphs as diagrams. With a Diagram Editor you can view and edit graphs as well as make or view explosions and decompositions between several graphs. Basically, except for the notation of the selected method, the tool always looks the same. For example, in Figure 3-1 we have two Diagram Editors open, containing different types of graph, i.e. graphs from different methods.

Figure 3-1. Two Diagram Editors.

3.1.1 Diagrams

Opening diagrams with a Diagram Editor

To open a Diagram Editor:
1)Choose Editors | Diagram Editor... in the Launcher.

Figure 3-2. Selecting a graph to open.

2)Select a graph from the dialog (e.g. ‘Sales system’) that will appear (Figure 3-2), and click the OK button.
3)Select the available representation from the dialog that appears, and click OK (Figure 3-3). If you want to make a new representation select ‘Create new diagram’ (the last item in the list). This selection opens the selected graph but allows you to make a different representation version of it. Thus, you can have a different layout and subset of the contents of the graph.

Figure 3-3. Selecting a diagram to open.

The dialog for representation selection does not necessarily appear. It depends on the representations available and the current dialog options (see Section 2.1.3 Options Tool).

As a result, you should now have a Diagram Editor open on the selected graph. If you selected ‘Sales system’ from the ‘demo’ repository the Diagram Editor window is shown as in Figure 3-4. Depending on your preferences a toolbar may open below the menu bar.
By keeping shift pressed during the open operation, you can open the graph without locking it. This is especially useful in a multi-user environment when you just want to view the graph and allow another user to change it at the same time.


Figure 3-4. Diagram Editor opened on a graph.

Creating diagrams

To create a new diagram:
1)Choose Editors | Diagram Editor in the Launcher.
2)Select the last item ‘create new graph’ from the dialog that opens (see Figure 3-2), and click OK. You can also double-click the item on the list to make a selection and accept it.
3)As a result a dialog like that in Figure 3-5 appears asking you to select a method. Choose one from the method list and click OK.
4)After selecting a method a new graph is created and you are prompted for its properties, e.g. its name: fill them in and click OK.

Figure 3-5. Selecting a graph type to create.

As a result, you should now have an empty Diagram Editor open on a new graph of the selected method.

Managing diagrams

As in all editors in MetaEdit+, the Graph menu allows users to create, open and edit graphs. For example, the same function that was previously used to open a diagram can be accessed from Graph | Open... as well. Similarly, new diagrams can be created by selecting Graph | New... and by following the same instructions as described above.

To edit the properties of the graph itself select Graph | Properties..., and a dialog similar to that in Figure 3-6 will appear. In the dialog, properties of the graph can be edited and modifications accepted by selecting OK. See Section 2.3.1 for more information on such property dialogs.

Figure 3-6. Property dialog for a graph.

The Graph menu also includes functions to view a diagram in other representations (i.e. as a matrix or as a table) or to browse the diagram in a Graph Browser. Basically, the Graph | View functions open this graph in the tool chosen. The other editors, i.e. Matrix Editor and Table Editor, are described in later sections.

You can also open the Info Tool for the graph by selecting Graph | Info... (see Section 2.3.3).

Importing existing graph elements into a Diagram Editor

The Diagram Editor also allows you to update a diagram representation of a graph with information that has been added in another representation of the same graph.

To update a diagram with changes made to the same graph in a Matrix Editor or other tool select Graph | Import Graph. This function automatically fetches and adds all representations of new objects and their relationships to the Diagram Editor so that the user can edit or move them to the positions he or she wants.

Note that this function is called automatically when opening a new diagram on an existing graph.

Printing a diagram

To print the diagram select Graph | Print.... You are first asked for the printer, then for the scale of the printout or how many pages you want to print over (see Figure 3-7). By default, printing is of the whole used area of the diagram at a single page.

Figure 3-7. Print settings dialog.

When you press OK in the print scale dialog the output is sent to the printer. You may also use a print preview tool by pressing Preview button. The preview tool shows the output a page at a time. Pressing the Print button actually sends the output to the printer and closing the window cancels printing. You can choose to print only the visible area of the diagram or the whole used area of the diagram, at a specific scale or over a certain number of pages. These more advanced features are described in Section 4.2.

Exporting diagrams

Diagrams can be exported in several formats. The choice of format will largely depend on the capabilities of the program in which you want to import the resulting picture.

Clipboard as Bitmap lets you select an area of the visible diagram and export it as a bitmap to the system Clipboard. The exporting function asks you to frame the area to export by clicking at its top left corner and dragging to its bottom right corner.

GIF file... exports the whole diagram with the current zoom factor into a GIF file. GIF files are the standard format for diagram-like pictures on the World Wide Web.

PICT file... exports the whole diagram at 100% zoom into a PICT vector graphics .pct file. PICT files can be imported and edited as vector graphics by most word processing, desktop publishing and graphics software.

In all exporting formats, the current view filtering (View | Selected...) settings in the Diagram Editor will be applied to the exported diagram.

Accessing reports

All reporting functions can be accessed through the Graph | Reports menu. To select a report to be run:
1)Select Graph | Reports | Run....
2)Select a report from the dialog list. Note that the reports are listed indented under the graph types that define them: choosing a graph type instead of a report will have no effect. Figure 3-8 shows an example of a dialog list for choosing a report.

Figure 3-8. Choosing a report to run.

After you have selected a report, the tool runs it and opens a window showing the report output, or a dialog showing the file(s) to which report output has been sent (see Figure 3-9).

Figure 3-9. Dialog showing report output files.

You can also access the report definition tool to make new reports or to modify existing ones. To do this choose Graph | Reports | Create. The reporting tools are explained in more detail in Section 4.1.4.

Closing a Diagram Editor

To exit the Diagram Editor select Graph | Exit or use some other platform dependent closing mechanism: e.g. double-clicking the top-left corner of the window.

3.1.2 Objects

In general, all the basic functions needed to create, edit, link and delete elements in a diagram are collected in pop-up menus. Elements of a diagram include objects, relationships, roles and their properties. Management of each element is discussed in the following. More detailed descriptions of these elements can be found from Section 5.2.

Moreover, because diagrams normally have multiple elements and design situations differ, pop-up menus are implemented so that they automatically provide the right alternatives for selection. For example when you have selected an object the possible functions, and therefore also the object related pop-up menu, are different from when you have selected a relationship.

In the following we shall explain how different elements of a diagram can be created, updated and deleted.

Adding objects

Objects are the basic elements of graphs. Examples of objects are an entity ‘Order’ in an Entity-Relationship Diagram, or a process ‘Verify order’ in a Data Flow Diagram.

To add an object in the Diagram Editor:
1)Click the left mouse button at the place that you want to add an object.

 If you are creating the first object, or you have not selected any objects previously from the Types menu or the toolbar, a dialog opens showing possible object types to be added. Figure 3-10 shows such a dialog for a Data Flow Diagram. Select the object type and press OK.

Figure 3-10. Selecting the object type to create.

2)An empty dialog opens allowing you to enter design information about the selected object. In the case of adding a Store in a Data Flow Diagram the dialog looks like Figure 3-11. Enter a description of the object and click OK.

Figure 3-11. Property dialog for a Store.

An object can also be added with Create Object... from the pop-up menu available when no element is selected. This is useful when you want to add an object inside the area of a larger, probably transparent, object: clicking there normally would simply select the larger object.

Adding existing objects

In many cases it is more practical to reuse design elements already defined and stored in the repository than to create new elements. To add objects into the diagram that are already defined elsewhere use the ‘add existing’ function:
1)Keep the shift button pressed and click the left mouse button in a selected place of the drawing area. Note that none of the elements in the diagram must be selected.

As a result a dialog, like that in Figure 3-12, opens allowing you to pick objects that are already defined in the graph that you are using. Note that all of them are not necessarily represented in the opened diagram as they can be represented e.g. in a matrix or in another representation diagram of the same graph (see Section 5.2.2). The figure below shows all the objects of the ‘Sales system’ Data Flow Diagram.
2)Choose any of the objects in the list and press OK.

As a result, the chosen object will be added to the graph.

Figure 3-12. Selecting an existing object to add.

The dialog in Figure 3-12 also has additional functions for more complex reuse situations: to fetch information from other graphs, even if they have other representations, i.e. a matrix or a table. These options can be selected from the last two items in the list.

The first of these, ‘Get an object from another graph’ opens a new dialog (Figure 3-13) for selecting a source graph from which elements are to be reused.

Figure 3-13. Selecting the source graph for reuse.

Please note that only those objects can be reused whose type is legal in the target diagram. For example in a Data Flow Diagram you can only fetch processes, stores, externals, or notes. Thus, if you select an incompatible graph such as a Class Diagram, there will be no objects available from there for reuse in the Data Flow Diagram. Depending on your dialog answer preferences (see Section 2.1.3) the tool will not add any objects to the diagram, or it will open an empty dialog showing that no objects can be reused from that graph.

The second reuse option, ‘Get an object of a type legal in this graph’, first offers a dialog for selecting the object type to be reused (similar to that in Figure 3-10) and then offers a list of all the objects of the selected type currently loaded in MetaEdit+.

For example, in a Data Flow Diagram when the selected object type is ‘Process’ a dialog list like that in Figure 3-14 opens. It contains a list of all processes that are used in any loaded graph.
The dialog also includes those processes that are part of the diagram that is already opened in the Diagram Editor. Also, objects of that type may exist that have not yet been loaded, and hence not appear in the dialog.

Figure 3-14. List of all processes to be reused.

When you press OK, the selected object will be added into the diagram. If you edit any of these objects, i.e. change the information about the object through a property dialog, the change will be immediately propagated to that object elsewhere, and therefore also available to all graphs and tools that use the same object.

An existing object can also be added with Add Existing Object... from the pop-up menu available when no element is selected. This is useful when you want to add an existing object inside the area of a larger, probably transparent, object: shift-clicking there normally would simply select the larger object.

Editing objects

Information about each object can be edited by selecting Properties... from the element’s pop-up menu. To do this:
1)Select an object and open the pop-up menu that is related to the selected element (with the right mouse button).
2)Select Properties... from that menu. Figure 3-15 shows an example of this menu selection.

You can change the behaviour of the right mouse button to select an element first, then open the pop-up menu for it. Ssee Section 2.1.3 Options Tool.

Figure 3-15. Opening pop-up menu for an object.

You can also use a shortcut key for opening a property dialog: select the object with the mouse and then press Enter.

As a result a property dialog opens showing information about the selected object (Figure 3-16). Changes to the property fields in the dialog will update information related to the selected object (i.e. ‘Verify orders’) in the repository and in all related tools representing the particular object. See Section 2.3.1 for more information on property dialogs.

Figure 3-16. An example of property dialog for an object.

Moving objects

You can also move the positions of objects in the diagram. To do this:
1)Select the object to be moved with the left mouse button and keep the button pressed.
2)Drag the object to a new location.

You can select multiple objects for moving by selecting the first object by clicking it with the left mouse button, then holding shift down while you click each of the other objects. Alternatively, you can select all design elements in an area by holding Ctrl down while you click and drag with the left mouse button to define the area you want to select.

To move multiple selected objects, click and drag in one of the selected objects.

Scaling object symbols and aligning them to the grid is described at the end of Section 3.1.5.

Deleting objects

To remove an object:
1)Select it with the left mouse button.
2)Open the pop-up menu with the right mouse button.
3)Choose Delete.

As a result of the operation the object disappears from the diagram. There are, however, further actions that may happen if the object is not represented in any other representation of this graph, depending on the different deletion policies that you can choose through the Options Tool (see Section 2.1.3).

3.1.3 Relationships and Roles

Selecting relationships and roles

To select a relationship or role, you must click with mouse in or near one of its selection areas. The selection areas are marks at line segments: red dots allow to select roles and blue dots allow to select relationships. If the relationship has graphical symbols or label texts no blue dot is shown: you can select the relationship by clicking the symbol or label text area.

When a relationship is selected, the selection area is visible as the rectangle defined by black filled squares around its symbol or label, or a single black square at the relationships position (a vertex on the line or the midpoint if the line is straight).

When a role is selected, the selection areas are visible as hollow red squares at each vertex of the role line segment, and at the midpoints of the segments.

Managing relationships

Relationships are connections between objects. In the Diagram Editor these are represented as lines, possibly with an associated symbol. Examples of relationships are ‘Inheritance’ in an Object Diagram, or ‘Flow’ in a Data Flow Diagram.

Relationships can be viewed and edited similarly to objects. To edit the properties of a relationship:
1)Click on a selection area of the relationship (text label, symbol, or blue dot).
2)Open the relationship’s pop-up menu (with the right mouse button) and select Properties... Alternatively you may use a keyboard shortcut by pressing Enter.

You can change the behaviour of the right mouse button to first select an element then open the pop-up menu for it. See Section 2.1.3 Options Tool.

Figure 3-17. A dialog for editing properties of a relationship.

As a result a property dialog appears allowing you to edit the information about the relationship. Figure 3-17 illustrates an example of a property dialog for a flow named ‘Orders’.

Adding relationships

To add a new relationship:
1)Optionally, select the type for the relationship from the Types menu or toolbar. This choice stays in effect for future relationship creations in this Diagram Editor, until you click the same relationship type again (i.e. unselect it to allow any relationship to be created), or another relationship type.
2)Select the first object in the relationship.
3)Open the pop-up menu with the right mouse button.
4)Select Connect from the pop-up menu.
5)If you want a relationship other than a straight line, click the left mouse button where you want each of the break points to be. If the break point would be inside another object, e.g. a large enclosing object, you must hold shift down while you click to create a break point. If you want to abandon relationship creation, press the right mouse button (be careful not to hold it so long that you open a pop-up menu and choose an action!).
6)Select the second object in the relationship.

As a result a dialog window opens with possible relationships to be added. Each item is a binding of a relationship and the roles that will be created with the relationship, and which object will be in which role. Depending on your preference settings for relationship creation (Section 2.1.3), the order in which you select objects may affect the choices and assignment of roles to objects. If only one combination of relationships and roles is possible the tool bypasses this dialog and the property dialog appears immediately. This dialog contains a notebook allowing you to enter design information about the relationship and roles.
If a relationship or a role does not have properties, the tab label text on the notebook page is italicised. The tab label for roles also shows the name of the object to which that role attaches.

7)Fill in the properties of the new relationship and roles. Use the tab labels of the notebook to move between relationship and role pages.
8)Accept the new relationship by clicking All OK.

There is, however, another way to create a relationship: first select all the objects that belong to the relationship (with the shift key pressed and clicking the left mouse button) and then select Connect. In this case you are prompted for the centre point of the relationship, where any relationship symbol will appear.
If you are creating an n-ary relationship (i.e. a relationship that has more than two objects connected to each other) you have to select all the objects first in this way. Later on you can extend an existing relationship to include an extra object by selecting Add a New Role... from the pop-up menu of the relationship.

Adding existing relationships

As with objects you can also add a relationship that was already defined and stored in another representation of this graph, e.g. in a Matrix Editor or another Diagram Editor.

To add an existing relationship:
1)Select the objects to be connected (with the shift key pressed and clicking the left mouse button).
2)Open the pop-up menu with the right mouse button.
3)Choose Add existing connection... from the menu.

As a result of the operation the tool inserts an available relationship between the chosen objects. If multiple relationships exist the tool will ask which relationship to add.

Moving relationships

As with objects, relationships can be moved. To do this:
1)Click on the relationship with the left mouse button.

If the relationship has no symbol, click on the light blue dot that indicates its position. If it has a symbol that is currently not visible (e.g. an empty string property), you can find the relationship’s point by default as the midpoint of the centre points of the objects involved.

2)Drag the relationship to a new location.

The relationship symbol can be moved to the midpoint between the centres of its objects, and all existing break points in all roles of the relationship can be removed by selecting Straighten Line from the pop-up menu of the relationship.

Scaling relationship symbols and aligning them to the grid is described at the end of Section 3.1.5.

Management of roles

Relationships are connected to objects through roles. Typically each relationship has at least two roles and they too can have properties. An example of a property for a role is a cardinality constraint in Entity-Relationship-Attribute Diagrams.

Because roles are attached to relationships their management is closely related to the management of relationships. When a relationship is created, you are also asked for values for its roles, and when a relationship is removed the roles too are removed.

Property dialogs for roles can be accessed similarly than with relationships. To edit roles:
1)Select the role by clicking the role selection area (red dot).

You can change the behaviour of the right mouse button to first select an element and then open the pop-up menu for it. See Section 2.1.3 Options Tool.

2)Open the pop-up menu (with the right mouse button). As a result of the selection a role part of the relationship is marked with small squares. Figure 3-18 shows the Diagram Editor with a role selected.
3)Select Properties...

As in other editors, you may also use press Enter to open the property dialog for the selected role.

If the role has properties a dialog opens. Figure 3-19 shows an example of a role-related property dialog. It is taken from the object diagram that has aggregation structures in which the ‘whole’ part of the structure is specified with a property called ‘Amount/Range’. The dialog shows that selected amount is ‘0,M’. The property list also includes some other predefined values that could be used as a value for the property.

Figure 3-18. Role selected.

Moving roles

Normally roles move together with the relationship and objects. At some later time after drawing a relationship the relationship line may need additional break points. To add a new point to the existing line:

Select the role by clicking the role selection area (red dot) with the left mouse button.
1)To add a new point, select any of the small red dots at the midpoint of a role line segment with the left mouse button, and drag it to a new position. To move an existing point, select the small hollow red square at that point and drag it with the left mouse button.

Figure 3-19. Role dialog for cardinality.

All existing break points in all roles of a relationship can be removed by selecting Straighten Line from the pop-up menu of the relationship.

Alternatively, individual break points can be removed. To remove a break point:
1)Select the role by clicking the unwanted vertex of the role line segment with the left mouse button.
2)Start to drag the vertex role square with the left mouse button.
3)While dragging, press the shift key.

As a result, the vertex in the role line is removed.

Deleting and adding roles

Roles can be deleted by choosing Delete from the pop-up menu. Note that if the relationship has only two roles the relationship is removed as well. Later on you can add a new role to the relationship by selecting Add a New Role... from the relationship related pop-up menu.

Deleting relationships

To delete a relationship:
1)Select the relationship (with the left mouse button).
2)Choose Delete from the relationship’s pop-up menu.

When a relationship is deleted the attached roles are also deleted.

3.1.4 Subgraphs

Decomposition

Decomposition is an operation that allows the user to perform an arbitrary diagram levelling. If the method in use uses decomposition, MetaEdit+ allows the user to decompose elements of a diagram into a new sub-diagram. You can find out which object types can be decomposed into which graph types by selecting Help | Method... and the ‘Subgraphs’ help item.

In decomposition, knowledge about the connections of the decomposed element is stored in the sub-graph as well as the parent graph, allowing you to maintain consistency between different levels, and to reuse decompositions with a consistent interface. Thus, decomposition is normally allowed only between graphs of the same method. A typical example of a method that uses decomposition to level diagrams is a Data Flow Diagram, in which Processes can be decomposed into a new Data Flow Diagram. This new diagram describes the decomposed process in more detail.

In MetaEdit+ two ways of decomposition creation are supported: decomposing a single object (top-down) or grouping multiple objects into a new object (bottom-up). In the first case you select a single object and make a new lower-level subgraph in which you describe its decomposition. In the latter case you group together a set of objects in a diagram and move them into a new lower-level subgraph.

To decompose an element:
1)Select an object in a diagram (e.g. process ‘Verify orders’ in a Data Flow Diagram of the ‘demo’ repository).
2)Open the object’s pop-up menu.
3)Select Decompositions....

Decomposition is method-dependent. Thus, not all methods use decomposition and diagram levelling, nor is it necessarily supported in all predefined methods in MetaEdit+. If decomposition is not allowed for the object the tool opens a notification dialog.

Depending on your dialog answer preferences (see Section 2.1.3) you will be asked whether you want to attach an existing graph (if any of the right type exist), or create a new graph as the decomposition graph of the selected object (Figure 3-20). If you choose to create a new graph, you will be prompted for its type, and a property dialog will open on a new graph of that type. In either case, you will be prompted for which representation of the decomposition graph you want to open (if there is only one representation, it will open straight away), or whether you want to create a new representation.

Figure 3-20. Select the graph type for the new decomposition.

To view an existing decomposition made according to the previous decomposition creating guidelines:
1)Select the Process (like ‘Verify orders’),
2)Open the object related pop-up menu with the right mouse button.
3)Select Decompositions....
4)Select Open from the dialog that opens (Figure 3-21).

Figure 3-21. Opening a decomposition graph.

As can be seen from Figure 3-21, you can also replace an existing decomposition so that the selected object now decomposes to another graph, or remove an existing decomposition link from that object.

If you choose Open a new Diagram Editor opens. Figure 3-22 describes an example of decomposition in which a process called ‘Verify Orders’ is decomposed into a sub-diagram.
Note that possible decomposition information for the selected object can be found from the Info Tool for graphs and from the information bar at the bottom of the Diagram Editor window.

Figure 3-22. Decomposition in a Diagram Editor.

Another approach for decomposition is to select a set of existing objects and their relationships and move them as a group to a new lower-level diagram. In the parent diagram they are replaced by a new object whose decomposition is the new lower-level diagram.

To make several objects into a new decomposition graph:
1)Select several objects (by clicking each with the left mouse button with shift held down, or by holding down ctrl and dragging to outline their area).
2)Select Make into Decomposition... from the pop-up menu.

As a result, a new diagram is created and the selected objects together with their relationships are moved to this new diagram. During the decomposition the tool will ask for two sets of information:
1)The type and properties for the new subgraph.
2)The type and properties for the object to be created to substitute for the elements moved to the subgraph.

Note that this kind of decomposition can only be performed if there are no other representations of this graph.

You can also replace an object with the contents of its decomposition graph by selecting Replace with Decomposition either through the pop-up menu of the object or the Edit menu. If the decomposition was originally made from a group of objects in this graph, the relationships and roles to the decomposed object will be reattached to the correct objects from the decomposition graph. Note that this does not affect the decomposition graph itself, which still exists.

Explosions

Explosion forms another way to connect elements of a graph to other graphs. The difference from decomposition is that explosion creates a simpler link between an element and a graph whereas decomposition also handles the relationships attached to the element. Unlike decomposition, explosion is also possible for relationships and roles. It allows you to make links from a design element to several graphs, and to have different links for the same element used in different graphs, whereas an object can have only one decomposition, which is the same wherever that object is used.

Hence, explosion can also be used between graphs from different methods. A typical example of explosion can be found from most object-oriented methods in which an object in a Class Diagram can be exploded into a State Transition Diagram to describe the behaviour of the object.

Figure 3-23 illustrates the use of explosion: it shows two diagrams, in which an object ‘Passenger’ is exploded to a Object State Diagram which describes the dynamic part of ‘Passenger’.

To make, view or remove explosions select Explosions... from the object, relationship, or role pop-up menu, or from the Edit menu.
Note that any existing explosion information for the selected design element can be seen from the Info Tool for graphs and from the information bar at the bottom of the Diagram Editor window.

Figure 3-23. Explosion in Diagram Editors.

3.1.5 Viewing and formatting

Hiding and showing objects and relationships

The View function allows you to concentrate on different aspects of diagrams by hiding or showing selected object or relationship types. The menu selection View | Selected... opens a selection dialog, as in Figure 3-24, allowing you to choose the object and relationship types to be shown.

To select object or relationship types to be viewed mark them with a tick ‘ü’. For example, according to the selection dialog below all components of the Data Flow Diagram are shown except ‘External’ objects.

Figure 3-24. A dialog for selecting object and relationship types
to be shown.

Figure 3-25 shows the result of hiding External objects in a Data Flow Diagram. Relationships involving hidden objects are only shown if they also involve at least one object that is not hidden.

Figure 3-25. An example of hiding objects.

Similarly, View | All shows every object and relationship of a diagram. Hence, this command automatically ticks every object and relationship type in the selection dialog (Figure 3-24).

Zooming

The use of large diagrams necessitates that they can be scaled to different sizes. By selecting View | Zoom..., the dialog shown in Figure 3-26 will appear. By entering a zoom level, the diagram will be shown scaled to that level. You can also access zooming through the pop-up menu by pressing the right mouse button when nothing is selected in the diagram. The current zoom level is shown in the status bar at the bottom of the Diagram Editor.

Figure 3-26. Selecting the zoom level.

Grid and aligning elements

To help make your diagrams look neater, MetaEdit+ can show a grid over the diagram, to help you align objects with it. The command View | Show Grid allows you to show or hide the grid in the diagram. Merely showing the grid does not affect object placement, however; the command View | Align to Grid aligns all the object and relationship centres and role break points according to the selected grid.

You can force the use of the grid when elements are created or moved by selecting View | Snap to Grid. The centre of individual elements and role break points will be aligned to the grid in all operations. If multiple elements are selected and moved, they will maintain their relative positions to each other, and the whole area will maintain its relative offset to the grid. Thus elements that were previously aligned with the grid will still be aligned after the move.

You can change the size of the grid squares using View | Choose Grid... (Figure 3-27).

Figure 3-27. A dialog for selecting a grid size.

As with zooming you can also access the grid setting through a pop-up menu by pressing the right mouse button when nothing is selected in the diagram.

Scaling objects and relationships

You can scale an object or relationship symbol by selecting it and dragging any of the selection points at its corners or the midpoints of its sides. To set a particular scale, or scale several elements with the same scale factor, choose Scale symbol... from the element’s pop-up menu. The Scale Dialog that opens will initially show the current scale of the (first) selected object. Pressing Default will remove any scaling, returning the elements to their default size.

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