Working with Curved Markups

There are many tools in Revu that support curves, including Polygon, Polyline, Cloud markups as well as Area and Perimeter measurements. These markups can be created using straight or curved lines, but even when straight lines are used each acute or obtuse angle creates control points that can be curved. In addition, control points can be added anywhere along any line and also used to create curves.

ClosedCurves and Curved Segments

Each control point that defines the markup can be turned into a Bézier curve. A single Bézier curve is defined by a start point, an end point, and two control points. These control points are shown as handlebars in Revu.

Curved segments can be chained together in order to create more complicated shapes. There are many different ways that the segments can be joined.

If the handlebars on either side of a point are parallel, then the curves will be connected smoothly. If the handlebars are not parallel, the curves will come to a point. A handlebar doesn't have to exist on both sides of a point; in such cases the curve is connected to a straight line segment. Connected line segments have no handlebars.

ClosedCreating Curved Markups

There are two ways to create curved markups: drawing the markups with curves or adding curves to a straight-line markup. Each method is demonstrated below.

ClosedCreating a Curved Polygon by Dragging

In Revu, shapes are normally drawn by clicking points that define the shape. When the shape is being created with straight lines, each click defines a corner. Revu can be configured to draw the shape with curves so that, after clicking each "corner" you drag to define the curve before clicking on the next point. The following example demonstrates how to create a curved shape using the Polygon tool.

  1. Go to Settings > Preferences or press CTRL+K.

  2. Select Markup from the list to the left.

  3. Select Drag Curves from the Drag Behavior for Shapes menu.
  4. Click OK.
  5. Go to Markup > Shapes > Polygon.
  6. Click and hold to add the first point.

  7. While holding, drag the mouse to define the handlebar.

  8. Release the mouse and click again to define the first curved line segment.
  9. Click again to add another curved line.

  10. Continue until the shape is complete.

  11. To complete the shape, press ENTER, double-click, or click the origin point.
  12. After the shape is completed, select individual points and adjust to get the desired shape.

Note: When the default preference Drag Rectangle is selected, hold CTRL when dragging to drag a curve. With Draw Curves selected, holding CTRL will drag a rectangle.

ClosedConverting a Polygon to a Curved Polygon

A polygon that has been drawn with straight lines can be converted to have curves afterward. Polygonal cutouts behave slightly differently, see Cutout Tool: Working with the Control Points and Curves for more information.

Note: Lines at acute and obtuse (but not right or straight) angles can be converted into arcs.

  1. Go to Markup > Shapes > Polygon.

  2. Draw the desired shape.

  3. Right-click anywhere on a line segment and select Convert to Arc.

    The selected line segment is converted to a curve.

    Note: To convert only part of a line segment, add a control point to split the line segment as desired. Curves are created between two control points, so adding control points allows you to convert exact lengths.

  4. Click and drag any of the revealed handlebars to adjust the curve.

  5. Convert each desired point to a curve in the same way. Not all control points need to be curved; straight and curved segments can be mixed to create the desired shape.

ClosedModifying Curves

To modify curves, select the markup, then click and drag the handlebars to change the shape of the curve. Moving the point itself around will move the point and the handlebars in tandem. If the handlebars on either side of a point are parallel, they will still be parallel when any one of them are moved.

In addition to moving the points and handlebars, Revu also supports adding, subtracting, and changing the type of control points. This can be done through the Control Point Toolbar, through the context menu, or with the keyboard.

ClosedControl Point toolbar

Locate the Control Point toolbar on your interface. If the toolbar is currently hidden, go to View > Toolbars and select it to show it. See Control Point toolbar for more information about this toolbar.

ClosedControl Point Context Menu

To access the Control Point context menu, right-click a control point and hover over the Control Point submenu.

ClosedControl Point Keyboard Shortcuts

SHIFT: Holding down the SHIFT key accomplishes different tasks depending on what is clicked:

  • While clicking on a control point, it causes the point to be removed.
  • While clicking on a position on a line without a control point, it causes one to be added.
  • While moving handlebars, it causes them to snap in 45° increments.

CTRL: Holding down the CTRL key accomplishes different tasks depending on what is clicked:

  • While clicking on a control point, it causes the point to be converted (straight to curve or curve to straight).
  • While clicking on a handlebar, it allows the handlebars to be moved independently, allowing for the creation of curved segments that come to a point.
  • While dragging a control point, it causes the line segments to be connected smoothly.

Related topics

Taking a Curved Measurement