Overview of Objects

The most commonly used geometries in map drawing are points, lines, polygons, and text. The Features tab provides functionality for creating various geometric features on the map, including: point objects, line objects, polygon objects, and text drawing.

Drawing various geometries is performed with the layer set to editable. Multiple layers can be set editable simultaneously, but when creating points, lines, polygons, or text, geometric objects are only added to the currently selected layer. Therefore, to create new objects for a specific layer, you must first click the corresponding layer in the Layer Manager to set it as the current layer.

The following introduces some concepts involved in objects:

Object Overview

Object: Refers to geometry, which is an abstract representation of discrete spatial entities in GIS. An object has its own properties and behaviors. In SuperMap, some objects can be created directly, while others need to be generated through conversion.

  • Single Object: Refers to one object, be it a simple object, a complex object, a compound, or a part. Each is a single object.
  • Part: Refers to the constituent unit of simple and complex objects. A simple object consists of one part (itself). A complex object consists of two or more parts.
  • Simple Object: Refers to an object that has only one part (itself).
  • Complex Object: Refers to an object that has two or more parts of the same type.
  • Compound Object: Specifically refers to objects generated through combination operations in a CAD layer. Compound objects do not have the concept of parts.
  • Parametric Objects: Drawing geometry defined by primary parameters, resulting in continuous shapes. In contrast, regular geometry is drawn using coordinates of key points or point strings that constitute the object. For example, a parametric circle is precisely drawn using two parameters: a determined center point and radius. An ordinary circle discretizes the arc into points and connects these points to form a closed circle.

Angle Explanation in Objects

  • Angle Direction: The direction of angles involved in the application is counterclockwise.
  • Start Angle: In drawing objects, the start angle refers to the angle from the true north direction (starting side) to another side.

Parametric Drawing Explanation

When drawing the line, it will split the original and new object at the intersection, creating multiple line objects. Parametric drawing can make the drawing process more convenient. You can click the Parametric Drawing button in the Objects group of the Features tab, or use the shortcut Shift+P to enable the parametric drawing function.

  • Input Coordinate Values: Draw points, lines, polylines, curves, circles, polygons, etc., by specifying parameters for coordinate points. This includes coordinates for the object's start point, midpoint, turning points, endpoint, etc.
  • Input Length Values: Draw lines, polylines, polygons, sectors, circles, arcs, etc., by specifying length parameters. This includes line length, side length, radius, diameter, etc.
  • Input Angle Values: Draw objects by specifying angle values, which can determine the drawing direction and start angle.

Parametric objects.

Shift Key Feature Description

When drawing certain objects, using the Shift key in combination can make the drawing process more convenient.

  • Drawing Lines: When drawing lines by inputting length and angle parameters, holding the Shift key allows drawing only horizontal, vertical, or 45° direction lines.
  • Drawing Rectangles (Rounded Rectangles): When drawing rectangles by inputting width and height parameters, holding the Shift key results in a square with equal width and height.
  • Drawing Ellipses: When drawing inscribed ellipses, holding the Shift key results in a perfect circle with equal width and height.

A Key Feature Description

When drawing objects on the map, pressing the letter A key on the keyboard switches the mouse in the current map to pan mode. The mouse cursor state in the current window becomes .

After switching the mouse to pan mode during object drawing, you can switch the mouse state back to drawing mode and continue drawing objects using the following three methods:

  • Press the A key again to switch;
  • Right-click the mouse to switch;
  • Press the Esc key on the keyboard to switch.
Tip:
  • If you are in the process of inputting parameters such as coordinates, length, or angle for drawing an object, pressing the A key will not switch the mouse to pan mode.
  • For an empty map window (with a geographic coordinate system), the default range is the valid drawing bounds. This effectively avoids prompts about exceeding bounds when drawing objects in the default window range.

Q Key Feature Description

When drawing line or polygon objects on the map, pressing the Q key on the keyboard activates the snapping function. When the mouse stops at the boundary of an existing object, it automatically snaps to that boundary, helping to avoid topology errors.

  • First press of the Q key activates the snapping function.
  • Second press of the Q key deactivates the snapping function.