Drawing Library

jonnynolimits

Rate me:

4.78/5 (63 votes)

10 Dec 2007CPOL3 min read

293.6K

12.8K

211

117

A library for creating shapes and developing tools.

Introduction

This is a generic library for drawing (work in progress). It is composed of some base tools and shapes. It allows you to draw shapes that you want to create, and develop tools to manage your figures.

Using the code

This piece of code describes the implementation of a derived class from Shape and a a derived class from Tool.

public class Ellipse : Shape
{
    public Ellipse()
    {
        Geometric.AddEllipse(new System.Drawing.Rectangle(0, 0, 1, 1));
    }

    public Ellipse(Ellipse ellipse) : base(ellipse)
    {
    }

    public override object Clone()
    {
        return new Ellipse(this);
    }
}
// ....


public class Select : Tool    
{
    .....

    // Override IActions Interface functions

    public override void MouseDown(IDocument document, MouseEventArgs e)
    {
        base.MouseDown(document, e);

        if (SelectShape(document.Shapes, e.Location) == HitPositions.None)
            Select.UnselectAll(document.Shapes);

        if (SelectedShapes != null)
            SelectedShapes(this, Select.GetSelectedShapes(document.Shapes));
    }

    public override void MouseUp(IDocument document, MouseEventArgs e)
    {
        base.MouseUp(document, e);

        document.ActiveCursor = Cursors.Default;
    }
    
    .....
}

It is very important to implement the copy constructor and the function Clone for every new shape, while it is convenient to override the IActions interface during the implementation of a new tool.

Main schemes

In the documentation, there are these schemes:

Orange color describes a hot spot class (interface or abstract class usually).
Yellow color describes active classes.
Blue color describes passive classes (data containers or structs usually).
Light grey color describes classes of the framework but not important in the current scheme.
Dark grey color describes classes external to the framework.

This scheme represents the actual shapes hierarchy:

This scheme represents the actual tools hierarchy:

This scheme represents the communication channel between the drawing panel, tools, and shapes:

The IActions interface contains all the panel actions used by the tools; for example, mouse down and mouse move, and also the paint function. IDocument is an interface, but it is blue because it is only a connection point between tools and shapes, and so it is a passive class.

The following scheme represents the relation between transformers and shapes. Transformers are used to handle shapes moving, so if you want to add any new move, you must only derive two classes, Transformer and CompositeTransformer, and not all the classes in the shapes hierarchy.

This scheme represents the actual appearances hierarchy:

Other schemes are available in the documentation.

Points of interest

To rotate a shape, choose the rotate tool and select the shape. Do a mouse click down and move. To rotate relative to a non-center point, select a shape, click the Ctrl key, do mouse click down, and move.

To deform a shape, change the property Marked to true, and choose the deform tool, do a mouse click down on a marker, and move. Try to group shapes and do the same operations above.

Serialization

The serialization operations are made by XmlSerializer. The performance is not very great.

Updates

Zoom functionality.
Grid on panel.
DrawFreeLine tool with possibility to decide the minimum offset between two consecutive points.

See the Layout options for the Bring To Front and Send To Back functionalities.

Last updates

Added possibility to move shapes with arrows and Control key.

Bug fixes

Modified setter methods of the Text shape to maintain the text state after rotation.

Known bugs

Deform tool is not precise on shape border markers.
A problem with resize tool and grid enabled.
The Undo-Redo mechanism is not precise.

Future developments

Improvement of tools (for example, resize).
Improvement of performance.
Development of other tools.

References

For documentation:

Sandcastle -- Documentation Compilers for Managed Class Library

For object-oriented and color theory and other software development information:

Eptacom

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Written By

jonnynolimits

Software Developer

Italy

I am a biomedical engineer. I work in Genoa as software developer. I developed MFC ActiveX controls for industrial automation for 2 years and packages for Visual Studio 2005 for 1 year. Currently I'm working in .NET 3.5 in biomedical area.

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.