Magick::Drawable

Contents

Drawable provides a convenient interface for preparing vector, image, or text arguments for the Image::draw() method. Each instance of a Drawable sub-class represents a single drawable object. Drawable objects may be drawn "one-by-one" via multiple invocations of the Image draw() method, or may be drawn "all-at-once" by passing a list of Drawable objects to the Image draw() method. The one-by-one approach is convenient for simple drawings, while the list-based approach is appropriate for drawings which require more sophistication.

The following is an example using the Drawable subclasses with a one-by-one approach to draw the following figure:

Figure showing drawing example 
#include <string>
#include <iostream>
#include <Magick++.h>

using namespace std;
using namespace Magick;

int main(int /*argc*/,char **argv)
{
  try {
    InitializeMagick(*argv);

    // Create base image (white image of 300 by 200 pixels)
    Image image( Geometry(300,200), Color("white") );

    // Set draw options
    image.strokeColor("red"); // Outline color
    image.fillColor("green"); // Fill color
    image.strokeWidth(5);

    // Draw a circle
    image.draw( DrawableCircle(100,100, 50,100) );

    // Draw a rectangle
    image.draw( DrawableRectangle(200,200, 270,170) );

    // Display the result
    image.display( );
  }
  catch( exception &error_ )
    {
      cout << "Caught exception: " << error_.what() << endl;
      return 1;
    }

  return 0;
}

Since Drawable is an object it may be saved in an array or a list for later (perhaps repeated) use. The following example shows how to draw the same figure using the list-based approach:

#include <string>
#include <iostream>
#include <list>
#include <Magick++.h>

using namespace std;
using namespace Magick;

int main(int /*argc*/,char **/*argv*/)
{
  try {

    InitializeMagick(*argv);

    // Create base image (white image of 300 by 200 pixels)
    Image image( Geometry(300,200), Color("white") );

    // Construct drawing list
    std::list<Magick::Drawable> drawList;

    // Add some drawing options to drawing list
    drawList.push_back(DrawableStrokeColor("red")); // Outline color
    drawList.push_back(DrawableStrokeWidth(5)); // Stroke width
    drawList.push_back(DrawableFillColor("green")); // Fill color

    // Add a Circle to drawing list
    drawList.push_back(DrawableCircle(100,100, 50,100));

    // Add a Rectangle to drawing list
    drawList.push_back(DrawableRectangle(200,100, 270,170));

    // Draw everything using completed drawing list
    image.draw(drawList);

    // Display the result
    image.display( );
  }
  catch( exception &error_ )
    {
      cout << "Caught exception: " << error_.what() << endl;
      return 1;
    }

  return 0;
}

Coordinate structure

Drawable depends on the simple Coordinate structure which represents a pair of x,y coodinates. The Coordinate structure is defined as follows:

class Coordinate
{
public:

  // Default Constructor
  Coordinate ( void );

  // Constructor, setting first & second
  Coordinate ( double x_, double y_ );

  // Destructor
  virtual ~Coordinate ();

  // x coordinate member
  void   x ( double x_ );
  double x ( void ) const;

  // y coordinate member
  void   y ( double y_ );
  double y ( void ) const;
};

Drawable classes

Drawable classes represent objects to be drawn on the image.