Magick::Drawable

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 of using the Drawable subclasses with the one-by-one approach to draw the following figure:

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

using namespace std;
using namespace Magick;

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

Drawable depends on the simple Coordinate structure which represents a pair of x,y coodinates. The methods provided by the Coordinate structure are shown in the following table:

Coordinate Structure Methods
Method/Member Signature Description

Coordinate void Default Constructor

double x_, double y_ Constructor, setting first & second

x double x_ x coordinate member

y double y_ y coordinate member

Coordinate Structure Methods
Method/Member	Signature	Description
Coordinate	void	Default Constructor
double x_, double y_	Constructor, setting first & second
x	double x_	x coordinate member
y	double y_	y coordinate member

The Drawable classes are shown in the following table:

Drawable Classes
Sub-Class Constructor Signature Description

DrawableAffine double sx_, double sy_, double rx_, double ry_, double tx_, double ty_ Set scaling, rotation, and translation (coordinate transformation).

DrawableAngle double angle_ Set drawing angle

DrawableArc double startX_, double startY_, double endX_, double endY_, double startDegrees, double endDegrees_ Draw an arc using the stroke color and based on the circle starting at coordinates startX_,startY_, and ending with coordinates endX_,endY_, and bounded by the rotational arc startDegrees_,endDegrees_

DrawableBezier const std::list<Magick::Coordinate> &coordinates_ Draw a bezier curve using the stroke color and based on the coordinates specified by the coordinates_ list.

DrawableCircle double originX_, double originY_, double perimX_, double perimY_ Draw a circle using the stroke color and thickness using specified origin and perimeter coordinates. If a fill color is specified, then the object is filled.

DrawableColor double x_, double y_, PaintMethod paintMethod_ Color image according to paintMethod. The point method recolors the target pixel. The replace method recolors any pixel that matches the color of the target pixel. Floodfill recolors any pixel that matches the color of the target pixel and is a neighbor, whereas filltoborder recolors any neighbor pixel that is not the border color. Finally, reset recolors all pixels.

DrawableCompositeImage double x_, double y_, const std::string &image_ Composite current image with contents of specified image file, at specified coordinates. If the matte attribute is set to true, then the image composition will consider an alpha channel, or transparency, present in the image file so that non-opaque portions allow part (or all) of the composite image to show through.

double x_, double y_, double width_, double height_, const std::string &image_ Composite current image with contents of specified image file, rendered with specified width and height, at specified coordinates. If the matte attribute is set to true, then the image composition will consider an alpha channel, or transparency, present in the image file so that non-opaque portions allow part (or all) of the composite image to show through. If the specified width or height is zero, then the image is composited at its natural size, without enlargement or reduction.

double x_, double y_, double width_, double height_, const std::string &image_, CompositeOperator composition_ Composite current image with contents of specified image file, rendered with specified width and height, using specified composition algorithm, at specified coordinates. If the matte attribute is set to true, then the image composition will consider an alpha channel, or transparency, present in the image file so that non-opaque portions allow part (or all) of the composite image to show through. If the specified width or height is zero, then the image is composited at its natural size, without enlargement or reduction.

DrawableTextDecoration DecorationType decoration_ Set decoration to apply to text.

DrawableDashArray const unsigned int* dasharray_ Specify the pattern of dashes and gaps used to stroke paths. The strokeDashArray represents a zero-terminated array of numbers that specify the lengths of alternating dashes and gaps in pixels. If an odd number of values is provided, then the list of values is repeated to yield an even number of values. A typical strokeDashArray_ array might contain the members 5 3 2 0, where the zero value indicates the end of the pattern array.

DrawableDashOffset unsigned int offset_ Specify the distance into the dash pattern to start the dash. See documentation on SVG's stroke-dashoffset property for usage details.

DrawableEllipse double originX_, double originY_, double radiusX_, double radiusY_, double arcStart_, double arcEnd_ Draw an ellipse using the stroke color and thickness, specified origin, x & y radius, as well as specified start and end of arc in degrees. If a fill color is specified, then the object is filled.

DrawableFillColor const Magick::Color &color_ Set drawing object fill color.

DrawableFillRule FillRule fillRule_ Specify the algorithm which is to be used to determine what parts of the canvas are included inside the shape. See documentation on SVG's fill-rule property for usage details.

DrawableFillOpacity double opacity_ Set opacity to use when drawing using fill color.

DrawableFont const std::string &font_ Set font to use when drawing text.

DrawableGravity GravityType gravity_ Set text positioning gravity.

DrawableLine double startX_, double startY_, double endX_, double endY_ Draw a line using stroke color and thickness using starting and ending coordinates

DrawableMatte double x_, double y_, PaintMethod paintMethod_ Change the pixel matte value to transparent. The point method changes the matte value of the target pixel. The replace method changes the matte value of any pixel that matches the color of the target pixel. Floodfill changes the matte value of any pixel that matches the color of the target pixel and is a neighbor, whereas filltoborder changes the matte value of any neighbor pixel that is not the border color, Finally reset changes the matte value of all pixels.

DrawableMiterLimit unsigned int miterLimit_ Specify miter limit. When two line segments meet at a sharp angle and miter joins have been specified for 'lineJoin', it is possible for the miter to extend far beyond the thickness of the line stroking the path. The miterLimit' imposes a limit on the ratio of the miter length to the 'lineWidth'. The default value of this parameter is 4.

DrawablePath const std::list<Magick::VPath> &path_ Draw on image using vector path.

DrawablePoint double x_, double y_ Draw a point using stroke color and thickness at coordinate

DrawablePointSize double pointSize_ Set font point size.

DrawablePolygon const std::list<Magick::Coordinate> &coordinates_ Draw an arbitrary polygon using stroke color and thickness consisting of three or more coordinates contained in an STL list. If a fill color is specified, then the object is filled.

DrawablePolyline const std::list<Magick::Coordinate> &coordinates_ Draw an arbitrary polyline using stroke color and thickness consisting of three or more coordinates contained in an STL list. If a fill color is specified, then the object is filled.

DrawablePopGraphicContext void Pop Graphic Context. Removing the current graphic context from the graphic context stack returns the options to the values they had prior to the preceding DrawablePushGraphicContext operation.

DrawablePushGraphicContext void Push Graphic Context. When a graphic context is pushedcdc, options set after the context is pushed (such as coordinate transformations, color settings, etc.) are saved to a new graphic context. This allows related options to be saved on a graphic context "stack" in order to support heirarchical nesting of options. When DrawablePopGraphicContext is used to pop the current graphic context, the options in effect during the last DrawablePushGraphicContext operation.

DrawableRectangle double upperLeftX_, double upperLeftY_, double lowerRightX_, double lowerRightY Draw a rectangle using stroke color and thickness from upper-left coordinates to lower-right coordinates. If a fill color is specified, then the object is filled.

DrawableRotation double angle_ Set rotation to use when drawing (coordinate transformation).

DrawableRoundRectangle double centerX_, double centerY_, double width_, double hight_, double cornerWidth_, double cornerHeight_ Draw a rounded rectangle using stroke color and thickness, with specified center coordinate, specified width and height, and specified corner width and height. If a fill color is specified, then the object is filled.

DrawableScaling double x_, double y_ Apply scaling in x and y direction while drawing objects (coordinate transformation).

DrawableSkewX double angle_ Apply Skew in X direction (coordinate transformation)

DrawableSkewY double angle_ Apply Skew in Y direction

DrawableStrokeAntialias bool flag_ Antialias while drawing lines or object outlines.

DrawableStrokeColor const Color &color_ Set color to use when drawing lines or object outlines.

DrawableStrokeLineCap LineCap linecap_ Specify the shape to be used at the end of open subpaths when they are stroked. Values of LineCap are UndefinedCap, ButtCap, RoundCap, and SquareCap.

DrawableStrokeLineJoin Linejoin linejoin_ Specify the shape to be used at the corners of paths (or other vector shapes) when they are stroked. Values of LineJoin are UndefinedJoin, MiterJoin, RoundJoin, and BevelJoin.

DrawableStrokeOpacity double opacity_ Opacity to use when drawing lines or object outlines.

DrawableStrokeWidth double width_ Set width to use when drawing lines or object outlines.

DrawableText double x_, double y_, std::string text_ Annotate image with text using stroke color, font, font pointsize, and box color (text background color), at specified coordinates. If text contains special format characters the image filename, type, width, height, or other image attributes may be incorporated in the text (see label()).

DrawableTranslation double x_, double y_ Apply coordinate translation (set new coordinate origin).

DrawableTextAntialias bool flag_ Antialias while drawing text.

Vector Path Classes

The vector paths supported by Magick++ are based on those supported by the SVG XML specification. Vector paths are not directly drawable, they must first be supplied as a constructor argument to the DrawablePath class in order to create a drawable object. The DrawablePath class effectively creates a drawable compound component which may be replayed as desired. If the drawable compound component consists only of vector path objects using relative coordinates then the object may be positioned on the image by preceding it with a DrawablePath which sets the current drawing coordinate. Alternatively coordinate transforms may be used to translate the origin in order to position the object, rotate it, skew it, or scale it.

The "moveto" commands

The "moveto" commands establish a new current point. The effect is as if the "pen" were lifted and moved to a new location. A path data segment must begin with either one of the "moveto" commands or one of the "arc" commands. Subsequent "moveto" commands (i.e., when the "moveto" is not the first command) represent the start of a new subpath:

**Moveto Classes**
Sub-Class	Constructor Signature	Description
PathMovetoAbs	const Magick::Coordinate &coordinate_	Start a new sub-path at the given coordinate. PathMovetoAbs indicates that absolute coordinates will follow; PathMovetoRel indicates that relative coordinates will follow. If a relative moveto appears as the first element of the path, then it is treated as a pair of absolute coordinates. If a moveto is followed by multiple pairs of coordinates, the subsequent pairs are treated as implicit lineto commands.
	const std::list<Magick::Coordinate> &coordinates_
PathMovetoRel	const Magick::Coordinate &coordinate_
	const std::list<Magick::Coordinate> &coordinates_

The "closepath" command

The "closepath" command causes an automatic straight line to be drawn from the current point to the initial point of the current subpath:

**Closepath Classes**
Sub-Class	Constructor Signature	Description
PathClosePath	void	Close the current subpath by drawing a straight line from the current point to current subpath's most recent starting point (usually, the most recent moveto point).

The "lineto" commands

The various "lineto" commands draw straight lines from the current point to a new point:

**Lineto Classes**
Sub-Class	Constructor Signature	Description
PathLinetoAbs	const Magick::Coordinate& coordinate_	Draw a line from the current point to the given coordinate which becomes the new current point. PathLinetoAbs indicates that absolute coordinates are used; PathLinetoRel indicates that relative coordinates are used. A number of coordinates pairs may be specified in a list to draw a polyline. At the end of the command, the new current point is set to the final set of coordinates provided.
PathLinetoAbs	const std::list<Magick::Coordinate> &coordinates_
PathLinetoRel	const Magick::Coordinate& coordinate_
PathLinetoRel	const std::list<Magick::Coordinate> &coordinates_
PathLinetoHorizontalAbs	double x_	Draws a horizontal line from the current point (cpx, cpy) to (x, cpy). PathLinetoHorizontalAbs indicates that absolute coordinates are supplied; PathLinetoHorizontalRel indicates that relative coordinates are supplied. At the end of the command, the new current point becomes (x, cpy) for the final value of x.
PathLinetoHorizontalRel	double x_
PathLinetoVerticalAbs	double y_	Draws a vertical line from the current point (cpx, cpy) to (cpx, y). PathLinetoVerticalAbs indicates that absolute coordinates are supplied; PathLinetoVerticalRel indicates that relative coordinates are supplied. At the end of the command, the new current point becomes (cpx, y) for the final value of y.
PathLinetoVerticalRel	double y_

The curve commands

These three groups of commands draw curves:

Cubic Bézier commands. A cubic Bézier segment is defined by a start point, an end point, and two control points.
Quadratic Bézier commands. A quadratic Bézier segment is defined by a start point, an end point, and one control point.
Elliptical arc commands. An elliptical arc segment draws a segment of an ellipse.

The cubic Bézier curve commands

The cubic Bézier commands depend on the PathCurvetoArgs argument class, which has the constructor signature

PathCurvetoArgs( double x1_, double y1_,
double x2_, double y2_,
double x_, double y_ );

The commands are as follows:

Cubic Bézier Curve Classes
Sub-Class Constructor Signature Description

PathCurvetoAbs const Magick::PathCurvetoArgs &args_ Draws a cubic Bézier curve from the current point to (x,y) using (x1,y1) as the control point at the beginning of the curve and (x2,y2) as the control point at the end of the curve. PathCurvetoAbs indicates that absolutecoordinates will follow; PathCurvetoRel indicates that relative coordinates will follow. Multiple sets of coordinates may be specified to draw a polybezier. At the end of the command, the new current point becomes the final (x,y) coordinate pair used in the polybezier.

const std::list<Magick::PathCurvetoArgs> &args_

PathCurvetoRel const Magick::PathCurvetoArgs &args_

const std::list<Magick::PathCurvetoArgs> &args_

PathSmoothCurvetoAbs const Magick::Coordinate &coordinates_ Draws a cubic Bézier curve from the current point to (x,y). The first control point is assumed to be the reflection of the second control point on the previous command relative to the current point. (If there is no previous command or if the previous command was not an PathCurvetoAbs, PathCurvetoRel, PathSmoothCurvetoAbs or PathSmoothCurvetoRel, assume the first control point is coincident with the current point.) (x2,y2) is the second control point (i.e., the control point at the end of the curve). PathSmoothCurvetoAbs indicates that absolute coordinates will follow; PathSmoothCurvetoRel indicates that relative coordinates will follow. Multiple sets of coordinates may be specified to draw a polybezier. At the end of the command, the new current point becomes the final (x,y) coordinate pair used in the polybezier.

const std::list<Magick::Coordinate> &coordinates_

PathSmoothCurvetoRel const Magick::Coordinate &coordinates_

const std::list<Magick::Coordinate> &coordinates_

The quadratic Bézier curve commands

The quadratic Bézier commands depend on the PathQuadraticCurvetoArgs argument class, which has the constructor signature:

PathQuadraticCurvetoArgs( double x1_, double y1_,
double x_, double y_ );

The quadratic Bézier commands are as follows:

Quadratic Bézier Curve Classes
Sub-Class Constructor Signature Description

PathQuadraticCurvetoAbs const Magick::PathQuadraticCurvetoArgs &args_ Draws a quadratic Bézier curve from the current point to (x,y) using (x1,y1) as the control point. PathQuadraticCurvetoAbs indicates that absolute coordinates will follow; PathQuadraticCurvetoRel indicates that relative coordinates will follow. Multiple sets of coordinates may be specified to draw a polybezier. At the end of the command, the new current point becomes the final (x,y) coordinate pair used in the polybezier.

const std::list<Magick::PathQuadraticCurvetoArgs> &args_

PathQuadraticCurvetoRel const Magick::PathQuadraticCurvetoArgs &args_

const std::list<Magick::PathQuadraticCurvetoArgs> &args_

PathSmoothQuadraticCurvetoAbs const Magick::Coordinate &coordinate_ Draws a quadratic Bézier curve from the current point to (x,y). The control point is assumed to be the reflection of the control point on the previous
command relative to the current point. (If there is no previous command or if the previous command was not a PathQuadraticCurvetoAbs, PathQuadraticCurvetoRel, PathSmoothQuadraticCurvetoAbs or PathSmoothQuadraticCurvetoRel, assume the control point is coincident with the current point.) PathSmoothQuadraticCurvetoAbs indicates that absolute coordinates will follow; PathSmoothQuadraticCurvetoRel indicates that relative coordinates will follow. At the end of the command, the new current point becomes the final (x,y) coordinate pair used in the polybezier.

const std::list<Magick::Coordinate> &coordinates_

PathSmoothQuadraticCurvetoRel const Magick::Coordinate &coordinate_

const std::list<Magick::Coordinate> &coordinates_

The elliptical arc curve commands

The elliptical arc curve commands depend on the PathArcArgs argument class, which has the constructor signature:

   PathArcArgs( double radiusX_, double radiusY_,
                double xAxisRotation_, bool largeArcFlag_,
                bool sweepFlag_, double x_, double y_ );

The elliptical arc commands are as follows:

Elliptical Arc Curve Classes
Sub-Class Constructor Signature Description

PathArcAbs const Magick::PathArcArgs &coordinates_ Draws an elliptical arc from the current point to (x, y). The size and orientation of the ellipse are defined by two radii (radiusX, radiusY) and an xAxisRotation, which indicates how the ellipse as a whole is rotated relative to the current coordinate system. The center (cx, cy) of the ellipse is calculated automatically to satisfy the constraints imposed by the other parameters. largeArcFlag and sweepFlag contribute to the automatic calculations and help determine how the arc is drawn. If largeArcFlag is true then draw the larger of the available arcs. If sweepFlag is true, then draw the arc matching a clock-wise rotation.

const std::list<Magick::PathArcArgs> &coordinates_

PathArcRel const Magick::PathArcArgs &coordinates_

const std::list<Magick::PathArcArgs> &coordinates_