JavaFX – CubicCurveTo Path Object


JavaFX – CubicCurveTo Path Object

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A Cubic curve is a two dimensional structure that is a type of a Bezier curve. A Bezier curve is defined as a curve that passes through a set of control points (P0…Pn). It is called a Cubic curve when the number of control points are 4 (or, if the order of the curve is 3).

JavaFX also provides a CubicCurve Path object to draw a more complex shape. Here, we will be considering only the end points of the Cubic Curve and the control points in order to construct a Path object. Let us see how to construct it in detail further.

CubicCurve Path Object

The path element cubic curve is used to draw a cubic curve to a point in the specified coordinates from the current position.

It is represented by a class named CubicCurveTo. This class belongs to the package javafx.scene.shape.

This class has 6 properties of the double datatype namely −

  • setX − The x coordinate of the point to which a curve is to be drawn from the current position.

  • setX − The y coordinate of the point to which a curve is to be drawn from the current position.

  • controlX1 − The x coordinate of the 1st control point of the curve.

  • controlY1 − The y coordinate of the 1st control point of the curve.

  • controlX2 − The x coordinate of the 2nd control point of the curve.

  • controlY2 − The y coordinate of the 2nd control point of the curve.

To draw a cubic curve, you need to pass values to these properties. This can be done by passing them to the constructor of this class. These should be in the same order as they were at the time of instantiation; Or, by using their respective setter methods.

Steps to draw PathElement Cubic Curve

To draw a cubic curve to a specified point from the current position in JavaFX, follow the steps given below.

Step 1: Creating a Class

Create a Cubic Curve Path object inside the start() method of the Application class as shown below.

public class ClassName extends Application { 
   @Override     
   public void start(Stage primaryStage) throws Exception {
      //Creating a Path object 
      Path path = new Path();   
   }    
}

Step 2: Create a Path

Create the MoveTo path element and set the XY coordinates to the starting point of the line to the coordinates (100, 150). This can be done using the methods setX() and setY() of the class MoveTo as shown below.

//Moving to the starting point 
MoveTo moveTo = new MoveTo(); 
moveTo.setX(100.0f); 
moveTo.setY(150.0f);

Step 3: Creating an Object of the Class CubicCurveTo

Create the path element quadratic curve by instantiating the class named CubicCurveTo, which belongs to the package javafx.scene.shape as shown below −

//Creating an object of the class CubicCurveTo 
CubicCurveTo cubicCurveTo= new CubicCurveTo ();

Step 4: Setting Properties to the Cubic Curve Element

Specify the coordinates of the point to which a cubic curve is to be drawn from the current position. Then you should set the properties x, y, controlX1, controlY1, controlX2, controlY2 and the coordinates of the control point by their setter methods as shown below.

//Setting properties of the class CubicCurve            
cubicCurveTo.setControlX1(400.0f); 
cubicCurveTo.setControlY1(40.0f); 
cubicCurveTo.setControlX2(175.0f); 
cubicCurveTo.setControlY2(250.0f);
cubicCurveTo.setX(500.0f); 
cubicCurveTo.setY(150.0f);

Step 5: Adding Elements to the Observable List of Path Class

Add the path elements → MoveTo and CubicCurveTo, created in the previous steps to the observable list of the Path class as follows −

//Adding the path elements to Observable list of the Path class   
path.getElements().add(moveTo); 
path.getElements().add(cubicCurveTo);

Step 6: Launching Application

Once the CubicCurveTo path object is created, follow the given steps below to launch the application properly −

  • Firstly, instantiate the class named Scene by passing the Group object as a parameter value to its constructor. To this constructor, you can also pass dimensions of the application screen as optional parameters.

  • Then, set the title to the stage using the setTitle() method of the Stage class.

  • Now, a Scene object is added to the stage using the setScene() method of the class named Stage.

  • Display the contents of the scene using the method named show().

  • Lastly, the application is launched with the help of the launch() method.

Example

Following is the program which draws a cubic curve from the current point to a specified position using the class named Path of JavaFX. Save this code in a file with the name CubicCurveToExample.java.

import javafx.application.Application; 
import javafx.scene.Group; 
import javafx.scene.Scene; 
import javafx.stage.Stage; 
import javafx.scene.shape.CubicCurveTo; 
import javafx.scene.shape.MoveTo; 
import javafx.scene.shape.Path; 
         
public class CubicCurveToExample extends Application {  
   @Override 
   public void start(Stage stage) {        
      //Creating an object of the class named Path 
      Path path = new Path();  
      
      //Moving to the starting point 
      MoveTo moveTo = new MoveTo(); 
      moveTo.setX(100.0); 
      moveTo.setY(150.0);
      
      //Instantiating the class CubicCurve 
      CubicCurveTo cubicCurveTo = new CubicCurveTo(); 
       
      //Setting properties of the class CubicCurve            
      cubicCurveTo.setControlX1(400.0f); 
      cubicCurveTo.setControlY1(40.0f); 
      cubicCurveTo.setControlX2(175.0f); 
      cubicCurveTo.setControlY2(250.0f); 
      cubicCurveTo.setX(500.0f); 
      cubicCurveTo.setY(150.0f);       
       
      //Adding the path elements to Observable list of the Path class 
      path.getElements().add(moveTo);       
      path.getElements().add(cubicCurveTo);         
      
      //Creating a Group object  
      Group root = new Group(path); 
         
      //Creating a scene object 
      Scene scene = new Scene(root, 600, 300);  
      
      //Setting title to the Stage 
      stage.setTitle("Drawing a cubic through a specified path"); 
         
      //Adding scene to the stage 
      stage.setScene(scene); 
         
      //Displaying the contents of the stage 
      stage.show(); 
   }      
   public static void main(String args[]){ 
      launch(args); 
   }
}

Compile and execute the saved java file from the command prompt using the following commands.

javac --module-path %PATH_TO_FX% --add-modules javafx.controls CubicCurveToExample.java 
java --module-path %PATH_TO_FX% --add-modules javafx.controls CubicCurveToExample

Output

On executing, the above program generates a JavaFX window displaying a Cubic curve. This is drawn from the current position to the specified point as shown below.

Drawing Cubic Curve Path

Example

In another example, we are trying to apply Stroke Transition Animation on Cubic Curve Path. Here, the stroke of said 2D shape is set to change its color from BLACK to BROWN. Save this code in a file with the name CubicCurveToAnimation.java.

import javafx.application.Application;
import javafx.animation.StrokeTransition;
import javafx.scene.Group; 
import javafx.scene.Scene; 
import javafx.stage.Stage; 
import javafx.scene.shape.CubicCurveTo;
import javafx.util.Duration;
import javafx.scene.shape.MoveTo; 
import javafx.scene.shape.Path;
import javafx.scene.paint.Color;
         
public class CubicCurveToAnimation extends Application {  
   @Override 
   public void start(Stage stage) {        
      //Creating an object of the class named Path 
      Path path = new Path();  
      
      //Moving to the starting point 
      MoveTo moveTo = new MoveTo(); 
      moveTo.setX(100.0); 
      moveTo.setY(150.0);
      
      //Instantiating the class CubicCurve 
      CubicCurveTo cubicCurveTo = new CubicCurveTo(); 
       
      //Setting properties of the class CubicCurve            
      cubicCurveTo.setControlX1(400.0f); 
      cubicCurveTo.setControlY1(40.0f); 
      cubicCurveTo.setControlX2(175.0f); 
      cubicCurveTo.setControlY2(250.0f); 
      cubicCurveTo.setX(500.0f); 
      cubicCurveTo.setY(150.0f);       
       
      //Adding the path elements to Observable list of the Path class 
      path.getElements().add(moveTo);       
      path.getElements().add(cubicCurveTo);

      //creating stroke transition  
      StrokeTransition st = new StrokeTransition(); 
      
      //Setting the duration of the transition 
      st.setDuration(Duration.millis(1000)); 
      
      //Setting the shape for the transition 
      st.setShape(path); 
      
      //Setting the fromValue property of the transition (color) 
      st.setFromValue(Color.BLACK); 
      
      //Setting the toValue property of the transition (color) 
      st.setToValue(Color.BROWN); 
       
      //Setting the cycle count for the transition 
      st.setCycleCount(50); 
      
      //Setting auto reverse value to false 
      st.setAutoReverse(false); 
      
      //Playing the animation 
      st.play();        
      
      //Creating a Group object  
      Group root = new Group(path); 
         
      //Creating a scene object 
      Scene scene = new Scene(root, 600, 300);  
      
      //Setting title to the Stage 
      stage.setTitle("Drawing a cubic curve"); 
         
      //Adding scene to the stage 
      stage.setScene(scene); 
         
      //Displaying the contents of the stage 
      stage.show(); 
   }      
   public static void main(String args[]){ 
      launch(args); 
   }
}

Compile and execute the saved java file from the command prompt using the following commands.

javac --module-path %PATH_TO_FX% --add-modules javafx.controls CubicCurveToAnimation.java 
java --module-path %PATH_TO_FX% --add-modules javafx.controls CubicCurveToAnimation

Output

On executing, the above program generates a JavaFX window displaying a Cubic curve with the Stroke transition. This is drawn from the current position to the specified point as shown below.

Drawing Cubic Curve Path



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