JavaFX 3D - JavaFX 8: A Definitive Guide to Building Desktop, Mobile, and Embedded Java Clients - page 479

interior. The clip() method clips the Canvas by the path, so that future rendering method calls won't have any effect
outside of the path. The clearRect() method will clear a rectangular region of the Canvas with a transparent color
value. To clear the entire Canvas , you can call clearRect(0, 0, width, height) .
The following methods serve to provide additional information about the GraphicsContext :
•

Canvas getCanvas()

PixelWriter getPixelWriter() •

boolean isPointInPath(double x, double y)
The getCanvas() method returns the Canvas object. The getPixelWriter() method returns a PixelWriter that
can be used to manipulate the Canvas on a pixel-by-pixel basis. The PixelWriter class is part of the JavaFX Image Ops
API, which we cover in the next subsection. The isPointInPath() method returns true if the point (x, y) is within
the current path of the GraphicsContext .
The program in Listing 10-12 displays a Canvas and allows the user to drag the mouse across the screen to draw
an oval. The location and size of the oval is also shown on the Canvas .

•

Listing 10-12. CanvasExample.java
import javafx.application.Application;
import javafx.geometry.Point2D;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.stage.Stage;

import static java.lang.Math.abs;
import static java.lang.Math.min;

public class CanvasExample extends Application {
private Point2D p0;

public static void main(String[] args) {
launch(args);
}

@Override
public void start(Stage stage) {
stage.setTitle("Canvas Example");
stage.setScene(makeScene());
stage.show();
}

private Scene makeScene() {
Canvas canvas = new Canvas(640, 480);

GraphicsContext graphicsContext = canvas.getGraphicsContext2D();
graphicsContext.setFill(Color.BLUE);
graphicsContext.setStroke(Color.RED);
graphicsContext.setFont(Font.font(14));
graphicsContext.strokeText("Click and drag mouse to draw ovals", 20, 20);