编写Java代码实现画图工具，实现画笔粗细、画笔颜色选择。插入图片，实现裁剪功能

以下是一个简单的 JavaFX 画图工具示例，实现了画笔粗细、画笔颜色选择、插入图片和裁剪功能。

import javafx.application.Application;
import javafx.embed.swing.SwingFXUtils;
import javafx.geometry.Point2D;
import javafx.scene.Cursor;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.control.Button;
import javafx.scene.control.ColorPicker;
import javafx.scene.control.Slider;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.BorderPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.FileChooser;
import javafx.stage.Stage;

import javax.imageio.ImageIO;
import java.io.File;
import java.io.IOException;

public class DrawingTool extends Application {

    private Canvas canvas;
    private GraphicsContext gc;
    private Color color = Color.BLACK;
    private double lineWidth = 1.0;
    private Point2D startPoint;
    private Rectangle clipRect;
    private ImageView imageView;

    @Override
    public void start(Stage primaryStage) throws Exception {
        canvas = new Canvas(800, 600);
        gc = canvas.getGraphicsContext2D();
        gc.setFill(Color.WHITE);
        gc.fillRect(0, 0, canvas.getWidth(), canvas.getHeight());

        canvas.setOnMousePressed(event -> {
            startPoint = new Point2D(event.getX(), event.getY());
            gc.setStroke(color);
            gc.setLineWidth(lineWidth);
            gc.beginPath();
            gc.moveTo(startPoint.getX(), startPoint.getY());
        });

        canvas.setOnMouseDragged(event -> {
            gc.lineTo(event.getX(), event.getY());
            gc.stroke();
        });

        canvas.setOnMouseReleased(event -> {
            gc.closePath();
        });

        ColorPicker colorPicker = new ColorPicker();
        colorPicker.setOnAction(event -> color = colorPicker.getValue());

        Slider slider = new Slider(1, 10, 1);
        slider.setShowTickLabels(true);
        slider.setShowTickMarks(true);
        slider.valueProperty().addListener((observable, oldValue, newValue) -> lineWidth = newValue.doubleValue());

        Button insertImageButton = new Button("Insert Image");
        insertImageButton.setOnAction(event -> {
            FileChooser fileChooser = new FileChooser();
            fileChooser.setTitle("Open Image File");
            fileChooser.getExtensionFilters().addAll(
                    new FileChooser.ExtensionFilter("Image Files", "*.png", "*.jpg", "*.gif"));
            File selectedFile = fileChooser.showOpenDialog(primaryStage);
            if (selectedFile != null) {
                try {
                    Image image = new Image(selectedFile.toURI().toString());
                    imageView = new ImageView(image);
                    imageView.setPreserveRatio(true);
                    imageView.setSmooth(true);
                    imageView.setCache(true);
                    imageView.setOnMousePressed(insertImageEventHandler);
                    canvas.getChildren().add(imageView);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

        Button clipImageButton = new Button("Clip Image");
        clipImageButton.setOnAction(event -> {
            clipRect = new Rectangle();
            clipRect.setFill(Color.TRANSPARENT);
            clipRect.setStroke(Color.BLACK);
            clipRect.setStrokeWidth(1.0);
            canvas.setCursor(Cursor.CROSSHAIR);
            canvas.getChildren().add(clipRect);
            canvas.setOnMousePressed(clipImageEventHandler);
            canvas.setOnMouseDragged(clipImageEventHandler);
            canvas.setOnMouseReleased(clipImageEventHandler);
        });

        BorderPane root = new BorderPane();
        root.setCenter(canvas);
        root.setTop(colorPicker);
        root.setBottom(slider);
        root.setLeft(insertImageButton);
        root.setRight(clipImageButton);

        Scene scene = new Scene(root);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private void saveImage() {
        try {
            FileChooser fileChooser = new FileChooser();
            fileChooser.setTitle("Save Image File");
            fileChooser.getExtensionFilters().addAll(
                    new FileChooser.ExtensionFilter("PNG", "*.png"),
                    new FileChooser.ExtensionFilter("JPG", "*.jpg"),
                    new FileChooser.ExtensionFilter("GIF", "*.gif"));
            File file = fileChooser.showSaveDialog(null);
            if (file != null) {
                Image snapshot = canvas.snapshot(null, null);
                ImageIO.write(SwingFXUtils.fromFXImage(snapshot, null), "png", file);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void clipImage() {
        if (imageView != null && clipRect != null) {
            Image image = imageView.getImage();
            double scaleX = image.getWidth() / imageView.getFitWidth();
            double scaleY = image.getHeight() / imageView.getFitHeight();
            double x = clipRect.getX() * scaleX;
            double y = clipRect.getY() * scaleY;
            double w = clipRect.getWidth() * scaleX;
            double h = clipRect.getHeight() * scaleY;
            Image clippedImage = new Image(image.getPixelReader(), (int) x, (int) y, (int) w, (int) h);
            imageView.setImage(clippedImage);
            canvas.getChildren().remove(clipRect);
            clipRect = null;
        }
    }

    private final EventHandler<MouseEvent> insertImageEventHandler = new EventHandler<MouseEvent>() {
        @Override
        public void handle(MouseEvent event) {
            if (event.isSecondaryButtonDown()) {
                canvas.getChildren().remove(imageView);
                imageView = null;
            }
        }
    };

    private final EventHandler<MouseEvent> clipImageEventHandler = new EventHandler<MouseEvent>() {
        @Override
        public void handle(MouseEvent event) {
            if (event.getEventType() == MouseEvent.MOUSE_PRESSED) {
                clipRect.setX(event.getX());
                clipRect.setY(event.getY());
            } else if (event.getEventType() == MouseEvent.MOUSE_DRAGGED) {
                clipRect.setWidth(event.getX() - clipRect.getX());
                clipRect.setHeight(event.getY() - clipRect.getY());
            } else if (event.getEventType() == MouseEvent.MOUSE_RELEASED) {
                clipImage();
                canvas.setCursor(Cursor.DEFAULT);
                canvas.setOnMousePressed(null);
                canvas.setOnMouseDragged(null);
                canvas.setOnMouseReleased(null);
            }
        }
    };

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

这个实现可以让你在界面上进行绘制、选择画笔颜色和粗细、插入图片和裁剪图片。请注意，这只是一个简单的示例，你可以根据你的需求进行修改和扩展。