Question

我创建了一个创建图像的Java应用程序。我想将代码放在for循环中，放在另一个for循环中，每次代码完成时更新stage / screen并返回第一个for循环，但似乎使用setScene方法和如果我将它们放在第一个for循环中，show方法似乎没有帮助。

对于下面的示例，我希望圆绘图可以自行进行，而不是通过单击。我正在使用thread.sleep方法每隔100毫秒。

package javaFX;

import java.awt.Dimension;
import java.awt.Toolkit;

import javafx.application.Application;

import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

public class circles extends Application {

    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
    double WIDTH = screenSize.getWidth() - 80;
    double HEIGHT = screenSize.getHeight() - 80;

    @Override
    public void start(Stage primaryStage) {
        Group root = new Group();
        Scene scene = new Scene(root, WIDTH, HEIGHT, Color.WHITE);
        Canvas canvas = new Canvas(WIDTH, HEIGHT);
        root.getChildren().add(canvas);
        GraphicsContext graphics = canvas.getGraphicsContext2D();
        primaryStage.setTitle("Circles!");

        canvas.setOnMouseClicked(clickEvent -> {
            for (int i = 0; i < 50; i++) {
                double ran = Math.random() * WIDTH;
                double nu = Math.random()*1000;
                int ranNum = (int) nu;
                graphics.strokeOval(ran, ran, ran, ran);
            }
        });     
        primaryStage.setScene(scene);
        primaryStage.setResizable(false);
        primaryStage.show();
    }
}

Answer 1

问题解决了！使用AnimationTimer，如下所示：

import java.awt.Dimension;
import java.awt.Toolkit;

import javafx.animation.AnimationTimer;
import javafx.application.Application;
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.stage.Stage;

public class Testing extends Application {

    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
    double WIDTH = screenSize.getWidth() - 80;
    double HEIGHT = screenSize.getHeight() - 80;

    @Override public void start(Stage primaryStage) {
        Group root = new Group();
        Scene scene = new Scene(root, WIDTH, HEIGHT, Color.WHITE);
        Canvas canvas = new Canvas(WIDTH, HEIGHT);
        root.getChildren().add(canvas);
        GraphicsContext graphics = canvas.getGraphicsContext2D();
        primaryStage.setTitle("Circles!");

        // canvas.setOnMouseClicked(clickEvent -> {
        // for (int i = 0; i < 50; i++) {
        // double ran = Math.random() * WIDTH;
        // graphics.strokeOval(ran, ran, ran, ran);
        // }
        // });

        primaryStage.setScene(scene);
        primaryStage.setResizable(false);
        primaryStage.show();

        new AnimationTimer() {
            @Override public void handle(long currentNanoTime) {
                for (int i = 0; i < 50; i++) {
                    double ran = Math.random() * WIDTH;
                    graphics.strokeOval(ran, ran, ran, ran);
                }

                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    // Do nothing
                }
            }
        }.start();
    }
}

JavaFX不会为您更新它。使用类似while循环的问题是，JavaFX并不知道你已经完成了指令（或者至少，这是我从Docs获得的印象）并开始绘制过程。似乎也没有什么东西可以手动强制重绘。所以，你必须使用AnimationTimer。

Java，for循环中的更新阶段

1 个答案: