Java FX Canvas直到完成才显示

问题描述

我想创建一个Java FX应用程序，一次在Canvas上绘制线条，在线段之间有明显的时间.在下面的应用程序中，我可以想象绘制一条对角线，停顿一秒钟，然后绘制下一条对角线.而是，FX窗口弹出空白，等待2秒钟，然后同时显示两条对角线.如何达到我想要的效果? javafx.scene.canvas.Canvas不是要使用的正确对象吗?

I want to create a java FX application that draws lines on a Canvas one step at a time, with a noticable time between line segments. In the below application I have what I imagined would draw a diagonal line, stall a second and then draw the next diagonal line. Instead, the FX window pops up blank, waits 2 seconds, and then shows the two diagonal lines at the same time. How do I achieve the effect I am looking for? Is javafx.scene.canvas.Canvas not the right object to be using?

import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.layout.StackPane;

import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.paint.Color;

public class FrameCanvas extends Application{
  public static void main(String[] args){
    launch(args);
  }
  @Override
  public void start(Stage primaryStage)throws Exception{
    ////////////////////Basic FX stuff
    Canvas theCanvas = new Canvas(900,900);
    StackPane theLayout = new StackPane();
    theLayout.getChildren().add(theCanvas);
    Scene theScene = new Scene(theLayout,900,900);
    primaryStage.setScene(theScene);
    primaryStage.show();
    ///////////////////////
    /////Drawing an X
    ///////////////////////
    GraphicsContext gc = theCanvas.getGraphicsContext2D();
    Thread.sleep(1000);
    gc.strokeLine(0,0,200,200);
    Thread.sleep(1000);
    gc.strokeLine(200,0,0,200);
    /////////////////////////////
  }
}

推荐答案

请勿阻止(例如Thread.sleep(...))FX应用程序线程.该线程负责渲染场景，因此您将阻止渲染任何更新.

Don't block (e.g. Thread.sleep(...)) the FX Application Thread. That thread is responsible for rendering the scene, so you will prevent any updates from being rendered.

相反，使用动画来实现以下功能(毕竟，动画实际上就是您在此处创建的内容):

Instead, use an animation for functionality like this (after all, an animation is really what you're creating here):

public void start(Stage primaryStage)throws Exception{
    ////////////////////Basic FX stuff
    Canvas theCanvas = new Canvas(900,900);
    StackPane theLayout = new StackPane();
    theLayout.getChildren().add(theCanvas);
    Scene theScene = new Scene(theLayout,900,900);
    primaryStage.setScene(theScene);
    primaryStage.show();
    ///////////////////////
    /////Drawing an X
    ///////////////////////
    GraphicsContext gc = theCanvas.getGraphicsContext2D();

    Timeline timeline = new Timeline(
        new KeyFrame(Duration.seconds(1), e -> gc.strokeLine(0,0,200,200)),
        new KeyFrame(Duration.seconds(2), e -> gc.strokeLine(200,0,0,200))
    );
    timeline.play();
    /////////////////////////////
}

这篇关于Java FX Canvas直到完成才显示的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！