多窗口范例（二），做一个划线生成图像的应用，最后结果：





子窗口划线，主窗口复制多个画布叠加并添加了旋转动画。

范例程序

主程序：

package syf.demo.multiwindow2;

import processing.core.PApplet;
import processing.core.PGraphics;

public class TwoWindowApp extends PApplet {

    ChildWindow childwindow;
    Canvas canvas;
    PGraphics pg;

    @Override
    public void settings() {
        size(800,800);
    }
    @Override
    public void setup() {
        pg = createGraphics(200,200);
        pg.beginDraw();
        pg.clear();
        pg.background(0,0);
        pg.endDraw();
        canvas = new Canvas(this,pg);
        childwindow = new ChildWindow(this,pg);

        background(0);
    }
    @Override
    public void draw() {
        //background(20);   这里就暂时不刷新
        canvas.update();
        canvas.draw();
    }

    public static void main(String[] args) {
        String[] appletArgs = new String[] {"syf.demo.multiwindow2.TwoWindowApp"};
        PApplet.main(appletArgs);
    }
}

子窗口类：

package syf.demo.multiwindow2;

import javafx.stage.Screen;
import processing.core.PApplet;
import processing.core.PConstants;
import processing.core.PGraphics;

import java.awt.*;

public class ChildWindow extends PApplet{
    PGraphics pg;
    PApplet app;
    int preposx;
    int preposy;
    Dimension screen;
    ChildWindow(PApplet _app,PGraphics _pg){
        super();
        pg = _pg;
        app = _app;
        PApplet.runSketch(new String[]{this.getClass().getName()},this);

        Toolkit toolkit = Toolkit.getDefaultToolkit();
        screen = toolkit.getScreenSize();
    }

    @Override
    public void settings() {
        size(pg.width, pg.height);
    }

    @Override
    public void setup() {
        background(0);
	//让其窗口依附在主窗口左边
        surface.setLocation(screen.width/2-app.width/2-this.width,screen.height/2-app.height/2);
        pg.colorMode(PConstants.HSB,360,100,100);
        pg.strokeWeight(8);

    }

    @Override
    public void draw() {
        pg.beginDraw();
        pg.background(0,10);   //背景刷新，加点透明度
        //pg.stroke(250);
        pg.stroke((frameCount*2)%360,100,100,150);//变颜色，颜色模式 HSB
        pg.line(mouseX,mouseY,preposx,preposy);
        pg.endDraw();

        set(0,0,pg);

        preposx = mouseX;
        preposy = mouseY;
    }
}

画布类：

package syf.demo.multiwindow2;

import processing.core.PApplet;
import processing.core.PGraphics;

public class Canvas {

    private PApplet app;
    PGraphics pg;
    float rotvalue;

    Canvas(PApplet _app, PGraphics _pg){
        app = _app;
        pg = _pg;
    }

    void update(){
        rotvalue += 0.06; //让它自转
    }

    void draw(){
        for (int i = 0; i < 10; i++) {
            app.push();
                app.translate(app.width/2,app.height/2);
                app.rotate(360/10*i+rotvalue);   //中心旋转扩散呈现
                //app.set(0,0, pg);  set 位置不受translate影响
                app.image(pg, 0, 0);
            app.pop();
        }
    }
}

总结

可以看到有了子窗口能清楚的看到用户的绘制过程和结果，在日后开发和维护都能有作用，说白了，是应用更自然更有范儿了