绘图程序在加工中出现的问题

Question

我正在 Java 处理中创建一个基本的绘图程序，我有两种颜色（以及橡皮擦），我刚刚创建了一种新颜色（绿色）。出于某种原因，当我点击绿色时，它不会改变颜色。谢谢！

(注意，我运行这个程序是在Eclipse中导入的带processing的，如果你打算只用processing，把int color改成color1。去掉main函数，带[=的那个17=]("main");，你应该很好）如果你不想运行在日食中这样做（就像我一样）这里有一篇关于它的文章：https://processing.org/tutorials/eclipse/

// note: many imports aren't used yet
import java.util.ArrayList;
import java.util.Scanner;
import processing.core.PApplet;
import processing.core.PShape;

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class Main extends PApplet{

PShape rectangle;

String file = "";

char letter;

int color;
int color2;
int color3;
boolean red = false;
boolean blue = false;
boolean green = false;
boolean yellow = false;
boolean eraser = false;

boolean saving = false;

// needed to create this in order for Eclipse to work
public static void main(String[] args) {
    PApplet.main("Main");
}

public void settings(){
    size(1280, 720);
}

public void setup() {
    size(1280, 720);
    smooth();
    background(255, 255, 255);
    noStroke();

}

public void draw() {

    if (keyPressed) {

        if (key == 'c') {
            background(255, 255, 255);
        }

        if (key == 's') {
            save("Drawing.tif");

        }

    }
    else {
        color = 0;
    }
    fill(0);
    text("Press 'c' to clear the screen", 50, 700, 200, 50);
    text("Press 's' to save", 250, 700, 200, 50);

    fill(255, 0, 0);
    // red square
    rect(0, 50, 50, 50);
    fill(0, 10, 255);
    // blue square
    rect(0, 100, 50, 50);
    fill(0, 255, 40);
    // green square
    rect(0, 150, 50, 50);
    fill(255, 255, 0);
    // yellow square
    rect(0, 200, 50, 50);
    fill(0);


}

public void mousePressed() {
    if(red) {
        color = 255;
        color2 = 0;
        color3 = 0;
    }
    if(eraser) {
        color = 255;
        color2 = 255;
        color3 = 255;
    }
    if(blue) {
        color = 0;
        color2 = 10;
        color3 = 255;
    }
    if(green){
        color = 0;
        color2 = 255;
        color3 = 40;
    }
    else{
        fill(0);
    }
    // check if mouse is in drawing area
    if (mouseX >= 50 && mouseX <= 1280 && mouseY >= 0 && mouseY <= 680) {
        // change the drawing color 
        fill(color, color2, color3);
        rect(mouseX, mouseY, 50, 50);
    }
    // if red
    if (mouseX >= 0 && mouseX <= 50 && mouseY >= 50 && mouseY <= 100) {
        eraser = false;
        blue = false;
        green = false;
        red = true;
    }
    // if eraser (note: in top left corner)
    if (mouseX >= 0 && mouseX <= 50 && mouseY >= 0 && mouseY <= 50) {
        red = false;
        blue = false;
        green = false;
        eraser = true;
    }
    // if blue
    if (mouseX >= 0 && mouseX <=50 && mouseY >= 100 && mouseY <= 150) {
        eraser = false;
        red = false;
        green = false;
        blue = true;
    }
    // if green
    if (mouseX >= 0 && mouseY <= 50 && mouseY >= 150 && mouseY <= 200) {
        eraser = false;
        red = false;
        blue = false;
        green = true;
    }
}

// basically the same code for mousePressed
public void mouseDragged() {
    if(red) {
        color = 255;
        color2 = 0;
        color3 = 0;
    }
    if(eraser) {
        color = 255;
        color2 = 255;
        color3 = 255;
    }
    if(blue) {
        color = 0;
        color2 = 10;
        color3 = 255;
    }
    if(green){
        color = 0;
        color2 = 255;
        color3 = 40;
    }
    else{
        fill(0);
    }
    // check if mouse is in drawing area
    if (mouseX >= 50 && mouseX <= 1280 && mouseY >= 0 && mouseY <= 680) {
        // change the drawing color 
        fill(color, color2, color3);
        rect(mouseX, mouseY, 50, 50);
    }
    // if red
    if (mouseX >= 0 && mouseX <= 50 && mouseY >= 50 && mouseY <= 100) {
        eraser = false;
        blue = false;
        green = false;
        red = true;
    }
    // if eraser (note: in top left corner)
    if (mouseX >= 0 && mouseX <= 50 && mouseY >= 0 && mouseY <= 50) {
        red = false;
        blue = false;
        green = false;
        eraser = true;
    }
    // if blue
    if (mouseX >= 0 && mouseX <=50 && mouseY >= 100 && mouseY <= 150) {
        eraser = false;
        red = false;
        green = false;
        blue = true;
    }
    // if green
    if (mouseX >= 0 && mouseY <= 50 && mouseY >= 150 && mouseY <= 200) {
        eraser = false;
        red = false;
        blue = false;
        green = true;
    }
}

}

Answer 1

就像我在 , you really shouldn't use a variable named color. It might work for you in eclipse, but it's confusing. At the very least it makes it harder for us to help you. While you're at it, you should take care of things like unused import statements. See also: How to create a Minimal, Complete, and Verifiable example 中所说的那样。

要弄清楚这样的问题，您必须进行一些调试。我要检查的第一件事是：代码是否曾在 mousePressed() 函数中输入您的绿色 if 语句？所以我会在 if 语句中添加一个 println() 语句，如下所示：

  if (mouseX >= 0 && mouseY <= 50 && mouseY >= 150 && mouseY <= 200) {
    println("here");
    eraser = false;
    red = false;
    blue = false;
    green = true;
  }

运行程序并单击绿色方块，我们看到此 if 语句从未输入。这绝对是可疑的，所以让我们仔细看看 if 语句本身：

  if (mouseX >= 0 && mouseY <= 50 && mouseY >= 150 && mouseY <= 200) {

注意到什么了吗？如果没有，请大声朗读。

第二次检查正在比较 mouseY。看起来你打算使用 mouseX.

绘图程序在加工中出现的问题

Problems with drawing program in processing

eclipse

processing