處理繪圖程序的問題

Question

我在Java處理中創建了一個基本的繪圖程序，我有兩種顏色（以及橡皮擦），並且我剛創建了一種新顏色（綠色）。由於某些原因，當我點擊綠色時，它不會改變顏色。謝謝！ （注意，我在Eclipse中運行這個程序時導入了處理，如果你打算只使用處理，把int顏色改爲color1。除去主函數，用PApplet.main（「main」 ），和你應該是好），如果你wan't在Eclipse中運行這個（像我一樣）有關於它的文章在這裏：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your previous question說，你真不該」使用名爲color的變量。它可能在日食中適合你，但它很混亂。至少它讓我們很難幫助你。當你處於這種狀態時，你應該注意諸如未使用的導入語句之類的東西。另見：How to create a Minimal, Complete, and Verifiable example。

要找出這樣的問題，你必須做一些調試。我要檢查的第一件事是：代碼是否在mousePressed()函數中輸入了您的綠色if聲明？所以，我想補充一個println()聲明if語句中，就像這樣：

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

運行該程序，然後單擊綠色廣場，我們看到這款if語句是從來沒有進入。這絕對是可疑的，所以讓我們在if語句本身仔細一看：

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

注意什麼？如果沒有，請大聲讀出來。

第二次檢查是比較mouseY。看起來你打算使用mouseX。