处理：如何根据所单击的鼠标按钮为形状赋予值？

如何解决处理：如何根据所单击的鼠标按钮为形状赋予值？

我正在尝试在Processing上创建一个程序，该程序基于单击的按钮（向左或向右按钮）绘制矩形或椭圆形，并且我在如何将值保存在变量currentShape中class mousepressed。我应该在按下鼠标时获取一个值并将其保存到currentShape中，然后使用mouseDragged中的值来拖动并弄乱形状大小。这是我的代码：

int startX;
int startY;
int currentColor;
float currentShape;

float[] firstcornerX = {};
float[] firstcornerY = {};
float[] secondcornerX = {};
float[] secondcornerY = {};
color[] colors = {};
float[] shapes = {};

void setup() {
    size(500,500);
    rectMode(CORNERS);
    ellipseMode(CORNERS);
}

void draw() {}

void mousepressed() {
    startX = mouseX;
    startY = mouseY;
    currentColor = color(random(255),random(255),random(255));
    if (mouseButton == LEFT) {
        ellipse(mouseX,mouseY,100,100);
    } else if (mouseButton == RIGHT) {
        rect(mouseX,100);
    }
}

void mouseReleased() {
    firstcornerX = append(firstcornerX,startX);
    firstcornerY = append(firstcornerY,startY);
    secondcornerX = append(secondcornerX,mouseX);
    secondcornerY = append(secondcornerY,mouseY);
    colors = append(colors,currentColor);
    shapes = append(shapes,currentShape);
}

void mouseDragged() {
    background(255);
    for (int i = 0; i < firstcornerX.length; i++) {
        fill(colors[i]);
        rect(firstcornerX[i],firstcornerY[i],secondcornerX[i],secondcornerY[i]);
    }

    fill(currentColor);
    rect(startX,startY,mouseX,mouseY);
}

解决方法

您确实要附加currentShape，但是您没有在mousePressed()中的椭圆和矩形之间更改形状类型，因此currentShape在代码中将始终为0.0 。另外，您需要使用形状类型来检查将在屏幕上呈现的形状（在代码中您直接使用rect()和ellipse()的所有位置）

我个人会为形状类型（或enum）使用一个整数和几个常数，但是float currentShape;会做到。假设0.0代表椭圆，而1.0代表矩形。您可以存储这些常数，以便轻松记住哪个常数：

final float SHAPE_TYPE_ELLIPSE = 0.0;
final float SHAPE_TYPE_RECT    = 1.0;

由于需要在draw()中渲染形状，而且还需要在mouseDragged()时渲染形状，因此可以将功能封装到可重用的功能中（而不是复制代码）：

void drawShape(float x1,float y1,float x2,float y2,float shapeType){
  if(shapeType == SHAPE_TYPE_ELLIPSE){
    ellipse(x1,y1,x2,y2);
  }
  if(shapeType == SHAPE_TYPE_RECT){
    rect(x1,y2);
  }
}

本来可以达到if(shapeType == 0.0) ... else ...的条件，但是上面的内容更易于阅读/理解，将来可以扩展以支持更多形状。

剩下3个要仔细检查：

基于鼠标按钮更新mousePressed()中的形状类型
在mouseReleased()中添加形状类型（您已经这样做了）
在drawShape()和mouseDragged()中相应地调用draw()

完整的代码清单：

int startX;
int startY;
int currentColor;
float currentShape;
// constants for the supported shape types 
final float SHAPE_TYPE_ELLIPSE = 0.0;
final float SHAPE_TYPE_RECT    = 1.0;

float [] firstcornerX = {};
float [] firstcornerY = {};
float [] secondcornerX = {};
float [] secondcornerY = {};
color [] colors = {};
float [] shapes = {};

void setup () {
  size(500,500);
  rectMode(CORNERS);
  ellipseMode(CORNERS);
}

void draw() {
  background (255);
  for (int i=0; i < firstcornerX.length; i++) {
    fill(colors[i]);
    // draw the shape from memory
    drawShape(firstcornerX[i],firstcornerY[i],secondcornerX[i],secondcornerY[i],shapes[i]);
  }
}

void drawShape(float x1,y2);
  }
}

void mousePressed () {
  startX = mouseX;
  startY = mouseY;
  currentColor = color(random(255),random(255),random(255));
  if(mouseButton == LEFT) {
   currentShape = SHAPE_TYPE_ELLIPSE; 
  }else if(mouseButton == RIGHT) {
   currentShape = SHAPE_TYPE_RECT; 
  }
}

void mouseReleased () {
  firstcornerX = append(firstcornerX,startX);
  firstcornerY = append(firstcornerY,startY);
  secondcornerX = append(secondcornerX,mouseX);
  secondcornerY = append(secondcornerY,mouseY);
  colors = append(colors,currentColor);
  shapes = append(shapes,currentShape);
}

void mouseDragged () {
  fill(currentColor);
  // preview the shape live
  drawShape(startX,startY,mouseX,mouseY,currentShape);
}

我正在使用旧版本的Processing，并且在mouseDragged()下出现了一些闪烁。或者，可以在mousePressed中使用draw()布尔值：

int startX;
int startY;
int currentColor;
float currentShape;
// constants for the supported shape types 
final float SHAPE_TYPE_ELLIPSE = 0.0;
final float SHAPE_TYPE_RECT    = 1.0;

float [] firstcornerX = {};
float [] firstcornerY = {};
float [] secondcornerX = {};
float [] secondcornerY = {};
color [] colors = {};
float [] shapes = {};

void setup () {
  size(500,shapes[i]);
  }
  // preview the shape live if mouse is dragged:
  if(mousePressed){
    fill(currentColor);
    drawShape(startX,currentShape);
  }
}

void drawShape(float left,float top,float right,float bottom,float shapeType){
  if(shapeType == SHAPE_TYPE_ELLIPSE){
    ellipse(left,top,right,bottom);
  }
  if(shapeType == SHAPE_TYPE_RECT){
    rect(left,bottom);
  }
}

void mousePressed () {
  startX = mouseX;
  startY = mouseY;
  currentColor = color(random(255),currentShape);
}