我正在研究一个问题，我在尝试从Shape转换为区域时遇到了强制转换问题（请参阅上一篇文章cast exception question）。现在似乎我创建的形状没有正确创建。我没有在此处发布所有源代码，而是附加了所有源文件here的链接。
基本上我通过标准调用
创建如下形状YingYang shape = new YingYang();
shape = shape.moveTo(x, y);
shape = shape.scaleBy(size);
shape.setColor(getNextColor());
并且对区域类的调用是：
public YingYang()
{
Area mainCircle = new Area(new Ellipse2D.Double(...)
...
yingYang.add(mainCircle);
}
MoveTo致电：
public YingYang moveTo(double x, double y)
{
at.translate(x, y);
at.setToTranslation(x, y);
yingYang.transform(at);
return new YingYang(at.createTransformedShape(yingYang));
}
ScaleBy：
public YingYang scaleBy(double scale)
{
double cx = this.getBounds2D().getCenterX();
double cy = this.getBounds2D().getCenterY();
at.translate(cx, cy);
at.setToTranslation(cx, cy);
at.scale(scale, scale);
at.translate(-cx, -cy);
return new YingYang(at.createTransformedShape(yingYang));
}
当我在绘图面板中调用paintComponent（）时：
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
for(YingYang s : shapes)
{
System.out.println(s.getBounds2D());
g2.setColor(s.getColor());
g2.fill(s);
}
}
print语句打印出来：
java.awt.geom.Rectangle2D$Double[x=0.0,y=0.0,w=0.0,h=0.0]
我不知所措......有什么想法吗？
答案 0 :(得分：1)
看起来您已将我的建议合并到一段代码中。如果你打算使用变量yingYang，那么你应该在类上实现形状。但是，如果要扩展该区域，则需要删除yingYang变量并将该类用作区域，例如：yingYang.add（mainCircle）;变成add（mainCircle）; ...基本上删除了yingYang变量的所有引用。
因此，您使用“this”而不是“yingYang”变量。 heres是你的YingYang类的修改版本，删除了引用。
import java.awt.Color;
import java.awt.Rectangle;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import java.awt.geom.Area;
import java.awt.geom.Ellipse2D;
import java.awt.geom.PathIterator;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
public class YingYang extends Area
{
AffineTransform at = new AffineTransform();
private boolean movingRight = true;
private boolean movingUp = true;
private Color color = Color.BLACK;
private int dx = 10, dy = 10;
public YingYang(Shape shape)
{
super(shape);
}
public YingYang()
{
// Construct the Outer Circle & Lower Dot
Area mainCircle = new Area(new Ellipse2D.Double(-210, -210, 420, 420));
Area lowerDot = new Area(new Ellipse2D.Double(-10, 90, 40, 40));
mainCircle.subtract(lowerDot);
// Begin Construction of the whit side of symbol
Area whiteSide = new Area(new Ellipse2D.Double(-200, -200, 400, 400));
Area rect = new Area(new Rectangle2D.Double(0, -200, 200, 400));
whiteSide.subtract(rect);
// Construct the upper white Circle
Area upperCircle = new Area(new Ellipse2D.Double(-100, -200, 200, 200));
whiteSide.add(upperCircle);
// Construct the Upper Dot
Area upperDot = new Area(new Ellipse2D.Double(-10, -110, 40, 40));
whiteSide.subtract(upperDot);
// Remove the lower circle portion
Area lowerCircle = new Area(new Ellipse2D.Double(-100, 0, 200, 200));
whiteSide.subtract(lowerCircle);
// Add Main Circle
add(mainCircle);
// Subtract the white side
subtract(whiteSide);
}
//------------------------ Methods -----------------------------------------
/**
* Sets this shapes color
* (must call getColor before drawing this shape)
* @param color
*/
public void setColor(Color color)
{
this.color = color;
}
/**
* Gets this shapes current color
* @return color
*/
public Color getColor()
{
return this.color;
}
/**
* Determines if the shape is moving left to right
* @return - boolean
*/
public boolean isMovingRight()
{
return movingRight;
}
/**
* Determines if the shape is moving from down to up
* @return - boolean
*/
public boolean isMovingUp()
{
return movingUp;
}
/**
* Changes the Horizontal Path that this shape is traveling
*/
public void changeHorizonalMovement()
{
if(isMovingRight())
{
movingRight = false;
}
else
{
movingRight = true;
}
}
/**
* Changes the Vertical Path that this shape is traveling
*/
public void changeVerticalMovement()
{
if(isMovingUp())
{
movingUp = false;
}
else
{
movingUp = true;
}
}
/**
* Sets the direction of the Horizontal Path of this shape
* true = left to right : false = right to left
* @param dir - boolean
*/
public void setHorizonalMovement(boolean dir)
{
this.movingRight = dir;
}
/**
* Sets the direction of the Vertical Path of this shape
* true = down to up : false = up to down
* @param dir - boolean
*/
public void setVerticalMovement(boolean dir){
this.movingUp = dir;
}
/**
* Moves the current shape by the amount x,y
* @param x - double
* @param y - double
*/
public YingYang moveTo(double x, double y)
{
at.translate(x, y);
at.setToTranslation(x, y);
transform(at);
return new YingYang(at.createTransformedShape(this));
}
/**
* Rotate this shape
* @param theta - amount to rotate shape by
* @return
*/
public YingYang rotate(double theta)
{
double cx = getBounds2D().getCenterX();
double cy = getBounds2D().getCenterY();
at.translate(cx, cy);
at.setToTranslation(cx, cy);
at.rotate(Math.toRadians(theta));
at.translate(-cx, -cy);
return new YingYang(at.createTransformedShape(this));
}
public YingYang moveToAndRotate(double x, double y, double theta)
{
double cx = getBounds2D().getCenterX();
double cy = getBounds2D().getCenterY();
at.translate(cx, cy);
at.setToTranslation(cx, cy);
at.translate(x, y);
at.rotate(Math.toRadians(theta));
at.translate(-cx, -cy);
return new YingYang(at.createTransformedShape(this));
}
/**
* Scales this shape uniformly by the amount of scale
* about the origin
* @param scale - double
*/
public YingYang scaleBy(double scale)
{
double cx = this.getBounds2D().getCenterX();
double cy = this.getBounds2D().getCenterY();
at.translate(cx, cy);
at.setToTranslation(cx, cy);
at.scale(scale, scale);
at.translate(-cx, -cy);
return new YingYang(at.createTransformedShape(this));
}
/**
* Rotates this shape theta degrees about the origin
*/
public YingYang rotate(Double theta)
{
double cx = this.getBounds2D().getCenterX();
double cy = this.getBounds2D().getCenterY();
at.translate(cx, cy);
at.setToTranslation(cx, cy);
at.rotate(Math.toRadians(theta));
at.translate(-cx, -cy);
return new YingYang(at.createTransformedShape(this));
}
public int getDx()
{
return this.dx;
}
public void setDx(int x)
{
this.dx = x;
}
public int getDy()
{
return this.dy;
}
public void setDy(int y)
{
this.dy = y;
}
}