如何在Java中居中圖像？

我想中心一個現有的三角形。提示要求三角形的底部是畫布的長度，並且峯頂接觸頂部和居中。這是一個班級，代碼給了。如何在Java中居中圖像？

public class Triangle { 
    private int height; 
    private int width; 
    private int xPosition; 
    private int yPosition; 
    private String color; 
    private boolean isVisible; 

    public Triangle() { 
     height = 270; 
     width = 270; 
     xPosition = 120; 
     yPosition = 120; 
     color = "green"; 
     isVisible = false; 
    } 

    public void makeVisible() { 
     isVisible = true; 
     draw(); 
    } 

    public void makeInvisible() { 
     erase(); 
     isVisible = false; 
    } 

    public void moveRight() { 
     moveHorizontal(20); 
    } 

    public void moveLeft() { 
     moveHorizontal(-20); 
    } 

    public void moveUp() { 
     moveVertical(-20); 
    } 

    public void moveDown() { 
     moveVertical(20); 
    } 

    public void moveHorizontal(int distance) { 
     erase(); 
     xPosition += distance; 
     draw(); 
    } 

    public void moveVertical(int distance) { 
     erase(); 
     yPosition += distance; 
     draw(); 
    } 

    public void slowMoveHorizontal(int distance) { 
     int delta; 

     if(distance < 0) { 
      delta = -1; 
      distance = -distance; 
     } 
     else { 
      delta = 1; 
     } 

     for(int i = 0; i < distance; i++) { 
      xPosition += delta; 
      draw(); 
     } 
    } 

    public void slowMoveVertical(int distance) { 
     int delta; 

     if(distance < 0) { 
      delta = -1; 
      distance = -distance; 
     } 
     else { 
      delta = 1; 
     } 

     for(int i = 0; i < distance; i++) { 
      yPosition += delta; 
      draw(); 
     } 
    } 

    public void changeSize(int newHeight, int newWidth) { 
     erase(); 
     height = newHeight; 
     width = newWidth; 
     draw(); 
    } 

    public void changeColor(String newColor) { 
     color = newColor; 
     draw(); 
    } 

    private void draw() { 
     if(isVisible) { 
      Canvas canvas = Canvas.getCanvas(); 
      int[] xpoints = { xPosition, xPosition + (width/2), xPosition + width }; 
      int[] ypoints = { yPosition + height, yPosition, yPosition + height}; 
      canvas.draw(this, color, new Polygon(xpoints, ypoints, 3)); 
      canvas.wait(10); 
     } 
    } 

    private void erase() { 
     if(isVisible) { 
      Canvas canvas = Canvas.getCanvas(); 
      canvas.erase(this); 
     } 
    } 
}

來源

2017-02-16 Confused

嗨，歡迎來到堆棧溢出。請不要要求你的作業的解決方案，嘗試自己找一個好方法，以成爲一個更好的開發者;-) –

刪除多餘的評論 – stealthjong

您的三角形的中心將在

xPosition + (width/2) 
yPosition + (height/2)

爲「中心」，需要moveHorizontal/moveVertical，直到你的三角形的中心在空間的中心，它是要中心在

來源

2017-02-16 18:13:06 ControlAltDel

如何在Java中居中圖像？

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