Question

我想找一条线。我使用鼠标事件初始化坐标x1，y1，x2，y2。当我试图找到如下所示的距离时：

public class LineFunctions {
    static int dpi;
    static double pixel_per_cm;
    public LineFunctions(){
        Toolkit tk;
        tk=Main.frame.getToolkit();
        dpi=tk.getScreenResolution();
        pixel_per_cm=dpi/2.54;
    }
    public double lengthInPixel(int x1,int y1,int x2,int y2){
        double length_in_pixel;
        double x=Math.pow((x2-x1), 2);
        double y=Math.pow((y2-y1), 2);
        length_in_pixel = Math.sqrt(x+y);
        return length_in_pixel;
    }
    public double lengthInCm(int x1,int y1,int x2,int y2){

        double length_in_pixel=lengthInPixel(x1,y1,x2,y2);
        double length_in_cm = length_in_pixel / pixel_per_cm;
        System.out.println("Length in Cm= "+length_in_cm);
        return length_in_cm;
    }
}

Main.java

public class Main {
    public static JFrame frame;
    public static void main(String ar[]) {
        frame=new JFrame("LINE FRAME");
    }
    static class ImageComponent extends JComponent implements MouseListener {
        Line2D line;
            int x1,y1,x2,y2;
            public ImageComponent() {
                addMouseListener(this);
                addMouseMotionListener(this);
    }
            @Override
            public void paintComponent(Graphics g){
                  super.paintComponent(g);
                  Graphics2D gd=(Graphics2D)g;
                  line=new Line2D.Double(x1,y1,x2,y2);
                  gd.draw(line);
            }
            @Override
    public void mousePressed(MouseEvent e) {

        x1=e.getX();
                    y1=e.getY();
    }

    @Override
    public void mouseReleased(MouseEvent e) {
                    x2=e.getX();
                    y2=e.getY();
                    LineFunctions lf=new LineFunctions();
                    double length=lf.lengthInCm(x1,y1,x2,y2);
                    System.out.println("Line Length="+length);
                    repaint();                    
    }
    .......................
    ........................
}

此代码从坐标中查找线条的长度，但是当我从 RULER 中找到我在屏幕上绘制的线条的长度时，它看不到我的长度与我从上面的代码。那么，这有什么问题，我怎样才能找到确切的线长？

Answer 1

您可以使用GraphicsConfiguration GraphicsDevice的{{3}}来确定所需的几何图形。特别是，标识转换表示“用户空间中的72个单位等于设备空间中的1英寸。”

另请考虑getNormalizingTransform()以获得更高的准确性。

在JAVA中查找行长

1 个答案: