Java使用Graphics2D画波浪线的艰辛之路

朱雀 2021-09-25 00:36 485阅读 0赞

需求是根据飞机的线路情况,需要画直线,双直线,波浪线,虚线,连连接航路

其他都好说,这波浪线尤其不好画

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70][]

![20201206140737562.png][]

搜了一圈,基本都是建议使用drawArc方法画圆弧拼接波浪线,但是及其麻烦,效果如下,并不理想

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 1][]

在群里问了下大佬的建议,改变思路

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 2][]

那么接下来,开始研究下怎么画

1.已知条件,是飞机的两个点

先画出直线看看

代码:

效果:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 3][]

2.根据直线求平行线

草稿:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 4][]

代码:

public static void main(String[] args) throws IOException {
            BufferedImage res = null;
            res = new BufferedImage(500, 500,
                    BufferedImage.TYPE_INT_RGB);
            Graphics2D g = res.createGraphics();
            g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g.setBackground(Color.black);
            g.clearRect(0, 0, 500, 500);
    
    
            int x1=200,y1=100;
            int x2=400,y2=400;
            g.drawLine(x1,y1,x2,y2);
    
            int[] ps= parallelLines(x1,y1,x2,y2,3);
            g.setColor(Color.green);
            g.drawLine(ps[0],ps[1],ps[2],ps[3]);
            g.drawLine(ps[4],ps[5],ps[6],ps[7]);
    
            String imageDir = "D:\\出图测试\\波浪";
    
            ImageInfoUtil.write(res, imageDir, "test.png");
    
        }
        public static void write(BufferedImage subimage, String centerImageDir, String fileName) throws IOException {
            FileOutputStream pointOut = null;
            try {
                File f = new File(centerImageDir);
                if(!f.isDirectory()){
                    f.mkdirs();
                }
                pointOut = new FileOutputStream(centerImageDir+File.separator+fileName);//输出图片的地址
                ImageIO.write(subimage, "png", pointOut);
            }finally {
                if(pointOut!=null){
                    pointOut.close();
                }
            }
        }
    
    
    
        /**
         * 根据两点一直线和距离,算出两天平行线
         * @param x1
         * @param y1
         * @param x2
         * @param y2
         * @param l
         * @return
         */
        public static int[] parallelLines(int x1, int y1, int x2, int y2,int l) {
            int m = y2-y1;
            int n = x2-x1;
            double p = Math.sqrt(Math.pow(m, 2) + Math.pow(n, 2));
            double t = p/n;
            double s=m/p;
            double c = n/p;
            double ry=l*c;
            double rx=l*s;
    
            int x3 = (int) (x2-rx);
            int x4=(int)(x1-rx);
    
            int y3 = (int) (y2+ry);
            int y4=(int)(y1+ry);
    
    
    
            int x5 = (int) (x2+rx);
            int x6=(int)(x1+rx);
    
            int y5 = (int) (y2-ry);
            int y6=(int)(y1-ry);
    
            return new int[]{x3,y3,x4,y4,x5,y5,x6,y6};
        }

效果

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 5][]

3.以已知两点为首尾,两平行线上取点,进行连接为折线(需要用到直线公式计算斜率这不贴草稿了)

代码:稍微封装了一下

public class DTest {
        public static void main(String[] args) throws IOException {
            BufferedImage res = null;
            res = new BufferedImage(500, 500,
                    BufferedImage.TYPE_INT_RGB);
            Graphics2D g = res.createGraphics();
            g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g.setBackground(Color.black);
            g.clearRect(0, 0, 500, 500);
    
    
            int x1=200,y1=100;
            int x2=400,y2=400;
            g.drawLine(x1,y1,x2,y2);
    
            int[] ps= CoordinateUtil.parallelLines(x1,y1,x2,y2,3);
            g.setColor(Color.green);
            g.drawLine(ps[0],ps[1],ps[2],ps[3]);
            g.drawLine(ps[4],ps[5],ps[6],ps[7]);
    
    
    
            g.setColor(Color.red);
    
            int x3 = ps[0];
            int y3 = ps[1];
            int x4 = ps[2];
            int y4 = ps[3];
            int[] y34=null;
            int[] x34=null;
    
    
            int x5 = ps[4];
            int y5=  ps[5];
            int x6 = ps[6];
            int y6 = ps[7];
            int[] y56=null;
            int[] x56=null;
    
    
    
    
    
            if(x1==x2){
                y34 = CoordinateUtil.numbers(y3,y4);
                x34 = new int[y34.length];
                for (int i = 0; i < x34.length; i++) {
                    x34[i]=x3;
    
                }
                y56 = CoordinateUtil.numbers(y5,y6);
                x56 = new int[y56.length];
                for (int i = 0; i < x56.length; i++) {
                    x56[i]=x5;
                }
            }else{
    
                x34 = CoordinateUtil.numbers(x3,x4);
                double k34=CoordinateUtil.K(y3,y4,x3,x4);
                double b34=CoordinateUtil.B(y3,x3,k34);
                y34 = CoordinateUtil.pointY(x34,k34,b34);
    
    
    
                x56 = CoordinateUtil.numbers(x5,x6);
                double k56=CoordinateUtil.K(y5,y6,x5,x6);
                double b56=CoordinateUtil.B(y5,x5,k56);
                y56 = CoordinateUtil.pointY(x56,k56,b56);
            }
    
            CoordinateUtil.XY[] xy34=new  CoordinateUtil.XY[y34.length];
            CoordinateUtil.XY[] xy56=new  CoordinateUtil.XY[y56.length];
            for (int i = 0; i < y34.length; i++) {
                xy34[i] = new CoordinateUtil.XY(x34[i],y34[i]);
            }
    
            for (int i = 0; i < y56.length; i++) {
                xy56[i]=new CoordinateUtil.XY(x56[i],y56[i]);
            }
    
    
            CoordinateUtil.XY[] polys = CoordinateUtil.polyXYs(new CoordinateUtil.XY(x1,y1),new CoordinateUtil.XY(x2,y2),xy34,xy56,3);
    
    
            int[]  polyX = new int[polys.length];
            int[]  polyY = new int[polys.length];
    
            for (int i = 0; i < polys.length; i++) {
                polyX[i]=polys[i].x;
                polyY[i]=polys[i].y;
            }
    
    
            g.drawPolyline(polyX, polyY, polyX.length);
    
    
            String imageDir = "D:\\出图测试\\波浪";
    
            ImageInfoUtil.write(res, imageDir, "test.png");
    
        }
        public static void write(BufferedImage subimage, String centerImageDir, String fileName) throws IOException {
            FileOutputStream pointOut = null;
            try {
                File f = new File(centerImageDir);
                if(!f.isDirectory()){
                    f.mkdirs();
                }
                pointOut = new FileOutputStream(centerImageDir+File.separator+fileName);//输出图片的地址
                ImageIO.write(subimage, "png", pointOut);
            }finally {
                if(pointOut!=null){
                    pointOut.close();
                }
            }
        }
    
    
    
    
    }

public class CoordinateUtil {
    
    
        /**
         * 根据两个值,获取中间所有数
         * 包含首尾
         * @param x1
         * @param x2
         * @return
         */
        public static int[] numbers(int x1, int x2) {
            int max = Math.max(x1, x2);
            int min = Math.min(x1, x2);
            int index=0;
            int [] px = new int[max-min+1];
            for (int i = min; i <= max; i++) {
                px[index]=i;
                index++;
            }
            return px;
        }
    
    
        /**
         * 求常量B
         * @param y
         * @param x
         * @param k
         * @return
         */
        public static double B(int y, int x, double k) {
            double b = new BigDecimal(String.valueOf(y)).subtract(new BigDecimal(new BigDecimal(String.valueOf(k)).multiply(new BigDecimal(String.valueOf(x))).doubleValue())).doubleValue();
            return b;
        }
    
        /**
         * 求斜率k
         * @param y1
         * @param y2
         * @param x1
         * @param x2
         * @return
         */
        public static double K(int y1, int y2, int x1, int x2) {
            if(x2 - x1==0){
                throw new RuntimeException("x2与x1相等,没有斜率");
            }
            double k = new BigDecimal(String.valueOf(y2 - y1)).divide(new BigDecimal(String.valueOf(x2 - x1)),5, BigDecimal.ROUND_HALF_UP).doubleValue();
            return k;
        }
    
        /**
         * 根据两点一直线和距离,算出两天平行线
         * @param x1
         * @param y1
         * @param x2
         * @param y2
         * @param l
         * @return
         */
        public static int[] parallelLines(int x1, int y1, int x2, int y2,int l) {
            int m = y2-y1;
            int n = x2-x1;
            double p = Math.sqrt(Math.pow(m, 2) + Math.pow(n, 2));
            double t = p/n;
            double s=m/p;
            double c = n/p;
            double ry=l*c;
            double rx=l*s;
    
            int x3 = (int) (x2-rx);
            int x4=(int)(x1-rx);
    
            int y3 = (int) (y2+ry);
            int y4=(int)(y1+ry);
    
    
    
            int x5 = (int) (x2+rx);
            int x6=(int)(x1+rx);
    
            int y5 = (int) (y2-ry);
            int y6=(int)(y1-ry);
    
            return new int[]{x3,y3,x4,y4,x5,y5,x6,y6};
        }
    
        /**
         * 根据中间两点取首位点
         * @param xy1 首
         * @param xy2 尾
         * @param xy34 平行线1
         * @param xy56 平行线2
         * @param interval 波浪间隔
         * @return
         */
        public static XY[] polyXYs(XY xy1, XY xy2, XY[] xy34, XY[] xy56,int interval) {
            if(xy34.length!= xy56.length){
                throw  new RuntimeException("两条平行线长度应相同");
            }
            List<XY> xyList = new ArrayList<>();
            xyList.add(xy1);
            int lg=1;
            for (int i = interval; i < xy34.length; i+=interval) {
                if(i>xy34.length){
                    break;
                }
                if(lg%2==1){
                    xyList.add(xy34[i]);
                }else{
                    xyList.add(xy56[i]);
                }
                lg++;
            }
            xyList.add(xy2);
            return xyList.toArray(new XY[xyList.size()]);
        }
    
        public static class XY{
            public int x;
            public int y;
    
            public XY(int x, int y) {
                this.x = x;
                this.y = y;
            }
        }
    
        /**
         * y=kx+b
         * @param px
         * @param k
         * @param b
         * @return
         */
        public static int[] pointY(int[] px, double k, double b) {
            int[] py = new int[px.length];
            for (int i = 0; i < px.length; i++) {
                py[i]=new BigDecimal(k).multiply(new BigDecimal(px[i])).add(new BigDecimal(b)).intValue();
            }
            return py;
        }
    }

效果:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 6][]

去掉辅助的平行线和直线看看,对比一下效果还不错

![20201206142846113.png][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 7][]

代码未整理封装,有空再说

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70]: /images/20210923/68f06b19df0447c893e3ab666e7538a0.png
[20201206140737562.png]: /images/20210923/0cab9168af3d493e8ce63760e3a3d269.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 1]: /images/20210923/ceaed65bff5046579257e15c620c0786.png
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 4]: /images/20210923/b4079e6d058d4dc995cb556001ded633.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 5]: /images/20210923/aa86327e4ef148bf8653ac132289c513.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 6]: /images/20210923/9ded3fae09f54e1ab76288fdf3dcd17c.png
[20201206142846113.png]: /images/20210923/4b3daa88d8a146488b207b9f02c1d92f.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2Nvcmxlb25lXzRldmVy_size_16_color_FFFFFF_t_70 7]: /images/20210923/468237b51bb5410a8d46a124ea0ebe16.png