OpenCV.图形绘制.矩形

矩形绘制

使用rectangle() 方法在图像上绘制一个矩形。 该方法的一个构造方法如下：
rectangle(img, pt1, pt2, color, thickness);

参数意义如下：

• mat
  表示要在其上绘制矩形的图像的Mat对象
• pt1 和 pt2
  两个Point对象，表示要绘制的矩形的顶点。s
• calar
  表示矩形颜色的标量对象(BGR)。
• thickness
  表示矩形厚度的整数; 默认情况下，厚度值为1。

需要指出的是，pt1是待绘制的矩形左上角点，pt2是矩形待绘制的右下角点，二者为矩形对角线上的点。OpenCV中方向为屏幕左上角为坐标原点，依该点水平向右为X正半轴方向，依该点竖直向下为Y轴正半轴方向，与Android和iOS相同，但与OS X不同。

Java代码（JavaFX Controller层）

public class Controller{

    @FXML private Text fxText;
    @FXML private ImageView imageView;

    @FXML public void handleButtonEvent(ActionEvent actionEvent) throws IOException {

        Node source = (Node) actionEvent.getSource();
        Window theStage = source.getScene().getWindow();
        FileChooser fileChooser = new FileChooser();
        FileChooser.ExtensionFilter extFilter = new FileChooser.ExtensionFilter("PNG files (*.png)", "*.png");
        fileChooser.getExtensionFilters().add(extFilter);
        fileChooser.getExtensionFilters().add(new FileChooser.ExtensionFilter("JPG Files(*.jpg)", "*.jpg"));
        File file = fileChooser.showOpenDialog(theStage);

        runInSubThread(file.getPath());

    }

	// Run in sub thread to avoid trouble with main thread, and non JavaFX platform could call drawRectangle 
	// directly in handleButtonEvent().
    private void runInSubThread(String filePath){
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    WritableImage writableImage = drawRectangle(filePath);

                    Platform.runLater(new Runnable() {
                        @Override
                        public void run() {
                            imageView.setImage(writableImage);
                        }
                    });

                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    private WritableImage drawRectangle(String filePath) throws IOException {
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

        Mat src = Imgcodecs.imread(filePath);

        Imgproc.rectangle(src, new Point(187,90), new Point(251,165), new Scalar(0,0,255), 2);
        Imgproc.rectangle(src, new Point(10,10), new Point(100,100), new Scalar(0,255,255), 2);

        MatOfByte matOfByte = new MatOfByte();
        Imgcodecs.imencode(".jpg", src, matOfByte);

        byte[] bytes = matOfByte.toArray();
        InputStream in = new ByteArrayInputStream(bytes);
        BufferedImage bufImage = ImageIO.read(in);

        WritableImage writableImage = SwingFXUtils.toFXImage(bufImage, null);

        return writableImage;
    }

}

运行图