直线绘制
在OpenCV环境中，直线的绘制依赖于Imgproc.line() 这个方法。该方法的一个构造方法如下：
line(img, pt1, pt2, color);
其参数解释如下：
- mat
表示要在其上绘制线条的图像的Mat对象。 - pt1，pt2
表示要绘制线条的点的两个点对象。 - scalar
表示圆的颜色的标量对象(BGR)。
当然了，还可以控制直线的粗细，即上述构造方法最后追加一个参数，thickness来表示粗细，厚度值为1.
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);
imageView.setImage(drawLine(file.getPath()));
}
private WritableImage drawLine(String filePath) throws IOException {
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
Mat src = Imgcodecs.imread(filePath);
// Draw red, green blue and white line in src.
Imgproc.line(src, new Point(117,120), new Point(300,120), new Scalar(0,0,255));
Imgproc.line(src, new Point(117,130), new Point(300,130), new Scalar(0,255,0));
Imgproc.line(src, new Point(117,140), new Point(300,140), new Scalar(255,0,0));
Imgproc.line(src, new Point(117,150), new Point(300,150), new Scalar(255,255,255));
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;
}
}
在子线程中处理
然而OpenCV进行的操作大部分都是比较耗时的，在主线程里进行处理比较棘手，因此最佳方法是在子线程处理数据而后在回到主线程更新UI。下面是JavaFX的操作示例示例。
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());
}
// Consumer time task and return a WriteableImage for JavaFX platform.
private WritableImage drawLine(String filePath) throws IOException {
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
Mat src = Imgcodecs.imread(filePath);
// Draw red, green blue and white line in src.
Imgproc.line(src, new Point(117,120), new Point(300,120), new Scalar(0,0,255));
Imgproc.line(src, new Point(117,130), new Point(300,130), new Scalar(0,255,0));
Imgproc.line(src, new Point(117,140), new Point(300,140), new Scalar(255,0,0));
Imgproc.line(src, new Point(117,150), new Point(300,150), new Scalar(255,255,255));
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;
}
// Process CV task in sub thread and update View in main thread.
private void runInSubThread(String filePath){
new Thread(new Runnable() {
@Override
public void run() {
try {
WritableImage writableImage = drawLine(filePath);
// Switch to main thread, JavaFX's features.
Platform.runLater(new Runnable() {
@Override
public void run() {
imageView.setImage(writableImage);
}
});
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
}
}
运行图
