如何在 JavaFX 中创建填充动画（逐像素）canvas？

Question

我正在努力完成有关数字图像拓扑的学校项目。目标是编写一个应用程序，它有一个矩形，一条线穿过它，应用程序需要填充线下方的字段。它需要使用特定类型的像素邻域逐个像素地填充它。

我设法编写了一些应用程序来填充该行下方的字段，但它会在几秒钟内将其全部填满。我无法逐个像素地完成它。我试过停止线程，但你不能停止应用程序线程，你不能从应用程序以外的线程更新 UI。 Platform.runLater 或任务也不起作用。我希望 canvas 在每次添加新像素时刷新，所以我有这个动画展示了这个算法是如何工作的。

我希望我的解释足够了。您不必专注于我的项目，有人可以向我解释如何逐像素填充 canvas?

这是控制器的代码：

@FXML
private Canvas canvas;

@FXML
private ComboBox<String> optionsType;

@FXML
private Button drawBtn;

@FXML
private ComboBox<String> optionsNeighbourhood;

WritableImage wi;
PixelReader pr;
GraphicsContext gc;

(...)

public void drawLine() {
    gc.strokeLine(0, 0, canvas.getWidth(), canvas.getHeight());
}

private void fillShape(Neighbourhood type, int startX, int startY) {

    int width = (int) canvas.getWidth();
    int height = (int) canvas.getHeight();

    LinkedList<Point> list = new LinkedList<>();
    list.addFirst(new Point(startX, startY));
    while (!list.isEmpty()) {
        Point point = list.removeLast();
        int x = point.getX();
        int y = point.getY();

        if (x >= 0 && x < width && y >= 0 && y < height && isEmpty(x, y)) {
            gc.fillRect(x, y, 1, 1);
            gc.fill();
            canvas.snapshot(null, wi);

            list.addFirst(new Point(x + 1, y));
            list.addFirst(new Point(x, y + 1));
            list.addFirst(new Point(x, y - 1));
            list.addFirst(new Point(x - 1, y));
            if (type == Neighbourhood.SIX || type == Neighbourhood.EIGHT) {
                if (isEmpty(x - 1, y) || isEmpty(x, y - 1)) {
                    list.add(new Point(x - 1, y - 1));
                }

                if (isEmpty(x + 1, y) || isEmpty(x, y + 1)) {
                    list.add(new Point(x + 1, y + 1));
                }
            }

            if (type == Neighbourhood.EIGHT) {
                if (isEmpty(x - 1, y) || isEmpty(x, y + 1)) {
                    list.add(new Point(x - 1, y + 1));
                }

                if (isEmpty(x + 1, y) || isEmpty(x, y + 1)) {
                    list.add(new Point(x + 1, y - 1));
                }
            }
        }

    }
}

private boolean isEmpty(int x, int y) {

    if (x < 0 || x >= canvas.getWidth() || y < 0 || y >= canvas.getHeight()) {
        return false;
    }

    if (!pr.getColor(x, y).toString().equals("0xffffffff")) {
        return false;
    }

    return true;
}

}

现在我知道代码一开始可能看起来不太明显。该算法无关紧要，因为它似乎确实有效，但主要问题是：我如何逐个像素地填充这个字段（就像动画一样（是的，我也试过 AnimationTimer）。

Answer 1

有几种方法，一种是像这样使用 AnimationTimer：

import java.util.Random;

import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;

public class Main extends Application {

    private static double SCENE_WIDTH = 800;
    private static double SCENE_HEIGHT = 600;

    static Random random = new Random();

    Canvas canvas;
    GraphicsContext graphicsContext;

    AnimationTimer loop;

    Scene scene;

    @Override
    public void start(Stage primaryStage) {

        BorderPane root = new BorderPane();

        canvas = new Canvas(SCENE_WIDTH, SCENE_HEIGHT);

        graphicsContext = canvas.getGraphicsContext2D();

        Pane layerPane = new Pane();

        layerPane.getChildren().addAll(canvas);

        root.setCenter(layerPane);

        scene = new Scene(root, SCENE_WIDTH, SCENE_HEIGHT);

        primaryStage.setScene(scene);
        primaryStage.show();

        startAnimation();

    }

    private void startAnimation() {

        loop = new AnimationTimer() {

            double startX = 100;
            double endX = 200;
            double y = 100;
            double x = startX;
            double speed = 0.2;

            @Override
            public void handle(long now) {

                graphicsContext.fillOval(x, y, 5,5);

                x+=speed;

                if( x >= endX) {
                    loop.stop();
                }
            }
        };

        loop.start();

    }

    public static void main(String[] args) {
        launch(args);
    }
}

如何在 JavaFX 中创建填充动画（逐像素）canvas？

How to create filling animation in JavaFX(pixel by pixel) canvas?

java

animation

javafx

canvas

pixel