import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.image.Image;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.paint.ImagePattern;
import javafx.scene.text.Font;
import javafx.stage.Stage;

import javax.xml.bind.DatatypeConverter;
import java.io.ByteArrayInputStream;
import javafx.scene.Group;
import javafx.scene.shape.Rectangle;

public class ImagePatternTest extends Application {
    static int RECT_WIDTH = 200;
    static int RECT_HEIGHT = 100;

    GraphicsContext context;

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

    @Override public void start(Stage primaryStage) throws Exception {
        primaryStage.setScene(createScene());
        primaryStage.show();
    }

    Scene createScene() {
        // The pattern image has 2x2 size with the top left and bottom right pixels set to yellow
        // and the other two set to transparent. So, being shifted by 1 pixel, they together should
        // provide a solid yellow color.
        String base64Image = "iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAIAAAD91JpzAAAABnRSTlMAAAAAAABupgeRAAAABmJLR0QA/wD/AP+gvaeTAAAAEUlEQVR42mP4/58BCv7/ZwAAHfAD/abwPj4AAAAASUVORK5CYII=";
        byte[] imageBytes = DatatypeConverter.parseBase64Binary(base64Image);

        Canvas canvas = new Canvas(600, 400);
        context = canvas.getGraphicsContext2D();
        context.setFont(Font.font(16));

        Group nodes = new Group();
        
        // first, try to draw patterns that use separate images sharing same byte data
        // and observe correct solid yellow color fill
        int x = 0, y = 100;
        context.setFill(Color.BLACK);
        context.fillText("Correct - separate images", x, y / 2);
        Image separateImage1 = createImage(imageBytes);
        Image separateImage2 = createImage(imageBytes);
        drawPatterns(nodes, separateImage1, separateImage2, x, y);

        // second, try to draw patterns that share the image itself
        // and observe incorrect red-and-yellow chequered fill
        x = 300;
        context.setFill(Color.BLACK);
        context.fillText("Incorrect - shared image", x, y / 2);
        Image sharedImage = createImage(imageBytes);
        drawPatterns(nodes, sharedImage, sharedImage, x, y);

        VBox root = new VBox();
        Scene scene = new Scene(root);

        root.getChildren().addAll(canvas, nodes);
        return scene;
    }


    Image createImage(byte[] imageBytes) {
        return new Image(new ByteArrayInputStream(imageBytes));
    }


    /**
     * Fills a rectangle with red background then tiles two image patterns subsequently,
     * shifting the second one 1 pixel right. The rectangle size is set in static class fields.
     * @param image1 image for the 1st pattern to fill
     * @param image2 image for the 2nd pattern to fill
     * @param x x coordinate of the rectangle to fill
     * @param y y coordinate of the rectangle to fill
     */
    void drawPatterns(Group nodes, Image image1, Image image2, int x, int y) {
        context.setFill(Color.RED);
        context.fillRect(x, y, RECT_WIDTH, RECT_HEIGHT);
        Rectangle rect = new Rectangle(x, y, RECT_HEIGHT, RECT_HEIGHT);
        rect.setFill(Color.RED);
        nodes.getChildren().add(rect);
        drawPattern(nodes, image1, 0, x, y);
        drawPattern(nodes, image2, 1, x, y); // shifted 1 pixel right
    }

    /**
     * Fills a rectangle with a tiled image pattern. The rectangle size is set in static class fields.
     * @param image image to tile
     * @param anchorX the horizontal anchor point for image pattern
     * @param x x coordinate of the rectangle to fill
     * @param y y coordinate of the rectangle to fill
     */
    void drawPattern(Group nodes, Image image, double anchorX, double x, double y) {
        ImagePattern pattern = new ImagePattern(
                image, anchorX, 0, image.getWidth(), image.getHeight(), false);
        context.setFill(pattern);
        context.fillRect(x, y, RECT_WIDTH, RECT_HEIGHT);
        Rectangle rectangle = new Rectangle(x, y, RECT_WIDTH, RECT_HEIGHT);
        rectangle.setFill(pattern);
        nodes.getChildren().add(rectangle);
    }
}