FxCanvasExample6.java

import java.nio.ByteBuffer;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.image.PixelFormat;
import javafx.scene.image.PixelWriter;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;

public class FxCanvasExample6 extends Application
{
	private static final int RECT_WIDTH = 25;
	private static final int RECT_HEIGHT = 25;

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

	@Override
	public void start(Stage stage)
	{
		Canvas canvas = new Canvas(400, 200);
		// Get the graphics context of the canvas
		GraphicsContext gc = canvas.getGraphicsContext2D();
		// Set line width
		gc.setLineWidth(2.0);

		// Write custom pixels to create a pattern
		writePixels(gc);

		// Create the Pane
		Pane root = new Pane();
		// Set the Style-properties of the Pane
		root.setStyle("-fx-padding: 10;" +
				"-fx-border-style: solid inside;" +
				"-fx-border-width: 2;" +
				"-fx-border-insets: 5;" +
				"-fx-border-radius: 5;" +
				"-fx-border-color: blue;");

		// Add the Canvas to the Pane
		root.getChildren().add(canvas);
		// Create the Scene
		Scene scene = new Scene(root);
		// Add the Scene to the Stage
		stage.setScene(scene);
		// Set the Title of the Stage
		stage.setTitle("Writing Pixels on a Canvas");
		// Display the Stage
		stage.show();
	}

	private void writePixels(GraphicsContext gc)
	{
		// Define properties of the Image
		int spacing = 5;
		int imageWidth = 300;
		int imageHeight = 100;
		int rows = imageHeight/(RECT_HEIGHT + spacing);
		int columns = imageWidth/(RECT_WIDTH + spacing);

		// Get the Pixels
		byte[] pixels = this.getPixelsData();

		// Create the PixelWriter
		PixelWriter pixelWriter = gc.getPixelWriter();

		// Define the PixelFormat
		PixelFormat<ByteBuffer> pixelFormat = PixelFormat.getByteRgbInstance();

		// Write the pixels to the canvas
		for (int y = 0; y < rows; y++)
		{
			for (int x = 0; x < columns; x++)
			{
				int xPos = 50 + x * (RECT_WIDTH + spacing);
				int yPos = 50 + y * (RECT_HEIGHT + spacing);
				pixelWriter.setPixels(xPos, yPos, RECT_WIDTH, RECT_HEIGHT,
						pixelFormat, pixels, 0, RECT_WIDTH * 3);
			}
		}
	}

	private byte[] getPixelsData()
	{
		// Create the Array
		byte[] pixels = new byte[RECT_WIDTH * RECT_HEIGHT * 3];
		// Set the ration
		double ratio = 1.0 * RECT_HEIGHT/RECT_WIDTH;
		// Generate pixel data
		for (int y = 0; y < RECT_HEIGHT; y++)
		{
			for (int x = 0; x < RECT_WIDTH; x++)
			{
				int i = y * RECT_WIDTH * 3 + x * 3;
				if (x <= y/ratio)
				{
					pixels[i] = -1;
					pixels[i+1] = 1;
					pixels[i+2] = 0;
				}
				else
				{
					pixels[i] = 1;
					pixels[i+1] = 1;
					pixels[i+2] = 0;
				}
			}
		}

		// Return the Pixels
		return pixels;
	}
}