Add image to a java awt Canvas background

Question

I am trying to add a background image to java awt canvas but still couldn't make it through. can any body have the solutions for this or any piece of code for this problem. the code is given below,

thanks.

import java.awt.*;
import java.applet.*;
import java.util.Vector;
import java.util.Enumeration;

public class DiagramEditor extends Canvas {

private Vector diagrams = new Vector(16);
Diagram currentDiagram;
DiagramEditorControls controls;
Tool tool;
Image offscreen;
public final static int RECTANGLE = 0;

public final static int SELECTION = 3;
public String toolNames[] = {"Rectangle", "", "", "Selection"};

public DiagramEditor() {
    setBackground(Color.white);
    newDiagram();
}

public void setControls(DiagramEditorControls c) {
    controls = c;
}

public void setTool(int t) {
    switch (t) {
        case RECTANGLE:
            tool = new WrectangleTool(currentDiagram);
            break;

        case SELECTION:
            tool = new SelectionTool(currentDiagram);
            break;
    }
    repaint();
    if (controls != null) {
        controls.toolChoice.select(t);
    }
}

public void paint(Graphics g) {
    update(g);
}

public void update(Graphics g) {
    Dimension canvasSize = size();
    if (offscreen == null) {
        offscreen = this.createImage(canvasSize.width, canvasSize.height);
    }
    Graphics og = offscreen.getGraphics();
    og.setColor(getBackground());
    og.fillRect(0, 0, canvasSize.width, canvasSize.height);
    og.setColor(Color.black);
    og.drawRect(0, 0, canvasSize.width - 1, canvasSize.height - 1);
    og.setColor(Color.blue);
    currentDiagram.draw(og);
    tool.draw(og);
    g.drawImage(offscreen, 0, 0, this);
}

public void deleteElements() {
    tool.delete();
    repaint();
}

public void nextDiagram() {
    if (currentDiagram == diagrams.lastElement()) {
        currentDiagram = (Diagram) diagrams.firstElement();
    } else {
        int diagramIndex = diagrams.indexOf(currentDiagram);
        currentDiagram = (Diagram) diagrams.elementAt(diagramIndex + 1);
    }
    setTool(RECTANGLE);
}

public void newDiagram() {
    currentDiagram = new Diagram();
    diagrams.addElement(currentDiagram);
    setTool(RECTANGLE);
}

public boolean mouseDown(Event e, int x, int y) {
    tool.press();
    repaint();
    return true;
}

public boolean mouseDrag(Event e, int x, int y) {
    tool.move(new Point(x, y));
    repaint();
    return true;
}

public boolean mouseMove(Event e, int x, int y) {
    tool.move(new Point(x, y));
    repaint();
    return true;
}

public boolean mouseUp(Event e, int x, int y) {
    tool.release();
    repaint();
    return true;
}
}

this is a drawing canvas. default the background color is white ..i want it to be changed to an image...?

Answer 1

The line below:

offscreen = this.createImage(canvasSize.width, canvasSize.height);

should become something like:

try {
  offscreen = ImageIO.read(new File("path/to/image"));
} catch (IOException e) {
  e.printStackTrace();
}