Draw rectangle by dragging mouse

[Dheeraj Kasar]

Hi all,
I want to draw a rectangle by dragging mouse using SWT. I am getting co-ordinates of starting point and endpoint but rectangle is not drawn.
Please help me about this.
Thanks in advance...

[Campbell Ritchie]

Welcome to the Ranch

Can you print out the coordinates? Presumably yes.
How are you doing the drawing? Which Graphics object are you using?

[Dheeraj Kasar]

Here..I am posting my code...I have modified it. It is now displaying rectangle but during dragging mouse it is showing all mouse moves.

public void makeRectangle(int x1, int y1, int x2, int y2,Display display) {
		// TODO Auto-generated method stub
		GC gc = new GC(display);
		gc.drawRectangle(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1 - x2), Math.abs(y1 - y2));
		gc.dispose();
	}
	
	public void run(IAction action) {
		// TODO Auto-generated method stub
		final Display display = PlatformUI.getWorkbench().getDisplay();
		final Shell shell = display.getActiveShell();		
		Cursor crossCursor = display.getSystemCursor(SWT.CURSOR_CROSS);
		shell.setCursor(crossCursor);
		
		shell.addPaintListener(new PaintListener(){
			public void paintControl(PaintEvent e) {
				// TODO Auto-generated method stub
				 if (startDrag != null && endDrag != null){ 
					makeRectangle(startDrag.x,startDrag.y,endDrag.x,endDrag.y,display);
					System.out.println("In paintlistener StartDrag:"+startDrag+"  "+"end drag:"+endDrag);
				 }
			}
		});
		shell.addMouseListener(new MouseAdapter(){
			public void mouseDown(MouseEvent e){
				startDrag = new Point(e.x, e.y);
				endDrag = startDrag;
				System.out.println("In mouse Down StartDrag:"+startDrag+"  "+"end drag:"+endDrag);
				
			}
			public void mouseUp(MouseEvent e){
				makeRectangle(startDrag.x,startDrag.y,e.x,e.y,display);
				System.out.println("In mouse Up StartDrag:"+startDrag+"  "+"end drag:"+endDrag);
				System.out.println(e.x+"  "+e.y);
				startDrag = null;
		        endDrag = null;
		       // shell.redraw();
			}
		});
		shell.addMouseMoveListener(new MouseMoveListener(){
			public void mouseMove(MouseEvent me){
				endDrag = new Point(me.x,me.y);
				System.out.println("In mouse move StartDrag:"+startDrag+"  "+"end drag:"+endDrag);
				shell.redraw();
			}
		});
	}

[Campbell Ritchie]

How are you calling the makeRectangle method? Are you calling it from paintComponent? What's GC? Is it some sort of Graphics object? How did you write your PaintListener class?

Last time I had that exercise I created a Shape interface

public interface Shape
{
    void drawYourself(Graphics g);
}

and a Rectangle class which implemented that interface and I put the object into a List and drew all the elements in that List in the paintComponent method. Of course, there is a Graphics object implicitly passed to the paintComponent method, ready for you to use. What about calling repaint() on the display from your mouse listener methods?

Please note the code button makes your posts look much better. I have edited your post, since you are new, to show it to full effect.

[pete stein]

Campbell Ritchie wrote:How are you calling the makeRectangle method? Are you calling it from paintComponent? What's GC? Is it some sort of Graphics object? How did you write your PaintListener class?
...

I'm not sure if these concerns are relevant in GUI programs that use the SWT library, but I must plead ignorance since I don't use this library.

Pete

[Campbell Ritchie]

Thank you. I hadn't noticed we were using SWT. Sorry.