CODEWITHSUNDEEP
java-memidplcdui
iLearner
iLearner

Reputation: 1680

How to do scrolling in j2me canvas?

I have created a sample application where I want to do scrolling, but I am not able to achieve the desired output.

I have tried the following code inside paint method >>>>>

g.translate(x,y);

and passing the value for variable 'y' in keydown and keyup event.

Can anyone help me out to do this?

Upvotes: 2

Views: 1340

Answers (3)

iLearner
iLearner

Reputation: 1680

Have you tried with decrementing the value of Y in keyUP and calling repaint() method also do same with keyDown but now the value of Y will be decrementing and call repaint() method.

Use the g.translate(x, changingYvalue);

try this.

Upvotes: 1

Lucifer
Lucifer

Reputation: 29662

I think that the scrollbar should be drawn inside the paint method. And you implement the keyReleased method when clicking the arrow of the scrollbar. To implement the scrolling I would prefer call repaint(); and I will manage the paint method with boolean or some other type of private variable.

Upvotes: 0

Amir Uval
Amir Uval

Reputation: 14893

Easiest way (though memory intensive) is to use MutableImage, and draw it with negative y coordinates.

Mutable image is just a new Image(w,h).
Then you get its Graphics context, using myImage.getGraphics(), and draw with this Graphics object. It serves as an off-screen buffer.

Than in paint(Graphics g), you call:

g.drawImage(0,y,...);

where you loop decreasing y on each system call to paint.
(don't block paint! - each call is one frame, and you're doing frame by frame animation
do the animation loop from another thread, where you decrease y, than call repaint(), and sleep).

Upvotes: 2

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