Question

i took a uiview application.i placed a image on the controller’s view.my requirement is the image should be movable with the help of mouse.mouse should select the image and the image should be moved as the mouse is dragged.the image movement should be restricted to only a particular portion of the view.
can someone help me code the desirable task
tnx in advance

dinakar

Answer 1

This can be accomplished with touchesBegan and touchesMoved events.

- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
{
    // This gets you starting position of 
    UITouch *touch = [ [ event allTouches ] anyObject ] ;   

    float touchXBeginPoint = [ touch locationInView:touch.view ].x ;
    float touchYBeginPoint = [ touch locationInView:touch.view ].y ;

    // Calculate the offset between the current image center and the touched points.
    //  Moving image only along X - direction and try thinking as how to move in 
    // any direction using this as a reference. It isn't that hard.

    touchOffset = image.center.x - touchXBeginPoint ;
    // touchOffset should be a member variable of class or a variable with global scope

} 

- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    // Calculate the difference from previous position and the current position
    // Add this difference to the previous point and move the image center to that point.
    // How ever, you should have an UIImageView outlet connected on to the image placed
    // on the interface builder.

    // And regarding image movement restriction, since you always have co-ordinates with
    // you, you can set the boundaries.

    UITouch *touch = [ [ event allTouches ] anyObject ] ;

    float distanceMoved =( [ touch locationInView:touch.view ].x + touchOffset ) -  image.center.x  ;
    float newX = image.center.x + distanceMoved ;

    if( newX > 30 && newX < 290 ) // setting the boundaries
        image.center = CGPointMake(newX, image.center.y) ;
}

Hope this should be helpful.