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1.Create a cocoa application (not document-based)

2.Create a new class "StretchView"(subclass NSView)

3.Open the Interface builder and drag a "Scroll view" to the main window

4.Choose the "Scroll view" and set the class "StretchView" (in class identity window)

The size of the contentview is 500*500 and the size of the strechview is also 500*500 (horizontal Scroll is enabled).

Then I start to draw some numbers(1,2,3,4......) horizontally one after the other. When the number is out of ranger(the x pos is larger than 500) I increase the width of the StretchView. (Everything works fine up till this point)

Then I tried to make the horizontal scroller to automatically scroll to the end so that everytime I increase the width of the StretchView the last number coulde be seen.

Here's the code:

//The timer is called every sec
-(void)myTimerAction:(NSTimer *) timer
{  
    NSLog(@"myTimerAction");

       //......
    int i = _myArray.count;
    NSRect rect = [self frame];
    int width = rect.size.width;

       //The width between two number is 10
       //When the x pos of current num is bigger then the scroll's width
    if((i * 10) > width) {

           //reset the width
        width = i * 10;
        [self setFrameSize:CGSizeMake(width, rect.size.height)];
           //How to make it autoscroll???
           //...............................
    }
    //......
    [self setNeedsDisplay:YES];
}
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1 回答 1

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Try this:

NSView *contentView = [[self enclosingScrollView] contentView];
CGFloat newXPosition = width - NSWidth([contentView bounds]);
if (newXPosition > 0.0) [self scrollPoint:NSMakePoint(newXPosition, 0.0)];

contentView is the clipping view in the enclosing scroll view. You want to scroll your current view to the x point in your view such that this x point + the clipping view width give the last clipping view width points of your view.

于 2011-02-10T09:01:15.817 回答