Re: NSScroller question

FROM : Steve Weller
DATE : Sat Mar 29 16:39:15 2008

Try looking at the source for TextEdit. TextEdit adds a pop-up at the 
end of the horizontal scroller by overriding NSScrollView's tile: 
method. You may be able to change the layout so that the end of the 
NSScroller is clipped off.

On Mar 29, 2008, at 4:57 AM, <email_removed> wrote:
> Thanks Troy for the in-depth account. Yes, my goal is to customize the
> scroller's appearance, and yes, I wish this process involved less
> guess-work. As you say, there is no empty space when you let the
> scroller draw normally. You only see this when drawing a custom
> scroller based on the rects returned by -rectForPart:. That makes
> sense as those rects, as you say, are for hit-testing purposes only.
> Hence NSScrollerKnobSlot does not return the full rect for the slot,
> only the clickable part. I currently modify the rects returned by
> -rectForPart: for my drawings (eg. adjust the height and y position to
> cover the empty space), but I suppose calculating the parts based on
> the rect from the -drawRect: method would be even easier. My problem
> is I have a transparent table view and would prefer not to a have a
> slot for the knob at all, just a vertical scroller that goes all the
> way up to the edge of the table's header view, but it seems this is
> not possible. I can draw the knob in the designated slot cap area, but
> the drawing is messed up whenever the view is redisplayed. Oh well,
> the gap is only a few pixels, no big deal.
>
> On Fri, Mar 28, 2008 at 5:44 PM, Troy Stephens <<email_removed>> 
> wrote:

>> As Hamish Allan pointed out, a scroller has logical "parts", but they
>> are not subviews.  -rectForPart: returns the bounding rects that are
>> used for hit-testing those parts.  In the olden days of OpenStep-
>> style
>> Scrollers and their purely rectangular parts, these were exact and 
>> the
>> same rects used for drawing.  On Mac OS X, they are only hit testing
>> bounding rects (since Scrollers now have curved parts), and do not
>> affect drawing of the Scroller, only hit-testing.
>>
>> So all that rectForPart:NSScrollerNoParts is telling you is that
>> there's a skinny rect at the top of the scroller that is not 
>> sensitive
>> to hit-testing.  That makes sense, since there is a nonreactive end
>> cap on the scroll track that has no arrow (when Appearance prefs are
>> set for the scroll arrows to be shown "Together" at the other end).
>> This isn't an "empty" space when you let the scroller draw normally
>> though -- there's art there, or at least there should be.  If you're
>> seeing otherwise, something else must be wrong.  Can you clarify
>> whether you're seeing this when the scroller draws normally, or only
>> with your test drawing based on the -rectForPart: results in place?
>>
>> If your goal is to subclass NSScroller to customize its appearance, I
>> should add that the -drawParts and -drawArrow:highlight: methods are
>> obsolete and is no longer invoked by NSScroller's drawing code. 
>> Those
>> methods should be deprecated.  There are some other difficulties with
>> customizing Scroller appearance using the existing API, and we have 
>> at
>> least one request to make that easier in the future.
>>
>>
>>
>> On Mar 27, 2008, at 6:17 PM, <email_removed> wrote:

>>> Yes, I meant scroller, not slider. Just had a glass of wine too
>>> much :-)
>>>
>>> Actually I don't want to add an accessory view, I want to get rid of
>>> the one that appears to be there by default. I have attached a
>>> screenshot showing what I'm talking about. The yellow part is the
>>> knob, drawn by filling the rect return by calling [self
>>> rectForPart:NSScrollerKnob]. The green part is the slot,  [self
>>> rectForPart:NSScrollerKnobSlot]. The white part above the slot is by
>>> default black, but here I made it white by filling the rect returned
>>> by calling [self rectForPart:NSScrollerNoParts].
>>>
>>> I can move the knob/slot upwards by tampering with their designated
>>> rects ("rect.origin.y -= 5"), thus hiding the white part. But that
>>> messes up the drawing when the view is updated.
>>>
>>> I figured the white part was a view, but since you are telling me
>>> NSScroller has no subviews I really don't know what to think. Maybe
>>> there is something wrong with my implementation?
>>>
>>> @implementation TestScroller
>>>
>>> - (void)drawRect:(NSRect)rect
>>> {
>>>      [self drawKnobSlot];
>>>      [self drawKnob];
>>> }
>>>
>>> - (void)drawKnob
>>> {
>>>      NSRect rect = [self rectForPart:NSScrollerKnob];
>>>      [[NSColor yellowColor] set];
>>>      [NSBezierPath fillRect:rect];
>>> }
>>>
>>> - (void)drawKnobSlot
>>> {
>>>      NSRect rect = [self rectForPart:NSScrollerKnobSlot];
>>>      [[NSColor greenColor] set];
>>>      [NSBezierPath fillRect:rect];
>>> }
>>>
>>> @end
>>>
>>> On Fri, Mar 28, 2008 at 12:41 AM, Troy Stephens
>>> <<email_removed>> wrote:

>>>>
>>>> On Mar 27, 2008, at 4:26 PM, <email_removed> wrote:

>>>>> Thanks, but the corner view is the right side corner of the header
>>>>> view, right? I was talking about the small view just below it, on
>>>>> top
>>>>> of the vertical slider and part of the slider itself. It's a tiny
>>>>> view
>>>>> of about 2 pixels height. I believe it corresponds to
>>>>> NSScrollerNoPart, but I'm not sure.

>>>>
>>>> (By "slider" I take it you really mean "scroller", as NSSlider is
>>>> something else entirely. :-)
>>>>
>>>> An NSScroller (currently) has no subviews, but if your aim is to 
>>>> add
>>>> one or more accessory views above the scroller, that can be done by
>>>> subclassing NSScrollView.  The key is to override NSScrollView's -
>>>> tile
>>>> method to invoke [super tile], and then adjust the layout to
>>>> accommodate your accessory subview(s).  Figure out where you want
>>>> your
>>>> accessory subview(s) to go, set their frame(s), and change the
>>>> ScrollView's verticalScroller's frame (shrink and move down, since
>>>> ScrollViews are flipped) to make room for them.
>>>>
>>>>
>>>>

>>>>>
>>>>>
>>>>> On Thu, Mar 27, 2008 at 9:53 PM, Troy Stephens <<email_removed>
>>>>> >
>>>>> wrote:

>>>>>>
>>>>>> On Mar 27, 2008, at 9:50 AM, <email_removed> wrote:

>>>>>>> Hi,
>>>>>>>
>>>>>>> NSScroller has a small view, by default two pixels high, just
>>>>>>> above
>>>>>>> the scroller and below the NSTableHeaderView's corner view. How
>>>>>>> can I
>>>>>>> get at this view? If you look at the XCode interface you can see
>>>>>>> they
>>>>>>> have put an icon in this view (the one that splits the editor
>>>>>>> view)
>>>>>>> and made it larger. I would like to remove the view completely 
>>>>>>> so
>>>>>>> the
>>>>>>> scroller goes all the way up to the edge of the corner view.
>>>>>>>
>>>>>>> This question has been addressed before in the archives, but
>>>>>>> unfortunately the link pointing to an answer is no longer valid.
>>>>>>>
>>>>>>> Thanks.
>>>>>>> F.

>>>>>>
>>>>>> See NSTableView.h:
>>>>>>
>>>>>> /* Get and set the cornerView. The cornerView is the view that
>>>>>> appears
>>>>>> directly to the right of the headerView above the vertical
>>>>>> NSScroller.
>>>>>> The scroller must be present for the cornerView to be shown.
>>>>>> Calling -
>>>>>> setCornerView: may have the side effect of tiling the
>>>>>> enclosingScrollView to accomodate the size change. The default
>>>>>> value
>>>>>> is an internal class that properly fills in the corner.
>>>>>> */
>>>>>> - (void)setCornerView:(NSView *)cornerView;
>>>>>> - (NSView *)cornerView;
>>>>>>
>>>>>> --
>>>>>> Troy Stephens
>>>>>> Cocoa Frameworks
>>>>>> Apple, Inc.
>>>>>>
>>>>>>
>>>>>>
>>>>>>

>>>>
>>>>
>>>> --
>>>> Troy Stephens
>>>> Cocoa Frameworks
>>>> Apple, Inc.
>>>>
>>>>
>>>>
>>>>

>>> <Picture 2.png>

>>
>>
>>
>>
>> --
>> Troy Stephens
>> Cocoa Frameworks
>> Apple, Inc.
>>
>>
>>
>>

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