I am attempting to reveal (through animation) a UIView. Specifically I want to show the center portion of the view and then slowly reveal the outer edges of it (sort of like pulling back a curtain).
My first attempt was to simply set the bounds rect to be smaller and animate it to be the full size of the view's frame, but this did not have the desired effect since by changing the bounds I was also changing the frame.
If what I am trying to do does not sound possible (at least not in a simple manner), at least I would like to be able to have is some way to make the subviews of the main view stationary relative to the screen, NOT their parent view, as the parent resizes (this would give a similar effect).
Any ideas?
Thank you,
-Matt
It definitely is possible. What you need to do is
For the view you're animating, setAutoresizesSubviews:NO and setClipsToBounds:YES.
Set the view's bounds (NOT the frame) to a rect with zero size and origin at the center point of the rect you want the view to occupy when it is fully revealed (in the view's own coordinate system). In other words, startBounds.origin.x should equal half of endBounds.size.width and similarly for y.
Position the view by setting its center (in the parent view's coordinate system).
In an animation block, change the view's bounds to zero origin and full size.
In the animation's completion block, you probably want to setAutoresizesSubviews:YES again.
You may also need to set the view's autoresizing mask to be fully flexible (springs but no struts), depending on what other layout gets triggered as you resize.
Sounds like you want to change its clipping. A cheap (code-wise) way to do that would be to insert the view into a parent view (with autoresizing set to center it), set the parent to clip its children and then animate the parent's frame.
Related
What is the correct formula for the location of an NSRulerMarker on a vertical NSRulerView, if the client view is flipped?
The situation: I have a view (let's call it the "main view") that is embedded in an NSScrollView with rulers, and it has subviews. The user can drag these subviews around, and while dragging, I want to indicate the current position on the rulers.
The main view is flipped: The zero point is top-left.
The horizontal position is pretty simple:
NSPoint scroll = myScrollView.documentVisibleRect.origin;
NSRect rect = mySubView.frame;
rulerMarkerDragLeft.markerLocation = rect.origin.x - scroll.x;
However the same method for the vertical position...
rulerMarkerDragTop.markerLocation = rect.origin.y - scroll.y;
does not work. The marker is only in the correct position when the scrollview has been scrolled down to the extreme bottom. For every n points scrolled back up, the marker location is n points too high. This is independent of the main view's size or the size of the visible area.
I can't seem to wrap my head around this problem; I guess there is a value I need to subtract from my result that expresses how far up the scrollview has been scrolled (or rather, how much further it can be scrolled down), but I don't think I can derive that value from myScrollView.documentVisibleRect...?
I may have overlooked something simple, but I can't find the solution.
Edit 2022-11-02 17:17 CET: Found the problem. I had set the NSRulerViews clientView to the contentView of the window. I am now setting it to the "main view" (ie. the view inside the scroll view), and now it works "automagically": I just set the marker locations to the subviews frame, no correction for scroll position or anything else needed.
The solution was simple: the ruler views' clientView needs to be set to the view that is inside the scroll view, not the main content view of the window.
The positioning of the ruler markers is now very straightforward: you just use the local coordinates inside the view, ie. the subviews' frame values.
No correction for scroll position, view height or such necessary.
My mistake was assigning the window's main content view as the rulers' clientView.
I know how to use a background image with alpha channel to create a UIButton with an irregular tap area. But with this solution, only the ignore-tap area is transparent; the tap area consists of the opaque.
What I want is a totally transparent UIButton, with an irregular tap area. (It triggers an animation behind the button.)
It seems that some sort of extra UILayer with some hit-testing could work, but I don't quite see how. Suggestions welcome.
Here's my solution. The problem: A UIImageView (call it the base view) to which I want to attach an irregularly-shaped tap area. The area corresponds to something in the image, let's call it a river. It could be a non-connected region.
In the Finder, duplicate the view's image, and make all the non-river pixels transparent, using your favorite graphics app. Call this the mask image.
When the base view is tapped, check to see if the corresponding pixel in the mask image is or is not transparent. (Solution left to reader; examples abound.)
So the mask image is never actually rendered, it is just used as a reference.
Note that if the base view gets resized or moved around (as it does in my app, via animating its constraints) then you have to "move" the mask image too, or in some other way manage the coordinate translation between view and mask. The easiest way to do this is to make the mask image a hidden subview of the base view, with its left, top, leading and trailing anchors constrained to be equal to those of the base view. Then they move around together, and the coord translation between the two is the identity.
I wrapped all this up in a subclass of UIImageView so that it manages its own mask, and calls a delegate if the "river" (or whatever) is tapped.
Before AutoLayout I could do a view cut to a circle shape with setting .layer.cornerRadius to half of the view's height.
Now, using AutoLayout how can I achieve, to my view keep look like a circle?
I have already tried and failed:
using KVO to find out when frame changes. It gets called, but at that point setting cornerRadius on the view does not have any effect
calling -setNeedsLayout to have frame values before I set cornerRadius (does not work either)
You need to set the property masksToBounds on the layer.
xyz.layer.masksToBounds = YES;
Further, the reason why this actually won't affect Auto Layout is because the view's frame will remain the same regardless of its corner radius.
Right now, I have a UIScrollView which scales its UIView contents on zoom events. When I hit a certain zoomScale threshold, I want to be able to toggle on and off extra information within the UIViews. Right now, I am simply setting the hidden flag to YES/NO to accomplish this.
However, a problem occurs while attempting to get the bounds of the UIView. The bounds always returns a width and height that extends to include the invisible content.
Is there a way to limit the bounds to only return the size of visible content within a UIView?
You could derive new bounds as you zoom and not rely on the view's automatic bounds adjusting.
OR
If it doesn't make your code too complicated, I would remove those subviews from your resizing view instead of just hiding them.
Cocoa's NSScrollView is horribly under-explained. I hope someone here knows what it's all about and can spare me a few seconds.
So I have a custom NSView. I implement -drawRect: for it to draw something, fill itself with colour, whatever. Then I have an NSScrollView wrapping it (set up through the interface Builder).
Now the inner, custom, view must have a size larger than that which fits in the outer scroll view—for it to scroll. That much I realise. I have incidentally configured it so that the scroll view adjusts to the surrounding window’s size, but that shouldn’t matter.
I override my inner view’s -frame method to return a frame sized at least 1000x1000.
- (NSRect)frame {
CGFloat w = 1000;
CGFloat h = 1000;
if (self.superview.bounds.size.width > w)
w = self.superview.bounds.size.width;
if (self.superview.bounds.size.height > h)
h = self.superview.bounds.size.height;
return NSMakeRect(0, 0, w, h);
}
Here’s the outcome, which I have trouble interpreting:
I can scroll when the scroll view encloses an area smaller than 1000x1000
BUT
The only area filled with colour (i.e. that my -drawRect: method has any effect on) is
as large as the scroll view’s bounds
located at (0,0. I use flipped, so that’s top left, and it ends up being outside the visible area after scrolling.
The visible area that lies outside this irrelevant rectangle is not painted at all.
I don’t know anything beyond this point. It seems like the rect for drawing is clipped to the scroll view’s position in the window, and size, or something—but it does not take the scrolled "location" into account.
It should be noted that I don't really expect anything else to happen. I feel I am missing a piece, but can't find which. Sorry for the wall of text, but I can’t explain better right now. I hope it is easier to answer than it is to ask.
Regards and hope,
Not Rick Astley
It's a very very very bad idea to overwrite -frame. There is so much that depends on the actual instance variable having a correct value. Instead try to set the frame to the one you want using setFrame:, that might fix all your problems if you're lucky...
I agree with Max's warning that you shouldn't override -frame. If you want to constrain the set frame, override its setter ( -setFrame: ) and the designated initializer ( -initWithFrame: ) and adjust the proposed frame as desired.
Regarding your overall problem, I wonder if your problem is conceptual. The argument for -drawRect: (the dirty rectangle you're asked to redraw) is useful if you're drawing something that you can redraw incrementally in parts (like a grid - any grid blocks intersecting dirtyRect can be redrawn and the rest can be ignored). If you're doing something that has to be completely redrawn, you should use [self bounds] and not the dirty rect passed at drawRect.
For example, if you have just a standard gradient background, it's difficult to tell from dirtyRect which part of the gradient to redraw and infinitely easier just to redraw the whole view with the gradient, ignoring dirtyRect altogether.
You're right in assuming that only the area of your view exposed by the scroll view's clip rect will normally be asked to redraw when scrolling. There're also interactions with the scroll view's -copiesOnScroll to consider.
I hope this helps.
Use of the NSScroller really relies on a solid understanding of the MVC paradigm. Apple's docs really focus on showing a photo and a set of text, but not much else. The use of NSScrollView is something that I've struggled with in the past.
First off, do not override frame. Use setFrame to tell the scrollView how large the working area is, and then just simply draw in the area the frame encompasses. As I understand it, a custom NSView and the encompassing NSScrollView takes care of the rest, such as what to draw where when. In other words, ignore the bounds of the rect passed into drawRect and instead draw within the bounds of the frame you sent to scrollView; don't worry about what is visible and what isn't because that is the job of the framework.
Here is where the MVC paradigm comes in: setFrame should be used when your Model is updated. So, if an object falls outside of the current bounds of the frame, then use setFrame to set the newly expanded bounds, and then draw within that area.