I'd like to get some tip about how implement a PDF View that scrolls horizontally.
I know how implement a PDF reader using UIWebView, but just with vertically scroll.
I've done this. The code was private for a paying customer, so I can't share it directly, but the basic idea is to write:
One UIView subclass that renders a single page of a PDF, using a CGPDFPageRef and the CGPDFDocument* and CGContextDrawPDFPage families of functions. It helps a great deal for this view to return [CATiledLayer class] from the layerClass class method, and to set the layer's levelsOfDetail and tileSize properties appropriately. Mine also implements sizeThatFits to return the page size plus a small gutter, and renders a subtle dropshadow around the edge of the pdf page.
Remember that UIKit drawing is upside-down from CG drawing; so do a CGContextTranslateCTM(ctx, 0.0, layer.bounds.size.height); CGContextScaleCTM(ctx, 1.0, -1.0); before painting.
One UIView subclass containing and laying out (and being delegate for) a UIScrollView in paging mode (the main horizontal pager), and an individual UIScrollView for each page, each containing one of the above views (for zooming into individual pages.) Nested scroll views is Apple's explicitly endorsed way of doing this sort of thing. This view will need to lay out the pages how you want them; presumably in one long horizontal strip, each zoomed to a fitting size.
If you don't need page zooming, you can skip the nested scroll views and lay out the page views directly in the horizontal scroller.
TL;DR: Unfortunately it's not as simple as tossing it in a UIWebView; but it is doable, and the straightforward approach does work.
I found an open project with this feature =D
https://github.com/iamruinous/Reader
I found an open project with this feature
https://github.com/vfr/Reader
Related
I have two different UIImageViews. I'd like to make the top UIImageView blend in using the Screen blend mode with the bottom UIImageView.
I know of the property of CALayer: compositingFilter and I know that it doesn't work in iOS. I've searched a lot for solutions, and I've found how one should subclass UIView and override drawRect.
I've tried to set the context in drawRect to the screen blend mode, although it still draws every one of the images normally. Perhaps I am doing something wrong, or the approach should be different. Maybe I need OpenGL or CALayer to achieve this. Could someone assist?
Unfortunately there is no way to do a non-composite blend between UIViews on iOS. UIKit doesn't provide the functionality, and you've already noted, CALayer can't do it either.
In general, implementing -drawRect in a UIView won't help you. You're drawing into an empty bitmap -- it doesn't contain the bits of the views behind it, since those might change at any time (any view or layer might be animated). CA fundamentally assumes that layers' contents should be independent of each other.
You could try, in your -drawRect:
create an image context
capture the views under your view using -[CALayer renderInContext:] for each
create an image from the image context
draw that image into your view
set the blend mode and draw on top of that
But that will be slow and fragile, and won't work if you animate any of the views. I wouldn't recommend it.
If you really need to do this, you're going to have to switch your whole scene to render with OpenGL, where you've got more freedom.
I'm trying to make a page based application in iOS where the actual page is a non-rectangular image (contains clear color). However, the shadow that appears when I turn the page doesn't seem to ignore the transparency of the image (see below).
Screenshot http://img543.imageshack.us/img543/9730/pagecurl.png
Does anyone know if it's possible to modify this behavior?
Thanks in advance.
Have you tried setting your UIPageViewController's view's frame so that it sits just within the border defined by your custom page image?
(So in your case, the largest rectangle that fits inside your white page image)
The way UIPageViewController handles a page curl animation with views that extend beyond its own view's frame can be thought of as follows:
Think of the overhang as rigid. it does not bend like the rest of the page, but it does maintain the angle at the edge of the UIPageViewController's frame. If the overhang (i.e. parts of your image or view that extend beyond the UIPageViewController's frame), is small, the fact that the overhang animates as rigid (instead of the bendy, flexible page) is visually negligible.
However, without any further modifications, the pages will only flip when a touch is started INSIDE the UIPageViewController's view's frame. But it would be better if it could react to touches anywhere on your white page image. If you want the pages to react to touches inside another view's frame (e.g. the view holding your white page image), try the following:
otherView.gestureRecognizers = myPageViewController.gestureRecognizers;
The problem is that the iOS framework puts a shadow over the entire bounds of the view controller you specify for the page, so any transparent areas will look shadowed. You could try masking your view controller (viewController.view.layer.mask and viewController.view.layer.masksToBounds) and see if that helps.
Hopefully Apple improves this framework for a future iOS release. It sure would be nice to disable that shadow or have a way to do it yourself but there you go.
I need to create a scrollable composite view on iOS. That is to say, the view will contain at least one image, possibly a button, and some text (that we may wish to format with bold fonts, etc). The amount of data, and particularly the amount of text, is variable, from maybe 4 lines to maybe 100. The data is "variable" to a degree, and in particular the image and text do not come joined at the hip.
This all needs to fit in a "pane" of about 280h x 115w pixels in a portrait-only layout.
A single UITextView doesn't provide the facilities to display an image or format the text.
A UIWebView provides the ability to display the image and formatted text, but the button is a problem (not even sure if it's doable).
A UIScrollView would easily allow the image and button, and then a UIWebView could be embedded in the scroll view for the text, but then scrolling becomes a problem -- I'd like the entire view to scroll as one, without having to resize the web view to contain it's content, and without the confusion of a scrollable within a scrollable (the doc warns of "unexpected behavior").
(I'm guessing your thoughts at this point are that I want too much.)
So, any suggestions? What's the best way to get close to what I need here?
In iOS5 the UIWebView has a scrollView property, which is a normal UIScrollView. You should be able to add a UIButton as a subview of the scrollView to achieve what you want, although positioning it correctly may be a challenge. Prior to iOS5 you could cycle through the subviews of the UIWebView to find the UIScrollView with isKindOfClass...
I suggest testing with a UIWebView inside your UIScrollView. I don't see any interference in the iOS 5.0 simulator. I don't know if there are problems in iOS 4.0.
If you find that there is interference, you can prevent it by setting the web view's userInteractionEnabled property to NO, either in the nib or in code. This will prevent the web view from receiving any touches, so the user also won't be able to pinch-zoom it, follow links in it, or copy text from it.
In the web view's delegate, implement webViewDidFinishLoad: to set the web view's size and the scroll view's contentSize. For example:
- (void)webViewDidFinishLoad:(UIWebView *)webView {
CGRect frame = self.webView.frame;
frame.size = [self.webView sizeThatFits:CGSizeMake(frame.size.width, HUGE_VALF)];
self.webView.frame = frame;
self.scrollView.contentSize = CGSizeMake(CGRectGetMaxX(frame), CGRectGetMaxY(frame));
}
When I did a similar thing, I had a dozen of views which I added to the UIScrollView and then calculated the frames of all the views. Granted, it was an extremely tedious work, given that some views could get hidden under various conditions. The layout code was actually pretty simple, laying out views from top to bottom, but ugly. The upshot is that it works like a charm, fast and reliably. You can even trivially wrap it in an animation block.
I'm currently working on an app which needs to draw s.th. like a network graph. Unfortunately this graph can become very big with thousands of movable objects.
I tried to put a giant UIView inside a UIScrollView but soon noticed this won't work because of memory limitations.
So I tried another approach: currently I have a UIView which has exactly the size of the visible part of the UIScrollView. The scrollview is set to not handle the scrolling (only the pinching). Instead I handle the scrolling in the UIView. Everytime a user scrolls, all graphic objects (those graphic objects are currently just subclasses of NSObject, which contain custom drawing code) are moved, so it seems like the view is scrolling. In the drawRect I only draw the graphics that are currently visible.
Also I constantly add and remove sublayers if they are moved out/in the visible frame
This works very smooth even with thousands of objects.
Unfortunately this approach has some drawbacks:
I can't zoom out to see all the objects in the graph, instead the user can only see a part of it
I don't get the inertial scrolling the UIScrollView offers
Other approaches I tried, like the CATiledLayer, don't work either because all the objects in the graph are draggable by the user and it looks really ugly if I use a CATiledLayer...
Swapping out the UIView with other UIViews while the user scrolls may help with the inertial scrolling, but it makes everything more complicated and zooming out completely still won't work :-(
Do you know of any best practices to draw graphs that can be very big?
//edit: I ended up with a uiscrollview which has a subview which has a cascrolllayer which has many sublayers. While zooming in and out the frame of the uiscrollviews subview is constantly changed to the uiscrollviews bounds by view.frame = scrollview.bounds. While dragging the scrollview the cascrolllayer is always forced to scroll to the current offset of the scrollview.
I needed to subclass the uiscrollview and hack around in order to make the zooming work nicely, but it's working well now. This approach works very well and allows very big graphs with lots of draggable elements.
//edit: see my other answer below, the approach above didn't work out as well as I initially thought, especially the zooming part
CATiledLayer is definitely what you should use here—there’s not really another solution that’ll let you use Quartz/UIKit drawing on a huge zoomable canvas. For anything that needs to be interactive (dragged or animated or whatever), you can disable its display in the main tiled layer and overlay another view or layer on top of it that just contains the object being interacted with.
Couldn't find anything on the net about this and wondered if anyone on SO has a solution.
I have an NSView with several subviews that are centered by removing the left and right anchor points. When I resize my view, programatically or with the mouse, to a smaller width than the subviews: it pushes them off center. Has anyone come across this before and do you have a solution?
EDIT: I want to be able to resize my view to a zero width. The reason being, the view is actually part of a split view and I have hooked up a button to 'collapse' it. When it collapses all of the subviews are pushed off-center and aren't re-centered when the view is resized, effectively un-collapsing it.
I have solved my problem now and thought I would share incase anyone comes across this issue in the future.
No amount of playing with autosizing options or view layouts in Interface Builder seemed to stop my subviews from getting moved off center. I did manage to find this link here and from this page, the advice:
Springs and struts, as currently
implemented, are really no good for
anything but keeping either one or
both sides of a view "stuck" to the
nearest edge. Any sort of centering
behavior, division of gained/lost area
between multiple views, etc. has to be
done by hand.
Based on this I overrode my view's setFrame: method and manually laid out my subviews using their setFrame: method. This works great and gives me the results I'm looking for.
There is the same issue using NSSplitView, resizing here one Subview to be smaller than the Subview Subviews makes sense,e.g. having small charts in the upper subview, and an rss reader in the lower subview.
If you want to show only the rss reader in the lower subview, you can "hide" the upper subview, but after resizing the upper subview the NSImageView are not layed out the same as in the beginning. Check this nib/xCode Project and the following screenshot to see this behaviour.
Only workaroung is to override the resize function to stop getting smaller.