Third time I ask - please help. How to trace visible change in a UIView (UIWebView)
Hello everyone. I asked this several times before, but no one gave any hint -- I'd like to know if anyone here has any clue, at least where to search for an answer. I need to observe the visible contents of a UIWebView dIsplayed in my iOS application. Each time the visible contents changes, I need to capture the contents as image, and transmit it to our server. A bit like screen-sharing on the Mac, but not for the whole screen contents, just a single view. I already succeeded in capturing the contents of the view as an image-buffer (out of the CALAyer's context) and I can (brutally) solve my problem by setting up a timer that will sample the view's contents N times a second. However, I'd like to avoid transmitting anything when the view doesn't change, and I want to avoid comparing image-buffers N times a second (frame-differencing) on iOS devices, which is battery abuse. I DO NOT wish to re-transmit when the user rotates his iOS device and the view rotates. However I DO want to re-transmit when the user pinches to zoom in and out, or scroll through the view's contents. Also, I do not want the whole contents transmitted. just the visible part of it. This is why I'm not sure I need to ride the drawRect thing. I'm not sure a view must redraw when it undergoes visual translation/rotation/scaling etc. I started looking for the right delegate call, and quite soon got lost. My background is Cocoa on MacOS and iOS view/CALayer system still confuses me. This UIWebView might have subviews I'm not aware of, and it will usually be rendering a document file (such as PDF) via a given URL. The right way as I see it, is to get notified when the UIWebView decides to re-display or redraw its contents after something changes. (either content change - redrawing, or some user manipulation zoom, rotate, translate, animation). Can anyone hint on where to start here? I'll be grateful for any hint or direction. Thanks. Motti Shneor ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Third time I ask - please help. How to trace visible change in a UIView (UIWebView)
On 2013-04-22, at 3:26 AM, Motti Shneor su...@bezeqint.net wrote: Hello everyone. I asked this several times before, but no one gave any hint -- I'd like to know if anyone here has any clue, at least where to search for an answer. I need to observe the visible contents of a UIWebView dIsplayed in my iOS application. Each time the visible contents changes, I need to capture the contents as image, and transmit it to our server. A bit like screen-sharing on the Mac, but not for the whole screen contents, just a single view. My apologies: another possibility would be to poll at regular intervals, but, instead of capturing the entire view, use Javascript to pull its HTML tree, compare it with the previous version, and perform a new capture if you detect changes. It's still brutal, but, in this case, you'd be comparing two strings, which is probably less effort than comparing two images and can be easily delegated to a secondary thread. —Mt. ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Third time I ask - please help. How to trace visible change in a UIView (UIWebView)
Thanks Marco, Actually, we use the UIWebView not to display HTML contents, but because it so easily provide multi-document-format display. We will probably use it most for displaying PDF documents, Image files, Word documents, etc. Anyway, it will display a single, static, local document (not from the net). The user will share a document, and the document will be both displayed, and shared to other people through the server. Moreover, I doubt the efficiency of comparing HTML contents vs. comparing images, where I can very easily use the GPU to subtract pixel from pixel, then scan for non-zero data. To be very precise --- I'd like to know how to be notified about ANY UIView visual change. It somehow seems very obvious to me that such delegate call must exist. Maybe I'm overlooking something very basic here. Was it MY view, I'd ride the drawRect: I think. but again, I'm not sure on iOS, if you pinch a view to zoom-out, whether drawRect is called or not. Thanks again!. On 22 באפר 2013, at 15:29, Marco Tabini mtab...@me.com wrote: On 2013-04-22, at 3:26 AM, Motti Shneor su...@bezeqint.net wrote: Hello everyone. I asked this several times before, but no one gave any hint -- I'd like to know if anyone here has any clue, at least where to search for an answer. I need to observe the visible contents of a UIWebView dIsplayed in my iOS application. Each time the visible contents changes, I need to capture the contents as image, and transmit it to our server. A bit like screen-sharing on the Mac, but not for the whole screen contents, just a single view. If your UIWebView is displaying an HTML document, you could potentially inject some Javascript to watch for DOM changes on the html tag (Google “WebKitMutationObserver”); when a change is detected, your Javascript can force-load a URL with a custom scheme, which you can then trap inside your Objective-C code, where you can capture the view's state. There are other ways to achieve this, but this is the only one I can think of that might (a) capture all changes and (b) be in line with Apple's review guidelines. Note, however, that I haven't tried it, so it might not work at all for a number of reasons :-) —Mt. Motti Shneor Ceterum censeo Microsoftinem delendam esse ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Third time I ask - please help. How to trace visible change in a UIView (UIWebView)
On 2013-04-22, at 9:04 AM, Motti Shneor su...@bezeqint.net wrote: To be very precise --- I'd like to know how to be notified about ANY UIView visual change. It somehow seems very obvious to me that such delegate call must exist. Maybe I'm overlooking something very basic here. I think I had completely misunderstood what you wanted to do! I think what you want to do is interpose yourself as the delegate of the UIWebView's UIScrollView instance (accessible through the -scrollview property); that lets you track changes in scroll position, zoom level, etc. Is that what you meant? —Mt. ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
NSPredicate and NSString with whitespace gives runtime error
Is there a way I can use an NSPredicate to search an NSString that contains whitespaces (a sentence)? If I use this: NSPredicate *functionPredicate = [NSPredicate predicateWithFormat: @function CONTAINS[cd] %@, searchString]; I keep getting a runtime error: 'NSInvalidArgumentException', reason: 'Unable to parse the format string function CONTAINS[cd] %@' My guess is this happens because the attribute contains whitespace, since I have a bunch of similar NSPredicates that searches one-word attributes, and I don't get the error. Thanks, - Koen. ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: NSPredicate and NSString with whitespace gives runtime error
On Apr 22, 2013, at 10:58 AM, Koen van der Drift koenvanderdr...@gmail.com wrote: Is there a way I can use an NSPredicate to search an NSString that contains whitespaces (a sentence)? If I use this: NSPredicate *functionPredicate = [NSPredicate predicateWithFormat: @function CONTAINS[cd] %@, searchString]; I keep getting a runtime error: 'NSInvalidArgumentException', reason: 'Unable to parse the format string function CONTAINS[cd] %@' My guess is this happens because the attribute contains whitespace, since I have a bunch of similar NSPredicates that searches one-word attributes, and I don't get the error. The problem may be the use of the word function in your predicate string. See this SO question: http://stackoverflow.com/questions/15801537/unable-to-parse-the-format-string-function-when-using-nspredicates-pr -- Ben ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: NSPredicate and NSString with whitespace gives runtime error
On Apr 22, 2013, at 12:15 PM, Ben Gollmer bgoll...@tcnetworks.com wrote: The problem may be the use of the word function in your predicate string. That's it! I changed the name of the attribute to objectFunction, and it works as expected. Thanks, - Koen. ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Temporarily disabling autosave
The out-of-whackishness that I was seeing was caused by our own portable code which stored the current doc dirty state in a global. AUGH!! Yes, a global. *I* didn't write it that way. :) Anyhoo, it was preventing the document from ever being dirtied again. So to sum up, upon pausing autosave I explicitly tell it to autosave if needed via autosaveWithImplicitCancellability, in writeToURL return NO and set a userCancelled error if autosave is paused, and in hasUnautosavedChanges return NO if autosave is paused. This seems to handle all the cases I've tested so far. Thanks for the input, everyone. -- Steve Mills office: 952-818-3871 home: 952-401-6255 cell: 612-803-6157 ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Third time I ask - please help. How to trace visible change in a UIView (UIWebView)
On Apr 22, 2013, at 12:26 AM, Motti Shneor su...@bezeqint.net wrote: I already succeeded in capturing the contents of the view as an image-buffer (out of the CALAyer's context) and I can (brutally) solve my problem by setting up a timer that will sample the view's contents N times a second. However, I'd like to avoid transmitting anything when the view doesn't change A quick naive idea is to subclass UIWebView and override -drawRect: to call the inherited method and then set a timer that will capture the view's pixels a fraction of a second later. (You'd want a timer for coalescing purposes, since there are likely to be multiple calls in a short time interval.) The reason I say this is naive is because UIWebView almost certainly has a whole tree of views inside it that do the actual drawing, so the actual -drawRect: calls are probably going to those instead. But you could give this a try and see if you get anything useful. —Jens ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Third time I ask - please help. How to trace visible change in a UIView (UIWebView)
On Apr 22, 2013, at 10:30 AM, Jens Alfke j...@mooseyard.com wrote: On Apr 22, 2013, at 12:26 AM, Motti Shneor su...@bezeqint.net wrote: I already succeeded in capturing the contents of the view as an image-buffer (out of the CALAyer's context) and I can (brutally) solve my problem by setting up a timer that will sample the view's contents N times a second. However, I'd like to avoid transmitting anything when the view doesn't change A quick naive idea is to subclass UIWebView and override -drawRect: to call the inherited method and then set a timer that will capture the view's pixels a fraction of a second later. (You'd want a timer for coalescing purposes, since there are likely to be multiple calls in a short time interval.) The reason I say this is naive is because UIWebView almost certainly has a whole tree of views inside it that do the actual drawing, so the actual -drawRect: calls are probably going to those instead. But you could give this a try and see if you get anything useful. Another (likely dealbreaking) downside to this is that its going to call that -drawRect: implementation on every frame of a scroll. Since UIKit does some minimal work even if your -drawRect: is empty, and because you will then also allocate a buffer for the backing store, this is probably not a reasonable tradeoff. To the greater point the likely reason why you haven't gotten any responses before is simply because what you request is difficult, if not impossible, unless you are acting as the render server itself, which you aren't. Your probably better off doing a timed read and sending diffs to the client instead. -- David Duncan ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Temporarily disabling autosave
On 2013 Apr 22, at 09:43, Steve Mills smi...@makemusic.com wrote: So to sum up, upon pausing autosave which, per previous messages in this thread, I presume you do by sending the shared document controller -setAutosavingDelay:0.0. I'm surprised that this has any effect, because this method is Available in OS X v10.4 and later, and is apparently part of the the old Tiger autosave mechanism. But, OK. It's not marked as deprecated. Apparently Apple has tweaked this method to work for both the old Tiger autosave and the new Lion autosave. Surprising. I explicitly tell it to autosave if needed via autosaveWithImplicitCancellability, in writeToURL return NO and set a userCancelled error if autosave is paused, and in hasUnautosavedChanges return NO if autosave is paused. This seems to handle all the cases I've tested so far. You should try each of these three tests while autosave has been *paused*. • Activate another app. • Close the document window. • Quit the app. Debug -[NSDocument autosaveWithImplicitCancellability:completionHandler:] during this test. If this message is received, examine the implicitlyCancellable parameter and see if it is NO. Receiving that message with parameter NO is the most difficult case you need to handle, or else convince yourself that it can't happen. ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: NSScrollView in NSTabView autolayout problem
Hello My problems persist. So the NSScrolView as such work perfectly if they are in the active tab view. However if another tabview is active while window resizing the scrollviews on the inactive tabs get crazy and report NSClipVIew constraint with width 0. Best K On 19 Apr 2013, at 08:37, Krzysztof Wicher wrote: Thank you Chuck for pointing me to the answer I will try that. I know that NSScrollView is not build with Autolayout in mind but I hoped using it would save several boring layout managment problems arising in my design. Also, I did send the message last week but as it was my first to this mailing list, I was not sure how long it take so I did not resend. Thanks again K On 18/04/2013 17:37, Chuck Soper wrote: This message may be relevant for your issue: http://prod.lists.apple.com/archives/cocoa-dev/2013/Feb/msg00426.html Personally, I don't use auto layout in NSScrollView. I think that NSScrollView doesn't support it, but it appears that many people have gotten it to work. Chuck P.S. It looks like your message was sent to the list on Saturday, but I didn't receive it until this morning. On 4/13/13 1:57 PM, kwic...@wichry.net kwic...@wichry.net wrote: Hi I have an NSTabView with multiple tabs, each containing an NSScrollView. In the scrollviews I dynamically place custom views which are sized using autolayout and constraints. Now if I add my custom views to a scrollview in tab1 and resize the window with this tab active everything works fine and autolayout does not complain. On the other hand, if I add my custom views to a scrollview in tab1, switch to another tab, resize the window, and switch back to tab1 autolayout breaks with the following exemplar message: Unable to simultaneously satisfy constraints: ( NSAutoresizingMaskLayoutConstraint:0x4011d8f60 h=-- v=-- H:|-(0)-[FlippedDocumentView:0x4011b76e0] (Names: '|':NSClipView:0x40120eb80 ), NSLayoutConstraint:0x4012a5c80 H:|-(10)-[TextViewModuleView:0x401236e80] (Names: '|':FlippedDocumentView:0x4011b76e0 ), NSLayoutConstraint:0x4011148e0 H:[TextViewModuleView:0x401236e80]-(10)-| (Names: '|':FlippedDocumentView:0x4011b76e0 ), NSAutoresizingMaskLayoutConstraint:0x4011d8f00 h=-- v=-- H:[FlippedDocumentView:0x4011b76e0]-(0)-| (Names: '|':NSClipView:0x40120eb80 ), NSAutoresizingMaskLayoutConstraint:0x4011d5e00 h=-- v=-- H:[NSClipView:0x40120eb80(0)] ) What I noticed in the message is this H:[NSClipView:0x40120eb80(0)]. How come the NSClipView so in fact contentView of the scrollview has width = 0? My question is, why does the autolayout work fine for the active tab and does for inactive? Thanks k. ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/chucks%40veladg.com This email sent to chu...@veladg.com ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Third time I ask - please help. How to trace visible change in a UIView (UIWebView)
I had thought about this too, but was afraid that -drawRect: would be called
more often than the actual content of the view was being changed.
If you could limit the calls within -drawRect: perhaps by setting a content did
change flag in the subclass this might reduce the notifications to be
meaningful.
Like: (written in mail)
-drawRect:(NSRect)rect
{
if ( contentDidChange )
// post notification
[super drawRect:rect];
}
Sandor Szatmari
On Apr 22, 2013, at 13:30, Jens Alfke j...@mooseyard.com wrote:
On Apr 22, 2013, at 12:26 AM, Motti Shneor su...@bezeqint.net wrote:
I already succeeded in capturing the contents of the view as an image-buffer
(out of the CALAyer's context) and I can (brutally) solve my problem by
setting up a timer that will sample the view's contents N times a second.
However, I'd like to avoid transmitting anything when the view doesn't change
A quick naive idea is to subclass UIWebView and override -drawRect: to call
the inherited method and then set a timer that will capture the view's pixels
a fraction of a second later. (You'd want a timer for coalescing purposes,
since there are likely to be multiple calls in a short time interval.)
The reason I say this is naive is because UIWebView almost certainly has a
whole tree of views inside it that do the actual drawing, so the actual
-drawRect: calls are probably going to those instead. But you could give this
a try and see if you get anything useful.
—Jens
___
Cocoa-dev mailing list (Cocoa-dev@lists.apple.com)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
https://lists.apple.com/mailman/options/cocoa-dev/admin.szatmari.net%40gmail.com
This email sent to admin.szatmari@gmail.com
___
Cocoa-dev mailing list (Cocoa-dev@lists.apple.com)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com
This email sent to arch...@mail-archive.com
Re: Temporarily disabling autosave
On Apr 22, 2013, at 17:57:41, Jerry Krinock je...@ieee.org wrote: which, per previous messages in this thread, I presume you do by sending the shared document controller -setAutosavingDelay:0.0. I'm surprised that this has any effect, because this method is Available in OS X v10.4 and later, and is apparently part of the the old Tiger autosave mechanism. No, that was only something I tried, but it didn't work. The pause mechanism is something in our own code - a bool that says it's paused (it's actually an integer so it can be incremented/decremented in a nested fashion). I check this value in writeToURL and hasUnautosavedChanges. -- Steve Mills office: 952-818-3871 home: 952-401-6255 cell: 612-803-6157 ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
