Re: Updating progress of UIProgressView. And Getting Better Saving Performance
Re: Updating progress of UIProgressView. And Getting Better Saving Performance
- Subject: Re: Updating progress of UIProgressView. And Getting Better Saving Performance
- From: Gustavo Pizano <email@hidden>
- Date: Tue, 7 Dec 2010 17:27:29 +0100
David hello.
I didn't use blocks, in order to support 3.2, just in case, you never know who is out there still using it. so I sue normal [NSObject performSelectorOnThread methods,..
Now I divided the Saving operation and the thumbnail creation in 2 separate threads, the thumbnail is inside the thread of saving, now its much faster, encoding and saving takes little time, I believe that the thumbnail creation is the responsible for slowing the process.
Basically and I think Im very wrong in whatIm doing is create a screenshot of the View with all its subviews, following Apple docs to do so, so each view's layer renderInContext is called. Of course I previously create a UIImageCOntext, then after I get that image, I scaled it down
to the thumb dimensions, but here is where it get's messy:
The thumb must have a rounded corner mask + the border stroke, if I do that in the same UIImageContext I created to resize the screenShot I got, then I get no rounded corners for the image but the stroke of the path is rounded. So I was reading a little and to add a clip to a context I must have a BItMapContext, in this case the image gets rounded corners but if I try to stroke the path the clip I add goes away.
So what I did was, create the thumb with a UIImageContext, then clip it using a UIBitMapContext, then create a final Image using once again a UIImageContext which in this case I draw the rounded corner image and then stroke the path.
So I believe I can do better in this process.
Thx
Gustavo
On Dec 7, 2010, at 1:59 PM, David Reed wrote:
>
> On Dec 7, 2010, at 3:16 AM, Gustavo Pizano wrote:
>
>> Hello Guys..
>>
>> I see, I have been using GCD and blocks but on somme OSX app I did before, not on iPhone, I tough tit wasn't there... :P.
>
>
> Blocks/GCD are in iOS 4.0 and higher. Assuming you have a paid developer account, you may want to watch the relevant WWDC videos from last year.
>
>>
>> SO, I from within the method( block) that makes all the saving process, I do something like
>>
>>>> dispatch_async(dispatch_get_main_queue(), ^{
>>>> // code executed on main thread goes here (i.e., updating the progress indicator in your case
>>>>
>>>> });
>>
>>
>> and update the progress indicator bar, great im gonna try that..
>
>
> Yes.
>
>
>>
>> also I have the option to call from within the same method a [<MyConotroller With the Progress indicator> performSelectorinMainThread: withObject:<NSNumber with the float value to add> waitUntilDone:NO];
>>
>> right?
>
>
> Yes, ssuming the selector you pass (you left it out) takes the NSNumber and updates the progress bar.
>
>
>>
>>
>> What about the saving operation improving its saving time?, I will check today what takes longer, if creating the thumbnial, or encoding the views, maybe I shouldn't encode the whole view, but s just the image reference and the transform matrix... ?/ I will try that one also.
>
>
> I didn't look at your code closely and don't have the other code around it to profile which part is taking so long.
>
> Dave
>
>
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