Re: Optimized pixel manipulation
Re: Optimized pixel manipulation
- Subject: Re: Optimized pixel manipulation
- From: "Christian Giordano" <email@hidden>
- Date: Wed, 8 Oct 2008 17:02:24 +0100
After drawing the shapes, I do pixel operations, of course. For this
reason I create a bitmap context and after the drawing I get the
CGImageRef generated, I copy the pixels, I modify the pixels and then
I create a new image with those that will be drawn in the UIView
context.
Cheers, chr
On Wed, Oct 8, 2008 at 4:58 PM, Jean-Daniel Dupas
<email@hidden> wrote:
> I do not understand.
> If you just want to display some shapes and images, you don't need to draw
> into a bitmap, you just need to draw in your view.
> What do you mean by "creating a context". All views already have a context
> where you can draw whatever you want.
>
> Le 8 oct. 08 à 17:43, Christian Giordano a écrit :
>
>> At the moment I'm starting creating a context and drawing basic
>> shapes, is there another way to draw basic shapes on a bitmap?
>>
>> Cheers, chr
>>
>>
>> On Wed, Oct 8, 2008 at 4:32 PM, Christian Giordano
>> <email@hidden> wrote:
>>>
>>> I started questioning myself if maybe I need something else, but
>>> clearly I have no idea which other options I have. Maybe using OpenGL
>>> (ES)? The ultimate aim is of course to renderer the result of all the
>>> manipulation, at the moment this happens in a UIView.drawRect.
>>>
>>> Cheers, chr
>>>
>>>
>>> On Wed, Oct 8, 2008 at 4:25 PM, Jean-Daniel Dupas
>>> <email@hidden> wrote:
>>>>
>>>> CGImage does not provide an efficient way to update , but maybe CGImage
>>>> is
>>>> not what you want.
>>>> Where your image come from, why do you need a CGImageRef and what are
>>>> you
>>>> trying to do with it ?
>>>>
>>>>
>>>> Le 8 oct. 08 à 17:01, Christian Giordano a écrit :
>>>>
>>>>> I'm modifying frequently the pixels of the images, the way I found is
>>>>> creating a copy of the data
>>>>> (CGDataProviderCopyData(CGImageGetDataProvider(image));) modify the
>>>>> pixels and then create a new one. I'm facing performance issues and I
>>>>> fear that all this allocating and deallocating is not helping. Is
>>>>> there a way I could have access and modify the pixels of a CGImage
>>>>> without copying them?
>>>>>
>>>>> Thanks, chr
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