Mailing Lists: Apple Mailing Lists
Image of Mac OS face in stamp
 
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: How to grab IconRef from a .tiff file.

On 8/21/03 3:50 PM, Laurence Harris didst favor us with:

> On 8/21/03 3:31 PM, Mike Kluev didst favor us with:
>
>> On 21/08/2003 21:33, Laurence Harris wrote:
>>
>>> Do you know of any way to draw *just* the alpha channel?
>>
>> I found the way, I just not sure it is the most straightforward way.
>>
>>> Awsome, Mike! Thanks.
>>>
>>> BTW, shouldn't that be LockPixels();
>>>
>>> instead of
>>>
>>> HLock((Handle)GetGWorldPixMap());
>>
>> No, this is for a reason. QuickDraw does LockPixels for you
>> implicitly on every drawing operation, so it is not required.
>> On the other hand the was still is (as I rechecked it just
>> yesterday) a bug in QuickDraw that is caused by improper use
>> of dereferenced unlocked pixmap handle. This bug is still
>> clearly reproduced on 9 especially in case of picture recording.
>> I am sure the bug is still there in X, although it doesn't
>> reproduce itself because handles no longer move on X. So I
>> always lock pixmap handle with HLock either the next line
>> after creating GWorld or before CopyBits.
>
> Okay, thanks. I didn't know about that.
>>
>>> I tried this and the other problem is that the result is the reverse of what
>>> it should be. Is there more work involved or does it just need a different
>>> copy mode than subOver?
>>
>> First make sure you get expected image when you open it in
>> Preview app. It might be the case that this is alpha channel
>> in the image is inverted for some reason.
>
> Nope, it's a TIFF I created in Photoshop specifically for testing this code.
>
>> If image is ok but
>> you still get inverted result, put InvertRect(&r) after CopyBits.
>>
> That did it. Awesome!

Okay, latest installment: :-)

It turns out that some TIFFs need the InvertRect and some don't, and both
look fine in Preview. Is there some QuickTime API I can use to determine
when I need to use InvertRect()? Thanks,

Larry
_______________________________________________
carbon-development mailing list | email@hidden
Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/carbon-development
Do not post admin requests to the list. They will be ignored.
References: 
 >Re: How to grab IconRef from a .tiff file. (From: Laurence Harris <email@hidden>)



Visit the Apple Store online or at retail locations.
1-800-MY-APPLE

Contact Apple | Terms of Use | Privacy Policy

Copyright © 2007 Apple Inc. All rights reserved.