How to scale bitmaps in faster way?

[slinx]

I have checked and used CBitmapScaler for scaling bitmaps to larger size. But it provides scaling method asynchronous ways. For my use case, I don't need scaling asynchronous way. So What are the other ways of scaling bitmaps synchronous way? Is there any example available for basic image processing in Symbian C++, what are the available api for that? Thanks

[symbianyucca]

Can you tell me what is teh use case you need the scaling for ? for example can you simply load the image into right size already, or maybe if it is for showing, you could simply play with the source & target draw rects etc.

[slinx]

Thanks symbianyucca for reply. I have 2 things to do in SampleMethod(). My requirement is to resize image synchronously
which would be fast and gives good quality

void SampleMethod(CFbsBitmap* aBitmap)  
{
     //1. resize aBitmap to larger size  
     //2. Draw resized bitmap		
}

What is best available option here to resize CFbsBitmap synchronously here? Thanks

[symbianyucca]

do check the gc documentation, you can simply define source & target rects, effectively giving you the resizing option you are asking for.

Also there is really no point on increasing the image size, you would simply be consuming more memory with blurry image, since there is no algorithm used there to give you any additional resolution.

[slinx]

Thanks symbianyucca.

do check the gc documentation, you can simply define source & target rects, effectively giving you the resizing option you are asking for.

I have checked DrawBitmap(const TRect &aDestRect, const CFbsBitmap *aSource), but it is indeed slow as said in documentation.

As said in documentation:
If the bitmap has to be scaled, consider creating another bitmap along with an CFbsBitmapDevice etc., doing DrawBitmap() once and using BitBlt() subsequently.

Any example on how to do this?

Also there is really no point on increasing the image size, you would simply be consuming more memory with blurry image,
since there is no algorithm used there to give you any additional resolution.

yes, image quality will degrade to some extent but i think there are some common image resampling algorithm like nearest neighbor or bilinear implemented there.
I need to know using which method i can get faster image resizing. My preference is faster resize than image quality. Thanks

[symbianyucca]

You could check off-screen bitmap handling example from wiki for the CFbsBitmapDevice , basically the n you would simply make the target image as big as you want it to be, and then use the gc draw methods againt o draw it there, and then you would draw this in your containers draw, I would not think its any fatre than doing it directly in the container draw, anyway, as you only have partial area you should check the target & source rects ..

[wizard_hu_]

Synchronous-asynchronous do not really affect the speed. If you are familiar with graphics algorithms you can
- implement a completely own variant
- use TLinearDDA
- check http://www.developer.nokia.com/Commu...otate-an-image (that time I did not know about TLinearDDA)

[slinx]

Thanks wizard_hu_ for your reply.

Synchronous-asynchronous do not really affect the speed.

yes I agree.. only overhead of using asynchronous method in synchronous way.

If you are familiar with graphics algorithms you can. If you are familiar with graphics algorithms you can
- implement a completely own variant
- use TLinearDDA
- check http://www.developer.nokia.com/Commu...otate-an-image (that time I did not know about TLinearDDA)

I think I should try this way, one single routine to do the job. Thanks