Android Question What LoadBitmapSample does exactly?

[LucaMs]

...and why should I pass MaxWidth and MaxHeight but it could return bigger dimensions?

Thank you

 

[Erel]

Exactly as described:

The purpose of LoadBitmapSample is to reduce memory usage. It can be considered a bug to load an image with LoadBitmap instead of LoadBitmapSample (unless you know for sure that the image is not huge).

The variables names are less important.

 

[LucaMs]

"The decoder will subsample the bitmap if MaxWidth or MaxHeight are smaller that the bitmap dimensions."

subsample... I suppose it should return a proportional sample, smaller or equal to MaxWidth and MaxHeight. Is this correct?

In a project I get (w.h logs):

original (file): 3543.2215
ImageView : 293.293 (MaxWidth and MaxHeight I passed to LoadBitmapSample)
'sampled' : 443.277

442 is bigger than 293
277 is smaller than 293

 

[JordiCP]

I think that it searches for the "nearest" power-of-2 (1/2, 1/4th, 1/8th...) subsample of the original bitmap which "better fits" the given maxWidth and maxHeight.

3543/293 = 2215/277 = 8 aprox (this is the subsampling)

Also, the scale factor of the subsampled bitmap remains (3543/2215 = 442/277 = 1.6 aprox )

As in your case you gave square dimensions for a non-square original bitmap, it made its best

 

[sorex]

the proportions are right.

 

[LucaMs]

the proportions are right.

which "better fits" the given maxWidth and maxHeight.

442 is bigger than 293

then, it does not fits, it exceeds.

Anyway, I have a small project that does not work as it should. I make a few more attempts then I'll publish it, hoping in your abilities


Thank you

 

[sorex]

maybe you should show some code on how you use the routine.

 

[LucaMs]

maybe you should show some code on how you use the routine.

I still wanted to look for the bug, but since you're so helpful... I am attaching the "project" .

 

[sorex]

just had a quick look at it and the results are indeed strange.

I don't know if it is an implementation of @Erel or calls to standard api's.

 

[LucaMs]

just had a quick look at it and the results are indeed strange.

It seems to work well on an Android 4.4.2, not well on a 4.0.4.

 

[LucaMs]

I solved using the canvases.

This problem remains, however.


Thanks, especially to whom this is not interested

 

[victormedranop]

LucaMs, use canvases? how's that.

thanks

victor

 

[Erel]

Which problem are you trying to solve?

 

[LucaMs]

LucaMs, use canvases? how's that.

thanks

victor

https://www.b4x.com/android/forum/threads/imageview-bitmap-centered.43779/