Android Code Snippet [B4X] Create square Thumbnail

[CODE lang="b4x" title="CreateSquareThumbnail"]Sub CreateSquareThumbnail(Input As B4XBitmap) As B4XBitmap
If Input.Width <> Input.Height Then
'if the image is not square then we crop it to be a square.
Dim l As Int = Min(Input.Width, Input.Height)
Return Input.Crop(Input.Width / 2 - l / 2, Input.Height / 2 - l / 2, l, l)
Else
Return Input
End If
End Sub[/CODE]
[CODE lang="b4x" title="Usage"]CreateSquareThumbnail(xui.LoadBitmapResize(File.DirAssets,"Snapchat-248558753.jpg",150dip,150dip,True))[/CODE]

 

[LucaMs]

Shouldn't it be used to reduce the size of an image? (or, better, to return a miniature of an image)
I see that if the input image is square the routine does not perform the "reduction"

If Input.Width <> Input.Height Then
' ...
Else Return Input

 

[Alexander Stolte]

Shouldn't it be used to reduce the size of an image? (or, better, to return a miniature of an image)

But before you can do that, you need a square

I see that if the input image is square the routine does not perform the "transformation". It seems more a routine to square an image rather than a "transformation" to thumbnail.

So I wrote this example:

[B4X] Create Thumbnail and save it

SavePictureToFile(XUIImageToJPEGByteArray(CreateThumbnail(xui.LoadBitmapResize(File.DirAssets,"Snapchat-248558753.jpg",150dip,150dip,True)),150dip,150dip,50),File.DirRootExternal,"test.jpg") "quality" on "XUIImageToJPEGByteArray" results on a: 910kb image quality = 50 = 17,69KB quality = 100 =...

www.b4x.com

 

[LucaMs]

But before you can do that, you need a square

Yes, I understand, but if the image is already squared, you're not returning a smaller image, that way.

 

[Alexander Stolte]

Yes, I understand, but if the image is already squared, you're not returning a smaller image, that way.

The function is not designed to get a smaller picture. Otherwise a "width" would have been added as parameter.
If you want a smaller image, then look at my example...

 

[Alexander Stolte]

CreateThumbnail(xui.LoadBitmapResize(File.DirAssets,"Snapchat-248558753.jpg",150dip,150dip,True))

The clue is to load the image already in the target size. (150dip,150dip)

 

[LucaMs]

    Dim xBitmap As B4XBitmap
    ' help.png is squared, 96x96px
    xBitmap = xui.LoadBitmap(File.DirAssets, "help.png")
    Log("Size: " & xBitmap.Width & TAB & xBitmap.Height)

    Dim xThumbnail As B4XBitmap
    xThumbnail = CreateThumbnail(xBitmap)
    Log("Size: " & xThumbnail.Width & TAB & xThumbnail.Height)

Waiting for debugger to connect...
Program started.
Size: 96 96
Size: 96 96

 

[LucaMs]

The function is not designed to get a smaller picture.

This is what I'm saying; a thumbnail is a smaller image.
If your snippet just square an image, it shoud have a different name

 

[Alexander Stolte]

it's in the title.

 

[Alexander Stolte]

This is what I'm saying; a thumbnail is a smaller image.

The clue is to load the image already in the target size. (150dip,150dip)

 

[LucaMs]

View attachment 94848
it's in the title.

Sub CreateThumbnail

Alex, sorry, you should learn Italian (or I should learn German ?).

What your routine does? Does it create a thumbnail (which means: reduced its size) of an image?
No, it "creates" a square image.
So its name shouldn't be CreateThumbnail but SquareImage or similar.

 

[Alexander Stolte]

What your routine does? Does it create a thumbnail (which means: reduced its size) of an image?

->
Pictures say more than words

 

[Alexander Stolte]

The square image is so pixelated because it's the compressed version I have in my app, I don't have the normal version anymore.

 

[LucaMs]

 

[Alexander Stolte]

just have a look in your gallery, large images are cut out in the middle and are then the thumbnails. that's exactly what this function does, just turn a non-square image into a square without it looking stupid

 

[LucaMs]

just have a look in your gallery, large images are cut out in the middle and are then the thumbnails. that's exactly what this function does, just turn a non-square image into a square without it looking stupid

Yes, but If I pass a B4XBitmap 1500x1000, your routine returns a 1000x1000 bitmap (squared, centered, useful), not a small one to use as thumbnail (say 100x100).

To be a "CreateSquareThumbnail" it should also reduce the size. You should pass (and use, of course) other parameters, like SideSize and / or ReducingFactor (or change its name, because my new 1000x1000 B4XBitmap cannot be called "thumbnail", for sure.

 

[Alexander Stolte]

You are welcome to write your own function.

 

[LucaMs]

I'm just saying that the name of the routine can be misinterpreted.