B4J Question save canvas in jpg

[jota]

Hi I'm using this code to save the image of a canvas.

Dim out As OutputStream = File.OpenOutput(rutaDestio, fichero, False)
c.Snapshot.WriteToStream(out)
out.Close

It works well but I need to be in JPG format, how I can get it?

Thank you

 

[Erel]

There is no simple way to change the file format. The reason that JPG was not added is that there were all kinds of color issues with the JPEG encoder.

 

[jota]

And some way to modify the quality of PNG? I'm converting images and putting watermark and the end result gives me 350kb files and was expected to work on 110kb. Thank you

 

[Erel]

PNG is a lossless format. You cannot control its compression level.

 

[Daestrum]

There is a way, not elegant and requires java 8 and the jNashorn library.

Sub Process_Globals
    Private fx As JFX
    Private MainForm As Form
    Private label1 As Label
    Private nashorn As jNashorn
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    MainForm = Form1
    MainForm.RootPane.LoadLayout("labelstest") 'contains just a label 'label1'
    MainForm.Show
    label1.Text = "Hello"
    Dim out1 As OutputStream = File.OpenOutput("c:/temp/","img.png",False) 'temp file for png
    Dim out As InputStream = File.OpenInput("c:/temp/","img.png")
    label1.Snapshot.WriteToStream(out1) ' create snapshot of node
    Dim js As String = "x:/buffImage.js" ' path to where you put the buffImage.js file
    nashorn.evalFile(js) ' load the javascript file
    nashorn.enginePut("out",out) ' set var 'out' to inputstream
    nashorn.evalString("start(out ,""c:/temp/img.jpg"");") ' inputstream , output file name
End Sub

The required javascript file (buffImage.js) to convert from png to jpg

var bufferedImage = Java.type("java.awt.image.BufferedImage");

function start(source,dest){ 
     bufferedImage = javax.imageio.ImageIO.read(source);
     var newBufferedImage = new java.awt.image.BufferedImage(bufferedImage.getWidth(),
            bufferedImage.getHeight(), java.awt.image.BufferedImage.TYPE_INT_RGB);
            // Color.WHITE is the background colour of the jpg image no transparency in jpg
     newBufferedImage.createGraphics().drawImage(bufferedImage, 0, 0, java.awt.Color.WHITE, null);
     javax.imageio.ImageIO.write(newBufferedImage, "jpg", new java.io.File(dest));
 }

 

[jota]

Thank you very much for the help, I chose to make a small library with the code in this link

http://www.mkyong.com/java/convert-png-to-jpeg-image-file-in-java/

The adjoint if it helps someone. Thank you

 

[Daestrum]

Same place I got the code for the javascript file.

 

[almontgreen]

Thank you very much for the help, I chose to make a small library with the code in this link The adjoint if it helps someone. Thank you

Do you have an example for usage for pngTojpg library? I could really use!!! Thx! Also, does it require java8?

 

[jota]

It is not a library.
Rather it is a function to solve a small problem

Dim png4jpg As pngTojpg
png4jpg.convert("c:\photo.png","c:\photo.jpg" )

source code:
http://www.mkyong.com/java/convert-png-to-jpeg-image-file-in-java/


Regards