B4J Question [Solved] B4XCanvas DrawBitmap causes loss of quality

[CaptKronos]

I have only just noticed that the following code causes the bitmap's quality to be reduced. It's almost like it has been blurred. Can someone point me to the solution?
Thanks.

    Dim bc As BitmapCreator
    Dim bmp As B4XBitmap= xui.LoadBitmap(File.DirAssets, "test.jpg")
    bc.Initialize(bmp.Width, bmp.Height)
    bc.CopyPixelsFromBitmap(bmp)
    ImageView1.SetBitmap(bc.Bitmap) 'looks good here

    BasePanel=xui.CreatePanel("")
    BasePanel.SetLayoutAnimated(0,0,0,bmp.Width,bmp.Height)
    Dim cnv As B4XCanvas
    cnv.Initialize(BasePanel)
    cnv.DrawBitmap(bc.Bitmap, cnv.TargetRect)
    ImageView1.SetBitmap(cnv.CreateBitmap) 'looks bad here'

 

[Erel]

Can you upload a small project with this image and the drawing code?

 

[CaptKronos]

Can you upload a small project with this image and the drawing code?

I have attached the test project. The actual drawing code is part of a big project, so I can't upload it. But if the attached doesn't help, then I can cobble something together to include a drawing section.

 

[CaptKronos]

Just realised that the version of the project I uploaded had a rect with 0.5 added to it. (I did this because I read somewhere that making sure coordinates are not integers prevents anti-aliasing which I thought might have been the cause of what I'm seeing.) The attached is a version without the 0.5, however, both projects create the same result.

 

[peacemaker]

Tried bigger size of the panel:

BasePanel.SetLayoutAnimated(0,0,0,bmp.Width*5, bmp.Height*5)

and no this blurring...

No idea why

 

[teddybear]

There is no different between B4XCanvas DrawTBitmap and BitmapCreator as long as the imageview dimesion is the same as the bitmaps'.

 

[CaptKronos]

Teddybear: I'm not sure if you are saying that you can't see a difference, but look carefully at your ImageView2 and you should be able to see that it is slightly blurred compared to your ImageView1.

 

[Erel]

I don't see any difference between the two:

Maybe it is related to the screen DPI settings.

Comparing the inner fields of the bitmaps might reveal something.

In my case the pixelScale of both bitmaps is 1.

 

[peacemaker]

At my test it's the same strange problem.

Spoiler: Test1 - problem

Private Sub Button1_Click
    Dim bc As BitmapCreator
    Dim bmp As B4XBitmap= xui.LoadBitmap(File.DirAssets, "test.jpg")
    ImageView1.Width=bmp.Width
    ImageView1.Height=bmp.Height
    bc.Initialize(bmp.Width, bmp.Height)
    bc.CopyPixelsFromBitmap(bmp)
    ImageView1.SetBitmap(bc.Bitmap)
'    xui.MsgboxAsync("looks good at this point...", "")
'    Wait For Msgbox_Result (Result As Int)
    ImageView2.Width=bmp.Width
    ImageView2.Height=bmp.Height
    BasePanel=xui.CreatePanel("")
 
    BasePanel.SetLayoutAnimated(0,0,0,bmp.Width,bmp.Height)   'AS IS
 
    Dim cnv As B4XCanvas
    cnv.Initialize(BasePanel)
    cnv.DrawBitmap(bc.Bitmap, cnv.TargetRect)
    ImageView2.SetBitmap(cnv.CreateBitmap)
End Sub

Spoiler: Test2 - no problem

Private Sub Button1_Click
    Dim bc As BitmapCreator
    Dim bmp As B4XBitmap= xui.LoadBitmap(File.DirAssets, "test.jpg")
    ImageView1.Width=bmp.Width
    ImageView1.Height=bmp.Height
    bc.Initialize(bmp.Width, bmp.Height)
    bc.CopyPixelsFromBitmap(bmp)
    ImageView1.SetBitmap(bc.Bitmap)
'    xui.MsgboxAsync("looks good at this point...", "")
'    Wait For Msgbox_Result (Result As Int)
    ImageView2.Width=bmp.Width
    ImageView2.Height=bmp.Height
    BasePanel=xui.CreatePanel("")
    
    BasePanel.SetLayoutAnimated(0,0,0,bmp.Width * 5,bmp.Height * 5)   'bigger
    
    Dim cnv As B4XCanvas
    cnv.Initialize(BasePanel)
    cnv.DrawBitmap(bc.Bitmap, cnv.TargetRect)
    ImageView2.SetBitmap(cnv.CreateBitmap)
End Sub

 

[Erel]

Check the image pixelScale with the debugger.

 

[peacemaker]

Same, pixelScale of the "bmp" is 1.0

 

[Erel]

Compare it to the bitmap created with canvas.CreateBitmap.

 

[peacemaker]

Same = 1.0

 

[CaptKronos]

I have just checked as well and both bitmaps have a pixel scale of 1.0.

 

[Erel]

Is the output of this, other than 1.0?

Dim fx As JFX
Log(fx.PrimaryScreen.As(JavaObject).RunMethod("getOutputScaleX", Null))

 

[peacemaker]

other than 1.0?

Yes, 1.25

BasePanel.SetLayoutAnimated(0,0,0,bmp.Width * Scale,bmp.Height * Scale)    'solving

but, maybe it should be added into the libs ?

 

[CaptKronos]

Looks like you have found the issue, I get 2.0.

 

[peacemaker]

JDK-8211294: [windows] TextArea content is blurry with 125% scaling · Issue #225 · javafxports/openjdk-jfx

Test Code: import javafx.application.Application; import javafx.scene.Scene; import javafx.scene.control.Label; import javafx.scene.control.TextArea; import javafx.scene.control.TextField; import j...

github.com

Linux and MacOs are also impacted: https://github.com/helge17/tuxguitar/issues/96

 

[Erel]

Yes, 1.25

BasePanel.SetLayoutAnimated(0,0,0,bmp.Width * Scale,bmp.Height * Scale)    'solving

but, maybe it should be added into the libs ?

This is indeed a good solution.

 

[CaptKronos]

I'm not sure how to use the scaled BasePanel to solve this issue. Can you give an example? Thanks.