B4J Question Canvas/Image "PutPixel"?

Cableguy

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• Nov 23, 2016

• #2

You could use DrawLine and draw a 1pixel long line

 

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wonder

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• Nov 23, 2016

• #3

Hi Paulo!

I'm recreating a frame (1280x720) pixel-by-pixel... I rather not call DrawLine() 921600 times, as it probably uses some variation of a Bresenham's line drawing algorithm...

So as you see, I really need an ultra-fast lightweight PutPixel function...


EDIT: I found a DrawPoint() on Android @ https://developer.android.com/reference/android/graphics/Canvas.html#drawPoint(float, float, android.graphics.Paint)
...but how about B4J?

 

Last edited: Nov 23, 2016

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klaus

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• Nov 23, 2016

• #4

Have you tried DrawPoint?

 

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wonder

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• Nov 23, 2016

• #5

klaus said:

Have you tried DrawPoint?

Click to expand...

Is it B4A only or B4J as well? I have no access to the IDE's at the moment.

 

Last edited: Nov 23, 2016

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klaus

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• Nov 23, 2016

• #6

It seems to be B4A only.

 

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wonder

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• Nov 23, 2016

• #7

OK, I think I found it: http://docs.oracle.com/javase/7/docs/api/java/awt/image/BufferedImage.html#setRGB(int, int, int)
BufferedImage.SetRGB()

So, questions:
- Is this BufferedImage class the same as "Image" in B4J?
- If so, can I access the SetRGB method through reflection?

 

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MitchBu

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• Nov 23, 2016

• #8

DrawPoint works just fine.
https://www.b4x.com/android/help/drawing.html#canvas_drawpoint

 

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wonder

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• Nov 23, 2016

• #9

MitchBu said:

DrawPoint works just fine.
https://www.b4x.com/android/help/drawing.html#canvas_drawpoint

Click to expand...

In B4A, yes indeed, but now I need it in B4J...

 

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DonManfred

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• Nov 23, 2016

• #10

wonder said:

In B4A, yes indeed, but now I need it in B4J...

Click to expand...

Then you probably should have created the thread in the B4J forum? ;-)

 

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wonder

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• Nov 23, 2016

• #11

@DonManfred, yes indeed... My mistake. ;p

So... is the right solution "BufferedImage.SetRGB()" through reflection?

 

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MitchBu

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• Nov 23, 2016

• #12

On occasions in some languages that did not have DrawPoint equivalent, I have used DrawLine with a one pixel long line.

I would believe you can package that in a DrawPoint sub wrapper as to keep the same code.

But indeed, it can be worthwhile to open a new thread in B4J.

 

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alwaysbusy

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• Nov 23, 2016

• #13

You can use getArgb/setArgb.

See this post: https://www.b4x.com/android/forum/t...o-canvas-without-smoothing.42620/#post-257959

Extract from this post:

B4X:

Sub Resample(Input As Image,S As Int) As Image

   Dim W As Double = Input.Width
   Dim H As Double= Input.Height
   Dim SW As Int = Input.Width * S
   Dim SH As Int = Input.Height * S
   
   Dim InputJO,OutputJO,ReaderJO,WriterJO As JavaObject
   OutputJO.InitializeNewInstance("javafx.scene.image.WritableImage",Array As Object(SW,SH))
   InputJO = Input
   
   ReaderJO = InputJO.RunMethod("getPixelReader",Null)
   WriterJO = OutputJO.RunMethod("getPixelWriter",Null)
   
   Dim ARGB As Int
   
   For y = 0 To H-1
     For x = 0 To W -1
       ARGB = ReaderJO.RunMethod("getArgb",Array As Object(x,y))
       For dy = 0 To S - 1
         For dx = 0 To S -1
           WriterJO.RunMethod("setArgb",Array As Object(x * S + dx, y * S + dy,ARGB))
         Next
       Next
     Next
   Next
   
   Return OutputJO
   
End Sub

 

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wonder

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• Nov 23, 2016

• #14

Thank you so much!! I will try it out!

 

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