B4J Question B4J BitmapFactory.decodeByteArray ?

somed3v3loper · Mar 5, 2019

Hi all ,

Do we have an equivalent to this android method ? in Java or B4J

B4X:

public static Bitmap decodeByteArray (byte[] data,
               int offset,
               int length)

Erel · Mar 5, 2019

Yes. Use BitmapCreator.

somed3v3loper · Mar 5, 2019

Erel said:
Yes. Use BitmapCreator.

Sorry I was not clear

B4X:

fpdev.GetBmpImage(bmpdata,bmpsize);
                                    Bitmap bm1=BitmapFactory.decodeByteArray(bmpdata, 0, 74806);

I want to use same in java (library ) or B4J
I hope this makes it a bit clearer

Erel · Mar 5, 2019

Not clear to me. What are you trying to do?

somed3v3loper · Mar 5, 2019

Erel said:
Not clear to me. What are you trying to do?

It is a sample from fingerprint reader/scanner

The code is from its sample in android
I am trying to convert it to java (b4j)

Erel · Mar 5, 2019

What is the format of the image stored in the data array?

somed3v3loper · Mar 6, 2019

Erel said:
What is the format of the image stored in the data array?

I am not sure which format and so I am just trying to convert android sample to Java.

In android the library depends on a .jar and .so and it worked for me
But Windows version calls .dll methods(WINAPI) and the sample included was for C# and I couldn't find any support searching internet.
I used jna and managed to get part of library working

Erel · Mar 6, 2019

Save the data with File.WriteBytes and upload the file.

somed3v3loper · Mar 6, 2019

Erel said:
Save the data with File.WriteBytes and upload the file.

Forum did not allowed me to upload it with image extension so I zipped it

somed3v3loper · Mar 6, 2019

I am not sure I am allowed to share this or not but I can't find any information or support for this device
This code is decompiled from their dll

B4X:

 public int GetBmpImage(byte[] lpbmpdate, int[] lpsize)
  {
    lpsize[0] = 74806;
    memcpy(lpbmpdate, 0, this.bmpdata, 0, 74806);
    return 0;
  }

it might help you understand their way of retrieving Image

Erel · Mar 7, 2019

It is difficult to guess the format. Code to convert raw image data to bitmap:

B4X:

Sub ConvertToBitmap (data() As Byte, mWidth As Int, mHeight As Int) As B4XBitmap
   Dim WriteableImage As JavaObject
   WriteableImage.InitializeNewInstance("javafx.scene.image.WritableImage", Array(mWidth, mHeight))
   Dim writer As JavaObject = WriteableImage.RunMethod("getPixelWriter", Null)
   Dim PixelFormat As JavaObject
   PixelFormat.InitializeStatic("javafx.scene.image.PixelFormat")
   writer.RunMethod("setPixels", Array(0, 0, mWidth, mHeight, PixelFormat.RunMethod("getByteRgbInstance", Null), _
       data, 0, mWidth * 3))
   Return WriteableImage
End Sub

For this to work correctly you need to know the format.

https://docs.oracle.com/javase/8/javafx/api/javafx/scene/image/PixelFormat.html

somed3v3loper · Mar 7, 2019

Erel said:

It is difficult to guess the format. Code to convert raw image data to bitmap:

B4X:

Sub ConvertToBitmap (data() As Byte, mWidth As Int, mHeight As Int) As B4XBitmap
   Dim WriteableImage As JavaObject
   WriteableImage.InitializeNewInstance("javafx.scene.image.WritableImage", Array(mWidth, mHeight))
   Dim writer As JavaObject = WriteableImage.RunMethod("getPixelWriter", Null)
   Dim PixelFormat As JavaObject
   PixelFormat.InitializeStatic("javafx.scene.image.PixelFormat")
   writer.RunMethod("setPixels", Array(0, 0, mWidth, mHeight, PixelFormat.RunMethod("getByteRgbInstance", Null), _
       data, 0, mWidth * 3))
   Return WriteableImage
End Sub

For this to work correctly you need to know the format.

https://docs.oracle.com/javase/8/javafx/api/javafx/scene/image/PixelFormat.html

I think we are getting closer
The result does not seem to be the real fingerprint shown by the DrawImage method

B4J Question B4J BitmapFactory.decodeByteArray ?

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