PdfDocument page canvas is broken. Keep trying but nothing works

Need help making a PDF file with PdfDocument

The page canvas is empty or Blank.

I have tried many ways but nothing writes the page canvas.

I found this link for similar problem but it does not apply to my case as I am not executing the PdfDocument code in the Create function. It is already after the layout is displayed on screen.

I am using the following code:

class pdfSelection(
var pg: Int,
var bm: Bitmap
)

////// I have a PdfRenderer where I get the bitmap from the render page and save it in a List
selChk.setOnCheckedChangeListener { buttonView, isChecked ->
        val element: pdfSelection
        if (isChecked) {
            ////The pageW/pageH are the values from the render page not the ImageView
            element = pdfSelection(pdfnum, pdfview.drawable!!.toBitmap(pageW, pageH ,Bitmap.Config.ARGB_8888)) 
            savelist.add(element)
        } else {
            savelist.removeIf { x: pdfSelection -> x.pg == pdfnum }
        }
    }

    /// PdfDocument is called in a Button Click event so the Layout is completely active
    savebtn.setOnClickListener {
        if (savelist.isNotEmpty()) {

            // create document
            val document = PdfDocument()

            // create a page description
            val pageInfo = PdfDocument.PageInfo.Builder(pageW, pageH, 1).create()

            savelist.forEach { item ->

                // start 1st page
                val docpage = document.startPage(pageInfo)

                // draw something on the page
                binding.imageView.setImageBitmap(item.bm) //I use the new gradle directive viewBinding = true
                binding.imageView.draw(docpage.getCanvas())
     //// THIS CODE DOES NOT WORK. THE DOCUMENT PAGE GETS NULL BITMAP. EXECUTES WITHOUT ERROR 

                // finish 1st page
                document.finishPage(docpage)
            }


            val file: File = File(cacheDir,"Selected_${textview.text}")
            val fos: FileOutputStream
            try {
                val fileNameWithPath = file
                fos = FileOutputStream(fileNameWithPath, false)
                // write the document content
                document.writeTo(fos)
            } catch (e: FileNotFoundException) {
                e.printStackTrace()
            } catch (e: IOException) {
                e.printStackTrace()
            }

            // close the document
            document.close()
        }
    

Document is created with empty pages.

I verified the bitmaps in the list are added successfully and I inspected the [item.bm] variable in the line of code to setImageBitmap in the imageView and it is there. Also inspect the binding.imageView and has the drawable set to the bitmap successfully. The imageView.draw does not write to the page canvas.

For testing I Draw on a new Canvas not related to the page and it works correctly.

Notice the docpage debug values:

Finally I found a solution.

Instead of:

binding.imageView.setImageBitmap(item.bm) //I use the new gradle directive viewBinding = true
binding.imageView.draw(docpage.getCanvas())

Do:

scaledbmp = Bitmap.createScaledBitmap(item.bm, pageW, pageH, false)
var canvas: Canvas = docpage.canvas
canvas.drawBitmap(scaledbmp, 0F, 0F, paint) 
//Notice the parameters are a top/left location for the Bitmap not the width/heigh. 
//I was using the width/heigh values and that was the problem.

Still do not know why imageView.draw did not work, but I guess is also because it was drawing outside of the Canvas.

I think found another solution maybe better:

This is the code (next page perspective):

val psfound = pdfsizeselector.compareSizesPX(item.pW, item.pH)
val pageInfo = PDPage(psfound)

document.addPage(pageInfo)

////I compress the image because the resolution of the Bitmap is to high unnecessarily producing a huge page 
val byteOut = ByteArrayOutputStream()
                        
item.bm.compress(Bitmap.CompressFormat.JPEG, 75, byteOut)

////Do not use Canvas, the contentStream is already a Canvas
val contentStream = PDPageContentStream(document, pageInfo)

                        
val ximage = JPEGFactory.createFromStream(document, ByteArrayInputStream(byteOut.toByteArray()))

//// Scale Image to the Page size (Letter, Legal, Tabloid, etc.) and Orientation (Landscape/Portrait)
val xH = ximage.height.toFloat()
val xW = ximage.width.toFloat()
val scaleW = psfound.width/xW
val scaleH = psfound.height/xH
val scale = if (scaleW > scaleH) scaleH else scaleW

//// Draw the Image directly in the contentStream (this is the Canvas), 
//// set the Image location in the Page at coord. 0,0, to the calculated scale above
contentStream.drawImage(ximage, 0F, 0F, xW*scale, xH*scale)

contentStream.close()