From ba2a9cf8fd42a6b2162a93e4e49753075ff7fec1 Mon Sep 17 00:00:00 2001
From: Pierre-Yves Nicolas <6371790+pynicolas@users.noreply.github.com>
Date: Sun, 1 Jun 2025 17:40:43 +0200
Subject: [PATCH] Resize and compress bitmaps to decrease PDF size

---
 .../java/org/mydomain/myscan/PdfGeneration.kt | 27 ++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/app/src/main/java/org/mydomain/myscan/PdfGeneration.kt b/app/src/main/java/org/mydomain/myscan/PdfGeneration.kt
index 5500945..c894cd3 100644
--- a/app/src/main/java/org/mydomain/myscan/PdfGeneration.kt
+++ b/app/src/main/java/org/mydomain/myscan/PdfGeneration.kt
@@ -1,19 +1,27 @@
 package org.mydomain.myscan
 
 import android.graphics.Bitmap
+import android.graphics.BitmapFactory
 import android.graphics.pdf.PdfDocument
 import android.util.Log
+import androidx.core.graphics.scale
+import java.io.ByteArrayOutputStream
 import java.io.File
 import java.io.FileOutputStream
 import java.io.IOException
+import kotlin.math.max
 
 fun createPdfFromBitmaps(bitmaps: List<Bitmap>, outputFile: File): Boolean {
     val document = PdfDocument()
     try {
-        for ((index, bitmap) in bitmaps.withIndex()) {
+        for ((index, bitmap) in bitmaps.map { resizeImage(it) }.withIndex()) {
+            val jpegStream = ByteArrayOutputStream()
+            bitmap.compress(Bitmap.CompressFormat.JPEG, 72, jpegStream)
+            val compressedBytes = jpegStream.toByteArray()
+            val compressedBitmap = BitmapFactory.decodeByteArray(compressedBytes, 0, compressedBytes.size)
             val pageInfo = PdfDocument.PageInfo.Builder(bitmap.width, bitmap.height, index + 1).create()
             val page = document.startPage(pageInfo)
-            page.canvas.drawBitmap(bitmap, 0f, 0f, null)
+            page.canvas.drawBitmap(compressedBitmap, 0f, 0f, null)
             document.finishPage(page)
         }
         FileOutputStream(outputFile).use { outputStream ->
@@ -26,4 +34,17 @@ fun createPdfFromBitmaps(bitmaps: List<Bitmap>, outputFile: File): Boolean {
     } finally {
         document.close()
     }
-}
\ No newline at end of file
+}
+
+fun resizeImage(original: Bitmap): Bitmap {
+    val targetMax = 1500
+    if (max(original.width, original.height) < targetMax)
+        return original;
+    var targetWidth = targetMax
+    var targetHeight = original.height * targetWidth / original.width
+    if (original.width < original.height) {
+        targetHeight = targetMax
+        targetWidth = original.width * targetHeight / original.height
+    }
+    return original.scale(targetWidth, targetHeight)
+}