Fix raster quality on Android

@@ -4,6 +4,7 @@
 
 - Fix dispose state issue
 - Add onPageFormatChanged event
+- Fix raster quality on Android
 
 ## 5.7.1
 

@@ -248,7 +248,8 @@ class PrintingPlugin extends PrintingPlatform {
 
     for (final i in _pages) {
       final page = await promiseToFuture<PdfJsPage>(d.getPage(i + 1));
-      final viewport = page.getViewport(Settings()..scale = 1.5);
+      final viewport =
+          page.getViewport(Settings()..scale = dpi / PdfPageFormat.inch);
 
       canvas.height = viewport.height.toInt();
       canvas.width = viewport.width.toInt();

@@ -174,12 +174,12 @@ class _PdfPreviewState extends State<PdfPreview> {
   PdfPageFormat computeActualPageFormat() {
     var format = previewData.pageFormat;
     final pages = previewWidget.currentState?.pages ?? const [];
-    final dpi = previewWidget.currentState?.dpi ?? 72;
+    final dpi = previewWidget.currentState?.dpi ?? PdfPageFormat.inch;
 
     if (!widget.canChangePageFormat && pages.isNotEmpty) {
       format = PdfPageFormat(
-        pages.first.page!.width * 72 / dpi,
-        pages.first.page!.height * 72 / dpi,
+        pages.first.page!.width * PdfPageFormat.inch / dpi,
+        pages.first.page!.height * PdfPageFormat.inch / dpi,
         marginAll: 5 * PdfPageFormat.mm,
       );
     }

@@ -15,6 +15,7 @@
  */
 
 import 'dart:async';
+import 'dart:io';
 import 'dart:math';
 import 'dart:typed_data';
 
@@ -62,10 +63,12 @@ mixin PdfPreviewRaster on State<PdfPreviewCustom> {
     _previewUpdate?.cancel();
     _previewUpdate = Timer(_updateTime, () {
       final mq = MediaQuery.of(context);
+      final maxDPR = !kIsWeb && Platform.isAndroid ? 2.0 : 1.0;
+      final dpr = max(maxDPR, mq.devicePixelRatio);
       dpi = (min(mq.size.width - 16, widget.maxPageWidth ?? double.infinity)) *
-          mq.devicePixelRatio /
+          dpr /
           pageFormat.width *
-          72;
+          PdfPageFormat.inch;
 
       _raster();
     });