From 9dc756b41ddf33512da1bc058d4b7455a27870f2 Mon Sep 17 00:00:00 2001
From: David PHAM-VAN <dev.nfet.net@gmail.com>
Date: Sat, 3 Apr 2021 13:00:53 -0300
Subject: [PATCH] Remove unnecessary _raster call in PdfPreview

---
 README.md                         | 18 ++++++++++--------
 demo/lib/app.dart                 | 10 +++++-----
 printing/CHANGELOG.md             |  1 +
 printing/lib/src/pdf_preview.dart | 12 +++++++++++-
 4 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/README.md b/README.md
index 73942512..edb5e014 100644
--- a/README.md
+++ b/README.md
@@ -1,15 +1,17 @@
 # Pdf for Dart and Flutter
 
-![Dart CI](https://github.com/DavBfr/dart_pdf/workflows/Dart%20CI/badge.svg)
-[![pub package](https://img.shields.io/pub/v/pdf.svg)](https://pub.dartlang.org/packages/pdf)
-[![pub package](https://img.shields.io/pub/v/printing.svg)](https://pub.dartlang.org/packages/printing)
-[![codecov](https://codecov.io/gh/DavBfr/dart_pdf/branch/master/graph/badge.svg)](https://codecov.io/gh/DavBfr/dart_pdf)
-
+![Dart CI](https://github.com/DavBfr/dart_pdf/workflows/Dart%20CI/badge.svg) [![pub package](https://img.shields.io/pub/v/pdf.svg)](https://pub.dartlang.org/packages/pdf) [![pub package](https://img.shields.io/pub/v/printing.svg)](https://pub.dartlang.org/packages/printing) [![codecov](https://codecov.io/gh/DavBfr/dart_pdf/branch/master/graph/badge.svg)](https://codecov.io/gh/DavBfr/dart_pdf)
 
 This set of plugins allows Flutter apps to generate and print pdf files to the device printer. This plugin works for iOS and Android.
 
-* dart pdf: <https://pub.dev/packages/pdf>
-* flutter printing: <https://pub.dev/packages/printing>
-* Live Demo: <https://davbfr.github.io/dart_pdf/>
+- dart pdf: <https://pub.dev/packages/pdf>
+- flutter printing: <https://pub.dev/packages/printing>
+- Live Demo: <https://davbfr.github.io/dart_pdf/>
 
 [![Buy Me A Coffee](https://bmc-cdn.nyc3.digitaloceanspaces.com/BMC-button-images/custom_images/orange_img.png "Buy Me A Coffee")](https://www.buymeacoffee.com/JORBmbw9h "Buy Me A Coffee")
+
+## Contributing
+
+Follow the instructions here: [contributing](CONTRIBUTING.md).
+
+A Makefile is available on the project root directory to download and prepare the dependencies.
diff --git a/demo/lib/app.dart b/demo/lib/app.dart
index a35c1de8..d5c6d7f2 100644
--- a/demo/lib/app.dart
+++ b/demo/lib/app.dart
@@ -66,10 +66,11 @@ class MyAppState extends State<MyApp> with SingleTickerProviderStateMixin {
       initialIndex: _tab,
     );
     _tabController!.addListener(() {
-      setState(() {
-        _tab = _tabController!.index;
-        print('set state 1');
-      });
+      if (_tab != _tabController!.index) {
+        setState(() {
+          _tab = _tabController!.index;
+        });
+      }
       if (examples[_tab].needsData && !_hasData && !_pending) {
         _pending = true;
         askName(context).then((value) {
@@ -86,7 +87,6 @@ class MyAppState extends State<MyApp> with SingleTickerProviderStateMixin {
 
     setState(() {
       printingInfo = info;
-      print('set state 2');
     });
   }
 
diff --git a/printing/CHANGELOG.md b/printing/CHANGELOG.md
index b457191e..5457e7bd 100644
--- a/printing/CHANGELOG.md
+++ b/printing/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## 5.0.5
 
 - Fix PdfPreview timer dispose [wwl901215]
+- Remove unnecessary _raster call in PdfPreview [yaymalaga]
 
 ## 5.0.4
 
diff --git a/printing/lib/src/pdf_preview.dart b/printing/lib/src/pdf_preview.dart
index 024d2b97..de3797d4 100644
--- a/printing/lib/src/pdf_preview.dart
+++ b/printing/lib/src/pdf_preview.dart
@@ -128,6 +128,8 @@ class _PdfPreviewState extends State<PdfPreview> {
 
   Timer? previewUpdate;
 
+  var _rastering = false;
+
   static const defaultPageFormats = <String, PdfPageFormat>{
     'A4': PdfPageFormat.a4,
     'Letter': PdfPageFormat.letter,
@@ -138,6 +140,11 @@ class _PdfPreviewState extends State<PdfPreview> {
       : pageFormat;
 
   Future<void> _raster() async {
+    if (_rastering) {
+      return;
+    }
+    _rastering = true;
+
     Uint8List _doc;
 
     if (!info.canRaster) {
@@ -154,6 +161,7 @@ class _PdfPreviewState extends State<PdfPreview> {
         return true;
       }());
 
+      _rastering = false;
       return;
     }
 
@@ -177,6 +185,7 @@ class _PdfPreviewState extends State<PdfPreview> {
         informationCollector: collector,
       ));
       error = exception;
+      _rastering = false;
       return;
     }
 
@@ -193,6 +202,7 @@ class _PdfPreviewState extends State<PdfPreview> {
       pages: widget.pages,
     )) {
       if (!mounted) {
+        _rastering = false;
         return;
       }
       setState(() {
@@ -213,6 +223,7 @@ class _PdfPreviewState extends State<PdfPreview> {
     }
 
     pages.removeRange(pageNum, pages.length);
+    _rastering = false;
   }
 
   @override
@@ -256,7 +267,6 @@ class _PdfPreviewState extends State<PdfPreview> {
     if (oldWidget.build != widget.build) {
       preview = null;
       updatePosition = null;
-      pages.clear();
       _raster();
     }
     super.didUpdateWidget(oldWidget);