kmpdfkit_demo/lib/widgets/viewer/pdfbota/pdfthumbnail/cpdf_thumbnail_page.dart

import 'dart:typed_data';

import 'package:compdfkit_flutter/core/document/cpdf_document.dart';
import 'package:flutter/material.dart';

///  Copyright © 2014-2023 PDF Technologies, Inc. All Rights Reserved.
///
///  THIS SOURCE CODE AND ANY ACCOMPANYING DOCUMENTATION ARE PROTECTED BY INTERNATIONAL COPYRIGHT LAW
///  AND MAY NOT BE RESOLD OR REDISTRIBUTED. USAGE IS BOUND TO THE ComPDFKit LICENSE AGREEMENT.
///  UNAUTHORIZED REPRODUCTION OR DISTRIBUTION IS SUBJECT TO CIVIL AND CRIMINAL PENALTIES.
///  This notice may not be removed from this file.

class CPDFThumbnailPage extends StatefulWidget {
  final CPDFDocument document;
  final int currentPageIndex;

  const CPDFThumbnailPage(
      {Key? key, required this.document, required this.currentPageIndex})
      : super(key: key);

  @override
  State<CPDFThumbnailPage> createState() => _CPDFThumbnailPageState();
}

class _CPDFThumbnailPageState extends State<CPDFThumbnailPage> with AutomaticKeepAliveClientMixin{
  final ScrollController _scrollController = ScrollController();

  final GlobalKey globalKey = GlobalKey();

  @override
  void initState() {
    super.initState();
  }

  @override
  void dispose() {
    super.dispose();
    _scrollController.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
        initialData: 0,
        future: widget.document.getPageCount(),
        builder: (context, snapshot) {
          final size = MediaQuery.of(context).size;
          final widgetWidth = size.width - 16;
          return OrientationBuilder(builder: (context, orientation) {
            int crossAxisCount =
            orientation == Orientation.portrait ? 3 : 6;
            return GridView.builder(
                padding:  const EdgeInsets.symmetric(horizontal: 8),
                key: globalKey,
                controller: _scrollController,
                gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                    crossAxisCount: crossAxisCount,
                    mainAxisSpacing: 8,
                    crossAxisSpacing: 8,
                    childAspectRatio: 0.62),
                itemCount: snapshot.data ?? 0,
                itemBuilder: (context, index) => Padding(
                  padding: const EdgeInsets.only(top: 8),
                  child: _thumbnailItem(
                      index, ((widgetWidth - 22) / crossAxisCount)),
                ));
          });
        });
  }

  Widget _thumbnailItem(int index, double itemWidth) {
    double aspectRatio = 0.30;
    double itemHeight = itemWidth + (itemWidth * aspectRatio);
    bool selected = widget.currentPageIndex == index;
    return FutureBuilder(
        future: widget.document.getPageSize(index),
        builder: (context, snap) {
          if (snap.connectionState == ConnectionState.done && snap.hasData) {
            var size = snap.data!;
            var imageWidth = itemWidth;
            var imageHeight = (imageWidth / size[0]) * size[1];
            if (imageHeight > itemHeight) {
              imageHeight = itemHeight;
              imageWidth = (imageHeight / size[1]) * size[0];
            }
            return Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                InkWell(
                  child: FutureBuilder(
                      future: widget.document.renderPageAtIndex(
                          index, imageWidth.toInt(), imageHeight.toInt()),
                      builder: (context, snapshot) {
                        if (snapshot.connectionState == ConnectionState.done &&
                            !snapshot.hasError) {
                          Uint8List? imageData = snapshot.data;
                          if (imageData != null) {
                            return _imageItem(
                                Image.memory(
                                  imageData,
                                ),
                                selected,
                                imageWidth,
                                imageHeight);
                          } else {
                            return const Padding(padding: EdgeInsets.zero);
                          }
                        } else {
                          return const Padding(padding: EdgeInsets.zero);
                        }
                      }),
                  onTap: () {
                    Navigator.pop(context, index);
                  },
                ),
                _pageIndicator(index, selected)
              ],
            );
          } else {
            return const Padding(padding: EdgeInsets.zero);
          }
        });
  }

  Widget _imageItem(
      Widget child, bool selected, double imageWidth, double imageHeight) {
    return Container(
      width: imageWidth,
      height: imageHeight,
      decoration: BoxDecoration(
          border: Border.all(
              color: selected
                  ? Theme.of(context).colorScheme.primaryContainer
                  : const Color(0xFFDDE9FF),
              width: 2),
          borderRadius: const BorderRadius.all(Radius.circular(2))),
      child: child,
    );
  }

  Widget _pageIndicator(int index, bool selected) {
    return Container(
        margin: const EdgeInsets.only(top: 8),
        decoration: BoxDecoration(
            color: selected
                ? Theme.of(context).colorScheme.primaryContainer
                : Colors.transparent,
            borderRadius:
            const BorderRadius.all(Radius.circular(2))),
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 2),
          child: Text(
            (index + 1).toString(),
            style: TextStyle(
              fontSize: 12,
                color: selected ? Colors.white : Colors.black),
          ),
        ));
  }

  // Function to scroll to a specific item in the GridView
  void scrollToItem(int index) {
  }

  @override
  bool get wantKeepAlive => true;
}