downkyi/DownKyi/ViewModels/Toolbox/ViewExtractMediaViewModel.cs

using DownKyi.Core.FFmpeg;
using DownKyi.Events;
using DownKyi.Utils;
using Prism.Commands;
using Prism.Events;
using System;
using System.Threading.Tasks;
using System.Windows.Controls;

namespace DownKyi.ViewModels.Toolbox
{
    public class ViewExtractMediaViewModel : BaseViewModel
    {
        public const string Tag = "PageToolboxExtractMedia";

        // 是否正在执行任务
        private bool isExtracting = false;

        #region 页面属性申明

        private string videoPath;
        public string VideoPath
        {
            get { return videoPath; }
            set { SetProperty(ref videoPath, value); }
        }

        private string status;
        public string Status
        {
            get { return status; }
            set { SetProperty(ref status, value); }
        }

        #endregion

        public ViewExtractMediaViewModel(IEventAggregator eventAggregator) : base(eventAggregator)
        {
            #region 属性初始化

            VideoPath = string.Empty;

            #endregion
        }

        #region 命令申明

        // 选择视频事件
        private DelegateCommand selectVideoCommand;
        public DelegateCommand SelectVideoCommand => selectVideoCommand ?? (selectVideoCommand = new DelegateCommand(ExecuteSelectVideoCommand));

        /// <summary>
        /// 选择视频事件
        /// </summary>
        private void ExecuteSelectVideoCommand()
        {
            if (isExtracting)
            {
                eventAggregator.GetEvent<MessageEvent>().Publish(DictionaryResource.GetString("TipWaitTaskFinished"));
                return;
            }

            VideoPath = DialogUtils.SelectVideoFile();
        }

        // 提取音频事件
        private DelegateCommand extractAudioCommand;
        public DelegateCommand ExtractAudioCommand => extractAudioCommand ?? (extractAudioCommand = new DelegateCommand(ExecuteExtractAudioCommand));

        /// <summary>
        /// 提取音频事件
        /// </summary>
        private async void ExecuteExtractAudioCommand()
        {
            if (isExtracting)
            {
                eventAggregator.GetEvent<MessageEvent>().Publish(DictionaryResource.GetString("TipWaitTaskFinished"));
                return;
            }

            if (VideoPath == "")
            {
                eventAggregator.GetEvent<MessageEvent>().Publish(DictionaryResource.GetString("TipNoSeletedVideo"));
                return;
            }

            // 音频文件名
            string audioFileName = VideoPath.Remove(VideoPath.Length - 4, 4) + ".aac";
            Status = string.Empty;

            await Task.Run(() =>
            {
                // 执行提取音频程序
                isExtracting = true;
                FFmpegHelper.ExtractAudio(VideoPath, audioFileName, new Action<string>((output) =>
                {
                    Status += output + "\n";
                }));
                isExtracting = false;
            });
        }

        // 提取视频事件
        private DelegateCommand extractVideoCommand;
        public DelegateCommand ExtractVideoCommand => extractVideoCommand ?? (extractVideoCommand = new DelegateCommand(ExecuteExtractVideoCommand));

        /// <summary>
        /// 提取视频事件
        /// </summary>
        private async void ExecuteExtractVideoCommand()
        {
            if (isExtracting)
            {
                eventAggregator.GetEvent<MessageEvent>().Publish(DictionaryResource.GetString("TipWaitTaskFinished"));
                return;
            }

            if (VideoPath == "")
            {
                eventAggregator.GetEvent<MessageEvent>().Publish(DictionaryResource.GetString("TipNoSeletedVideo"));
                return;
            }

            // 视频文件名
            string videoFileName = VideoPath.Remove(VideoPath.Length - 4, 4) + "_onlyVideo.mp4";
            Status = string.Empty;

            await Task.Run(() =>
            {
                // 执行提取视频程序
                isExtracting = true;
                FFmpegHelper.ExtractVideo(VideoPath, videoFileName, new Action<string>((output) =>
                {
                    Status += output + "\n";
                }));
                isExtracting = false;
            });
        }

        // Status改变事件
        private DelegateCommand<object> statusCommand;
        public DelegateCommand<object> StatusCommand => statusCommand ?? (statusCommand = new DelegateCommand<object>(ExecuteStatusCommand));

        /// <summary>
        /// Status改变事件
        /// </summary>
        /// <param name="parameter"></param>
        private void ExecuteStatusCommand(object parameter)
        {
            if (!(parameter is TextBox output)) { return; }

            // TextBox滚动到底部
            output.ScrollToEnd();
        }

        #endregion

    }
}