WPF-clear-inkcanvas-with-StrokeCollection

1.网上的资料

如果是需要用brush进行erase那么用System.Windows.Controls.InkCanvasEditingMode.EraseByStroke
如果是希望Clear的话，用Strokes.Clear即可
Strokes是指和InkCanvas binding的对象

来源：WPF中Canvas画布怎么逐笔清除和清空画布？

本人理解错误，使用Strokes类去清除，结果自然是失败的。

2.解决办法

应该使用实例化后的inkcanvas之中的StrokeCollection.Clear()方法

接下来是代码，注意我使用了prism的mvvm模式

Views的xaml文件

<UserControl x:Class="TensorFlowApp.Views.Handwriting"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:TensorFlowApp.Views"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">
    <Grid Background="Gray" >
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="250"></ColumnDefinition>
            <ColumnDefinition>

            </ColumnDefinition>
        </Grid.ColumnDefinitions>
        <StackPanel Grid.Column="0">
            <Button
    Style="{StaticResource MaterialDesignRaisedButton}"
    Width="100"
    Margin="0,50,0,150"
    Command="{Binding OpenClearCanvasCommand}"
                CommandParameter="{Binding ElementName=inkCanvas1,Path=Strokes}"
    ToolTip="Resource name: MaterialDesignRaisedButton">
                清除字迹
            </Button>
            <Button
    Style="{StaticResource MaterialDesignRaisedButton}"
    Width="100"
    ToolTip="Resource name: MaterialDesignRaisedButton" Click="Button_Click">
                识别数字
            </Button>
        </StackPanel>
        <InkCanvas Grid.Column="1" DefaultDrawingAttributes="{Binding inkDrawingAttributes}"
            x:Name="inkCanvas1" Height="224" Width="224"></InkCanvas>
    </Grid>
</UserControl>

ViewsModels的cs文件

using Prism.Commands;
using Prism.Mvvm;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Ink;
using System.Windows.Media;

namespace TensorFlowApp.ViewModels
{
    public class HandwritingViewModel : BindableBase
    {
        //清除画布
        public DelegateCommand<StrokeCollection> OpenClearCanvasCommand { get; set ; }

        public DrawingAttributes inkDrawingAttributes { get; set; }
        public Stroke stroke { get; set; }

        public HandwritingViewModel()
        {
            this.inkDrawingAttributes = new DrawingAttributes();
            this.inkDrawingAttributes.Width = 20;
            this.inkDrawingAttributes.Height = 20;
            this.OpenClearCanvasCommand = new DelegateCommand<StrokeCollection>(ClearCanvasCommand);

        }

        public void ClearCanvasCommand(StrokeCollection obj)
        {
            obj.Clear();
        }

    }
}

3.效果