绑定的base64字符串图像到Windows手机8.1 SQLite数据库存储列表视图

问题描述

我已经转换图片为base64字符串，并在SQLite数据库保存为公共字符串ProfileImage {搞定;组; }
我想形象绑定到一个列表视图，我没有约束力的名称和地址。

XAML

 ＆LT; ListBox.ItemTemplate＆GT;
    ＆LT;＆DataTemplate的GT;
        ＆LT;网格和GT;
            ＆LT; Grid.ColumnDefinitions＆GT;
                ＆LT; ColumnDefinition WIDTH =自动/＆GT;
                ＆所述; ColumnDefinition宽度=*/＆GT;
            ＆LT; /Grid.ColumnDefinitions>            ＆LT;边框背景={ThemeResource ListViewItemPlaceholderBackgroundThemeBrush}保证金=0,10,0,0Grid.Column =0的Horizo​​ntalAlignment =左＆GT;
                ＆lt;图像X：NAME =proImg来源={结合ProfileImage}拉伸=UniformToFillHEIGHT =79WIDTH =79/＆GT;
            ＆LT; /边框＆GT;
            ＆LT; StackPanel的Grid.Column =1保证金=14.5,0,0,0＆GT;
                ＆LT; TextBlock的保证金=5,0,0,0Grid.Row =0X：NAME =NameTxtTextWrapping =自动换行文本={绑定名称}字号=32前景=白样式={ThemeResource ListViewItemTextBlockStyle}/＆GT;
                ＆LT; TextBlock的保证金=5,0,0,0Grid.Row =1×：NAME =PhoneTxtTextWrapping =包装前景色=白字号=20文本={绑定地址} /＆GT;
            ＆LT; / StackPanel的＆GT;
        ＆LT; /网格和GT;
    ＆LT; / DataTemplate中＆GT;
＆LT; /ListBox.ItemTemplate>
 

code我曾经为base64字符串转换为其他地方的图像

 公共静态的BitmapImage Base64StringToBitmap（字符串源）
{
    VAR IMS =新InMemoryRandomAccessStream（）;
    VAR字节= Convert.FromBase64String（源）;
    VAR dataWriter =新DataWriter（IMS）;
    dataWriter.WriteBytes（字节）;
    dataWriter.StoreAsync（）;
    ims.Seek（0）;
    VAR IMG =新的BitmapImage（）;
    img.SetSource（IMS）;
    返回IMG;
}
 

是否有可能像源类似的方式把它绑定

 来源={结合Base64StringToBitmap（ProfileImage）}
 

解决方案

您不能在XAML中调用方法绑定这样。你需要通过实施的IValueConverter，将其转换，然后绑定。您应该使用ValueConverter这样。

 公共类StringToBitmapConverter：的IValueConverter
{
    公共对象转换（对象的值，类型TARGETTYPE，对象参数，字符串语言）
    {
        如果（值！= NULL）
        {
        字符串源= value.ToString（）;
VAR IMS =新InMemoryRandomAccessStream（）;
    VAR字节= Convert.FromBase64String（源）;
    VAR dataWriter =新DataWriter（IMS）;
    dataWriter.WriteBytes（字节）;
    dataWriter.StoreAsync（）;
    ims.Seek（0）;
    VAR IMG =新的BitmapImage（）;
    img.SetSource（IMS）;
    返回IMG;
        }
返回null;
    }    公共对象ConvertBack（对象的值，类型TARGETTYPE，对象参数，字符串语言）
    {
        抛出新NotImplementedException（）;
    }
}
 

和在XAML中使用此转换器这样的

 的xmlns：MyConverter =使用：您转换器的命名空间路径＆LT; Page.Resources＆GT;
    ＆LT; MyConverter：StringToBitmapConverter X：键=ImageShow/＆GT;
＆LT; /Page.Resources>＆lt;图像X：NAME =proImg来源={结合ProfileImage，转换器= {StaticResource的ImageShow}}拉伸=填充HEIGHT =60WIDTH =60/＆GT;
 

I have converted Image to base64 string and saved it in SQLite database as public string ProfileImage { get; set; } I want to bind image into a List view as I did binding Name and Address.

XAML

<ListBox.ItemTemplate>
    <DataTemplate>
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>

            <Border Background="{ThemeResource ListViewItemPlaceholderBackgroundThemeBrush}" Margin="0,10,0,0" Grid.Column="0" HorizontalAlignment="Left">
                <Image  x:Name="proImg" Source="{Binding ProfileImage}"  Stretch="UniformToFill" Height="79" Width="79"/>
            </Border>
            <StackPanel Grid.Column="1" Margin="14.5,0,0,0">
                <TextBlock Margin="5,0,0,0" Grid.Row="0" x:Name="NameTxt" TextWrapping="Wrap" Text="{Binding Name}" FontSize="32" Foreground="White" Style="{ThemeResource ListViewItemTextBlockStyle}"/>
                <TextBlock Margin="5,0,0,0" Grid.Row="1" x:Name="PhoneTxt"  TextWrapping="Wrap" Foreground="White" FontSize="20" Text="{Binding Address}" />
            </StackPanel>
        </Grid>
    </DataTemplate>
</ListBox.ItemTemplate>

Code I used to convert base64 String to Image in other Places

public static BitmapImage Base64StringToBitmap(string source)
{
    var ims = new InMemoryRandomAccessStream();
    var bytes = Convert.FromBase64String(source);
    var dataWriter = new DataWriter(ims);
    dataWriter.WriteBytes(bytes);
    dataWriter.StoreAsync();
    ims.Seek(0);
    var img = new BitmapImage();
    img.SetSource(ims);
    return img;
}

Is it possible to bind image source similar way to this

Source="{Binding Base64StringToBitmap(ProfileImage)}"

解决方案

You cannot call method in Xaml Binding like this. You need to convert it by implementing IValueConverter and then bind it. You should use a ValueConverter like this.

public class StringToBitmapConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, string language)
    {
        if (value != null)
        {
        string source = value.ToString();
var ims = new InMemoryRandomAccessStream();
    var bytes = Convert.FromBase64String(source);
    var dataWriter = new DataWriter(ims);
    dataWriter.WriteBytes(bytes);
    dataWriter.StoreAsync();
    ims.Seek(0);
    var img = new BitmapImage();
    img.SetSource(ims);
    return img;
        }
return null;
    }

    public object ConvertBack(object value, Type targetType, object parameter, string language)
    {
        throw new NotImplementedException();
    }
}

and use this converter in Xaml like this

xmlns:MyConverter="using:Your converter namespace  path"

<Page.Resources>
    <MyConverter:StringToBitmapConverter x:Key="ImageShow"/>
</Page.Resources>

<Image  x:Name="proImg" Source="{Binding ProfileImage,Converter={StaticResource ImageShow}}"  Stretch="Fill" Height="60" Width="60"/>

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