如何使用实时绑定将blob字段绑定到TImage控件？

Question

我正在使用Delphi XE2编写VCL win32应用程序.Delphi XE2支持实时绑定.我将示例Biolife.xml加载到TClientDataSet实例中.

我能够将TEdit控件绑定到数据集的字符串字段:Species Name:

object BindLinkEdit11: TBindLink
  Category = 'Links'
  SourceMemberName = 'Species Name'
  ControlComponent = Edit1
  SourceComponent = BindScopeDB1
  ParseExpressions = <>
  FormatExpressions = <
    item
      ControlExpression = 'Text'
      SourceExpression = 'DisplayText'
    end>
  ClearExpressions = <>
end

然后我尝试将Graphic字段绑定到TImage控件:

object BindLinkImage11: TBindLink
  Category = 'Links'
  SourceMemberName = 'Graphic'
  ControlComponent = Image1
  SourceComponent = BindScopeDB1
  ParseExpressions = <>
  FormatExpressions = <
    item
      ControlExpression = 'Picture'
      SourceExpression = 'Value'
    end>
  ClearExpressions = <>
end

显然,它不起作用.这可能吗？

Answer 1

看看BindLinkVCLProject演示项目.还显示了图像的绑定,所以我猜你需要这样做(Selfin SourceExpression代表一个blob字段):

object BindLinkImageHandler: TBindLink
  Category = 'Links'
  SourceMemberName = 'Graphic'
  ControlComponent = Image1
  SourceComponent = BindScopeDB1
  ParseExpressions = <
    item
      ControlExpression = 'Picture'
      SourceExpression = 'Self'
    end>
  FormatExpressions = <
    item
      ControlExpression = 'Picture'
      SourceExpression = 'Self'
    end>
  ClearExpressions = <
    item
      ControlExpression = 'Picture'
      SourceExpression = 'nil'
    end>
end