保存VirtualStringTree节点数据 [英] Saving VirtualStringTree Node Data

问题描述

我正在尝试将项目从D6移至D-XE3.使用VirtualStringTree版本5.10在OnSaveNode和OnLoadEvents中保存和加载树数据时，我得到了垃圾.我可能无法正确处理Unicode，但是我可能还有其他一些无知之处:

I am trying to move a project from D6 to D-XE3. I am getting garbage when saving and loading the tree data in the OnSaveNode and OnLoadEvents using version 5.10 of VirtualStringTree. I'm probably not handling Unicode correctly, but there could be some other ignorance on my part:

procedure TfMain.vstGridSaveNode(Sender: TBaseVirtualTree; Node: PVirtualNode;
  Stream: TStream);
var
  Data: PStkData;
begin
  Data := Sender.GetNodeData(Node);

  //  Owned: boolean;
  Stream.Write(Data.Owned, SizeOf(boolean) );

  //  Symbol: string;
  Stream.Write(PChar(Data.Symbol)^, Length(Data.Symbol) * SizeOf(Char));

  //  AvgTarget: currency;
  //Stream.Write(Data.AvgTarget, SizeOf(currency));

  //  PE: double;
  Stream.Write(Data.PE, SizeOf(double));
end;

procedure TfMain.vstGridLoadNode(Sender: TBaseVirtualTree; Node: PVirtualNode;
  Stream: TStream);
var
  Data: PStkData;
begin
  Data := Sender.GetNodeData(Node);

  //Owned: boolean;
  Stream.Read(Data.Owned, SizeOf(boolean));

  //Symbol: string;
  Stream.Read(PChar(Data.Symbol)^, Length(Data.Symbol) * SizeOf(Char));

  //AvgTarget: currency;
  Stream.Read(Data.AvgTarget, SizeOf(currency));

  //PE: double;
  Stream.Read(Data.PE, SizeOf(double));
end;

感谢您的帮助.

推荐答案

在写入字符数据时，需要确保以知道要读取 多少的方式进行写入.再次在加载时.您当前正在写 just 字符数据，因此您不知道以后需要再读多少.相反，您假设Symbol已经是正确的长度，而我已经指出，这可能是一个无效的假设.

When you write the character data, you need to make sure you write it in such a way that you know how much to read again while loading. You're currently writing just the character data, so you have no idea how much you need to read again later. You're instead assuming that Symbol will already be the right length, which, now that I've pointed it out, is something you probably realize is an invalid assumption.

写入字符串时，请先写入其长度，以便在加载时可以读取它:

When you write the string, first write its length so it will be available to read while loading:

var
  SymbolLen: Integer;

SymbolLen := Length(Data.Symbol);
Stream.Write(SymbolLen, SizeOf(SymbolLen));
Stream.Write(PChar(Data.Symbol)^, Length(Data.Symbol) * SizeOf(Data.Symbol[1]));

然后您可以阅读它:

Stream.Read(SymbolLen, SizeOf(SymbolLen));
SetLength(Data.Symbol, SymbolLen);
Stream.Read(PChar(Data.Symbol)^, SymbolLen * SizeOf(Data.Symbol[1]));

这篇关于保存VirtualStringTree节点数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！