似乎每当调用使用
Synchronize()
完成后,该过程将停止,直到我摇动鼠标或与键盘交互。
一种理论是,将同步调用限制在最后一个调用以更新整个UI将使此工作正常,尽管我不完全了解这是否会有帮助,或者为什么会有帮助——这可能与不频繁切换CPU所做的事情有关吗?考虑到我必须迭代不同的查询结果来填充TListViews,似乎不可能只有一个Synchronize。我希望继续使用如图所示的列表视图,而不更改显示数据行的方法。
unit ExampleCode;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ComCtrls, ExtCtrls, ADODB;
type
TRefreshThread = class(TThread)
public
Procedure Execute; override;
procedure UpdateLabel1;
procedure UpdateLabel2;
procedure UpdateLabel3;
procedure UpdateLabel4;
procedure populateListView1;
procedure populatelistView2;
procedure populatelistview3;
procedure OnThreadTerminate(Sender : Tobject);
constructor Create;
end;
TForm1 = class(TForm)
Label1: TLabel;
Label2: TLabel;
Label3: TLabel;
Label4: TLabel;
ListView1: TListView;
ListView2: TListView;
ListView3: TListView;
Timer1: TTimer;
procedure FormCreate(Sender: TObject);
procedure Timer1Timer(Sender: TObject);
end;
var
Form1: TForm1;
RefreshThread : TRefreshThread;
Query : TADOQuery;
someDatabase : TADOConnection;
implementation
{$R *.dfm}
procedure TRefreshThread.UpdateLabel1;
begin
Form1.Label1.Caption := Query.FieldByName('Field1').AsString;
end;
procedure TRefreshThread.UpdateLabel2;
begin
Form1.Label1.Caption := Query.FieldByName('Field2').AsString;
end;
constructor TRefreshThread.Create;
begin
FreeOnTerminate := true;
OnTerminate := OnThreadTerminate;
inherited Create(false);
end;
procedure TRefreshThread.OnThreadTerminate(sender : TObject);
begin
sender := nil;
end;
procedure TRefreshThread.UpdateLabel3;
begin
Form1.Label1.Caption := Query.FieldByName('Field3').AsString;
end;
procedure TRefreshThread.UpdateLabel4;
begin
Form1.Label1.Caption := Query.FieldByName('Field4').AsString;
end;
procedure TRefreshThread.populateListView1;
var
Item1 : TListItem;
begin
Item1 := Form1.ListView2.Items.Add;
Item1.Caption := Query.FieldByName('Field5').AsString;
Item1.SubItems.Add(Query.FieldByName('Field6').AsString);
Item1.SubItems.Add(Query.FieldByName('Field7').AsString);
end;
procedure TRefreshThread.populateListView2;
var
Item1 : TListItem;
begin
Item1 := Form1.ListView2.Items.Add;
Item1.Caption := Query.FieldByName('Field8').AsString;
Item1.SubItems.Add(Query.FieldByName('Field9').AsString);
Item1.SubItems.Add(Query.FieldByName('Field10').AsString);
end;
procedure TRefreshThread.populateListView3;
var
Item1 : TListItem;
begin
Item1 := Form1.ListView2.Items.Add;
Item1.Caption := Query.FieldByName('Field11').AsString;
Item1.SubItems.Add(Query.FieldByName('Field12').AsString);
Item1.SubItems.Add(Query.FieldByName('Field13').AsString);
end;
procedure TRefreshThread.Execute;
begin
Query.Create(nil);
Query.Connection := SomeDatabase;
Query.SQL.Add('select FIELD1 from TABLE');
Query.Active := true;
Synchronize(UpdateLabel1);
Query.Close;
Query.SQL.Clear;
Query.SQL.Add('select FIELD2 from TABLE');
Query.Active := true;
Synchronize(UpdateLabel2);
Query.Close;
Query.SQL.Clear;
Query.SQL.Add('select FIELD3 from TABLE');
Query.Active := true;
Synchronize(UpdateLabel3);
Query.Close;
Query.SQL.Clear;
Query.SQL.Add('select FIELD4 from TABLE');
Query.Active := true;
Synchronize(UpdateLabel4);
Query.Close;
Query.SQL.Clear;
Query.SQL.Add('select FIELD5, Field6, Field7 from TABLE');
Query.Active := true;
try
while not Query.Eof do
begin
Synchronize(PopulateListView1);
Query.Next;
end;
finally
Query.Close;
Query.SQL.Clear;
end;
Query.SQL.Add('select FIELD8, Field9, Field10 from TABLE');
Query.Active := true;
try
while not Query.Eof do
begin
Synchronize(PopulateListView2);
Query.Next;
end;
finally
Query.Close;
Query.SQL.Clear;
end;
Query.SQL.Add('select FIELD11, Field12, Field13 from TABLE');
Query.Active := true;
try
while not Query.Eof do
begin
Synchronize(PopulateListView3);
Query.Next;
end;
finally
Query.Close;
Query.SQL.Clear;
end;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
Timer1.Create(nil);
Timer1.Interval := 1000;
RefreshThread := TRefreshThread.Create();
end;
procedure TForm1.Timer1Timer(Sender: TObject);
begin
if RefreshThread = nil then
RefreshThread := RefreshThread.Create();
end;
end.
