能够处理任何数据库字段的Panel

核心提示：unit DBPanel;interfaceuses windows, messages, sysutils, classes,graphics, controls, forms, dialogs, extctrls, dbctrls, stdctrls, db;type TDBPanel = class(tpa

unit DBPanel;

interface

uses
  windows, messages, sysutils, classes,graphics, controls, forms, dialogs,
  extctrls, dbctrls, stdctrls, db;

type
  TDBPanel = class(tpanel)
  PRivate
　  { private declarations }
　  fleft: integer;
　  ftop: integer;
　  maxtextlen: integer;
　  maxlabellen: integer;
　  fscrollbox: tscrollbox;　　　  {滚动控件}
　  flineheight: integer;
　  fclick: tnotifyevent;
　  editors: array of tdbcombobox;
file://- >具体进行编辑所用的数据控件数组，动态生成
　  labels: array of tlabel;
file://- >各字段的标题，动态生成
　  okbutton: tbutton;
file://- >最后增加的确定按钮，用于实现提交动作。
　  { 数据源}
　  fdatasource: tdatasource;
　  fcolumns: integer;
file://- >输入表格的列数
　  protected
　  { protected declarations }
　  procedure freeeditors;
file://- >释放数据输入控件的内存
　  public
　  procedure createeditors(ds: tdatasource; colcount: integer);
file://- >创建各字段的数据输入控件
　  constructor create(aowner:
　  tcomponent); override;
　  destructor destroy; override;
　  procedure akeypress(sender:
　  tobject; var key: char);
　  procedure akeydown(sender:
　  tobject; var key: Word; shift:
　  tshiftstate);
　  procedure clearhits(itemindex: integer);
　  procedure addhits(itemindex:
　  integer; hits: array of string);
　  function editor(index: integer):
　  tdbcombobox;
　  { public declarations }
　  published
　  property leftlimit: integer read
　  fleft write fleft default 10;
　  property toplimit: integer read
　  ftop write ftop default 10;
　  property editorlen: integer read
　  maxtextlen write maxtextlen;
　  property labellen: integer read
　  maxlabellen write maxlabellen　  default 100;
　  property lineheight: integer read
　  flineheight write flineheight　  default 15;
　  property onokclick: tnotifyevent
　  read fclick write fclick;
　  property datasource: tdatasource
　  read fdatasource write　  fdatasource;
 file://数据源
　  property columns: integer read
　  fcolumns write fcolumns;//- >表列数
　  { published declarations }
  end;
procedure Register;

implementation

{ 为第i字段增加提示信息的方法}
procedure tdbpanel.addhits(itemindex:
integer; hits: array of string);
var
  m,n,i: integer;
begin
  n := length(editors);
  m := length(hits);
  if itemindex< n then begin
　  for i:=0 to m-1 do editors[itemindex].items.add(hits[i]);
  end;
end;

procedure tdbpanel.akeydown
(sender: tobject; var key: word;
  shift: tshiftstate);
begin
  if (sender is tdbcombobox) then begin
　  case key of
　　  vk_next: (sender as tdbcombobox)
　　  .datasource.dataset.next;
　　  vk_prior: (sender as tdbcombobox)
　　  .datasource.dataset.prior;
　  end;
  end;
end;

procedure tdbpanel.akeypress(sender: tobject; var key: char);
begin
  if (sender is tdbcombobox) then begin
if key=#13 then (owner as tform).perform(wm_nextdlgctl, 0, 0);
  end;
end;

procedure tdbpanel.clearhits(itemindex: integer);
var
  n: integer;
begin
  n := length(editors);
  if itemindex< n then editors[itemindex].items.clear;
end;

constructor tdbpanel.create(aowner: tcomponent);
begin
  inherited create(aowner);
  fleft :=10;
  ftop := 10;
  maxtextlen := 100;
  maxlabellen := 100;
  flineheight := 15;
end;

{ 创建各字段的数据输入控件的方法}
procedure tdbpanel.createeditors(ds: tdatasource; colcount: integer);
var
  i, n, rowcount: integer;
  textheight: integer;
begin
  if datasource.dataset.active then begin
　  n := datasource.dataset.fieldcount;
　  { 计算最大的标题长度及显示长度}
　  datasource.dataset.first;
　  { 计算高度}
　  textheight := canvas.textheight(datasource
　  .dataset.fields[0].displaylabel) + flineheight; file://10;
　  { 计算行列数}
　  rowcount := n div columns;
　  if n mod columns <> 0 then inc(rowcount);
　  { 分配内存}
　  freeeditors;
　  setlength(editors, n);
　  setlength(labels, n);
　  { 创建滚动盒}
　  fscrollbox := tscrollbox.create(owner);
　  fscrollbox.parent := self;
　  fscrollbox.align := alclient;
　  { 创建编辑}
　  for i:=0 to n-1 do begin
　　  { 创建标题}
　　  labels[i] := tlabel.create(owner);
　　  labels[i].parent := fscrollbox; file://self;
　　  labels[i].caption := datasource.dataset.fields[i].displaylabel;
　　  labels[i].left := fleft + (maxlabellen +
　　  maxtextlen + 10) * (i div rowcount);
　　  labels[i].width := maxlabellen;
　　  labels[i].top := ftop + (i mod rowcount) * textheight + 5;
　　  { 创建编辑对象}
　　  editors[i] := tdbcombobox.create(owner);
　　  editors[i].parent := fscrollbox; file://self;
　　  editors[i].left := labels[i].left + labels[i].width;
　　  editors[i].width := maxtextlen;
　　  editors[i].top := ftop + (i mod rowcount) * textheight;
　　  editors[i].datasource := datasource;
　　  editors[i].datafield := datasource.dataset.fields[i].fieldname;
　　  editors[i].onkeypress := akeypress;
　　  editors[i].onkeydown := akeydown;
　  end;
　  { 创建ok按钮}
　  okbutton := tbutton.create(owner);
　  okbutton.parent := fscrollbox;
　  okbutton.left := editors[n-1].left;
　  okbutton.top := editors[n-1].top + textheight;
　  okbutton.caption := '确定';
　  okbutton.onclick := fclick;
  end;
end;

destructor tdbpanel.destroy;
begin
  freeeditors;
  inherited destroy;
end;

function tdbpanel.editor(index: integer): tdbcombobox;
begin
  if index< length(editors) then result := editors[index]
  else result := nil;
end;

procedure tdbpanel.freeeditors;
var
  i,n: integer;
begin
  { 内存的释放是要有顺序的！必须以创建的相反的顺序进行！
  尤其是当组件之间有父子关系时}
  if okbutton<>nil then okbutton.free;
  if editors<>nil then begin
　  n := length(editors);
　  for i:=0 to n-1 do editors[i].free;
　  editors := nil;
　  n := length(labels);
　  for i:=0 to n-1 do labels[i].free;
　  labels := nil;
  end;
  if fscrollbox<>nil then begin
　  fscrollbox.free;
　  fscrollbox := nil;
  end;
end;

procedure Register;
begin
  RegisterComponents('OK', [TDBPanel]);
end;

end.