Курсовая работа - Б-деревья во внешней памяти
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249
250 SelectByKey(LastAdded);
251 SetNodeBoldState(TreeView.Selected, false);
252
253 SelectByKey(key);
254 SetNodeBoldState(TreeView.Selected, true);
255 if TreeView.Selected.GetPrev <> nil then
256 begin
257 if TreeView.Selected.GetPrev.Text[1] = '>' then
258 prev := strtoint(copy(TreeView.Selected.GetPrev.Text, 2,
length(TreeView.Selected.GetPrev.Text)))
259 else prev := strtoint(TreeView.Selected.GetPrev.Text);
260 end;
261
262 // удаляем
263 bt.Remove(bt.RootPos, key);
264
265 // выводим дерево и переходим туда, где должен был бы быть ключ
266 ChangeTrees();
267 PrintTree();
268 SelectByKey(prev);
269 NumOfKeys := NumOfKeys - 1;
270 end;
271 end;
272
273 procedure TfMain.btnOpenClick(Sender: TObject);
274 begin
275 OpenDialog.InitialDir := ExtractFilePath(paramstr(0));
276 if OpenDialog.Execute then
277 begin
278 if bt = nil then
279 begin
280 bt := TBTree.Create('BTree.bts');
281 btnDraw.Enabled := true;
282 btnAdd.Enabled := true;
283 btnDelete.Enabled := true;
284 btnSave.Enabled := true;
285 btnSearch.Enabled := true;
286 end
287 else
288 if OpenDialog.FileName = bt.FileName then exit;
289 eOpenFile.Text := OpenDialog.FileName;
290 bt.Open(OpenDialog.FileName);
291 PrintTree();
292 ChangeTrees();
293 PrintTree();
294 end;
295 end;
296
297 procedure TfMain.btnSaveClick(Sender: TObject);
298 begin
299 SaveDialog.InitialDir := ExtractFilePath(paramstr(0));
300 if SaveDialog.Execute then
301 begin
302 eOpenFile.Text := SaveDialog.FileName;
303 if SaveDialog.FileName = bt.FileName then
304 bt.UpdateFile()
305 else
306 bt.SaveAs(SaveDialog.FileName);
307 end;
308 end;
309
310 procedure TfMain.btnSearchClick(Sender: TObject);
311 var key: integer;
34
312 begin
313 Randomize();
314 fInput.Caption := 'Найти элемент';
315 fInput.lbQ.Caption := 'Введите ключ для поиска:';
316 fInput.eInput.Value := Random(200) + 1;
317
318 if fInput.ShowModal = mrOk then
319 begin
320 key := fInput.eInput.Value;
321 if bt.Search(bt.RootPos, key) then
322 SelectByKey(key)
323 else MessageDlg('Элемент не найден', mtInformation, [mbOK], 0);
324 end;
325 end;
326
327 procedure TfMain.btnDrawClick(Sender: TObject);
328 begin
329 if NumOfKeys < 250 then
330 begin
331 fTreePicture.Show();
332 fTreePicture.Draw(NumOfKeys);
333 end
334 else
335 MessageDlg('Количество элементов слишком велико.',mtError, [mbOK], 0);
336 end;
337
338 procedure TfMain.FormClose(Sender: TObject; var Action: TCloseAction);
339 begin
340 if bt <> nil then
341 begin
342 bt.UpdateFile();
343 bt.Free();
344 end;
345 end;
346
347 procedure TfMain.tvBTree1Enter(Sender: TObject);
348 begin
349 if tvBTree1.Left < tvBTree2.Left then
350 tvBTree2.SetFocus()
351 else
352 tvBTree1.SetFocus();
353 end;
354
355 end.
35
Приложение В. Модуль класса формы для отображения дерева в
традиционной форме.
1 unit uImageBTree;
2
3 interface
4
5 uses
6 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
7 Dialogs, StdCtrls, ExtCtrls;
8
9 type
10 TfTreePicture = class(TForm)
11 iBTree: TImage;
12 sbVert: TScrollBar;
13 sbHoriz: TScrollBar;
14 procedure BTreeDraw(var Pos: integer; X, Y, Level, H: integer);
15 procedure Draw(NumOfKeys: integer);
16 procedure FormCreate(Sender: TObject);
17 procedure sbVertChange(Sender: TObject);
18 procedure FormMouseWheel(Sender: TObject; Shift: TShiftState;
19 WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
20 private
21 { Private declarations }
22 public
23 { Public declarations }
24 end;
25
26 const rh = 20;
27 rw = 30;
28
29 var
30 fTreePicture: TfTreePicture;
31 bmp: TBitmap;
32
33 implementation
34
35 uses uMain, BTree, Math;
36
37 {$R *.dfm}
38
39 function Pow(a, b: integer): integer;
40 begin
41 Result := Round(Power(a, b));
42 end;
43
44 //BTreeDraw(bt.RootPos, 30, 10, 1, 0, 3);
45
46 procedure TfTreePicture.BTreeDraw(var Pos: integer; X, Y, Level, H: integer);
47 var g, j, i: integer;
48 newx, newy: integer;
49 curx, cury: integer;
50 Node: BTreeNode;
51 begin
52 Node := bt.DiskRead(pos);
53 if not Node.leaf then
54 begin
55 for i := 1 to node.n do
36
56 begin
57 curx := X + i * rw;
58 cury := Y;
59 bmp.Canvas.Rectangle(curx, cury, curx + rw + 1, cury + rh);
60 bmp.Canvas.TextOut(curx + 5, cury + 3, IntToStr(Node.key[i]));
61
62
63 j := i - (node.n + 1) div 2 - 1; // центрирование
64
65 // лесенкой
66 newx := X + pow(t - 1, H - Level - 1) * (rw + 2) * j;
67 newy := y + 150 + i * (rh + 2);
68 // в линию
69 // newx := X + pow(2*t-1, H - Level - 2) * (rw+2) * j;
70 // newy := y + 150;
71
72 bmp.Canvas.MoveTo(curx, cury + rh);
73 bmp.Canvas.LineTo(newx + rw, newy);
74
75 BTreeDraw(Node.c[i], newx, newy, Level + 1, h);
76 end;
77 newx := X + pow(t-1, H - Level - 1) * (rw + 2) * ((node.n+1) div 2);
78 newy := y + 150 + (node.n + 1) * (rh + 2);
79 // newx := X + pow(2*t-1, H - Level - 1) * (rw+2) * (node.n div 2+1);
80
81 bmp.Canvas.MoveTo(curx + rw, cury + rh);
82 bmp.Canvas.LineTo(newx + rw, newy);
83
84 BTreeDraw(Node.c[Node.n + 1], newx, newy, level + 1, h);
85 end
86 else
87 for i := 1 to Node.n do
88 begin
89 curx := x + i * rw;
90 cury := y;
91 bmp.Canvas.Rectangle(curx, cury, curx + rw + 1, cury + rh);
92 bmp.Canvas.TextOut(curx + 5, cury + 3, IntToStr(Node.key[i]));
93 end;
94 end;
95
96 procedure TfTreePicture.Draw(NumOfKeys: integer);
97 var h: integer;
98 begin
99 H := Floor(ln(NumOfKeys)/ln(t)) + 1;
100 bmp.Width := pow(t-1, H+1)*(rw+2);
101
102 if bmp.Width < Width then bmp.Width := Width + 100;
103
104 bmp.Height := H*200;
105
106 if bmp.Height < Height then bmp.Height := Height+ 100;
107
108 bmp.Canvas.FillRect(bmp.Canvas.ClipRect);
109 BTreeDraw(bt.RootPos, bmp.Width div 2, 10, 0, H);
110 iBTree.Picture.Bitmap.Assign(bmp);
111 sbHoriz.Max := bmp.Width - 1 - iBTree.Width;
112 sbVert.Max := bmp.Height - 1 - iBTree.Height;
113
114 sbHoriz.Position := sbHoriz.Max div 2+60;
115 end;
116
117 procedure TfTreePicture.FormCreate(Sender: TObject);
118 begin
119 bmp := TBitmap.Create;
37
120 end;
121
122 procedure TfTreePicture.sbVertChange(Sender: TObject);
123 var
124 RectDest, RectSource: TRect;
125 begin
126 RectDest := Rect(0, 0, iBTree.Width, iBTree.Height);
127 RectSource := Rect(sbHoriz.Position, sbVert.Position, sbHoriz.Position +
iBTree.Width, sbVert.Position + iBTree.Height);
128 iBTree.Canvas.CopyRect(RectDest, bmp.Canvas, RectSource);
129 end;
130
131 procedure TfTreePicture.FormMouseWheel(Sender: TObject; Shift: TShiftState;
132 WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
133 begin
134 if WheelDelta > 0 then
135 sbHoriz.Position := sbHoriz.Position + 10
136 else sbHoriz.Position := sbHoriz.Position - 10;
137 end;
138
139 end.
38