15-puzzle: what changed

Revision 2 to 3. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		## 15-puzzle
2	2
3	3		![](/wiki-images/2/20/Puzzle15.png)
4	4
5	5		The 15-puzzle is a sliding puzzle that consists of a frame of numbered square tiles in random order with one tile missing. The object of the puzzle is to place the tiles in order by making sliding moves that use the empty space.
6	6
7	7		## Create code
8	8
9	9		- Create a new blank GUI application with the form [[TForm\|Form1]]
10	10		- Change caption Form1 to 15Puzzle'.
11	11		- Add New [[Unit]] [[15-puzzle\|unitGameBoard.pas]]
12	12		- Create the OnCreate event handler for the form, by clicking on your form, use the Object Inspector, the tab events, select the OnCreate event and click the button \[...\] or double click the button in the form.
13	13		- Add following code:
14	14
15	15		``` pascal
16	16		procedure TForm1.FormCreate(Sender: TObject);
17	17		var
18	18		i : Integer;
19	19		aButton: TButton;
20	20		point:TPoint;
21	21		begin
22	22		Randomize;
23	23		Puzzle15:= TGameBoard.Create;
24	24		i := 1;
25	25		while i < 16 do
26	26		begin //create 15 Buttons
27	27		aButton:=TButton.Create(Self); //create Button, Owner is Form1, where the button is released later
28	28		aButton.Parent:=Self; //determine where it is to be displayed
29	29		aButton.Caption:=IntToStr(i); //Captions of the buttons
30	30		aButton.Width:=aButton.Height; //Width should correspond to the height of the buttons
31	31		point := Puzzle15.ButtonPlace(aButton.Caption);
32	32		aButton.Left:= point.x* aButton.Width; //Distance from left
33	33		aButton.Top := point.y* aButton.Height;
34	34
35	35		aButton.OnClick:=@aButtonClick; //the event handler for the button -> will be created yet
36	36		inc(i);
37	37		end;
38	38		Self.Height:=aButton.Height*6; //Height of the form should correspond to the height of the buttons
39	39		Self.Width:=aButton.Width*6; //Width of the form to match the width of all buttons
40	40		end;
41	41		```
42	42
43	43		- Create in the Object Inspector the event handler for the event FormDestroy, by clicking on the button \[...\].
44	44		- Add the following code to the handler:
45	45
46	46		``` pascal
47	47		procedure TForm1.FormDestroy(Sender: TObject);
48	48		begin
49	49		FreeAndNil(Puzzle15);
50	50		end;
51	51		```
52	52
53	53		- Now you must create the event handler for the button clicks.
54	54		- In the source editor, entering your [[Class\|class]] TForm1 in the section [[Private\|private]].
55	55		- Add [[Procedure\|procedure]] `procedure aButtonClick(Sender: TObject);` and then press the keys `Ctrl`+`Shift`+`c` (the code completion becomes active and creates the `procedure TForm1.aButtonClick(Sender: TObject);`.
56	56		- Paste following code:
57	57
58	58		``` pascal
59	59		procedure TForm1.aButtonClick(Sender: TObject); //the event handler for the button
60	60		var
61	61		i:integer;
62	62		point : TPoint;
63	63		begin
64	64		if (Sender is TButton) and //called the event handler of a button out?
65	65		TryStrToInt(TButton(Sender).Caption, i) //then try to convert the label in a integer
66	66		then
67	67		begin
68	68		if Puzzle15.CanMove(TButton(Sender).Caption) then
69	69		begin
70	70		point := Puzzle15.Change(TButton(Sender).Caption);
71	71		TButton(Sender).Left:= point.x* TButton(Sender).Width; //Distance from left
72	72		TButton(Sender).Top := point.y* TButton(Sender).Height;
73	73		end;
74	74		end;
75	75		end;
76	76		```
77	77
78	78		## Source code
79	79
80	80		### unit1.pas
81	81
82	82		``` pascal
83	83		unit Unit1;
84	84
85	85		{$mode objfpc}{$H+}
86	86
87	87		interface
88	88
89	89		uses
90	90		Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls,
91	91		unitGameBoard;
92	92
93	93		type
94	94
95	95		{ TForm1 }
96	96
97	97		TForm1 = class(TForm)
98	98		procedure FormCreate(Sender: TObject);
99	99		procedure FormDestroy(Sender: TObject);
100	100		private
101	101		{ private declarations }
102	102		Puzzle15:TGameBoard;
103	103		procedure aButtonClick(Sender: TObject);
104	104
105	105		public
106	106		{ public declarations }
107	107		end;
108	108
109	109		var
110	110		Form1: TForm1;
111	111
112	112		implementation
113	113
114	114		{$R *.lfm}
115	115
116	116		{ TForm1 }
117	117
118	118		procedure TForm1.FormCreate(Sender: TObject);
119	119		var
120	120		i : Integer;
121	121		aButton: TButton;
122	122		point:TPoint;
123	123		begin
124	124		Randomize;
125	125		Puzzle15:= TGameBoard.Create;
126	126		i := 1;
127	127		while i < 16 do
128	128		begin //create 15 Buttons
129	129		aButton:=TButton.Create(Self); //create Button, Owner is Form1, where the button is released later
130	130		aButton.Parent:=Self; //determine where it is to be displayed
131	131		aButton.Caption:=IntToStr(i); //Captions of the buttons
132	132		aButton.Width:=aButton.Height; //Width should correspond to the height of the buttons
133	133		point := Puzzle15.ButtonPlace(aButton.Caption);
134	134		aButton.Left:= point.x* aButton.Width; //Distance from left
135	135		aButton.Top := point.y* aButton.Height;
136	136		aButton.OnClick:=@aButtonClick; //the event handler for the button -> will be created yet
137	137		inc(i);
138	138		end;
139	139		Self.Height:=aButton.Height*6; //Height of the form should correspond to the height of the buttons
140	140		Self.Width:=aButton.Width*6; //Width of the form to match the width of all buttons
141	141		end;
142	142
143	143		procedure TForm1.FormDestroy(Sender: TObject);
144	144		begin
145	145		FreeAndNil(Puzzle15);
146	146		end;
147	147
148	148		procedure TForm1.aButtonClick(Sender: TObject); //the event handler for the button
149	149		var
150	150		i:integer;
151	151		point : TPoint;
152	152		begin
153	153		if (Sender is TButton) and //called the event handler of a button out?
154	154		TryStrToInt(TButton(Sender).Caption, i) //then try to convert the label in a integer
155	155		then
156	156		begin
157	157		if Puzzle15.CanMove(TButton(Sender).Caption) then
158	158		begin
159	159		point := Puzzle15.Change(TButton(Sender).Caption);
160	160		TButton(Sender).Left:= point.x* TButton(Sender).Width; //Distance from left
161	161		TButton(Sender).Top := point.y* TButton(Sender).Height;
162	162		end;
163	163		end;
164	164		end;
165	165
166	166		end.
167	167		```
168	168
169	169		### Unit1.lfm
170	170
171		-	~~``` pascal~~
	171	+	``` lfm
172	172		object Form1: TForm1
173	173		Left = 362
174	174		Height = 184
175	175		Top = 162
176	176		Width = 432
177	177		Caption = '15Puzzle'
178	178		OnCreate = FormCreate
179	179		OnDestroy = FormDestroy
180	180		LCLVersion = '1.6.0.4'
181	181		end
182	182		```
183	183
184	184		### unitGameBoard.pas
185	185
186	186		``` pascal
187	187		unit unitGameBoard;
188	188
189	189		{$mode objfpc}{$H+}
190	190
191	191		interface
192	192
193	193		uses
194	194		Classes, SysUtils;
195	195
196	196		const
197	197		GB_MAX_BUTTONS = 15;
198	198		GB_MAX_X = 4;
199	199		GB_MAX_Y = 4;
200	200		GB_EMPTY_PLACE ='-';
201	201		type
202	202
203	203		{ TGameBoard }
204	204
205	205		TGameBoard = class
206	206		private
207	207		GameArray:array[1..GB_MAX_X, 1..GB_MAX_Y] of string;
208	208		function ValidPoint(a_point:TPoint):boolean;
209	209		public
210	210		constructor Create;
211	211		function ButtonPlace(a_name:string):TPoint;
212	212		function CanMove(a_name:string):Boolean;
213	213		function Change(a_name: string): TPoint;
214	214		procedure RandomArray;
215	215		destructor Destroy; override;
216	216		end;
217	217		implementation
218	218
219	219		{ TGameBoard }
220	220
221	221		function TGameBoard.ValidPoint(a_point: TPoint): boolean;
222	222		begin
223	223		result := true;
224	224		if a_point.y > GB_MAX_Y then result := false;
225	225		if a_point.x > GB_MAX_X then result := false;
226	226		if a_point.y < 1 then result := false;
227	227		if a_point.x < 1 then result := false;
228	228		end;
229	229
230	230		constructor TGameBoard.Create;
231	231		var
232	232		i, x, y : integer;
233	233		begin
234	234		i := 1;
235	235		for y := 1 to GB_MAX_Y do
236	236		for x := 1 to GB_MAX_X do
237	237		begin
238	238		if i < GB_MAX_BUTTONS+1
239	239		then GameArray[x,y] := IntToStr(i)
240	240		else GameArray[x,y] := GB_EMPTY_PLACE;
241	241		inc(i);
242	242		end;
243	243		RandomArray;
244	244		end;
245	245
246	246		function TGameBoard.ButtonPlace(a_name: string): TPoint;
247	247		var
248	248		x,y:integer;
249	249		begin
250	250		result.x := 0;
251	251		result.y := 0;
252	252		for y := 1 to GB_MAX_Y do
253	253		for x := 1 to GB_MAX_X do
254	254		if GameArray[x,y] = a_name then
255	255		begin
256	256		result.x := x;
257	257		result.y := y;
258	258		end;
259	259		end;
260	260
261	261		function TGameBoard.CanMove(a_name: string): Boolean;
262	262		var
263	263		empty, point:TPoint;
264	264		begin
265	265		result := false;
266	266		empty := ButtonPlace( GB_EMPTY_PLACE );
267	267		point := ButtonPlace(a_name);
268	268		if (abs(empty.x-point.x)=1) and (empty.y=point.y) then result := true;
269	269		if (abs(empty.y-point.y)=1) and (empty.x=point.x) then result := true;
270	270		end;
271	271
272	272		function TGameBoard.Change(a_name: string): TPoint;
273	273		var
274	274		empty, point:TPoint;
275	275		begin
276	276		empty := ButtonPlace( GB_EMPTY_PLACE );
277	277		result := empty;
278	278		point := ButtonPlace(a_name);
279	279		GameArray[point.x, point.y] := '-';
280	280		GameArray[empty.x, empty.y] := a_name;
281	281		end;
282	282
283	283		procedure TGameBoard.RandomArray;
284	284		var
285	285		j,i:integer;
286	286		name:string;
287	287		point,point2:TPoint;
288	288		begin
289	289		for i := 0 to 1000 do
290	290		begin
291	291		j := random(4);
292	292		point := ButtonPlace( GB_EMPTY_PLACE );
293	293		point2 := point;
294	294		case j of
295	295		0: point2.x := point.x-1;
296	296		1: point2.x := point.x+1;
297	297		2: point2.y := point.y-1;
298	298		3: point2.y := point.y+1;
299	299		end;
300	300		if ValidPoint( point2 ) then
301	301		begin
302	302		name := GameArray[point2.x, point2.y];
303	303		GameArray[point.x, point.y] := name;
304	304		GameArray[point2.x, point2.y] := GB_EMPTY_PLACE;
305	305		end;
306	306		end;
307	307		end;
308	308
309	309		destructor TGameBoard.Destroy;
310	310		begin
311	311		inherited Destroy;
312	312		end;
313	313
314	314		end.
315	315		```
316	316
317	317		## See also
318	318
319	319		- [[TButton]]
320	320
321	321		---
322	322		From the Free Pascal wiki, page "15-puzzle", as it stood on 2022-08-06 after a change by Kai Burghardt, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).

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