BGRABitmap tutorial 1/ru: what changed

Revision 1 to 2. Removed lines have a minus sign; added lines have a plus sign.

Old	New		Line
1	1		Этот первый урок покажет Вам как использовать [[BGRABitmap]] библиотеку.
2	2
3	3		Вы можете скачать библиотеку по ссылке [GitHub](https://github.com/bgrabitmap).
4	4
5	5		### Создаём новый проект
6	6
7	7		Создайте оконное приложение с помощью меню Project \> New project.
8	8
9	9		The main form unit should look like this (the 2015 Linux version cannot process the below files, for working samples see the test-apps ("test 4 lcl") in the BGRA source tar-ball) :
10	10
11	11		``` pascal
12	12		unit UMain;
13	13
14	14		{$mode objfpc}{$H+}
15	15
16	16		interface
17	17
18	18		uses
19	19		Classes, SysUtils, FileUtil, LResources, Forms, Controls, Graphics, Dialogs;
20	20
21	21		type
22	22
23	23		{ TForm1 }
24	24
25	25		TForm1 = class(TForm)
26	26		private
27	27		{ private declarations }
28	28		public
29	29		{ public declarations }
30	30		end;
31	31
32	32		var
33	33		Form1: TForm1;
34	34
35	35		implementation
36	36
37	37		initialization
38	38		{$I UMain.lrs}
39	39
40	40		end.
41	41		```
42	42
43	43		If you do not find it, use Ctrl-F12 to show file list.
44	44
45	45		Save your project next to BGRABitmap library with menu File \> Save all (not necessarily in the same folder).
46	46
47	47		### Add reference to BGRABitmap
48	48
49	49		The first time you use BGRABitmap, open bgrabitmappack.lpk with Lazarus and click on "Use \> Add to Project". Then, if you need to add the reference in another project, you can do it through the Project inspector and click on "Add... \> New condition" and choose BGRABitmapPack.
50	50
51	51		In the unit clause, add a reference to BGRABitmap and BGRABitmapTypes after Dialogs.
52	52
53	53		``` pascal
54	54		uses
55	55		Classes, SysUtils, FileUtil, LResources, Forms, Controls, Graphics, Dialogs,
56	56		BGRABitmap, BGRABitmapTypes;
57	57		```
58	58
59	59		#### Alternative ways of referencing
60	60
61	61		##### By installing BGRABitmap package
62	62
63	63		Open bgrabitmappack.lpk as a package. Make sure it is possible to install it by going in the package window into "Options \> IDE Integration" and setting the package type to "designtime and runtime". Then in the package window, click on install. A dialog pops up, asking if the package must be added to Lazarus and if it needs to be compiled again. Choose Yes twice.
64	64
65	65		If everything is fine, Lazarus restarts and BGRABitmap units are available. If it does not work, you can simply add BGRABitmap to the search path without compiling Lazarus.
66	66
67	67		##### By adding BGRABitmap units to the search path
68	68
69	69		Another way is to add BGRABitmap units to the search path of the project. To do this, go to compiler options with menu Project \> Compiler options. In other unit files path, add the relative path to BGRABitmap. For example, if BGRABitmap is in a folder next to your project, the relative path could be "..\BGRABitmap".
70	70
71	71		If you copy BGRABitmap files in the same folder as your project, then you do not need to add such search path. However, it is not recommended because if you have multiple projects using the library, it could become a repetitive task to update to a new version of the library.
72	72
73	73		If you are lost with relative path, you can also add the relative path by adding the BGRABitmap unit to your project. To do so, open within your project the file bgrabitmap.pas. Then use menu Project \> Add file to project. Lazarus will ask if you want to add the file and the new directory to the project.
74	74
75	75		### Add some drawing
76	76
77	77		Add a painting event. To do this, click on the form, then go to the object inspector, in the event tab, and double click on the OnPaint line. Lazarus will add automatically a FormPaint handler to the main form unit. Add for example the following code inside it :
78	78
79	79		``` pascal
80	80		procedure TForm1.FormPaint(Sender: TObject);
81	81		var bmp: TBGRABitmap;
82	82		begin
83	83		bmp := TBGRABitmap.Create(ClientWidth, ClientHeight, BGRABlack);
84	84		bmp.FillRect(20, 20, 100, 40, BGRA(255,192,0), dmSet); //fill an orange rectangle
85	85		bmp.Draw(Canvas, 0, 0, True); //render BGRABitmap on the form
86	86		bmp.Free; //free memory
87	87		end;
88	88		```
89	89
90	90		As you can see, you need to define a [[TBGRABitmap class\|TBGRABitmap]] variable and create it. There are several constructors for [[TBGRABitmap class\|TBGRABitmap]]. The one used here creates a bitmap of size ClientWidth x ClientHeight and filled with black. ClientWidth and ClientHeight are form properties that return the available space for drawing inside the form.
91	91
92	92		The FillRect procedure takes usual parameters for drawing a rectangle, that is the upper-left corner followed by the lower-right corner plus 1. It means that the pixel at (100,40) is excluded from the rectangle.
93	93
94	94		After that, there is a color parameter with red/green/blue components, and a drawing mode. dmSet means to simply replace the pixels.
95	95
96	96		Do not forget to free the object after using it, to avoid a memory leak.
97	97
98	98		### Resulting code
99	99
100	100		You should obtain the following code:
101	101
102	102		``` pascal
103	103		unit UMain;
104	104
105	105		{$mode objfpc}{$H+}
106	106
107	107		interface
108	108
109	109		uses
110	110		Classes, SysUtils, FileUtil, LResources, Forms, Controls, Graphics, Dialogs,
111	111		BGRABitmap, BGRABitmapTypes;
112	112
113	113		type
114	114
115	115		{ TForm1 }
116	116
117	117		TForm1 = class(TForm)
118	118		procedure FormPaint(Sender: TObject);
119	119		private
120	120		{ private declarations }
121	121		public
122	122		{ public declarations }
123	123		end;
124	124
125	125		var
126	126		Form1: TForm1;
127	127
128	128		implementation
129	129
130	130		{ TForm1 }
131	131
132	132		procedure TForm1.FormPaint(Sender: TObject);
133	133		var bmp: TBGRABitmap;
134	134		begin
135	135		bmp := TBGRABitmap.Create(ClientWidth,ClientHeight,BGRABlack);
136	136		bmp.FillRect(20,20,100,40,BGRA(255,192,0),dmSet);
137	137		bmp.Draw(Canvas,0,0,True);
138	138		bmp.Free;
139	139		end;
140	140
141	141		initialization
142	142		{$I UMain.lrs}
143	143
144	144		end.
145	145		```
146	146
147	147		### Run the program
148	148
149	149		You should obtain a window filled in black with an orange rectangle in it.
150	150
151		-	~~<figure>~~
152		-	~~<img src="BGRATutorial1.png" title="BGRATutorial1.png" />~~
153		-	~~<figcaption>BGRATutorial1.png</figcaption>~~
154		-	~~</figure>~~
	151	+	![](/wiki-images/e/ea/BGRATutorial1.png)
155	152
156	153		[[BGRABitmap tutorial 2\|Go to next tutorial (image loading)]]
157	154
158	155		---
159	156		From the Free Pascal wiki, page "BGRABitmap tutorial 1/ru", as it stood on 2020-02-09 after a change by Trev, 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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