TBrush: what changed

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

Old	New		Line
1	1		Along with [[TPen]] and [[TFont]], `TBrush` belongs to the most fundamental properties of [[TCanvas]] and defines how a geometric shape is filled.
2	2
3	3		## Properties
4	4
5	5		- `Color`: specifies the basic color (type `TColor`) used to fill the shape
6	6		- `Style`: an enumeration of type `TBrushStyle` which defines the pattern used for filling
7	7		- `bsClear`: no filling at all, `Color` is ignored.
8	8		- `bsSolid`: uniform fill of the shape with the `Color` specified
9	9		- The following styles define hatch patterns which are drawn in the `Color` specified. By default the background between the hatch lines is left empty. In Windows, gtk2 and qt5, it can be filled after calling `SetBkColor(Canvas.Handle, AColor)` if background mode has been set to `OPAQUE`: `SetBkMode(Canvas.Handle, OPAQUE)` which is the default, but can be reverted by calling with the argument `TRANSPARENT` instead of `OPAQUE`. Both functions require the units LCLIntf and LCLType in the uses clause. In other widgetsets the background has to be drawn twice, with `fsSolid` at first. Note that an alpha-channel for transparency seems to be ignored.
10	10		- `bsHorizontal`, `bsVertical`, `bsFDiagonal`, `bsBDiagonal` define a single-line hatch pattern.
11	11		- `bsCross` and `bsDiagCross` define a crossed pattern.
12	12		- `bsImage` and `bsPattern` tile the shape with the image set to the `Bitmap` property of the `Brush`.
13	13		- `Bitmap` defines the image which fills the shape by tiling if `Style` is `bsImage`. Any instance of a class descending from `TCustomBitmap` can be used here (`TBitmap`, `TJpegImage`, `TPortableNetworkgraphic`, etc). But note that `TCanvas.Bitmap` is not created and destroyed by the `Canvas`, it is your responsibility to take care of this. There are also `Image` (type `TFPCustomImage`) and `Pattern` (type `TBrushPattern`) properties which seem to have a similar purpose, but they are inherited from ancestor [[TFPCustomBrush]] and are ignored by `TCanvas`. Using a bitmap for filling the shape does not work on all widgetsets; at the time of this writing it was tested to work on win32/64, qt5 and cocoa.
14	14
15	15		These properties are applied in all subsequent drawing commands.
16	16
17	17		Above description is valid for Windows. Several restrictions may apply for other widgetsets.
18	18
19	19		## Sample code
20	20
21		-	~~<figure>~~
22		-	~~<img src="tbrush_style_bk.png" title="tbrush_style_bk.png" />~~
23		-	~~<figcaption>tbrush_style_bk.png</figcaption>~~
24		-	~~</figure>~~
	21	+	![](/wiki-images/5/53/Tbrush_style_bk.png)
25	22
26	23		The following project draws ten rectangles on the canvas of a `TForm`, fills them with each style and labels them with the appropriate style name. The result is shown in the image above.
27	24
28	25		``` pascal
29	26		type
30	27		TForm1 = class(TForm)
31	28		procedure FormCreate(Sender: TObject);
32	29		procedure FormDestroy(Sender: TObject);
33	30		procedure FormPaint(Sender: TObject);
34	31		private
35	32		FPattern: TCustomBitmap;
36	33		public
37	34		end;
38	35
39	36		uses
40	37		...,
41	38		LCLIntf, LCLType, // for SetBkColor, OPAQUE and TRANSPARENT
42	39		Types, // for OffsetRect
43	40		TypInfo; // for GetEnumName
44	41
45	42		procedure TForm1.FormCreate(Sender: TObject);
46	43		begin
47	44		Width := 550;
48	45		Height := 290;
49	46
50	47		FPattern := TPortableNetworkGraphic.Create;
51	48		FPattern.LoadFromFile('C:\Lazarus\images\debugger\debugger.png'); // path to the image used for filling
52	49		end;
53	50
54	51		procedure TForm1.FormDestroy(Sender: TObject);
55	52		begin
56	53		FPattern.Free;
57	54		end;
58	55
59	56		procedure TForm1.FormPaint(Sender: TObject);
60	57		var
61	58		R: TRect;
62	59		bs: TBrushStyle;
63	60		styleName: String;
64	61		x, y, h: Integer;
65	62		begin
66	63		R := Rect(8, 8, 108, 108);
67	64		h := Canvas.TextHeight('Tg');
68	65
69	66		// Set fill color
70	67		Canvas.Brush.Color := clRed;
71	68
72	69		// Set border color
73	70		Canvas.Pen.Color := clBlack;
74	71
75	72		// Iterate over all available brush styles
76	73		for bs in TBrushStyle do
77	74		begin
78	75		// Set background color
79	76		SetBkMode(Canvas.Handle, OPAQUE);
80	77		SetBkColor(Canvas.Handle, clYellow);
81	78		// Set brush style
82	79		Canvas.Brush.Style := bs;
83	80		if (bs = bsImage) or (bs =bsPattern) then
84	81		Canvas.Brush.Bitmap := FPattern
85	82		else
86	83		Canvas.Brush.Bitmap := nil;
87	84		// Fill a rectangle with the selected brush
88	85		Canvas.Rectangle(R);
89	86		// Get name of brush style and draw it below the rectangle
90	87		styleName := GetEnumName(TypeInfo(TBrushStyle), ord(bs));
91	88		x := (R.Left + R.Right - Canvas.TextWidth(styleName)) div 2;
92	89		y := R.Bottom + 8;
93	90		// No text background
94	91		SetBkMode(Canvas.Handle, TRANSPARENT); // or: Canvas.Brush.Style := bsClear;
95	92		// Draw the brush name
96	93		Canvas.TextOut(x, y, styleName);
97	94		// Position the rectangle for next brush
98	95		if ord(bs) = ord(High(bs)) div 2 then
99	96		OffsetRect(R, -R.Left + 8, R.Height + 20 + h)
100	97		else
101	98		OffsetRect(R, R.Width + 8, 0);
102	99		end;
103	100		end;
104	101		```
105	102
106	103		---
107	104		From the Free Pascal wiki, page "TBrush", as it stood on 2023-11-24 after a change by Wp, 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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