TextOutAngle with subscript and superscript chars

[vertnik]

Hi!

It is possible to use subscript or superscript chars with text routines (TextOutAngle or Canvas2D.Text)?
I would like to draw text with chemical formulas.

Robert

[Handoko]

If you don't need angle calculation, subscript and superscript can be easily done using TCanvas:

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, Forms, Graphics, StdCtrls, Types;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     Button1: TButton;
16.     procedure Button1Click(Sender: TObject);
17.   private
18.     fTextPosX: Integer;
19.     fTextPosY: Integer;
20.     fFontSize: Integer;
21.     fFontColor: TColor;
22.   public
23.     procedure TextInit(X, Y, S: Integer; C: TColor);
24.     procedure TextColor(C: TColor);
25.     procedure TextNormal(const S: string);
26.     procedure TextSuperscript(const S: string);
27.     procedure TextSubscript(const S: string);
28.   end;
29.  
30. var
31.   Form1: TForm1;
32.  
33. implementation
34.  
35. {$R *.lfm}
36.  
37. { TForm1 }
38.  
39. procedure TForm1.Button1Click(Sender: TObject);
40. begin
41.  
42.   TextInit(30, 20, 18, clBlack);
43.   TextNormal('E := MC');
44.   TextSuperscript('2');
45.  
46.   TextInit(30, 60, 18, clBlack);
47.   TextNormal('H');
48.   TextSubscript('3');
49.   TextNormal('O');
50.   TextSuperscript('+');
51.  
52.   TextInit(30, 100, 18, clBlack);
53.   TextNormal('Lazarus is ');
54.   TextColor(clRed);    TextNormal('a');
55.   TextColor(clPurple); TextNormal('w');
56.   TextColor(clGreen);  TextNormal('e');
57.   TextColor(clBlue);   TextNormal('s');
58.   TextColor(clWhite);  TextNormal('o');
59.   TextColor(clMaroon); TextNormal('m');
60.   TextColor(clYellow); TextNormal('e');
61.  
62. end;
63.  
64. procedure TForm1.TextInit(X, Y, S: Integer; C: TColor);
65. begin
66.   fTextPosX  := X;
67.   fTextPosY  := Y;
68.   fFontSize  := S;
69.   fFontColor := C;
70. end;
71.  
72. procedure TForm1.TextColor(C: TColor);
73. begin
74.   fFontColor := C;
75. end;
76.  
77. procedure TForm1.TextNormal(const S: string);
78. var
79.   TextSize: TSize;
80. begin
81.   with Canvas do
82.   begin
83.     Brush.Style := bsClear;
84.     Font.Color  := fFontColor;
85.     Font.Size   := fFontSize;
86.     TextSize    := TextExtent(S);
87.     TextOut(fTextPosX, fTextPosY, S);
88.   end;
89.   Inc(fTextPosX, TextSize.cx);
90. end;
91.  
92. procedure TForm1.TextSuperscript(const S: string);
93. var
94.   NewSize  : Integer;
95.   TextSize : TSize;
96. begin
97.   NewSize := (fFontSize*2) div 3;
98.   with Canvas do
99.   begin
100.     Brush.Style := bsClear;
101.     Font.Color  := fFontColor;
102.     Font.Size   := NewSize;
103.     TextSize    := TextExtent(S);
104.     TextOut(fTextPosX, fTextPosY, S);
105.   end;
106.   Inc(fTextPosX, TextSize.cx);
107. end;
108.  
109. procedure TForm1.TextSubscript(const S: string);
110. var
111.   NewSize  : Integer;
112.   TextSize : TSize;
113. begin
114.   NewSize := (fFontSize*2) div 3;
115.   with Canvas do
116.   begin
117.     Brush.Style := bsClear;
118.     Font.Color  := fFontColor;
119.     Font.Size   := NewSize;
120.     TextSize    := TextExtent(S);
121.     TextOut(fTextPosX, fTextPosY+NewSize, S);
122.   end;
123.   Inc(fTextPosX, TextSize.cx);
124. end;
125.  
126. end.

The code above doesn't need BGRABitmap but you can modify it to use BGRABitmap with no or some little changes.

[wp]

ChemText is a ready-made component to display chemical formulas. Install via Online-Package-Manager.

[vertnik]

Handoko, I implemented your approach with BGRABitmap. It works.

With Bitmap.Canvas2D:

Code: Pascal  [Select][+][-]

1. Bitmap.Canvas2D.resetTransform; // to reset previous transformations
2. Bitmap.Canvas2D.translate(x,y); // move pen to start position of text
3. Bitmap.Canvas2D.rotate(rotation); // in case we need rotation
4. Bitmap.Canvas2D.beginPath;
5.   {here, I use Bitmap.Canvas2D.measureText(S) and
6.   Bitmap.Canvas2D.Text(S, fTextPosX, fTextPosY) to draw normal,
7.   superscript or subscript text}
8. Bitmap.Canvas2D.fill; // to draw whole text    
9.  

wp, chemtext is very good component, but I think can not be used in BGRABitmap.

Thank you both,

Robert

[winni]

@vertnik:

You can use ChemText together with BGRABitmap. The main drawing function in ChemText is:

Code: Pascal  [Select][+][-]

1. function ChemTextOut(ACanvas: TCanvas;  X, Y:integer; const AText: String;
2.   Arrow: TChemArrow = caAsciiSingle; Measure: Boolean = false): TSize;

So you only need a canvas to paint on. The BGRABitmap has a "normal and simple" canvas.

You can write

Code: Pascal  [Select][+][-]

1. Var bit: TBGRABitmap;
2.       ts: Tsize;
3.  
4. begin
5. .......
6. ts := ChemTextOut ( bit.canvas, 10, 10, 'C21H30O2', caUTF8, false);
7. end;
8.  

Winni

[vertnik]

@winni:

Thanks, but I also need rotation and antialliasing. I will use chemtextout in other
controls, like drawing into the cell of stringgrid.

vertnik