[Screenshot Tool] Capture Select Region [Not Whole Screen]

[SniperX]

I am able to get the screenshot of full desktop which is drawn out on the form2.canvas

Form2 Properties:

BorderStyle : bsNone
FormStyle : fsSystemStayOnTop
Top : 0
Left : 0
WindowState : wsFullScreen

Now, i want to draw a rectangle on the form2 and crop out the image from original screenshot based on the Position and width and height of the rectangle. The problem is i do not know how to do it...

Also, this is the first time i am working with things related to drawing on form etc so any help is appreciated
Thanks

[aradeonas]

Welcome,

For graphic stuff in Lazarus, we have powerful BGRABitmap. I think you should look at it tutorials and it will be much easy for you and if you got question come back.
http://wiki.freepascal.org/BGRABitmap_tutorial
http://wiki.freepascal.org/BGRABitmap_tutorial_3
http://wiki.freepascal.org/BGRABitmap_tutorial_5

[SniperX]

Thanks for posting but i don't really think i would get into using BGRABitmap for screenshot purposes but if and when i dive into doing something complicated i would probably end up using it

[aradeonas]

Using it is easy and if you want to do graphic stuff do it easily with power.
1-Download and install it.
2-Use this code for simple screen shot.
3-Try to write the code or get help for region select(it will be as easy as other way or easier).

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls,
9.   BGRABitmap,BGRABitmapTypes;
10.  
11. type
12.  
13.   { TForm1 }
14.  
15.   TForm1 = class(TForm)
16.     Button1: TButton;
17.     procedure Button1Click(Sender: TObject);
18.   private
19.     { private declarations }
20.   public
21.     { public declarations }
22.   end;
23.  
24. var
25.   Form1: TForm1;
26.  
27. implementation
28.  
29. {$R *.lfm}
30.  
31. { TForm1 }
32.  
33. procedure TForm1.Button1Click(Sender: TObject);
34. var
35.   bmp:TBGRABitmap;
36. begin
37.   bmp:=TBGRABitmap.Create(Monitor.Width,Monitor.Height);
38.   bmp.TakeScreenshotOfPrimaryMonitor;
39.   bmp.Draw(Canvas,0,0);
40.   bmp.Free;
41. end;
42.  
43. end.
44.  

[SniperX]

I already know how to take screenshot of whole screen, i just want to know how to draw a rectangle on a form and crop out the selected region from existing snapshot.

[aradeonas]

OK, here is a full test demo.

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls, ExtCtrls,
9.   BGRABitmap, BGRABitmapTypes;
10.  
11. type
12.  
13.   { TForm1 }
14.  
15.   TForm1 = class(TForm)
16.     Button1: TButton;
17.     Panel1: TPanel;
18.     procedure Button1Click(Sender: TObject);
19.     procedure FormMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
20.     procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
21.     procedure FormMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
22.     procedure FormPaint(Sender: TObject);
23.   private
24.     { private declarations }
25.   public
26.     ssbmp: TBGRABitmap;
27.     DS: TPoint;
28.     DR: TRect;
29.     MD: boolean;
30.     procedure CalculateDR(X, Y: integer);
31.   end;
32.  
33. var
34.   Form1: TForm1;
35.  
36. implementation
37.  
38. {$R *.lfm}
39.  
40. { TForm1 }
41.  
42. procedure TForm1.Button1Click(Sender: TObject);
43. begin
44.   ssbmp.Free;
45.   ssbmp := TBGRABitmap.Create(Monitor.Width, Monitor.Height);
46.   ssbmp.TakeScreenshotOfPrimaryMonitor;
47.   Invalidate;
48. end;
49.  
50. procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
51. begin
52.     MD := True;
53.  
54.   with DR do
55.   begin
56.     Left := X;
57.     Top := Y;
58.     Right := Left;
59.     Bottom := Top;
60.   end;
61.   DS.X := DR.Left;
62.   DS.Y := DR.Top;
63. end;
64.  
65. procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
66. begin
67.     if not MD then
68.     Exit;
69.   CalculateDR(X, Y);
70.   Invalidate;
71. end;
72.  
73. procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
74. begin
75.     MD := False;
76.   Invalidate;
77. end;
78.  
79. procedure TForm1.FormPaint(Sender: TObject);
80. var
81.   bmp: TBGRABitmap;
82.   regionbmp:TBGRABitmap;
83. begin
84.   if not Assigned(ssbmp) then
85.     Exit;
86.   bmp := TBGRABitmap.Create(Width, Height);
87.   bmp.PutImage(0, 0, ssbmp, dmSet);
88.   if MD then
89.   begin
90.     bmp.Rectangle(DR.Left, DR.Top, DR.Right, DR.Bottom, BGRA(255, 0, 0, 200), dmDrawWithTransparency);
91.     regionbmp:=bmp.GetPart(DR) as TBGRABitmap;
92.     if Assigned(regionbmp) then
93.     regionbmp.Draw(Panel1.Canvas,0,0);
94.     //Do what you want here, if you want just save it after selection is done do this stuff in mouseup
95.     regionbmp.Free;
96.   end;
97.   bmp.Draw(Canvas, 0, 0);
98.   bmp.Free;
99. end;
100.  
101. procedure TForm1.CalculateDR(X, Y: integer);
102. begin
103.   if x >= DS.x then
104.   begin
105.     DR.Left := DS.x;
106.     DR.Right := x;
107.   end
108.   else
109.   begin
110.     DR.Right := DS.x;
111.     DR.Left := x;
112.   end;
113.   if y >= DS.y then
114.   begin
115.     DR.Top := DS.y;
116.     DR.Bottom := y;
117.   end
118.   else
119.   begin
120.     DR.Bottom := DS.y;
121.     DR.Top := y;
122.   end;
123. end;
124.  
125. end.
126.  

Test the attachment.

[molly]

i just want to know how to draw a rectangle on a form

Code: [Select]

Self.Canvas.DrawFocusRect(FSelectionRect);
Where self is the form and FSelectionRect the rectangle that was selected

... and crop out the selected region from existing snapshot.

Code: [Select]

var
  Bitmap : TBitmap;
  W,H    : Integer;
begin
    Bitmap := TBitmap.Create;
    W := FSelectionRect.Right  - FSelectionRect.Left;
    H := FSelectionRect.Bottom - FSelectionRect.Top;
    Bitmap.SetSize(W, H);
    Bitmap.Canvas.CopyRect(Rect(0,0,W,H), Self.Canvas, FSelectionRect);
    Bitmap.SaveToFile('MyCroppedScreenShot.bmp');
    Bitmap.Free;
end;
Where self is the form and FSelectionRect the rectangle that was selected

edit: whoops and sorry. I completely forgot to add the project as attachment.
Hmz, never mind as howardpc provided an excellent example of the whole thing. I added mine just in case interested: My selection procedure is a bit different.

[howardpc]

Here's another  example using  TBitmap rather than TBGRABitmap.

[SniperX]

@aradeonas @ molly @howardpc  Thanks for all the effort you all put in, im really really thankfull to all of you
i just need to ask two things from howardpc though 1) Is it possible to highlight the selection rectangle with red color while the selction process is in action and before the mouseup event fires ? 2) Can we save the selected image without the colored highlight to desktop ?

Thanks for everyones help

Edit:
1) Instead of DrawFocusRect i used Rectangle()
2) Commented out the use of Frame() method which excludes the selection ink before saving the image