[Screenshot Tool] Capture Select Region [Not Whole Screen]
lazarus / 39-Graphics

----------------------------------------------------------------------
SniperX · 2016-06-26 09:50

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 · 2016-06-26 10:18

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 · 2016-06-26 10:58

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 · 2016-06-26 16:25

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][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i unit
Unit1; {$mode objfpc}{$H+} interface uses  Classes, SysUtils,
FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls, 
BGRABitmap,BGRABitmapTypes; type   { TForm1 }   TForm1 = class(TForm) 
  Button1: TButton;    procedure Button1Click(Sender: TObject); 
private    { private declarations }  public    { public declarations
}  end; var  Form1: TForm1; implementation {$R *.lfm} { TForm1
} procedure TForm1.Button1Click(Sender: TObject);var 
bmp:TBGRABitmap;begin 
bmp:=TBGRABitmap.Create(Monitor.Width,Monitor.Height); 
bmp.TakeScreenshotOfPrimaryMonitor;  bmp.Draw(Canvas,0,0); 
bmp.Free;end; end.

----------------------------------------------------------------------
SniperX · 2016-06-26 17:56

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 · 2016-06-26 19:34

OK, here is a full test demo.
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i unit
Unit1; {$mode objfpc}{$H+} interface uses  Classes, SysUtils,
FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls, ExtCtrls, 
BGRABitmap, BGRABitmapTypes; type   { TForm1 }   TForm1 =
class(TForm)    Button1: TButton;    Panel1: TPanel;    procedure
Button1Click(Sender: TObject);    procedure FormMouseDown(Sender:
TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);   
procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y:
Integer);    procedure FormMouseUp(Sender: TObject; Button:
TMouseButton; Shift: TShiftState; X, Y: Integer);    procedure
FormPaint(Sender: TObject);  private    { private declarations } 
public    ssbmp: TBGRABitmap;    DS: TPoint;    DR: TRect;    MD:
boolean;    procedure CalculateDR(X, Y: integer);  end; var  Form1:
TForm1; implementation {$R *.lfm} { TForm1 } procedure
TForm1.Button1Click(Sender: TObject);begin  ssbmp.Free;  ssbmp :=
TBGRABitmap.Create(Monitor.Width, Monitor.Height); 
ssbmp.TakeScreenshotOfPrimaryMonitor;  Invalidate;end; procedure
TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton; Shift:
TShiftState; X, Y: Integer);begin    MD := True;   with DR do  begin 
 Left := X;    Top := Y;    Right := Left;    Bottom := Top;  end; 
DS.X := DR.Left;  DS.Y := DR.Top;end; procedure
TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y:
Integer);begin    if not MD then    Exit;  CalculateDR(X, Y); 
Invalidate;end; procedure TForm1.FormMouseUp(Sender: TObject; Button:
TMouseButton; Shift: TShiftState; X, Y: Integer);begin    MD :=
False;  Invalidate;end; procedure TForm1.FormPaint(Sender:
TObject);var  bmp: TBGRABitmap;  regionbmp:TBGRABitmap;begin  if not
Assigned(ssbmp) then    Exit;  bmp := TBGRABitmap.Create(Width,
Height);  bmp.PutImage(0, 0, ssbmp, dmSet);  if MD then  begin   
bmp.Rectangle(DR.Left, DR.Top, DR.Right, DR.Bottom, BGRA(255, 0, 0,
200), dmDrawWithTransparency);    regionbmp:=bmp.GetPart(DR) as
TBGRABitmap;    if Assigned(regionbmp) then   
regionbmp.Draw(Panel1.Canvas,0,0);    //Do what you want here, if you
want just save it after selection is done do this stuff in mouseup   
regionbmp.Free;  end;  bmp.Draw(Canvas, 0, 0); 
bmp.Free;end; procedure TForm1.CalculateDR(X, Y: integer);begin  if x
>= DS.x then  begin    DR.Left := DS.x;    DR.Right := x;  end  else 
begin    DR.Right := DS.x;    DR.Left := x;  end;  if y >= DS.y then 
begin    DR.Top := DS.y;    DR.Bottom := y;  end  else  begin   
DR.Bottom := DS.y;    DR.Top := y;  end;end; end. Test the attachment.

----------------------------------------------------------------------
molly · 2016-06-26 19:43

Quote from: SniperX on June 26, 2016, 07:56:29 pm 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

Quote... 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 · 2016-06-26 22:09

Here's another  example using  TBitmap rather than TBGRABitmap.

----------------------------------------------------------------------
SniperX · 2016-06-26 23:26

@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