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 How to Draw Rectangle that stays proper		  New Topic  Reply to Topic
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yogiyang

India
727 Posts
Posted - Jun 17 2016 :  01:49:25  Show Profile  Reply
Hello,

I am finding it hard to describe the problem properly but let me try....

I am trying to draw a border in ImageEnView. With help from Bill I managed to draw a border by placing code in DrawBackBuffer event.

But the problem is that the border drawn changes size when the view changes. Meaning if the zoom of ImageEnView is changed the border does not stay as it is. Instead it is always drawn in the visible part of ImageEnView.

How to draw a border around ImageEnView leaving 25 pixels as margin which will stay the same even when user zooms in or out?

For better understanding here are a few screen shots.





Here is the code that I am using:
procedure TForm1.ImageEnVect1DrawBackBuffer(Sender: TObject);
{ Automatically draw the grid in the background, eliminates the need to use objects and is much faster and much better
  than using objects }
var
  ix1: Integer;
  iy1: Integer;
  ix2: Integer;
  iy2: Integer;
begin
  { Get the corners of the bitmap }
  ix1 := ImageEnVect1.OffsetX;
  iy1 := ImageEnVect1.OffsetY;
  ix2 := ImageEnVect1.ExtentX;
  iy2 := ImageEnVect1.ExtentY;
  { Draw a blue rectangle around the bitmap }
  ImageEnVect1.BackBuffer.Canvas.Pen.Width := 1;
  ImageEnVect1.BackBuffer.Canvas.Pen.Color := clGreen;
  ImageEnVect1.BackBuffer.Canvas.Pen.Style := psSolid;
  ImageEnVect1.BackBuffer.Canvas.Brush.Style := bsClear;
  ImageEnVect1.BackBuffer.Canvas.Rectangle(ix1 + 25, iy1 + 25, ix1 + ix2 - 25, iy1 + iy2 - 25);
  { Draw crosshairs }
  ImageEnVect1.BackBuffer.Canvas.Pen.Color := clBlack;
  ImageEnVect1.BackBuffer.Canvas.MoveTo(ix1 + ix2 div 2, iy1);
  ImageEnVect1.BackBuffer.Canvas.LineTo(ix1 + ix2 div 2, iy1 + iy2);
  ImageEnVect1.BackBuffer.Canvas.MoveTo(ix1, iy1 + iy2 div 2);
  ImageEnVect1.BackBuffer.Canvas.LineTo(ix1 + ix2, iy1 + iy2 div 2);
  {Draw 4 Simple Lines}
  ImageEnVect1.BackBuffer.Canvas.Pen.Color := clBlue;
  ImageEnVect1.BackBuffer.Canvas.MoveTo(ix1 + ix2 div 4 + 12, iy1);
  ImageEnVect1.BackBuffer.Canvas.LineTo(ix1 + ix2 div 4 + 12, iy1 + iy2);
  ImageEnVect1.BackBuffer.Canvas.MoveTo(ix1 + (ix2 div 4) * 3 - 12, iy1);
  ImageEnVect1.BackBuffer.Canvas.LineTo(ix1 + (ix2 div 4) * 3 - 12, iy1 + iy2);

  ImageEnVect1.BackBuffer.Canvas.MoveTo(ix1, iy1 + iy2 div 4 + 12);
  ImageEnVect1.BackBuffer.Canvas.LineTo(ix1 + ix2, iy1 + iy2 div 4 + 12);
  ImageEnVect1.BackBuffer.Canvas.MoveTo(ix1, iy1 + (iy2 div 4) * 3 - 12);
  ImageEnVect1.BackBuffer.Canvas.LineTo(ix1 + ix2, iy1 + (iy2 div 4) * 3 - 12);

end;

TIA


Yogi Yang

xequte

39052 Posts
Posted - Jun 21 2016 :  21:52:14  Show Profile  Reply
Hi Yogi

To convert values between what is visible on-screen (given zoom and scrolling) and the underlying bitmap, see the methods such as:

http://www.imageen.com/help/TImageEnView.XBmp2Scr.html
http://www.imageen.com/help/TImageEnView.XScr2Bmp.html

Nigel
Xequte Software
www.xequte.com
nigel@xequte.com
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yogiyang

India
727 Posts
Posted - Jul 13 2016 :  08:03:34  Show Profile  Reply
Hello Nigel,

I have put this code in DrawBackBuffer Event

procedure TfrmMain.ievMainDrawBackBuffer(Sender: TObject);
var
  ix1: Integer;
  iy1: Integer;
  ix2: Integer;
  iy2: Integer;
begin
  if ievMain.IsEmpty2 then
    Exit;

  { Get the corners of the bitmap }
  ix1 := ievMain.XBmp2Scr(ievMain.OffsetX);
  iy1 := ievMain.YBmp2Scr(ievMain.OffsetY);
  ix2 := ievMain.XBmp2Scr(ievMain.IEBitmap.Width);
  iy2 := ievMain.YBmp2Scr(ievMain.IEBitmap.Height);

  //--------
  { Draw a blue rectangle around the bitmap }
  ievMain.BackBuffer.Canvas.Pen.Width := 1;
  ievMain.BackBuffer.Canvas.Pen.Color := clRed;
  ievMain.BackBuffer.Canvas.Pen.Style := psSolid;
  ievMain.BackBuffer.Canvas.Brush.Style := bsClear;
  ievMain.BackBuffer.Canvas.Rectangle(ix1 + ievMain.XBmp2Scr(10), iy1 +
    ievMain.YBmp2Scr(10), ix1 + ix2 - ievMain.XBmp2Scr(10),
       iy1 + iy2 - ievMain.YBmp2Scr(10));
  { Draw crosshairs }
  ievMain.BackBuffer.Canvas.Pen.Color := clBlack;
  ievMain.BackBuffer.Canvas.MoveTo(ix1 + ix2 div 2, iy1);
  ievMain.BackBuffer.Canvas.LineTo(ix1 + ix2 div 2, iy1 + iy2);

end;

But it is now drawing the required rectangle properly. Can you help correct my mistakes.

What I want is:


Again this should stay proper irrespective of Zoom.

TIA


Yogi Yang
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yogiyang

India
727 Posts
Posted - Jul 13 2016 :  10:50:21  Show Profile  Reply
Hello,

One more thing that I observed is that the rectangle gets drawn even when we select a layer and at that time the size of the layer seems to apply.

TIA


Yogi Yang
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