Base operations with TsgCADdxfImage - please help

[h.o.o.k]

Hello cadsofttools team Our company bought your library VCL Import 10 and please i need advice.

I need prepare this operation with DXF file through TsgCADdxfImage objekt.

Scale (zooming):

Why not work this?:

Code: Select all

  vDrawing := TsgCADdxfImage.Create;
  vDrawing.LoadFromFile('map.dxf');
  vDrawing.GetExtents;
  vDrawing.ScaleDrawMatrix(2,2,2);
  vDrawing.GetExtents;

 // ...draw on canvas
 MyImage.Canvas.draw(0,0,vDrawing);

And moving with all??

Code: Select all

  vDrawing := TsgCADdxfImage.Create;
  vDrawing.LoadFromFile('map.dxf');
  vDrawing.GetExtents;
  vDrawing.ScaleDrawMatrix(2,2,2);
  vDrawing.TranslateDrawMatrix(200,200,0);  

  // .. draw to canvas
  MyImage.Canvas.draw(0,0,vDrawing);

this not work too:

Code: Select all

  vDrawing := TsgCADdxfImage.Create;
  vDrawing.LoadFromFile('map.dxf');
  vDrawing.GetExtents;
  TsgCADImageAccess(vDrawing).ApplyScale(rect(500,500,1000,1000));
  vDrawing.GetExtents;

  // .. draw to canvas
  MyImage.Canvas.draw(0,0,vDrawing); 

etc. vDrawing.Rotate(axisZ,90) work fine.

I must write than i need this operation without TsgDrawingNavigator , beceause TsgDrawingNavigator does not fit to my conception.

Exist some example code on this oepration only with TsgCADdxfImage ?

Thank you very much for some reply

Peter

[support]

Hello Peter,

You should set TsgCADImage.CustomDraw property value to False, then initialize the drawing matrix before scaling. The following code is correct:

Code: Select all

uses
  ..., CADImage, DXF, sgFunction, sgConsts;

   ...
   vDrawing.GetExtents;
   vDrawing.CustomDraw := False;
   // Initialize the drawing matrix
   vDrawing.SetDrawMatrix(StdMat(MakeFPoint(1, -1, 1), cnstFPointZero));
   // Scale the drawing matrix
   vDrawing.ScaleDrawMatrix(2,2,2);
   vDrawing.GetExtents;

   // Draw on canvas
   MyImage.Canvas.Draw(0, 0, vDrawing);

Mikhail

[h.o.o.k]

Hi Mikhail, beforehand thank you for quickly reply. In our company project implement time is running out (

But.. code not work:

Code: Select all

   vDrawing := TsgCADdxfImage.Create;
   vDrawing.LoadFromFile('map.dxf');
   vDrawing.GetExtents;
   vDrawing.CustomDraw := False;
   vDrawing.SetDrawMatrix(StdMat(MakeFPoint(1, -1, 1), cnstFPointZero));
   vDrawing.ScaleDrawMatrix(2,2,2);
   vDrawing.GetExtents;
   //draw
   Image1.Canvas.Draw(0, 0, vDrawing);

When i use vDrawing.CustomDraw := False; so Image1´s canvas is white/clear.

This Code works fine and DXF is nicely drawed on Canvas

Code: Select all

   vDrawing := TsgCADdxfImage.Create;
   vDrawing.LoadFromFile('map.dxf');
   vDrawing.GetExtents;
   //draw
   Image1.Canvas.Draw(0, 0, vDrawing);

What i do wrong ? unfortunately i dont have time for VLC library code-diving (

Thank you.

[support]

Hello Peter,

TImage canvas is white, because the drawing objects went off the canvas area and not visible after scaling. I would recommend to use the following code for scaling operation:

Code: Select all

TsgCADImageAccess = class(TsgCADImage);
...

procedure TForm1.ScaleDrawing(AValue: Double);
var
  vRect: TRect;
begin
  Image1.Picture := nil;
  vRect := Rect(0, 0, Round(vDrawing.AbsWidth * AValue), Round(vDrawing.AbsHeight * AValue));
  TsgCADImageAccess(vDrawing).ApplyScale(vRect);
  Image1.Canvas.StretchDraw(vRect, vDrawing);
end;

This procedure uses TsgCADImage.ApplyScale method for scaling the drawing relative to the point (0,0). Note that TsgCADImage.CustomDraw property value is not set to False here.


Mikhail

[h.o.o.k]

Its true, thank you Mikhail, you are my rescuer

Please last question, i promise

I have a map of city in DXF/DWG. I need gets map scale 1:X of this file.

I think that:

Code: Select all

   _oDxf.CustomDraw := False;
   defM := StdMat(MakeFPoint(1,1,1), cnstFPointZero);
  _oDxf.SetDrawMatrix(defM);
  _oDxf.GetExtents; 
 //now i have loaded file in created scale 1:1 (?)
 
 // my resolution in scale is METER. 

  dWidth := _oDxf.AbsWidth; // real widh of "dxf canvas" in pixels
  dWorldWidth := Abs(_oDxf.CurrentLayout.Box.Left - _oDxf.CurrentLayout.Box.Right); // suppos that units ar meters
  dPixelAsMeter := (PixelPerInch / 25.4 / 1000);
  dMetersOnOnePixel = dWorldWidth / dWidth; 
  bMapScale = (1/dPixelAsMeter) * dMetersOnOnePixel;  

Its true?

For gets world units i must use _oDxf.CurrentLayout.Box or _oDxf.Extends ?

Thanks again.

Peter

[support]

Hello Peter,

DXF drawings are measured in drawing units, so dWidth and dWorldWidth values in your code will be in decimal drawing units, not in pixels or meters as you supposed. In order to get the width/height in drawing units, I would recommend to use TsgCADImage.AbsWidth and TsgCADImage.AbsHeight properties whose values can also be calculated in the following way:

Code: Select all

vAbsWidth := Abs(_oDxf.Extents.Left - _oDxf.Extents.Right);
vAbsHeight := Abs(_oDxf.Extents.Top - _oDxf.Extents.Bottom);

_oDxf.CurrentLayout.Box returns the bounding rectangle coordinates for a current layout.

Note that a loaded drawing contains the additional empty space (borders) by default that affects its width and height. TsgCADImage.IsWithoutBorder property specifies whether to add a border or not.


Mikhail

[h.o.o.k]

Thanks Mikhail. But Still i dont understan how i cals how much DXF units is one pixel on screen. But I will fight Thank you for your help on our project.

with respect

Peter

[h.o.o.k]

For all (maybe usefull)

When i set default Draw matrix

Code: Select all

m := StdMat(MakeFPoint(1,-1,1), cnstFPointZero);

//.. draw

So 1 CAD UNIT = 1px on display device.

Peter