Turning layers on and off

[AndyStephenson]

Hi,

I am using the following code snippets to turn layers on and off:

sgImagePlan.LoadFromFile(DBTextPlanFilename.Caption);
sgImagePlan.Align := alNone;
sgImagePlan.Align := alClient;
Fimg := TsgDXFImage(sgImagePlan.Picture.Graphic);


Fimg.Converter.LayerByName(LayerName).Visible := true; //on
or
Fimg.Converter.LayerByName(LayerName).Visible := false; //on

sgImagePlan.Refresh;

It all works fine. But, the refresh call updates all of the drawing, so it's quite a visible flicker. Is there a better way to do this so that a minimalist repaint occurs?

...Andy

[support]

Hello Andy,

Set the following property to true:

Code: Select all

TsgImage.Parent.DoubleBuffered := true;

Sergey.

please post questions to the forum or write to support@cadsofttools.com

[AndyStephenson]

Sergey,

I gave that a try, but I still get the whole of the image repainted.

What I would like is that only the active area of the layer that I have turned on or off is drawn, not the whole image.

Is this possible?

...Andy

[support]

Hello Andy,

The following example demonstrates how to redarw only necessary part of the drawing:

Code: Select all

<b>uses</b>
  ... sgConsts, SGImage, DXFImage, DXFConv;

<b>type</b>
  TForm1 = <b>class</b>(TForm)
    ..
    <b>procedure</b> btnSwitchLayerOnOffClick(Sender: TObject);
  <b>private</b>
   <i><font color="blue">{ Private declarations }</font id="blue"></i>
    FImg: TsgDXFImage;

<b>procedure</b> TForm1.btnSwitchLayerOnOffClick(Sender: TObject);
<b>var</b>
  I: Integer;
  vRect: TRect;
<b>begin
  if</b> FImg = <b>nil then</b>
    Exit;
  <b>for</b> I := <font color="blue">0</font id="blue"> <b>to</b> FImg.Converter.Counts[csLayers] - <font color="blue">1</font id="blue"> <b>do
  begin
    if</b> TsgDXFLayer(FImg.Converter.Sections[csLayers].Entities[I]).Name = '<font color="blue">LayerToFreeze</font id="blue">' <b>then</b>
      TsgDXFLayer(FImg.Converter.Sections[csLayers].Entities[I]).Frozen := <b>not</b> TsgDXFLayer(FImg.Converter.Sections[csLayers].Entities[I]).Frozen;
  <b>end</b>;
  vRect.TopLeft := FImg.GetPoint(MakeFPoint(<font color="blue">..</font id="blue">, <font color="blue">..</font id="blue">, <font color="blue">..</font id="blue">));
  vRect.BottomRight := FImg.GetPoint(MakeFPoint(<font color="blue">..</font id="blue">, <font color="blue">..</font id="blue">, <font color="blue">..</font id="blue">));
  vRect.Left := vRect.Left + sgImage1.Left;
  vRect.Right := vRect.Right + sgImage1.Left + <font color="blue">1</font id="blue">;
  vRect.Top := vRect.Top + sgImage1.Top + <font color="blue">1</font id="blue">;
  vRect.Bottom := vRect.Bottom + sgImage1.Top;

  InvalidateRect(sgImage1.Parent.Handle, @vRect,false);
  UpdateWindow(sgImage1.Parent.Handle)
<b>end</b>;

Two conditions:
<ul><li>You have to know what layer has to be frosen</li>
<li>You have to know the drawing coordinates of the area to be redrawn. Use this coordinates when calling function <b>TsgDXFImage.GetPoint</b></li></ul>
Sergey.

please post questions to the forum or write to support@cadsofttools.com