URGENT PLEASE - Image over controls in a form

Posted on 2002-06-13
Last Modified: 2010-04-04

I have a form that contains a grid, an image and some buttons.

I want to move the image at runtime over the other controls, EVEN OVER the grid.

How can I do that ?

Question by:sruel
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LVL 34

Expert Comment

ID: 7077192
a TImage is Not a WinControl, so you might try putting the Image on a TPanel (which is a WinControl) and making the panel the size of the image, then moving the Panel around, you can reduce the panel borders if you don't want to see the panel.

Expert Comment

ID: 7077346
Do you want to move Image programmaticaly or with a mouse?

Author Comment

ID: 7077736
I want to move Image programmaticaly ...

Also, my image is a triangle. If I put it on a frame, there will be 2 "empty" spaces in the left and rigth upper corner and i want to see what is behind this...
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Expert Comment

ID: 7078033

TImage is not windowed control, so it can never be visible on top of windowed controls (that is, most of visible VCL components, not only TStringGrid).
What you need is transparent windowed control, which has to be created from scratch. This is not few lines of code, so I don't think you should create your class dynamically.

Since you tagged your post URGENT i presume you don't have time to create your own component. This free component does exactly what you want:

(Readme.txt will tell you all you need to know)
LVL 34

Expert Comment

ID: 7079228
are there anymore design specs that you havent mentionded like  the transparent triangle edges? You can set you Panel's shape with a region. This makees a Star shape panel

procedure TForm1.ButtonClick(Sender: TObject);
  RadConvert = PI/180;
  Degrees    = 360;
  MaxLines   = 100;
  rgn: HRGN;
  x, y, xCenter,
  yCenter, radius,
  pts, I: Integer;
  angle, rotation: Extended;
  DoStarShape: Boolean;
  arPts   : Array[0..MaxLines] of TPoint;
DoStarShape := True;
    xCenter := (Image3.BoundsRect.Right- Image3.BoundsRect.Left) div 2;
  yCenter := (Image3.BoundsRect.Bottom - Image3.BoundsRect.Top) div 2;
  if DoStarShape then
      rotation := Degrees/(12);
      pts := 2 * 6;
      rotation := Degrees/6;
      pts := 6 {points in Star}
  radius := yCenter;

  for I := 0 to pts - 1 do begin
    if DoStarShape then
      if (I mod 2) = 0 then //which means that
        radius := Round(radius/2)
        radius := yCenter;

    angle := ((I * rotation) + 90) * RadConvert;
    x := xCenter + Round(cos(angle) * radius);
    y := yCenter - Round(sin(angle) * radius);
    arPts[I].X := x;
    arPts[I].Y := y;

rgn := CreatePolygonRgn(arPts, pts, WINDING);
  SetWindowRgn(Panel1.Handle, rgn, TRUE);

 - - - - - - - -  - - - - - - - -  - - -

but you could simplify it to a triangle
LVL 34

Accepted Solution

Slick812 earned 50 total points
ID: 7080018
Here's the code in the Form create to make a Triangle shaped Panel3 with Image3 on it.

procedure TForm1.FormCreate(Sender: TObject);
  Rgn1: HRGN;
  arrayPts: Array[0..2] of TPoint;
arrayPts[0].y := 0;
arrayPts[0].x := Image3.Width div 2;

arrayPts[1].y := Image3.Height;
arrayPts[1].x := 0;

arrayPts[2].y := Image3.Height;
arrayPts[2].x := Image3.Width;

Rgn1 := CreatePolygonRgn(arrayPts, 3, WINDING);
SetWindowRgn(Panel3.Handle, Rgn1, False);

if you want to make a region shape from a bitmap image then it gets harder. I can post the code for that if you need it.
LVL 12

Expert Comment

ID: 7080134
why not simply draw that triangle bitmap on the forms canvas ?
that way it will be always on top
and I'm guessing that triangle image is some sort of a pointer (pointing at controls) ?
you can use the froms canvas functions like Canvas.Draw(...params...);
before each draw invalidate the area you previously painted on so it gets updated

Expert Comment

ID: 7082734

Do you want to draw in a string grid (like to show a status graphic of some kind)?

I admit to not having read everything which has been said but when I need to draw on a grid, I use the OnSelectCell to prevent the user from selecting the cell (that would cause the InPlaceEditor to activate, thereby hiding my graphic.

Then I use the OnDrawCell to paint the graphic in the cell.


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