asked on

Transparent rectangle component

I'm trying to make a resizable and moveable component at runtime, well I got that to work from someones example. But I can't get the darn thing to draw transparent. Basically I need a framed rectangle. here's the code I'm working from.
also when I switch what its inherited from to TGraphicControl transparency works, but I loose the ability to move and resize the component.

unit analysisControl;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs;

type
TAnalysisControl = class(TCustomControl)
private
FCanvas: TCanvas;
protected
procedure Paint; override;
property Canvas: TCanvas read FCanvas;
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
procedure MouseDown(Button : TMouseButton; Shift : TShiftState; X,Y:integer); override;
procedure MouseMove(Shift : TShiftState; X,Y:integer); override;
end;

procedure Register;

implementation

uses WinProcs;
const
sizeBorder = 2;
sc_SizeLeft = $F001;
sc_SizeRight = $F002;
sc_SizeTop = $F003;
sc_SizeTopLeft = $F004;
sc_SizeTopRight = $F005;
sc_SizeBottom = $F006;
sc_SizeBottomRight = $F008;
sc_SizeBottomLeft = $F007;
sc_DragMove = $F012;

procedure TAnalysisControl.MouseDown(Button : TMouseButton; Shift : TShiftState; X,Y:integer);
begin
if Button = mbLeft then
begin
WinProcs.ReleaseCapture;
if(X >= Width - sizeBorder) and
NOT((Y<=sizeborder) or (Y >= Height - sizeborder)) then
Self.Perform(WM_SysCommand, sc_SizeRight,0)
else
If NOT((X<= sizeBorder) or (X >= Width - sizeBorder)) and
(Y <= sizeBorder) then
self.Perform(WM_SysCommand,sc_SizeTop,0)
else
if(X<= sizeborder) and (y <= sizeborder) then
self.Perform(WM_SysCommand,sc_SizeTopLeft,0)
else
if(X >= width - sizeborder) and (y<= sizeborder) then
self.Perform(WM_SysCommand, sc_SizeTopRight,0)
else
if NOT((X<= sizeborder) or (X>= width - sizeborder)) and
(y>= height - sizeborder) then
self.Perform(WM_SysCommand,sc_SizeBottom,0)
else
if(Y>= height - sizeborder) and (x<=sizeborder) then
self.Perform(WM_SysCommand,sc_sizebottomleft,0)
else
if(Y >= height - SizeBorder) and (X>=width-sizeborder) then
self.Perform(WM_SysCommand,sc_SizeBottomRight,0)
else
if NOT((Y <= sizeBorder) or (Y>= height - sizeborder)) and
(X<= sizeborder) then
self.Perform(WM_SysCommand,sc_SizeLeft,0)
else
begin
self.Perform(WM_SysCommand,sc_DragMove,0);
end;
end;
end;

procedure TAnalysisControl.Paint;
begin
canvas.pen.color := clMaroon;
canvas.brush.Color := clWhite;
canvas.brush.style := bsClear;
canvas.Rectangle(GetClientRect.Left,GetClientRect.Top,GetClientRect.Right,GetClientRect.Bottom);
end;

procedure Tanalysiscontrol.MouseMove(Shift:TShiftState; x,y:integer);
begin
if(X <= sizeborder) or (X >= width - sizeborder) then
begin
if(Y>= height-sizeborder) then
begin
if(X>= width - sizeborder) then
Cursor := crSizeNWSE
else
cursor := crSizeNESW;
end
else
if(Y <= sizeborder) then
begin
if(x >= width - sizeborder) then
cursor := crSizeNESW
else
cursor := crSizeNWSE;
end
else
cursor := crSizeWE;
end
else
if(Y <= sizeBorder) or (Y >= height - sizeborder) then
begin
cursor := crSizeNS;
end
else
Cursor := crDefault;
end;

procedure Register;
begin
RegisterComponents('Samples', [TanalysisControl]);
end;

constructor TAnalysisControl.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FCanvas := TControlCanvas.Create;
TControlCanvas(FCanvas).Control := Self;
width := 96;
height := 16;
end;

destructor TAnalysisControl.Destroy;
begin
FCanvas.Free;
inherited Destroy;
end;

end.

I know its a bit long to post, but its driving me nuts, and I'm sure its probably something pretty easy, I've tried several different methods, from several diferent tips and tricks sites, but its just my luck none of them worked for me.

retnuh

ASKER

Edited text of question

ZifNab

Hi tenuh,

try this out, it draws an animated rectangle around an image :

Is this the thing you need?

procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;Shift : TShiftState; X,Y:integer);
begin
ImageMouse := True;
ImageRect.Left := X;
ImageRect.Top := Y;
ImageRect.Right := X;
ImageRect.Bottom := Y;
Image1.Canvas.DrawFocusRect(ImageRect);
end;

procedure TForm1.Image1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
Var
NewRect : tRect;
begin
if ImageMouse then
If (X > ImageRect.Left) AND (Y > ImageRect.Top) then begin
{Restore the background}
Image1.Canvas.DrawFocusRect(ImageRect);
{Change Rectangle}
ImageRect.Right := X;
ImageRect.Bottom := Y;
{Draw Focus Rectangle}
Image1.Canvas.DrawFocusRect(ImageRect);
end;
end;

procedure TForm1.Image1MouseUp(Sender: TObject; Button: TMouseButton;Shift: TShiftState; X, Y: Integer);

begin
{Restore the background}
if ImageMouse then begin
ImageRect.Right := X;
ImageRect.Bottom := Y;
Image1.Canvas.DrawFocusRect(ImageRect);
ImageMouse := False;
Image1.Canvas.CopyRect(Image1.Canvas.ClipRect,
Image1.Canvas,ImageRect)
end;
end;

Zif.

retnuh

ASKER

With the code below when the component is inherited from TCustomControl it still fills the rectangle even though the brush style is set to bsClear, when the component is inherited from TGraphicControl the rectangle is transparent, but I loose the ability to move and resize it. If I could base it off of TGraphicControl and still move and resize it that would work great. Also if I could figure out what it is in TWinControl that stops the bsClear style from working correctly that would work.

canvas.pen.color := clMaroon;
canvas.brush.Color := clWhite;
canvas.brush.style := bsClear;
canvas.Rectangle(GetClientRect.Left,GetClientRect.Top,GetClientRect.Right,GetClientRect.Bottom);

ASKER CERTIFIED SOLUTION

Jacco

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d003303

Yo,
bsClear as a brush style only affects drawing operations on the canvas. To get your component transparent, you have to stick to TGraphicControl. All descendants of TWinControl get a WM_ERASEBACKGROUND message that you will have to work around then. Difficult, because you have to notify the underlying controls to repaint themselves. Flicker on the screen and nasty programming is the result of this approach.
TControl introduces protected MouseMove/MouseUp/MouseDown handlers that you can overwrite to implement your move/resize behaviour at runtime.
If this is what you need and if I should give you an example, please re-open the question.

Slash/d003303

retnuh

ASKER

The CreateParams works, now if only I could get it to refresh on mouseup, I can deal with it not being transparent while dragging. I have notice that it refreshes when you resize it, I'm playing around with that now. Any more info would be great.

d003303

try to override the MouseUp handler, call inherited and invalidate.

Slash/d003303

retnuh

ASKER

I tried overriding the MouseUp, but its not working, I've also tried messing with WMERASEBACKGROUND but the redrawing is so often that the flicking is terrible.

retnuh

ASKER

Well I figured it out, after
self.Perform(WM_SysCommand,sc_DragMove,0);
I called:
parent.repaint;
paint;
then I found that I had to call every paint method for this type of component other wise all the other ones disappear.