Title: TEdit that damn background
Question: TEdit is a fairly low level component utilizing the standard widows edit window. How on earth do we get the background to be something other than a color.. Can we make it transparent or put a picture in.
I don't know if it works in versions previous to 6 but I can't see why it would not.
Answer:
This unit is a transparent TEdit descendant. I wrote it for my new program Zeta9. www.zeta9.net
If you want to put your own background in instead of it being transparent change the else clause of the if Transparent in WMEraseBkGnd.
Matt.
unit Z9Edit;
interface
uses
Windows, Messages, SysUtils, Classes, Controls, StdCtrls, Graphics;
type
TZ9Edit = class(TEdit)
private
{ Private declarations }
FAlignText: TAlignment;
FTransparent: Boolean;
FPainting: Boolean;
procedure SetAlignText(Value: TAlignment);
procedure SetTransparent(Value: Boolean);
protected
{ Protected declarations }
procedure RepaintWindow;
procedure CreateParams(var Params: TCreateParams); override;
procedure Change; override;
procedure SetParent(AParent: TWinControl); override;
procedure WMPaint(var Message: TWMPaint); message WM_PAINT;
procedure WMNCPaint (var Message: TMessage); message WM_NCPAINT;
procedure WMEraseBkGnd(var Message: TWMEraseBkGnd); message WM_ERASEBKGND;
procedure CNCtlColorEdit(var Message: TWMCtlColorEdit); message CN_CTLCOLOREDIT;
procedure CNCtlColorStatic(var Message: TWMCtlColorStatic); message CN_CTLCOLORSTATIC;
procedure CMParentColorChanged(var Message: TMessage); message CM_PARENTCOLORCHANGED;
procedure WMSize(var Message: TWMSize); message WM_SIZE;
procedure WMMove(var Message: TWMMove); message WM_MOVE;
procedure PaintParent(ACanvas: TCanvas);
public
{ Public declarations }
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
published
{ Published declarations }
property Align;
property AlignText: TAlignment read FAlignText write SetAlignText default taLeftJustify;
property Transparent: Boolean read FTransparent write SetTransparent default false;
end;
implementation
{ TZ9Edit }
uses
Forms;
type
TParentControl = class(TWinControl);
const
BorderRec: array[TBorderStyle] of Integer = (1, -1);
constructor TZ9Edit.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FAlignText := taLeftJustify;
FTransparent := false;
FPainting := false;
end;
destructor TZ9Edit.Destroy;
begin
inherited Destroy;
end;
procedure TZ9Edit.SetAlignText(Value: TAlignment);
begin
if FAlignText Value then
begin
FAlignText := Value;
RecreateWnd;
Invalidate;
end;
end;
procedure TZ9Edit.SetTransparent(Value: Boolean);
begin
if FTransparent Value then
begin
FTransparent := Value;
Invalidate;
end;
end;
procedure TZ9Edit.WMEraseBkGnd(var Message: TWMEraseBkGnd);
var
DC: hDC;
i: integer;
p: TPoint;
canvas : TCanvas;
begin
if FTransparent and not(csDesigning in componentstate) then
begin
canvas := TCanvas.create;
try
canvas.handle := message.dc;
PaintParent(Canvas);
finally
canvas.free;
end;
end
else
begin
canvas := TCanvas.create;
try
canvas.handle := message.dc;
canvas.brush.color := Color;
canvas.brush.style := bsSolid;
canvas.fillrect(clientrect);
finally
canvas.free;
end;
end;
end;
procedure TZ9Edit.WMPaint(var Message: TWMPaint);
begin
inherited;
if FTransparent then
if not FPainting then RepaintWindow;
end;
procedure TZ9Edit.WMNCPaint(var Message: TMessage);
begin
inherited;
end;
procedure TZ9Edit.CNCtlColorEdit(var Message: TWMCtlColorEdit);
begin
inherited;
if FTransparent then SetBkMode(Message.ChildDC, 1);
end;
procedure TZ9Edit.CNCtlColorStatic(var Message: TWMCtlColorStatic);
begin
inherited;
if FTransparent then SetBkMode(Message.ChildDC, 1);
end;
procedure TZ9Edit.CMParentColorChanged(var Message: TMessage);
begin
inherited;
if FTransparent then Invalidate;
end;
procedure TZ9Edit.WMSize(var Message: TWMSize);
var
r : TRect;
begin
inherited;
r := ClientRect;
InvalidateRect(handle,@r,false);
end;
procedure TZ9Edit.WMMove(var Message: TWMMove);
var
r : TRect;
begin
inherited;
Invalidate;
r := ClientRect;
InvalidateRect(handle,@r,false);
end;
procedure TZ9Edit.RepaintWindow;
var
DC: hDC;
TmpBitmap, Bitmap: hBitmap;
begin
if FTransparent then
begin
FPainting := true;
HideCaret(Handle);
DC := CreateCompatibleDC(GetDC(Handle));
TmpBitmap := CreateCompatibleBitmap(GetDC(Handle), Succ(ClientWidth), Succ(ClientHeight));
Bitmap := SelectObject(DC, TmpBitmap);
PaintTo(DC, 0, 0);
BitBlt(GetDC(Handle), BorderRec[BorderStyle] + BorderWidth, BorderRec[BorderStyle] + BorderWidth, ClientWidth, ClientHeight, DC, 1, 1, SRCCOPY);
SelectObject(DC, Bitmap);
DeleteDC(DC);
ReleaseDC(Handle, GetDC(Handle));
DeleteObject(TmpBitmap);
ShowCaret(Handle);
FPainting := false;
end;
end;
procedure TZ9Edit.CreateParams(var Params: TCreateParams);
const
Alignments: array [TAlignment] of DWord = (ES_LEFT, ES_RIGHT, ES_CENTER);
begin
inherited CreateParams(Params);
Params.Style := Params.Style or ES_MULTILINE or Alignments[FAlignText];
end;
procedure TZ9Edit.Change;
begin
RepaintWindow;
inherited Change;
end;
procedure TZ9Edit.SetParent(AParent: TWinControl);
begin
inherited SetParent(AParent);
end;
procedure TZ9Edit.PaintParent(ACanvas: TCanvas);
var
I, Count, X, Y, SaveIndex: integer;
DC: cardinal;
R, SelfR, CtlR: TRect;
Control : TControl;
begin
Control := Self;
if Control.Parent = nil then Exit;
Count := Control.Parent.ControlCount;
DC := ACanvas.Handle;
SelfR := Bounds(Control.Left, Control.Top, Control.Width, Control.Height);
X := -Control.Left; Y := -Control.Top;
// Copy parent control image
SaveIndex := SaveDC(DC);
SetViewportOrgEx(DC, X, Y, nil);
IntersectClipRect(DC, 0, 0, Control.Parent.ClientWidth, Control.Parent.ClientHeight);
TParentControl(Control.Parent).Perform(WM_ERASEBKGND,DC,0);
TParentControl(Control.Parent).PaintWindow(DC);
RestoreDC(DC, SaveIndex);
//Copy images of graphic controls
for I := 0 to Count - 1 do begin
if (Control.Parent.Controls[I] nil) then
begin
if Control.Parent.Controls[I] = Control then break;
with Control.Parent.Controls[I] do
begin
CtlR := Bounds(Left, Top, Width, Height);
if Bool(IntersectRect(R, SelfR, CtlR)) and Visible then
begin
SaveIndex := SaveDC(DC);
SetViewportOrgEx(DC, Left + X, Top + Y, nil);
IntersectClipRect(DC, 0, 0, Width, Height);
Perform(WM_ERASEBKGND,DC,0);
Perform(WM_PAINT, integer(DC), 0);
RestoreDC(DC, SaveIndex);
end;
end;
end;
end;
end;
end.