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.

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;