unit PixelPointer;

interface

uses
  Math, Classes, SysUtils, Graphics;

type
  TColor32 = type Cardinal;
  TColor32Component = (ccBlue, ccGreen, ccRed, ccAlpha);
  TColor32Planes = array[0..3] of Byte;

  { TPixel32 }

  TPixel32 = packed record
  private
    procedure SetRGB(AValue: Cardinal); inline;
    function GetRGB: Cardinal; inline;
  public
    class function CreateRGB(R, G, B: Byte): TPixel32; static;
    class function CreateRGBA(R, G, B, A: Byte): TPixel32; static;
    property RGB: Cardinal read GetRGB write SetRGB;
    case Integer of
      0: (B, G, R, A: Byte);
      1: (ARGB: TColor32);
      2: (Planes: TColor32Planes);
      3: (Components: array[TColor32Component] of Byte);
  end;
  PPixel32 = ^TPixel32;

  { TPixelPointer }

  TPixelPointer = record
  private
    function GetPixelARGB: TColor32; inline;
    function GetPixelB: Byte; inline;
    function GetPixelG: Byte; inline;
    function GetPixelPlane(Index: Byte): Byte; inline;
    function GetPixelR: Byte; inline;
    function GetPixelA: Byte; inline;
    function GetPixelPlanes: TColor32Planes;
    function GetPixelRGB: Cardinal; inline;
    procedure SetPixelARGB(Value: TColor32); inline;
    procedure SetPixelB(Value: Byte); inline;
    procedure SetPixelG(Value: Byte); inline;
    procedure SetPixelPlane(Index: Byte; AValue: Byte); inline;
    procedure SetPixelR(Value: Byte); inline;
    procedure SetPixelA(Value: Byte); inline;
    procedure SetPixelRGB(Value: Cardinal); inline;
  public
    Base: PPixel32;
    Pixel: PPixel32;
    Line: PPixel32;
    RelLine: PPixel32;
    BytesPerPixel: Integer;
    BytesPerLine: Integer;
    Data: PPixel32;
    Width: Integer;
    Height: Integer;
    procedure NextLine; inline; // Move pointer to start of next line
    procedure PreviousLine; inline; // Move pointer to start of previous line
    procedure NextPixel; inline; // Move pointer to next pixel
    procedure PreviousPixel; inline; // Move pointer to previous pixel
    procedure SetXY(X, Y: Integer); inline; // Set pixel position relative to base
    procedure SetX(X: Integer); inline; // Set horizontal pixel position relative to base
    procedure CheckRange; inline; // Check if current pixel position is not out of range
    function PosValid: Boolean;
    class function Create(Bitmap: TRasterImage; BaseX: Integer = 0; BaseY: Integer = 0): TPixelPointer; static;
    property PixelARGB: TColor32 read GetPixelARGB write SetPixelARGB;
    property PixelRGB: Cardinal read GetPixelRGB write SetPixelRGB;
    property PixelB: Byte read GetPixelB write SetPixelB;
    property PixelG: Byte read GetPixelG write SetPixelG;
    property PixelR: Byte read GetPixelR write SetPixelR;
    property PixelA: Byte read GetPixelA write SetPixelA;
    property PixelPlane[Index: Byte]: Byte read GetPixelPlane write SetPixelPlane;
  end;
  PPixelPointer = ^TPixelPointer;

  function SwapRedBlue(Color: TColor32): TColor32;
  procedure BitmapCopyRect(DstBitmap: TRasterImage; DstRect: TRect; SrcBitmap: TRasterImage; SrcPos: TPoint);
  procedure BitmapStretchRect(DstBitmap: TRasterImage; DstRect: TRect;
    SrcBitmap: TRasterImage; SrcRect: TRect);
  procedure BitmapFill(Bitmap: TRasterImage; Color: TColor32);
  procedure BitmapFillRect(Bitmap: TRasterImage; Color: TColor32; Rect: TRect);
  procedure BitmapSwapRedBlue(Bitmap:TRasterImage);
  procedure BitmapInvert(Bitmap: TRasterImage);
  procedure BitmapBlendColor(Bitmap: TRasterImage; Color: TColor32);
  function Color32(A, R, G, B: Byte): TColor32;
  function Color32ToPixel32(Color: TColor32): TPixel32;
  function Pixel32ToColor32(Color: TPixel32): TColor32;
  function Color32ToColor(Color: TColor32): TColor;
  function ColorToColor32(Color: TColor): TColor32;


implementation

resourcestring
  SOutOfRange = 'Pixel pointer out of range [X: %d, Y: %d, Width: %d, Height: %d]';
  SWrongBitmapSize = 'Wrong bitmap size [width: %d, height: %d]';

{ TPixel32 }

function TPixel32.GetRGB: Cardinal;
begin
  Result := ARGB and $ffffff;
end;

class function TPixel32.CreateRGB(R, G, B: Byte): TPixel32;
begin
  Result.R := R;
  Result.G := G;
  Result.B := B;
  Result.A := 0;
end;

class function TPixel32.CreateRGBA(R, G, B, A: Byte): TPixel32;
begin
  Result.R := R;
  Result.G := G;
  Result.B := B;
  Result.A := A;
end;

procedure TPixel32.SetRGB(AValue: Cardinal);
begin
  ARGB := (ARGB and $ff000000) or (AValue and $ffffff);
end;

{ TPixelPointer }

procedure TPixelPointer.NextLine; inline;
begin
  Line := Pointer(Line) + BytesPerLine;
  Pixel := Line;
end;

procedure TPixelPointer.PreviousLine;
begin
  Line := Pointer(Line) - BytesPerLine;
  Pixel := Line;
end;

procedure TPixelPointer.NextPixel; inline;
begin
  Pixel := Pointer(Pixel) + BytesPerPixel;
end;

procedure TPixelPointer.PreviousPixel;
begin
  Pixel := Pointer(Pixel) - BytesPerPixel;
end;

procedure TPixelPointer.SetXY(X, Y: Integer); inline;
begin
  Line := Pointer(Base) + Y * BytesPerLine;
  SetX(X);
end;

procedure TPixelPointer.SetX(X: Integer); inline;
begin
  Pixel := Pointer(Line) + X * BytesPerPixel;
end;

procedure TPixelPointer.CheckRange;
{$IFOPT R+}
var
  X: Integer;
  Y: Integer;
{$ENDIF}
begin
  {$IFOPT R+}
  if (PByte(Pixel) < PByte(Data)) or
    (PByte(Pixel) >= PByte(Data) + Height * BytesPerLine) then begin
    X := PByte(Pixel) - PByte(Data);
    Y := Floor(X / BytesPerLine);
    X := X - Y * BytesPerLine;
    X := Floor(X / BytesPerPixel);
    raise Exception.Create(Format(SOutOfRange, [X, Y, Width, Height]));
  end;
  {$ENDIF}
end;

function TPixelPointer.PosValid: Boolean;
begin
  Result := not ((PByte(Pixel) < PByte(Data)) or
    (PByte(Pixel) >= PByte(Data) + Height * BytesPerLine));
end;

function TPixelPointer.GetPixelPlanes: TColor32Planes;
begin
  CheckRange;
  Result := Pixel^.Planes;
end;

function TPixelPointer.GetPixelRGB: Cardinal;
begin
  CheckRange;
  Result := Pixel^.RGB;
end;

procedure TPixelPointer.SetPixelARGB(Value: TColor32);
begin
  CheckRange;
  Pixel^.ARGB := Value;
end;

procedure TPixelPointer.SetPixelB(Value: Byte);
begin
  CheckRange;
  Pixel^.B := Value;
end;

procedure TPixelPointer.SetPixelG(Value: Byte);
begin
  CheckRange;
  Pixel^.G := Value;
end;

procedure TPixelPointer.SetPixelPlane(Index: Byte; AValue: Byte);
begin
  CheckRange;
  Pixel^.Planes[Index] := AValue;
end;

procedure TPixelPointer.SetPixelR(Value: Byte);
begin
  CheckRange;
  Pixel^.R := Value;
end;

procedure TPixelPointer.SetPixelA(Value: Byte);
begin
  CheckRange;
  Pixel^.A := Value;
end;

function TPixelPointer.GetPixelARGB: TColor32;
begin
  CheckRange;
  Result := Pixel^.ARGB;
end;

function TPixelPointer.GetPixelB: Byte;
begin
  CheckRange;
  Result := Pixel^.B;
end;

function TPixelPointer.GetPixelG: Byte;
begin
  CheckRange;
  Result := Pixel^.G;
end;

function TPixelPointer.GetPixelPlane(Index: Byte): Byte;
begin
  CheckRange;
  Result := Pixel^.Planes[Index];
end;

function TPixelPointer.GetPixelR: Byte;
begin
  CheckRange;
  Result := Pixel^.R;
end;

function TPixelPointer.GetPixelA: Byte;
begin
  CheckRange;
  Result := Pixel^.A;
end;

procedure TPixelPointer.SetPixelRGB(Value: Cardinal);
begin
  CheckRange;
  Pixel^.RGB := Value;
end;

procedure BitmapCopyRect(DstBitmap: TRasterImage; DstRect: TRect;
  SrcBitmap: TRasterImage; SrcPos: TPoint);
var
  SrcPtr, DstPtr: TPixelPointer;
  X, Y: Integer;
begin
  SrcBitmap.BeginUpdate(True);
  DstBitmap.BeginUpdate(True);
  SrcPtr := TPixelPointer.Create(SrcBitmap, SrcPos.X, SrcPos.Y);
  DstPtr := TPixelPointer.Create(DstBitmap, DstRect.Left, DstRect.Top);
  for Y := 0 to DstRect.Height - 1 do begin
    for X := 0 to DstRect.Width - 1 do begin
      DstPtr.PixelARGB := SrcPtr.PixelARGB;
      SrcPtr.NextPixel;
      DstPtr.NextPixel;
    end;
    SrcPtr.NextLine;
    DstPtr.NextLine;
  end;
  SrcBitmap.EndUpdate;
  DstBitmap.EndUpdate;
end;

procedure BitmapStretchRect(DstBitmap: TRasterImage; DstRect: TRect;
  SrcBitmap: TRasterImage; SrcRect: TRect);
var
  SrcPtr, DstPtr: TPixelPointer;
  X, Y: Integer;
  XX, YY: Integer;
  R: TRect;
  C: TColor32;
begin
  if (DstRect.Width = SrcRect.Width) and (DstRect.Height = SrcRect.Height) then begin
    BitmapCopyRect(DstBitmap, DstRect, SrcBitmap, Point(SrcRect.Left, SrcRect.Top));
    Exit;
  end;
  SrcBitmap.BeginUpdate(True);
  DstBitmap.BeginUpdate(True);
  SrcPtr := TPixelPointer.Create(SrcBitmap, SrcRect.Left, SrcRect.Top);
  DstPtr := TPixelPointer.Create(DstBitmap, DstRect.Left, DstRect.Top);
  for Y := 0 to DstRect.Height - 1 do begin
    for X := 0 to DstRect.Width - 1 do begin
      R := Rect(Trunc(X * SrcRect.Width / DstRect.Width),
        Trunc(Y * SrcRect.Height / DstRect.Height),
        Trunc((X + 1) * SrcRect.Width / DstRect.Width),
        Trunc((Y + 1) * SrcRect.Height / DstRect.Height));
      DstPtr.SetXY(X, Y);
      SrcPtr.SetXY(R.Left, R.Top);
      C := SrcPtr.PixelARGB;
      DstPtr.PixelARGB := C;
      for YY := 0 to R.Height - 1 do begin
        for XX := 0 to R.Width - 1 do begin
          DstPtr.PixelARGB := C;
          DstPtr.NextPixel;
        end;
        DstPtr.NextLine;
      end;
    end;
  end;
  SrcBitmap.EndUpdate;
  DstBitmap.EndUpdate;
end;

procedure BitmapFill(Bitmap: TRasterImage; Color: TColor32);
var
  X, Y: Integer;
  Ptr: TPixelPointer;
begin
  Bitmap.BeginUpdate(True);
  Ptr := TPixelPointer.Create(Bitmap);
  for Y := 0 to Bitmap.Height - 1 do begin
    for X := 0 to Bitmap.Width - 1 do begin
      Ptr.PixelARGB := Color;
      Ptr.NextPixel;
    end;
    Ptr.NextLine;
  end;
  Bitmap.EndUpdate;
end;

procedure BitmapFillRect(Bitmap: TRasterImage; Color: TColor32; Rect: TRect);
var
  X, Y: Integer;
  Ptr: TPixelPointer;
begin
  Bitmap.BeginUpdate(True);
  Ptr := TPixelPointer.Create(Bitmap, Rect.Left, Rect.Top);
  for Y := 0 to Rect.Height - 1 do begin
    for X := 0 to Rect.Width - 1 do begin
      Ptr.PixelARGB := Color;
      Ptr.NextPixel;
    end;
    Ptr.NextLine;
  end;
  Bitmap.EndUpdate;
end;

procedure BitmapSwapRedBlue(Bitmap: TRasterImage);
var
  X, Y: Integer;
  Ptr: TPixelPointer;
begin
  Bitmap.BeginUpdate(True);
  Ptr := TPixelPointer.Create(Bitmap);
  for Y := 0 to Bitmap.Height - 1 do begin
    for X := 0 to Bitmap.Width - 1 do begin
      Ptr.PixelARGB := SwapRedBlue(Ptr.PixelARGB);
      Ptr.NextPixel;
    end;
    Ptr.NextLine;
  end;
  Bitmap.EndUpdate;
end;

procedure BitmapInvert(Bitmap: TRasterImage);
var
  X, Y: Integer;
  Ptr: TPixelPointer;
begin
  Bitmap.BeginUpdate(True);
  Ptr := TPixelPointer.Create(Bitmap);
  for Y := 0 to Bitmap.Height - 1 do begin
    for X := 0 to Bitmap.Width - 1 do begin
      Ptr.PixelARGB := Ptr.PixelARGB xor $ffffff;
      Ptr.NextPixel;
    end;
    Ptr.NextLine;
  end;
  Bitmap.EndUpdate;
end;

procedure BitmapBlendColor(Bitmap: TRasterImage; Color: TColor32);
var
  X, Y: Integer;
  Ptr: TPixelPointer;
  A, R, G, B: Word;
  Pixel: TPixel32;
begin
  Pixel := Color32ToPixel32(Color);
  Bitmap.BeginUpdate(True);
  Ptr := TPixelPointer.Create(Bitmap);
  for Y := 0 to Bitmap.Height - 1 do begin
    for X := 0 to Bitmap.Width - 1 do begin
      A := Ptr.PixelA; //(Ptr.PixelA + Pixel.A) shr 1;
      R := (Ptr.PixelR + Pixel.R) shr 1;
      G := (Ptr.PixelG + Pixel.G) shr 1;
      B := (Ptr.PixelB + Pixel.B) shr 1;
      Ptr.PixelARGB := Color32(A, R, G, B);
      Ptr.NextPixel;
    end;
    Ptr.NextLine;
  end;
  Bitmap.EndUpdate;
end;

function Color32(A, R, G, B: Byte): TColor32;
begin
  Result := ((A and $ff) shl 24) or ((R and $ff) shl 16) or
    ((G and $ff) shl 8) or ((B and $ff) shl 0);
end;

function Color32ToPixel32(Color: TColor32): TPixel32;
begin
  Result.ARGB := Color;
end;

function Pixel32ToColor32(Color: TPixel32): TColor32;
begin
  Result := Color.ARGB;
end;

function Color32ToColor(Color: TColor32): TColor;
begin
  Result := ((Color shr 16) and $ff) or (Color and $00ff00) or
    ((Color and $ff) shl 16);
end;

function ColorToColor32(Color: TColor): TColor32;
begin
  Result := $ff000000 or ((Color shr 16) and $ff) or (Color and $00ff00) or
    ((Color and $ff) shl 16);
end;

class function TPixelPointer.Create(Bitmap: TRasterImage; BaseX: Integer;
  BaseY: Integer): TPixelPointer;
begin
  Result.Width := Bitmap.Width;
  Result.Height := Bitmap.Height;
  if (Result.Width < 0) or (Result.Height < 0) then
    raise Exception.Create(Format(SWrongBitmapSize, [Result.Width, Result.Height]));
  Result.BytesPerLine := Bitmap.RawImage.Description.BytesPerLine;
  Result.BytesPerPixel := Bitmap.RawImage.Description.BitsPerPixel shr 3;
  Result.Data := PPixel32(Bitmap.RawImage.Data);
  Result.Base := PPixel32(Bitmap.RawImage.Data + BaseX * Result.BytesPerPixel +
    BaseY * Result.BytesPerLine);
  Result.SetXY(0, 0);
end;

function SwapRedBlue(Color: TColor32): TColor32;
begin
  Result := (Color and $ff00ff00) or ((Color and $ff) shl 16) or ((Color shr 16) and $ff);
end;

end.