Preliminary realizes the rotating (arbitrary Angle, clockwise/counterclockwise), fixed Angle rotation (90180270 degrees clockwise/counterclockwise), flip, mirror, and other functions, converting speed can also,
There may be some BUGs, have time to test the,

 

{the VCL TBitmap Helper} 
{Supplemental methods to TBitmap for supporting} 
{the rotate, flip, mirror, etc.} 
{version 0.01} 
{written by DG, 2020-03-14} 

The unit Vcl. Graphics. BitmapHelper; 

Interface 

USES the Vcl. Graphics; 

Type 
TDirection=(dir90 dir180, dir270); 

TBitmapHelper=class helper for Vcl. Graphics. TBitmap 
Procedure Rotate (Rads: single; Clockwise: Boolean=false; 
AdjustSize: Boolean=true; BkColor: TColor=clWhite); The phrase "; 
Procedure Rotate (Direction: TDirection; Clockwise: Boolean=false); The phrase "; 
Procedure Flip. The inline. 
Procedure Mirror; The inline. 
Procedure FlipAndMirror; The inline. 
end; 

Implementation 

USES System. Classes, WinApi. Windows; 

//-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
//TBitmapHelper 

//the function TBitmapHelper. Rotate (Rads: single; . ) references to 
//following STACKOVERFLOW thread: 
//https://stackoverflow.com/questions/10633400/rotate-bitmap-by-real-angle 
Procedure TBitmapHelper. Rotate (Rads: single; Clockwise: Boolean=false; 
AdjustSize: Boolean=true; BkColor: TColor=clWhite); 
Var 
C: Single; 
S: Single; 
Tmp: Vcl. Graphics. TBitmap; 
OffsetX: Single; 
OffsetY: Single; 
Points: array [0.. 2] of TPoint; 
The begin 
If not Clockwise then//counterclockwise 
The begin 
Rads:=Frac (Rads/PI * PI); 
If Rads & lt; 0 then 
Rads:=PI * 2 + Rads 
The else 
Rads:=PI * 2 - Rads; 
end; 

C:=Cos (Rads); 
S:=Sin (Rads); 
Tmp:=the Vcl. Graphics. TBitmap. Create; 
Try 
Tmp. TransparentColor:=the Self. The TransparentColor; 
Tmp. TransparentMode:=Self. TransparentMode; 
Tmp. Transparent:=Self. Transparent; 
Tmp. Canvas. Brush. Color:=BkColor; 

If AdjustSize then 
The begin 
Tmp. Width:=Round (Self. Width * Abs (C) + Self in Height * Abs (S)); 
Tmp. Height:=Round (Self. Width * Abs (S) + Self in Height * Abs (C)); 
OffsetX:=(Tmp) Width - Self) Width * C + Self in Height * S)/2; 
OffsetY=(Tmp) Height - Self) Width * S - Self. The Height * C)/2; 
End 
The else 
The begin 
Tmp. Width:=the Self. The Width; 
Tmp. Height:=Self. Height; 
OffsetX:=(Self. Width - Self. Width * C + Self in Height * S)/2; 
OffsetY=(Self. Height - Self. Width * S - Self. The Height * C)/2; 
end; 

Points [0]. X:=Round (OffsetX); 
Points [0]. Y:=Round (OffsetY); 
Points. [1] : X=Round (OffsetX + Self. Width * C); 
Points [1]. Y:=Round (OffsetY + Self. Width * S); 
Points [2]. X:=Round (OffsetX - Self. Height * S); 
Points [2]. Y:=Round (OffsetY + Self. Height * C); 
PlgBlt (Tmp) Canvas) Handle, Points, 
Self. Canvas. Handle, 0, 0, the Self. The Width of the Self. The Height, 
0, 0, 0); 
The Self. The Assign (Tmp); 
The finally 
Tmp. Free; 
end; 
end; 

{$POINTERMATH ON} 
Procedure __RotateBitmap90 (var ABitmap: Vcl. Graphics. TBitmap; Clockwise: Boolean=false); 
Type 
TPtrMultiplex=record 
In case the integer of 
1: (P1: PByte); 
2: (P2: PWord); 
3: (P3: PRGBTriple); 
4: (P4: PCardinal); 
end; 
Var 
Tmp: Vcl. Graphics. TBitmap; 
BMP: WinApi. Windows. BITMAP; 
PixelSize: integer; 
SrcLineSize DestLineSize: integer; 
Src to Dest: pointer; 
PSrc, PDest: TPtrMultiplex; 
I, j: integer; 
The begin 
If not Assigned (ABitmap) or ABitmap. Empty then the exit; 

Tmp:=the Vcl. Graphics. TBitmap. Create; 
Tmp. TransparentColor:=ABitmap. TransparentColor; 
Tmp. TransparentMode:=ABitmap. TransparentMode; 
Tmp. Transparent:=ABitmap. Transparent; 

If ABitmap. PixelFormat in [pfDevice pf1bit, pf4bit, pfCustom] then 
The begin 
If ABitmap. PixelFormat=pfDevice then 
Tmp. PixelFormat:=pf32bit 
The else 
Tmp. PixelFormat:=pf8bit; 
Tmp. SetSize (ABitmap. Width, ABitmap. Height); 
Tmp. Canvas. The Draw (0, 0, ABitmap); 
ABitmap. Assign (Tmp); 
End 
The else 
Tmp. PixelFormat:=ABitmap. PixelFormat; 
Tmp. SetSize (ABitmap. Height, ABitmap. Width); 

If ABitmap. PixelFormat=pf8bit then 
SelectPalette (Tmp) Canvas) Handle, ABitmap. The Palette, false); 
GetObject (ABitmap. Handle, sizeof (BMP), @ BMP); 
If BMP. BmBitsPixel & gt; 8 then=
The begin 
PixelSize:=(BMP. BmBitsPixel + 7) div 8; 
SrcLineSize:=BMP. BmWidthBytes; 
Src:=BMP. BmBits; 
GetObject (Tmp) Handle, sizeof (BMP), @ BMP); 
DestLineSize:=BMP. BmWidthBytes; 
Dest:=BMP. BmBits; 

Case PixelSize of 
1: 
The begin 
PSrc. P1:=Src; 
If Clockwise, then 
For I:=0 to ABitmap. Do Height - 1 
The begin 
PDest. P1:=Dest; 
For j:=0 to ABitmap. Do Width - 1 
The begin 
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