[图像的旋转和翻转]
以下代码只能用于24位色的位图，用于处理其它色深的位图请自行修改。
//旋转90度
procedure Rotate90(const Bitmap:TBitmap);
var
i, j: Integer;
rowIn,rowOut: PRGBTriple;
Bmp: TBitmap;
Width,Height: Integer;
begin
Bmp := TBitmap.Create;
Bmp.Width := Bitmap.Height;
Bmp.Height := Bitmap.Width;
Width := Bitmap.Width - 1;
Height := Bitmap.Height - 1;
for j := 0 to Height do
begin
rowIn := Bitmap.ScanLine[j];
for i := 0 to Width do
begin
rowOut := Bmp.ScanLine[i];
Inc(rowOut, Height - j);
rowOut^ := rowIn^;
Inc(rowIn);
end;
end;
Bitmap.Assign(Bmp);
end;
//旋转180度
procedure Rotate180(const Bitmap:TBitmap);
var
i, j: Integer;
row1, row2, row3, rowRGB: PRGBTriple;;
Width, Height: Integer;
begin
Width := Bitmap.Width;
Height := Bitmap.Height;
GetMem(rowRGB, Width * 3);
Bitmap.PixelFormat := pf32bit;
for j := 0 to (Height div 2) - 1 do
begin
row1 := Bitmap.ScanLine[j];
row3 := row1;
Inc(row3, Width - 1);
for i := 0 to (Width div 2) - 1 do
begin
rowRGB^ := row1^;
row1^ := row3^;
row3^ := rowRGB^;
Inc(row1);
Dec(row3);
end;
row2 := Bitmap.ScanLine[Height - j - 1];
row3 := row2;
Inc(row3, Width - 1);
for i := 0 to (Width div 2) - 1 do
begin
rowRGB^ := row2^;
row2^ := row3^;
row3^ := rowRGB^;
Inc(row2);
Dec(row3);
end;
Dec(row1, (Width div 2));
Dec(row2, (Width div 2));
CopyMemory(rowRGB, row1, Width * 3);
CopyMemory(row1, row2, Width * 3);
CopyMemory(row2, rowRGB, Width * 3);
end;
if Height mod 2 = 1 then
begin
row1 := Bitmap.ScanLine[(Width div 2) + 1];
row2 := row1;
Inc(row2, Width - 1);
for i := 0 to (Width div 2) - 1 do
begin
rowRGB^ := row1^;
row1^ := row2^;
row2^ := rowRGB^;
Inc(row1);
Dec(row2);
end;
end;
FreeMem(rowRGB);
end;
//旋转270度
procedure Rotate270(const Bitmap:TBitmap);
var
i, j: Integer;
rowIn, rowOut: PRGBTriple;
Bmp: TBitmap;
Width,Height: Integer;
begin
Bmp := TBitmap.Create;
Bmp.Width := Bitmap.Height;
Bmp.Height := Bitmap.Width;
Width := Bitmap.Width - 1;
Height:= Bitmap.Height - 1;
for j := 0 to Height do
begin
rowIn := Bitmap.ScanLine[j];
for i := 0 to Width do
begin
rowOut := Bmp.ScanLine[Width - i];
Inc(rowOut,j);
rowOut^ := rowIn^;
Inc(rowIn);
end;
end;
Bitmap.Assign(Bmp);
end;
前面为判断部分，如果是90,180,270这类特殊角度，将调用上面的代码，这样效率更高！
//任意角度
function RotateBitmap(const Bitmap:TBitmap;Angle:Integer;BackColor:TColor):TBitmap;
var
i,j,iOriginal,jOriginal,CosPoint,SinPoint : integer;
RowOriginal,RowRotated : pRGBTriple;
SinTheta,CosTheta : Extended;
AngleAdd : integer;
begin
Result:=TBitmap.Create;
Result.PixelFormat := pf24bit;
Result.Canvas.Brush.Color:=BackColor;
Angle:=Angle Mod 360;
if Angle<0 then Angle:=360-Abs(Angle);
if Angle=0 then
Result.Assign(Bitmap)
else if Angle=90 then
begin
Result.Assign(Bitmap);
Rotate90(Result);//如果是旋转90度，直接调用上面的代码
end
else if (Angle>90) and (Angle<180) then
begin
AngleAdd:=90;
Angle:=Angle-AngleAdd;
end
else if Angle=180 then
begin
Result.Assign(Bitmap);
Rotate180(Result);//如果是旋转180度，直接调用上面的过程
end
else if (Angle>180) and (Angle<270) then
begin
AngleAdd:=180;
Angle:=Angle-AngleAdd;
end
else if Angle=270 then
begin
Result.Assign(Bitmap);
Rotate270(Result);//如果是旋转270度，直接调用上面的过程
end
else if (Angle>270) and (Angle<360) then
begin
AngleAdd:=270;
Angle:=Angle-AngleAdd;
end
else
AngleAdd:=0;
if (Angle>0) and (Angle<90) then
begin
SinCos((Angle + AngleAdd) * Pi / 180, SinTheta, CosTheta);
if (SinTheta * CosTheta) < 0 then
begin
Result.Width := Round(Abs(Bitmap.Width * CosTheta - Bitmap.Height * SinTheta));
Result.Height := Round(Abs(Bitmap.Width * SinTheta - Bitmap.Height * CosTheta));
end
else
begin
Result.Width := Round(Abs(Bitmap.Width * CosTheta + Bitmap.Height * SinTheta));
Result.Height := Round(Abs(Bitmap.Width * SinTheta + Bitmap.Height * CosTheta));
end;
CosTheta:=Abs(CosTheta);
SinTheta:=Abs(SinTheta);
if (AngleAdd=0) or (AngleAdd=180) then
begin
CosPoint:=Round(Bitmap.Height*CosTheta);
SinPoint:=Round(Bitmap.Height*SinTheta);
end
else
begin
SinPoint:=Round(Bitmap.Width*CosTheta);
CosPoint:=Round(Bitmap.Width*SinTheta);
end;
for j := 0 to Result.Height-1 do
begin
RowRotated := Result.Scanline[j];
for i := 0 to Result.Width-1 do
begin
Case AngleAdd of
0:
begin
jOriginal := Round((j+1)*CosTheta-(i+1-SinPoint)*SinTheta)-1;
iOriginal := Round((i+1)*CosTheta-(CosPoint-j-1)*SinTheta)-1;
end;
90:
begin
iOriginal := Round((j+1)*SinTheta-(i+1-SinPoint)*CosTheta)-1;
jOriginal := Bitmap.Height-Round((i+1)*SinTheta-(CosPoint-j-1)*CosTheta);
end;
180:
begin
jOriginal := Bitmap.Height-Round((j+1)*CosTheta-(i+1-SinPoint)*SinTheta);
iOriginal := Bitmap.Width-Round((i+1)*CosTheta-(CosPoint-j-1)*SinTheta);
end;
270:
begin
iOriginal := Bitmap.Width-Round((j+1)*SinTheta-(i+1-SinPoint)*CosTheta);
jOriginal := Round((i+1)*SinTheta-(CosPoint-j-1)*CosTheta)-1;
end;
end;
if (iOriginal >= 0) and (iOriginal <= Bitmap.Width-1)and
(jOriginal >= 0) and (jOriginal <= Bitmap.Height-1)
then
begin
RowOriginal := Bitmap.Scanline[jOriginal];
Inc(RowOriginal,iOriginal);
RowRotated^ := RowOriginal^;
Inc(RowRotated);
end
else
begin
Inc(RowRotated);
end;
end;
end;
end;
end;
虽然这已经实现了图像任意角度的旋转，但注意看看上面的代码，都是用Round取整，也就是在原图中找最近的像素填充到新图中，这样在边缘会产生锯齿！如果想效果更好，应该是用四个像素的值运算后得到新像素的值！
如对应到原图的坐标是(6.3,8.6)，用第一种方法可能就用(6,9)填充了该像素，但如果想消除边缘锯齿，就应该用(6,8)、(6,9)、(7,8)、(7,9)运算得出新点的像素，而边缘就用颜色等于背景色的点代替！
感兴趣的朋友可以找些二次线性插值资料看看，或者以后再讨论，这里就不多说了！
//水平翻转
procedure FlipHorz(const Bitmap:TBitmap);
var
i, j: Integer;
row1, row2, rowRGB: pRGBTriple;
Width, Height: Integer;
begin
Width := Bitmap.Width;
Height := Bitmap.Height;
GetMem(rowRGB, 3);
for j := 0 to Height - 1 do
begin
row1 := Bitmap.ScanLine[j];
row2 := row1;
Inc(row2, Width - 1);
for i := 0 to (Width div 2) - 1 do
begin
rowRGB^ := row1^;
row1^ := row2^;
row2^ := rowRGB^;
Inc(row1);
Dec(row2);
end;
end;
FreeMem(rowRGB);
end;
//垂直翻转
procedure FlipVert(const Bitmap:TBitmap);
var
i, j: Integer;
row1, row2, rowRGB: pRGBTriple;
Width, Height: Integer;
begin
Height := Bitmap.Height;
Width := Bitmap.Width;
GetMem(rowRGB, Width * 3);
for j := 0 to (Height div 2) - 1 do
begin
row1 := Bitmap.ScanLine[j];
row2 := Bitmap.ScanLine[Height - j -1];
CopyMemory(rowRGB, row1, Width * 3);
CopyMemory(row1, row2, Width * 3);
CopyMemory(row2, rowRGB, Width * 3);
end;
FreeMem(rowRGB);
end;
