[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); v [1] [2] 下一页 没有相关教程
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