请问如何水平翻转Bitmap？

[yancey]

var b:=TBitmap.Create();
b.assign(jpeg);

请问，如何将b水平翻转？

[winasm]

用IMAGE EN 控键

[qiujsh]

Here's code to rotate a bitmap 90 degrees

From: Dave Shapiro <[e-mail]>
Counterclockwise, that is. This rotates a 640x480 24-bit bitmap 90 degrees in about 2/10 of sec on my P133 (4MB video card, 128MB RAM). It works for Delphi 2, and should work for 1 and 3, too.

One thing: This does not work for bitmaps that aren't an integral number of colors per pixel. If that's the case, you'll have to do some bit twiddling. I'm working on that part right now (I need it too), but it'll be a few days. Anyways, suggestions, comments, etc., always welcome.

Special thanks to David Ullrich (ooh, I hope I spelled that correctly) for pointing out the non-published-but-public-anyway SaveToStream method for the TBitmap class.

Advance apologies for any formatting problems. Netscape's editor is so ridiculously crippled that I can't accomplish anything (give me rtin and vim any day).



--------------------------------------------------------------------------------

procedure RotateBitmap90Degrees(ABitmap: TBitmap);

const
BITMAP_HEADER_SIZE = SizeOf(TBitmapFileHeader) +
SizeOf(TBitmapInfoHeader);

var
{ Things that end in R are for the rotated image. }
PbmpInfoR: PBitmapInfoHeader;
bmpBuffer, bmpBufferR: PByte;
MemoryStream, MemoryStreamR: TMemoryStream;
PbmpBuffer, PbmpBufferR: PByte;
PbmpBufferRFirstScanLine, PbmpBufferColumnZero: PByte;
BytesPerPixel, BytesPerScanLine, BytesPerScanLineR: Integer;
X, Y, T: Integer;

begin
{
Don't *ever* call GetDIBSizes! It screws up your bitmap.
I'll be posting about that shortly.
}

MemoryStream := TMemoryStream.Create;

{
To do: Put in a SetSize, which will eliminate any reallocation
overhead.
}

ABitmap.SaveToStream(MemoryStream);

{
Don't need you anymore. We'll make a new one when the time comes.
}
ABitmap.Free;

bmpBuffer := MemoryStream.Memory;

{ Set PbmpInfoR to point to the source bitmap's info header. }
{ Boy, these headers are getting annoying. }
Inc( bmpBuffer, SizeOf(TBitmapFileHeader) );
PbmpInfoR := PBitmapInfoHeader(bmpBuffer);

{ Set bmpBuffer to point to the original bitmap bits. }
Inc(bmpBuffer, SizeOf(PbmpInfoR^));
{ Set the ColumnZero pointer to point to, uh, column zero. }
PbmpBufferColumnZero := bmpBuffer;

with PbmpInfoR^ do
begin
BytesPerPixel := biBitCount shr 3;
{ ScanLines are DWORD aligned. }
BytesPerScanLine := ((((biWidth * biBitCount) + 31) div 32) * SizeOf(DWORD));
BytesPerScanLineR := ((((biHeight * biBitCount) + 31) div 32) * SizeOf(DWORD));

{ The TMemoryStream that will hold the rotated bits. }
MemoryStreamR := TMemoryStream.Create;
{
Set size for rotated bitmap. Might be different from source size
due to DWORD aligning.
}
MemoryStreamR.SetSize(BITMAP_HEADER_SIZE + BytesPerScanLineR * biWidth);
end;

{ Copy the headers from the source bitmap. }
MemoryStream.Seek(0, soFromBeginning);
MemoryStreamR.CopyFrom(MemoryStream, BITMAP_HEADER_SIZE);

{ Here's the buffer we're going to rotate. }
bmpBufferR := MemoryStreamR.Memory;
{ Skip the headers, yadda yadda yadda... }
Inc(bmpBufferR, BITMAP_HEADER_SIZE);

{
Set up PbmpBufferRFirstScanLine and advance it to end of the first scan
line of bmpBufferR.
}
PbmpBufferRFirstScanLine := bmpBufferR;
Inc(PbmpBufferRFirstScanLine, (PbmpInfoR^.biHeight - 1) * BytesPerPixel);

{ Here's the meat. Loop through the pixels and rotate appropriately. }

{ Remember that DIBs have their origins opposite from DDBs. }
for Y := 1 to PbmpInfoR^.biHeight do
begin
PbmpBuffer := PbmpBufferColumnZero;
PbmpBufferR := PbmpBufferRFirstScanLine;

for X := 1 to PbmpInfoR^.biWidth do
begin
for T := 1 to BytesPerPixel do
begin
PbmpBufferR^ := PbmpBuffer^;
Inc(PbmpBufferR);
Inc(PbmpBuffer);
end;
Dec(PbmpBufferR, BytesPerPixel);
Inc(PbmpBufferR, BytesPerScanLineR);
end;

Inc(PbmpBufferColumnZero, BytesPerScanLine);
Dec(PbmpBufferRFirstScanLine, BytesPerPixel);
end;

{ Done with the source bits. }
MemoryStream.Free;

{ Now set PbmpInfoR to point to the rotated bitmap's info header. }
PbmpBufferR := MemoryStreamR.Memory;
Inc( PbmpBufferR, SizeOf(TBitmapFileHeader) );
PbmpInfoR := PBitmapInfoHeader(PbmpBufferR);

{ Swap the width and height of the rotated bitmap's info header. }
with PbmpInfoR^ do
begin
T := biHeight;
biHeight := biWidth;
biWidth := T;
end;

ABitmap := TBitmap.Create;

{ Spin back to the very beginning. }
MemoryStreamR.Seek(0, soFromBeginning);
ABitmap.LoadFromStream(MemoryStreamR);

MemoryStreamR.Free;
end;

[xiaoxiao197821]

procedure RotateBmp(bmp: TBitmap; Center: TPoint; angle: Integer);
var
tmpbmp: TBitmap;
i, j, x, y, px, py: Integer;
cAngle, sAngle: extended;
p1, p2: Pchar;
begin
while angle < 0 do
angle := angle + 360;
angle := angle mod 360;
sAngle := sin(- angle * pi / 180);
cAngle := cos(- angle * pi / 180);
tmpbmp := tbitmap.create;
tmpbmp.assign(bmp);
for i := 0 to tmpbmp.height - 1 do
begin
p1 := pchar(tmpbmp.scanline[i]);
py := 2 * (i - center.y) - 1;
for j := 0 to tmpbmp.width - 1 do
begin
px := 2 * (j - center.x) - 1;
x := (round(px * cAngle - py * sAngle) - 1) div 2 + center.x;
y := (round(px * sAngle + py * cAngle) - 1) div 2 + center.y;
if (x>=0) and (x<tmpbmp.width) and (y>=0) and (y<=tmpbmp.height) then
begin
p2 := pchar(bmp.scanline[y]) + x * 3;
move(p1^, p2^, 3);
end;
inc(p1, 3);
end;
end;
end;

[XuDunYu]

study

[火猴]

楼上的够长~~

[caiso]

哥们，都来关注一下，
关注ing...........

[Kshape]

关注ing...........

[alexanda2000]

procedure TForm1.Button1Click(Sender: TObject);
var
bmp1,bmp2:TBitmap;
SrcR,DesR:TRect;
x,y:Integer;
begin
bmp1:=TBitmap.Create;
bmp2:=Tbitmap.Create;
Try
bmp1.LoadFromFile('e:\test.bmp');
x:=bmp1.Width;
y:=bmp1.Height;
SrcR:=Rect(0,0,x,y);
DesR:=Rect(x,0,0,y);
bmp2.Width:=x;
bmp2.Height:=y;
bmp2.Canvas.CopyRect(DesR,bmp1.Canvas,SrcR);
canvas.Draw(0,0,bmp2); //将反转后的图像画在窗体上
Finally
bmp1.Free;
bmp2.Free;
end;
end;

[jackie168]

//水平翻转：

procedure FlipHorz(const Bitmap:TBitmap);

var

i,j:Integer;

rowIn,rowOut:pRGBTriple;

Bmp:TBitmap;

Width,Height:Integer;

begin

Bmp:=TBitmap.Create;

Bmp.Width := Bitmap.Width;

Bmp.Height := Bitmap.Height;

Bmp.PixelFormat := pf24bit;

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[j];

Inc(rowOut,Width - i);

rowOut^ := rowIn^;

Inc(rowIn);

end;

end;

Bitmap.Assign(Bmp);

end;

[blfriend_2000]

其实我觉得只要把握好原理就好。

其实原理很简单的就是把水平的象素点的RGB值对称的换掉就行

比如象素点 1 2 3 4 5 6……n
1 2 3 4 5 6……n
……
……

只要把每一行的 1<->n , 2<->n-1 , 3<->n-2 ……象素点的RGB值互换就行。

如果垂直反转的话就互换列对应的象素点的RGB值。

[ehom]

type
PBGRA = ^TBGRA;
TBGRA = packed record
B, G, R, A: Byte;
end;

procedure FlipHorz(const ABitmap: TBitmap);
var
i, j: Integer;
SrcRow, DestRow, Row: PBGRA;
Width, Height: Integer;
begin
//for pf32bit;
Width := ABitmap.Width;
Height := ABitmap.Height;
GetMem(Row, 4);
for J := 0 to Height - 1 do
begin
SrcRow := ABitmap.ScanLine[j];
DestRow := SrcRow;
Inc(DestRow, Width - 1);
for I := 0 to (Width div 2) - 1 do
begin
Row^ := SrcRow^;
SrcRow^ := DestRow^;
DestRow^ := Row^;
Inc(SrcRow);
Dec(DestRow);
end;
end;
FreeMem(Row);
end;

[eWong2016]

学习：）

[todouwang]

mark;

[constantine]

用copyrect直接吧rect参数坐标调一下就可以了

[newlife2005]

学习

[luxuinstan]

procedure TForm1.Button1Click(Sender: TObject);
var
bmp1,bmp2:TBitmap;
SrcR,DesR:TRect;
x,y:Integer;
begin
bmp1:=TBitmap.Create;
bmp2:=Tbitmap.Create;
Try
bmp1.LoadFromFile('e:\test.bmp');
x:=bmp1.Width;
y:=bmp1.Height;
SrcR:=Rect(0,0,x,y);
DesR:=Rect(x,0,0,y);
bmp2.Width:=x;
bmp2.Height:=y;
bmp2.Canvas.CopyRect(DesR,bmp1.Canvas,SrcR);
canvas.Draw(0,0,bmp2); //将反转后的图像画在窗体上
Finally
bmp1.Free;
bmp2.Free;
end;
end;

这个方法正确

[hexenzhou]

CopyRect这个方法最简单了，还真没有想到，学习！