关于图像合成所引申的几个函数

偶然在论坛上看到提问，将图片B合成到图片A上，并且在A上写字

于是，随手写的一个函数，具体代码如下：

{作者：不得闲

2009-02-11}

function HeCheng(A,b:TBitmap;const TransPercent: integer=50):TBitmap;
var
i,j: integer;
p1,p2: PByteArray;
count,MinBegin: Integer;
MinHeight: integer;
MinWidth,MaxWidth: Integer;
r: TRect;
begin
A.PixelFormat := pf32bit;
b.PixelFormat := pf32bit;

MinHeight := Min(A.Height,B.Height);
MinWidth := Min(A.Width,B.Width);
MaxWidth := Max(A.Width,B.Width);

MinBegin := 4 * ((MaxWidth - MinWidth) Div 2);
count := 4 * (MaxWidth-(MaxWidth - MinWidth) Div 2 - 1);

for i := 0 to MinHeight - 1 do
begin
if MinHeight = B.Height then
begin
p1 := A.ScanLine[i];
p2 := B.ScanLine[i];
end
else
begin
p1 := B.ScanLine[i];
p2 := A.ScanLine[i];
end;
j := MinBegin;
while j < count do
begin
if (p2[j - MinBegin] = 255) and (p2[j-MinBegin+1] = 255) and (p2[j-MinBegin+2]=255) then
inc(j,4)
else
begin
p1[j] := p1[j] + TransPercent * (p2[j-MinBegin] - p1[j]) div 100;
inc(j);
end;
end;
end;
if MinHeight = B.Height then
begin
r.Top := A.Height - A.Canvas.TextHeight('你好')-5;
r.Bottom := A.Height;
r.Left := 0;
r.Right := A.Width;
A.Canvas.Brush.Style := bsclear;
windows.DrawText(A.Canvas.Handle,'你好',-1,r,DT_Center or DT_VCenter or DT_SIngleLine);
Result := A;
end
else
begin
r.Top := B.Height - B.Canvas.TextHeight('你好')-5;
r.Bottom := B.Height;
r.Left := 0;
r.Right := B.Width;
B.Canvas.Brush.Style := bscleae r;
windows.DrawText(B.Canvas.Handle,'你好',-1,r,DT_Center or DT_VCenter or DT_SIngleLine);
Result := B;
end;
end;

这里，我先将位图A和B都转化成了pf32bit，此时每个位图的每个像素点由4个字节存储

存储的方式为 BGRL，所以，总的字节数应该是 4*宽度

过滤掉白色，也就是RGB分别为255的时候，不处理合成则可。

由上面我们又可以引申一个函数，可以用来过滤任何颜色的，也就是说，指定一个颜色，只要图片中含有该颜色的区域就过滤掉，比如，图片B中含有红蓝两色，此时设置一个红色过滤色，哪么合成之后B图中的红色被过滤掉

代码如下：

{-------------------------------------------------------------------------------
过程名: TColorToRGB
作者: 不得闲
日期: 2009.02.11
参数: const Color: TColor; var R, G, B: Byte
返回值: 无
用途： 获得颜色的RGB值
-------------------------------------------------------------------------------}
procedure TColorToRGB(const Color: TColor; var R, G, B: Byte);
var
C: Integer;
begin
C := ColorToRGB(Color);
R := C and $FF;
G := (C shr 8) and $FF;
B := (C shr 16) and $FF;
end;
{-------------------------------------------------------------------------------
过程名: HeCheng
作者: 不得闲
日期: 2009.02.11
参数: A,b: 指定合成位图
TransPercent: 设置透明度
ignoreColor: 设置合成时忽略的颜色
ColorOffset: 透明色的边缘色差(在该色差内的颜色都将忽略掉)

返回值: TBitmap
用途： 合成两张位图
-------------------------------------------------------------------------------}
function HeCheng(A,b:TBitmap;const TransPercent: integer=50;const ignoreColor: TColor = clwhite;Const ColorOffset: byte=0):TBitmap;
var
i,j: integer;
p1,p2: PByteArray;
count,MinBegin: Integer;
MinHeight: integer;
MinWidth,MaxWidth: Integer;
r: TRect;
RColor,GColor,BColor: Byte;
begin
A.PixelFormat := pf32bit;
b.PixelFormat := pf32bit;
TColorToRGB(ignoreColor,RColor,GColor,BColor);

MinHeight := Min(A.Height,B.Height);
MinWidth := Min(A.Width,B.Width);
MaxWidth := Max(A.Width,B.Width);

MinBegin := 4 * ((MaxWidth - MinWidth) Div 2);
count := 4 * (MaxWidth-(MaxWidth - MinWidth) Div 2 - 1);

for i := 0 to MinHeight - 1 do
begin
if MinHeight = B.Height then
begin
p1 := A.ScanLine[i];
p2 := B.ScanLine[i];
end
else
begin
p1 := B.ScanLine[i];
p2 := A.ScanLine[i];
end;
j := MinBegin;
while j < count do
begin

//比较字节的值，位图该点像素的RGB值是否为需要过滤的颜色值，如果是，则过滤掉
if (abs(p2[j - MinBegin] - BColor)<=ColorOffset) and

(abs(p2[j-MinBegin+1] - GColor)<=ColorOffset) and

(abs(p2[j-MinBegin+2]-RColor)<=ColorOffset) then
inc(j,4)
else
begin
p1[j] := p1[j] + TransPercent * (p2[j-MinBegin] - p1[j]) div 100;
inc(j);
end;
end;
end;
if MinHeight = B.Height then
begin
r.Top := A.Height - A.Canvas.TextHeight('你好')-5;
r.Bottom := A.Height;
r.Left := 0;
r.Right := A.Width;
A.Canvas.Brush.Style := bsclear;
windows.DrawText(A.Canvas.Handle,'你好',-1,r,DT_Center or DT_VCenter or DT_SIngleLine);
Result := A;
end
else
begin
r.Top := B.Height - B.Canvas.TextHeight('你好')-5;
r.Bottom := B.Height;
r.Left := 0;
r.Right := B.Width;
B.Canvas.Brush.Style := bsclear;
windows.DrawText(B.Canvas.Handle,'你好',-1,r,DT_Center or DT_VCenter or DT_SIngleLine);
Result := B;
end;
end;

比如，现在要透明一个图片合成上去

HeCheng(Image1.Picture.Bitmap,Image4.Picture.Bitmap,100,Image4.Canvas.Pixels[0,0]，20);

在加一个透明图画法的函数，效果不大好

{-------------------------------------------------------------------------------
过程名: TransparentDraw
作者: 不得闲
日期: 2009.02.12
参数: DestCanvas: 目标画布
DestRect: 目标区域
Graphic: 位图
ColorOffset 背景色附近的颜色差值，在该差值之内的颜色，都会被透明掉
返回值: 无
-------------------------------------------------------------------------------}

procedure TransparentDraw(DestCanvas: TCanvas;DestRect: TRect;Graphic: TBitmap;const ColorOffset: Byte=0);
var
i,j,Count: integer;
RectH,RectW: integer;
p: PByteArray;
RColor,GColor,BColor: Byte;
begin
//区域高度
Graphic.PixelFormat := pf32bit;
RectH := DestRect.Bottom - DestRect.Top;
if RectH > Graphic.Height then
RectH := Graphic.Height;
RectH := DestRect.Top + RectH;
RectW := DestRect.Right - DestRect.Left;
TColorToRGB(Graphic.Canvas.Pixels[0,0],RColor,GColor,BColor);
if RectW > Graphic.Width then
RectW := Graphic.Width;
Count := 4*RectW - 1;
for i := DestRect.Top to RectH - 1 do
begin
p := Graphic.ScanLine[i - DestRect.Top];
j := 0;
while j < Count do
begin
if (abs(p[j] - BColor)<=ColorOffset) and (abs(p[j+1] - GColor) <= ColorOffset) and (abs(p[j+2] - RColor)<=ColorOffset) then
inc(j,4)
else
begin
BColor := p[j];
GColor := p[j + 1];
RColor := p[j+2];
DestCanvas.Pixels[j div 4,i] := RGB(RColor,GColor,BColor);
inc(j,4);
end;
end;
end;
end;

同时，也写下了一个更换图片背景色的函数，代码如下：

{-------------------------------------------------------------------------------
过程名: ChangeBmpBackGround
作者: 不得闲
日期: 2009.02.12
参数: bmp: TBitmap;
ChangeToBack: 要修改为的背景色
ColorOffset 背景色附近的颜色差值，在该差值之内的颜色，也会被修改
返回值: 无
-------------------------------------------------------------------------------}

procedure ChangeBmpBackGround(bmp: TBitmap;ChangeToBack: TColor;const ColorOffset: Byte = 0);
var
i,j,Count: integer;
RColor,GColor,BColor: Byte;
TRColor,TGColor,TBColor: Byte;
p: PByteArray;
begin
bmp.PixelFormat := pf32bit;
TColorToRGB(bmp.Canvas.Pixels[0,0],RColor,GColor,BColor);
TColorToRGB(ChangeToBack,TRColor,TGColor,TBColor);
count := 4 * bmp.Width - 1;
for i := 0 to bmp.Height - 1 do
begin
j := 0;
p := bmp.ScanLine[i];
while j < count do
begin
if (abs(p[j] - BColor)<=ColorOffset) and (abs(p[j+1] - GColor) <= ColorOffset) and (abs(p[j+2] - RColor)<=ColorOffset) then
begin
p[j] := TBColor;
P[j+1] := TGColor;
p[j+2] := TRColor;
end;
inc(j,4);
end;
end;
end;

今天在公司由于要用到一个图片遮罩的效果，于是按照同样的思路写了一个图像遮罩函数：

代码如下：

{-------------------------------------------------------------------------------
过程名: SoftBmp
作者: 不得闲
日期: 2009.02.13
参数: bmp: TBitmap;
DarkRect: 不遮罩的区域
SoftColor:指定遮罩色

SoftPercent指定遮罩度（取1-100，100为完全遮罩）

返回值: 无
-------------------------------------------------------------------------------}

procedure SoftBmp(bmp: TBitmap;var DarkRect: TRect;const SoftColor: TColor;const SoftPercent: Integer=50);
var
i,j : integer;
pB : PByteArray;
BmpFormatXs: Integer;
w,h:Integer;
R,G,B: Integer;
begin
if bmp.PixelFormat <> pf32bit then
bmp.PixelFormat := pf32bit;
BmpFormatXs := 4;

w:= DarkRect.Right - DarkRect.Left;
h:= DarkRect.Bottom - DarkRect.Top;

if DarkRect.Right > bmp.Width then
begin
DarkRect.Left:=bmp.Width - w;
DarkRect.Right:=bmp.Width;
end;
if (DarkRect.Bottom > bmp.Height) then
begin
DarkRect.Top:= bmp.Height - h;
DarkRect.Bottom:=bmp.Height;
end;
if DarkRect.Left <0 then
begin
DarkRect.Left:=0;
DarkRect.Right:=w;
end;
if DarkRect.Top <0 then
begin
DarkRect.Top:=0;
DarkRect.Bottom:=h;
end;
TColorToRGB(SoftColor,R,G,B);
for i := 0 to DarkRect.Top - 1 do
begin
pb:=bmp.ScanLine[i];
j := 0;
while j < BmpFormatXs*bmp.Width - 1 do
begin
pb[j] := B + (100-SoftPercent) * (pb[j] - B) div 100;
pb[j+1] := G + (100-SoftPercent) * (pb[j+1] - G) div 100;
pb[j+2] := R + (100-SoftPercent) * (pb[j+2]-R) div 100;
inc(j,BmpFormatXs);
end;
end;

for i := DarkRect.Top to bmp.Height - 1 do
begin
pb:=bmp.ScanLine[i];
j := 0;
while j < BmpFormatXs*DarkRect.Left - 1 do
begin
pb[j] := B + (100-SoftPercent) * (pb[j] - B) div 100;
pb[j+1] := G + (100-SoftPercent) * (pb[j+1] - G) div 100;
pb[j+2] := R + (100-SoftPercent) * (pb[j+2]-R) div 100;
inc(j,BmpFormatXs);
end;
end;
for i := DarkRect.Bottom to bmp.Height - 1 do
begin
pb:=bmp.ScanLine[i];
j := BmpFormatXs*DarkRect.Left;
while j < BmpFormatXs*bmp.Width - 1 do
begin
pb[j] := B + (100-SoftPercent) * (pb[j] - B) div 100;
pb[j+1] := G + (100-SoftPercent) * (pb[j+1] - G) div 100;
pb[j+2] := R + (100-SoftPercent) * (pb[j+2]-R) div 100;
inc(j,BmpFormatXs);
end;
end;

for i := DarkRect.Top to DarkRect.Bottom - 1 do
begin
pb:=bmp.ScanLine[i];
j := BmpFormatXs*DarkRect.Right;
while j < BmpFormatXs*bmp.Width - 1 do
begin
pb[j] := B + (100-SoftPercent) * (pb[j] - B) div 100;
pb[j+1] := G + (100-SoftPercent) * (pb[j+1] - G) div 100;
pb[j+2] := R + (100-SoftPercent) * (pb[j+2]-R) div 100;
inc(j,BmpFormatXs);
end;
end;
end;