delphi JPG图片 旋转 切边 缩放

unit UCutFigure_JPG;
//JPG 切图


interface

uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
     Dialogs, ExtCtrls, StdCtrls,Math, jpeg
 ;

//向左旋转X度 
procedure Rotate(Srcbmp, DestBmp: TBitmap; dbTheta: Double);
 //毫米单位转换为英寸单位 
function MmToInch(Length: Extended): Extended;
//英寸单位转换为毫米单位
function InchToMm(Length: Extended): Extended;
function CutFigure_JPG(图片文件名:string;旋转角度:integer;切边_上,切边_下,切边_左,切边_右:real;缩放_宽,缩放_高:real):Integer;
implementation

 function CutFigure_JPG(图片文件名:string;旋转角度:integer;切边_上,切边_下,切边_左,切边_右:real;缩放_宽,缩放_高:real):Integer;
var
  JpgSrc,JpgDest : TJpegImage;
  BmpSrc, BmpDest: TBitmap;
  F_上,F_下,F_左,F_右,F_长,F_宽:integer;//切边值
  F_缩放比率:real;
  F_处理状态:boolean;
 begin
  //文件名，含全路径
  if not FileExists(图片文件名) then  exit;//文件不存在则退出
  
   JpgSrc := TJpegImage.Create;
   JpgDest:=TJpegImage.Create ;
   BmpSrc:=TBitmap.Create;
   BmpDest:=TBitmap.Create ;


   JpgSrc.LoadFromFile(图片文件名);//加载文件
   BmpSrc.Assign(JpgSrc);
   F_处理状态:=False;//未处理过
  if 旋转角度>0 then
  begin
   Rotate(BmpSrc, BmpDest,旋转角度); //由于函数是左向旋转，所以这里角度设置为270。
   F_处理状态:=true;
  end;


  if (切边_上>0)  or (切边_下>0) or (切边_左>0)  or (切边_右>0)  then
  begin
    //需要切边
   if F_处理状态=true then     
    BmpSrc.Assign(BmpDest);
    //切边传进来的参数，为cm
    if 切边_上0 then 切边_上:=0;
    if 切边_下0 then 切边_下:=0;
    if 切边_左0 then 切边_左:=0;
    if 切边_右0 then 切边_右:=0;

    
    F_上:=Round(MmToInch(切边_上)*10*96);
    F_下:=Round(MmToInch(切边_下)*10*96);
    F_左:=Round(MmToInch(切边_左)*10*96);
    F_右:=Round(MmToInch(切边_右)*10*96);

    if (F_上+F_下and (F_左+F_右>=BmpSrc.Width ) then
    begin    //值超范围，不处理
      BmpDest.Height:=BmpSrc.Height-(F_上+F_下);
      BmpDest.Width:=BmpSrc.Width-(F_左+F_右);
      SetStretchBltMode(BmpDest.Canvas.Handle,HALFTONE);//设置指位图拉伸模式
      stretchblt(BmpDest.Canvas.Handle,0,0,BmpDest.Width,BmpDest.Height,BmpSrc.Canvas.Handle,F_左,F_上,BmpDest.Width,BmpDest.Height,srccopy); //从源矩形中复制一个位图到目标矩形并适当压缩
       F_处理状态:=true;
    end ;

  end;

  if  (缩放_高>0) or (缩放_宽>0) then
  begin
    //需要缩放
    if F_处理状态=true then
       BmpSrc.Assign(BmpDest);

    F_长:=Round(MmToInch(缩放_高)*10*96);
    F_宽:=Round(MmToInch(缩放_宽)*10*96);


    if (F_长>0) and (F_宽>0)  and  (BmpSrc.Height>F_长) and (BmpSrc.Width >F_宽) then
    begin
      //如果都超过，则等比缩小到其中较大的一个值等于目标值
      if (F_长/BmpSrc.Height)>(F_宽/BmpSrc.Width) then
      begin
        F_缩放比率:=F_宽/BmpSrc.Width;
      end
      else
      begin
        F_缩放比率:=F_长/BmpSrc.Height;
      end;
    end
    else
    if (F_长>0)  and  (BmpSrc.Height>F_长) then
    begin
       F_缩放比率:=F_长/BmpSrc.Height;
    end
    else
    if (F_宽>0) and (BmpSrc.Width >F_宽) then
    begin
      F_缩放比率:=F_宽/BmpSrc.Width;
    end
    else
    begin
      F_缩放比率:=-1;//如果没取到值，或原图已经小于设定值则不处理
    end;

    if F_缩放比率>0 then
    begin
      BmpDest.Height:=Round(BmpSrc.Height*F_缩放比率);
      BmpDest.Width:=Round(BmpSrc.Width *F_缩放比率);

      SetStretchBltMode(BmpDest.Canvas.Handle,HALFTONE);//设置指位图拉伸模式
      stretchblt(BmpDest.Canvas.Handle,0,0,BmpDest.Width,BmpDest.Height,BmpSrc.Canvas.Handle,0,0,BmpSrc.Width,BmpSrc.Height,srccopy); //从源矩形中复制一个位图到目标矩形并适当压缩
      F_处理状态:=true;
    end;
  end;

  if F_处理状态=true then
  begin
    //处理后，保存图片
    JpgDest.CompressionQuality := 100;
    JpgDest.Assign(BmpDest);
    JpgDest.SaveToFile(图片文件名);
  end;

   JpgSrc.Free;
   JpgDest.free;
   BmpSrc.Free;
   BmpDest.Free;

 end;



 procedure Rotate(Srcbmp, DestBmp: TBitmap; dbTheta: Double);//此过程是网上找的，不记得原博文地址了，抱歉
var
  ptOrgCenter, ptTarCenter, ptc: TPoint;
  pta: array[0..3] of TPoint;
  ba: array[0..3] of integer;
  i: integer;
  function RotateXY(dbTheda: double; p1: TPoint): TPoint;
  var
    dbA: double;
    _cosA, _sinA, _dbLastT: double;
  begin
    _dbLastT := -99999.999;
    _cosA :=0.0;
    _sinA :=0.0;
 
    if dbTheda  _dbLastT then
    begin
      dbA := dbTheda * Pi / 180;
      _sinA := sin(dbA);
      _cosA := cos(dbA);
      _dbLastT := dbTheda;
    end;
 
    Result.x := round(p1.x * _cosA + p1.y * _sinA);
    Result.y := round(-p1.x * _sinA + p1.y * _cosA);
  end;
begin
  ptOrgCenter.x := Srcbmp.Width div 2;
  ptOrgCenter.y := Srcbmp.Height div 2;
 
  pta[0] := RotateXY(dbTheta,Point(0, 0));
  //这里不知道原来为何减1
  {pta[1]:=RotateXY(dbTheta,Point(Srcbmp.Width - 1, 0));
  pta[2]:=RotateXY(dbTheta,Point(0, Srcbmp.Height - 1));
  pta[3]:=RotateXY(dbTheta,Point(Srcbmp.Width - 1, Srcbmp.Height - 1));
  }
  pta[1] := RotateXY(dbTheta,Point(Srcbmp.Width, 0));
  pta[2] := RotateXY(dbTheta,Point(0, Srcbmp.Height));
  pta[3] := RotateXY(dbTheta,Point(Srcbmp.Width, Srcbmp.Height));
 
 
  DestBmp.PixelFormat := pf32bit;
  DestBmp.Canvas.Brush.Color := clWindow;
 
  for i := 0 to 3 do
    ba[i] := pta[i].x;
 
  DestBmp.width := MaxIntValue(ba) - MinIntValue(ba);
 
  for i := 0 to 3 do
    ba[i] := pta[i].y;

  DestBmp.Height := MaxIntValue(ba) - MinIntValue(ba);
 
  ptc := RotateXY(dbTheta, Point(Srcbmp.Width div 2, Srcbmp.Height div 2));
 
  ptTarCenter.x := DestBmp.Width div 2;
  ptTarCenter.y := DestBmp.Height div 2;
 
  pta[0].x := pta[0].x + ptTarCenter.x - ptc.x;
  pta[0].y := pta[0].y + ptTarCenter.y - ptc.y;
  pta[1].x := pta[1].x + ptTarCenter.x - ptc.x;
  pta[1].y := pta[1].y + ptTarCenter.y - ptc.y;
  pta[2].x := pta[2].x + ptTarCenter.x - ptc.x;
  pta[2].y := pta[2].y + ptTarCenter.y - ptc.y;
 
  if PlgBlt(DestBmp.Canvas.Handle, pta, Srcbmp.Canvas.Handle,
         0, 0, Srcbmp.Width - 1, Srcbmp.Height - 1, 0, 0, 0) then
    DestBmp.Canvas.Draw(0, 0, DestBmp)
  else
    DestBmp.Canvas.TextOut(0,0,‘只支持WinNT内核操作系统.‘);
end;

  //毫米单位转换为英寸单位
function MmToInch(Length: Extended): Extended;
begin
 Result := Length/25.4;
end;
//英寸单位转换为毫米单位
function InchToMm(Length: Extended): Extended;
begin
 Result := Length*25.4;
end;
end.