gdiplus Path GdipWindingModeOutline问题

Question

我正在使用Mitov的Delphi IGDIPlus库。 我在完全无辜的情况下得到异常“通用错误”。 我有五个重叠的矩形，并希望使用aPath.outline()来查找轮廓路径（我在Win7上运行此示例，并应用了所有轮廓相关的修补程序）。

uses 
System.Types, IGDIPlus, VCL.IGDIPlusExt; 


procedure TForm1.FormPaint(Sender: TObject); 
var 
    AGraphics  : IGPGraphics; 
    APath,aPathO : IGPGraphicsPath; 

begin 
    AGraphics := TIGPGraphics.Create(Canvas); 
    AGraphics.SmoothingMode := SmoothingModeAntiAlias; 
    AGraphics.TextRenderingHint := TextRenderingHintAntiAlias; 
    aPath := TIGPGraphicsPath.create() ; 
    // this path gives generic error 
    aPath.addRectangle(73,201,108,96); 
// --------the difference---------- 
    aPath.addRectangle(73,292,58,96); 
// --------the difference---------- 
    aPath.addRectangle(73,383,108,96); 
    aPath.addRectangle(177,201,108,96); 
    aPath.addRectangle(177,383,108,96); 

    try 
    aPathO := apath.clone().Outline(); 
    AGraphics.DrawPath(TIGPPen.Create(aclRed,1), 
     aPathO); 
    except 
    on E: Exception do 
    begin 
     AGraphics.DrawStringF(e.message, 
          TIGPFont.Create('Microsoft Sans Serif', 16, [ fsBold ]), 
          TPointF.Create(23, 23), 
          TIGPSolidBrush.Create(aclRed)) ; 

     AGraphics.DrawPath(TIGPPen.Create(aclRed,1), 
     aPath); 
    end; 
    end; 
    aPath.reset(); 
// this path works fine 
    aPath.addRectangle(373,201,108,96); 
// --------the difference---------- 
    aPath.addRectangle(373,292,108,96);  
// --------the difference---------- 
    aPath.addRectangle(373,383,108,96); 
    aPath.addRectangle(477,201,108,96); 
    aPath.addRectangle(477,383,108,96); 

    try 
    aPathO := apath.clone().Outline(); 
    AGraphics.DrawPath(TIGPPen.Create(aclRed,1), 
     aPathO); 
    AGraphics.DrawStringF('it works', 
          TIGPFont.Create('Microsoft Sans Serif', 16, [ fsBold ]), 
          TPointF.Create(423, 23), 
          TIGPSolidBrush.Create(aclRed)) ; 

    except 
    on E: Exception do 
    begin 
     AGraphics.DrawStringF(e.message, 
          TIGPFont.Create('Microsoft Sans Serif', 16, [ fsBold ]), 
          TPointF.Create(223, 23), 
          TIGPSolidBrush.Create(aclRed)) ; 

     AGraphics.DrawPath(TIGPPen.Create(aclRed,1), 
     aPath); 
    end; 
    end; 
end; 

欢迎任何想法，建议。

运行在C＃中相同的例子给出了（使用Outline a path with GDI+ in .Net）

    GraphicsPath aPath = new GraphicsPath(); 
       aPath.AddRectangle(new Rectangle(73, 201, 108, 96)); 
       aPath.AddRectangle(new Rectangle(73, 292, 58, 96)); 
       aPath.AddRectangle(new Rectangle(73, 383, 108, 96)); 
       aPath.AddRectangle(new Rectangle(177, 201, 108, 96)); 
       aPath.AddRectangle(new Rectangle(177, 383, 108, 96)); 

       HandleRef handle = new HandleRef(aPath, (IntPtr)aPath.GetType().GetField("nativePath", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(aPath)); 
       try 
       { 

        int status = GdipWindingModeOutline(handle, IntPtr.Zero, 0.25F); 
        using (Pen outlinePen = new Pen(Color.FromArgb(255, Color.Red), 2)) 
        { 
         g.DrawPath(outlinePen, aPath); 
        } 
       } 

       catch (Exception exp) 
       { ... 
       } 

GdipWindingModeOutline函数返回相同的错误状态= 1（一般错误）

因为我真的需要使用轮廓曲线和直接的方式aPath.clone().outline()是由于gdi +错误不可能，我不得不周围。合适的解决方案 - 也许不是最好的，但工程 - 可能是：如果你使用的接口（此库显然不会）

     procedure TForm1.FormPaint(Sender: TObject); 
     var 
      AGraphics  : IGPGraphics; 
      APath,aPathO : IGPGraphicsPath; 
      aRegion   : IGPRegion; 
      aScan   : TArray; 
      aMatrix   : IGPmatrix; 

     begin 
      AGraphics := TIGPGraphics.Create(Canvas); 
      AGraphics.SmoothingMode := SmoothingModeAntiAlias; 
      AGraphics.TextRenderingHint := TextRenderingHintAntiAlias; 
      aPath := TIGPGraphicsPath.create() ; 
      aRegion := TIGPRegion.create().MakeEmpty(); 
      aRegion.Union( TIGPRect.create(73,201,108,96)); 
      aRegion.Union( TIGPRect.create(73,292,58,96)); 
      aRegion.Union( TIGPRect.create(73,383,108,96)); 
      aRegion.Union( TIGPRect.create(177,201,108,96)); 
      aRegion.Union( TIGPRect.create(177,383,108,96)); 
      aMatrix := TIGPMatrix.Create(); 
      aScan := lRegion.GetRegionScans(aMatrix); 
      for i := 0 to High(aScan) do 
      aPath.addRectangle(GPInflateRect(aScan[i], 1)); 


      aPathO := aPath.Clone().Outline(); 
      AGraphics.DrawPath(TIGPPen.Create(aclRed,1), aPathO); 

     end; 

Answer 1

你行AGraphics.DrawPath(TIGPPen.Create(aclRed,1), ...是在格兰德尔福全球危险。在涉及到函数调用中的引用计数和对象创建时，Delphi有一些问题（我不记得哪个......）。尽量不要在函数调用中创建对象，而是定义一个新的局部变量来保存参考界面。