控件显示没问题... 但当在运行时更改其Left/Top属性移动其位置, 则显示不完整, 显示区域被限制在0, 0, Width, Height这样的区域里...
想来是因为Paint里给的Canvas的区域被限制了, 但看了一下TWinControl的PaintControls里的处理又是正常的(根据控件的Left/Top/Width/Height来自动限制), 原Paint函数处理如下:
TRect rt( Left, Top, Left + Width, Top + Height );
Canvas->Brush->Color = clWhite;
Canvas->FrameRect( rt );
rt.left++;
rt.top++;
rt.right--;
rt.bottom--;
Canvas->Brush->Color = clBlack;
Canvas->FrameRect( rt );
rt.left++;
rt.top++;
rt.right--;
rt.bottom--;
Canvas->Brush->Color = clWhite;
Canvas->FrameRect( rt );
于是我又尝试用API来画, DC还是用的Canvas的Handle, 问题依旧.... 所以就直接用其父窗口的整个区域DC去绘制, 结果就OK了...代码如下
HDC dc = GetDC( Parent->Handle );
TBrush *pBrush = new TBrush;
pBrush->Style = bsClear;
TPen *pPen = new TPen;
pPen->Color = clWhite;
SelectObject( dc, pBrush->Handle );
SelectObject( dc, pPen->Handle );
Rectangle( dc,
Left,
Top,
Left + Width,
Top + Height );
pPen->Color = clBlack;
SelectObject( dc, pPen->Handle );
Rectangle( dc,
Left + 1,
Top + 1,
Left + Width - 1,
Top + Height - 1 );
pPen->Color = clWhite;
SelectObject( dc, pPen->Handle );
Rectangle( dc,
Left + 2,
Top + 2,
Left + Width - 2,
Top + Height - 2 );
ReleaseDC( Parent->Handle, dc );
delete pBrush;
delete pPen;
希望有朋友帮忙回答下是为什么...
