_beginPaint _impl beginPaint beginPaintBuffered beginPath bezierTo clearCachedBitmap clearRect clearWindow clipPath clipRect closePath drawBitmap drawCachedBitmap drawCachedBitmap2 drawEllipse drawHandle drawLine drawPath drawRect drawTextAt endPaint getEncoder GiGdipCanvas hasCachedBitmap isBufferedDrawing lineTo moveTo quadTo restoreClip save saveCachedBitmap saveClip setBrush setPen thumbnailImage ~GiGdipCanvas

thumbnailImage() GiGdipCanvas * GiGdipCanvas::thumbnailImage ( int  maxWidth, int  maxHeight  ) 从缓冲位图生成指定宽高上限的缩略图，该图为新画布对象的缓冲位图