_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

clearCachedBitmap() void GiGdipCanvas::clearCachedBitmap ( bool  clearAll = false ) virtual 清除后备缓冲位图，以便重新绘图 重载 GiCanvas .