MFC 基于对话框的查看图片的软件，可以打开一张图片，当图片小于区域时，没有滚动条出现，当图片大于区域的时候，出现滚动条，并且可以拉动滚动条查看完成图片。(MFC based on dialog box to view the picture software, you can open a picture. When the picture is smaller than the area, there is no scrollbar. When the image is larger tha