Thanks a lot. 1. My hardware (use 8080 parallel MCU interface) doesn't support multi-buffering (or the SW need change a lot to support that). So I try to use MEMDEV. 2. I use WM_PRE_PAINT and WM_POST_PAINT so that I can create MEMDEV and then delete it share the lifetime with the dialog. Now I understand that WM_INIT_DIALOG and WM_DELETE is a better chooice.
I have created a emwin window, which has a jpg image as background. The code is as the following: C Source Code (122 lines)In order to speed up the PAINT process, I use MEMDEV to display the image. The strange thing is: 1. When I enable macro CREATE_MEMDEV_IN_PREPAINT, the background image can not be displayed if I call 'WM_SetCreateFlags(WM_CF_MEMDEV);' before the window creation. Without this function call, everything looks fine. 2. When I enable macro CREATE_MEMDEV_IN_INIT, both works with/wi…