First post, by superfury
I just downloaded the latest Dosbox version (0.74) from dosbox.com, but I still notice the old RDP bug that's out there for as long as I use RDP with my PC: each time I move the mouse right/down/left/up, the mouse moves a ridiculous amount and is barely controllable using RDP on the current Windows 10(14393.693). To be exact, it's probably the same bug I noticed in UniPCemu, where the SDL driver is reporting ridiculous amounts of movement when moving the mouse during a RDP session, with the mouse mounted(when the mouse is grabbed using SDL). This bug is there in both SDL 1 and 2 versions of SDL. The ratios only change to other values when changing the display resolution of the RDP session(by (re)connecting with a different resolution setting in the Remote Desktop Connection program settings).
So when the mouse is moved, instead of reporting 1 or 2 pixels for moving the mouse a little notch to the right/down/left/up, the values reported are multiplied with(divide by these values to get the actual mouse movement in pixels):
horizontal movement x vertical movement at (output resolution of the RDP session)xres x yres
-----------------------------------------------------------------------
164 x 109 at 800x600
64 x 85 at 1024x768
51 x 64 at 1280x1024
34 x 60 at 1920x1080
Even more multiplication ratios when in other display modes. All of these are the minimal movement values, which are 1 when not controlling an SDL application through remote desktop and mounting the mouse.
So it even depends on the current display resolution somehow? So to fix that bug, you need to know the actual used screen display resolution(not the SDL surface Dosbox creates) to calculate a multiplication factor for horizontal and vertical movement to apply to every mouse movement event received from SDL.
See also the thread at viewtopic.php?f=9&t=51284
I also can't find any logic between the used display resolutions and reported movement(for 1 pixel mouse movement) during RDP, based on the RDP display resolution. The display resolution of the computer that's remote controlling is 1920x1080 in all cases.
Author of the UniPCemu emulator.
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UniPCemu for Android, Windows, PSP, Vita and Switch on itch.io