If anyone would like to see what my tool looks like in action, there are videos of several games on my quite fresh YouTube channel. It took a lot of work, but thanks to this Richtris does not interfere with the work of the emulator and desktop recording program. I have achieved this performance by having two back buffers (standard TBitmap classes) and only repainting those areas of the back buffer that need to change the contents (and then flip onto the window canvas). Despite this, Richtris maintains a constant 60fps, consuming at most only 40% of the power of one CPU core (Lenovo T60, a laptop that is already 14 years old), which is from 200 to 800 MHz, depending on the scene. This project is written entirely in Free Pascal, and the whole rendering code is based on the standard Canvas - only the Canvas.Draw, Canvas.CopyRect and Canvas.TextOut methods are used to render the final frame. It is a overlay for the FCEUX emulator - it scans the emulator client area, recognizes data (such as scenes, stack and counters etc.) and renders a rich vizualization of the gameplay in real time, with many completely custom data. A month ago I finished a tool for NES Tetris, called Richtris.

The problem is not the technology, but at best your code and approach to solving the problem. You can use standard Canvas and avoid flickering by using back buffers and other tricks.

Ms directdraw