Hello Kangmin,
thank you I'm fine. I hope you are doing well these days too.
Concerning your question, well, you can draw pixel by using FillRectangle or DrawLine. In fact, you draw 1-pixel large line or rectangle. However, I expect in this case very bad performance. The drawing functions have an overhead resulting from the necessary preparation of the drawing instructions, time needed to trigger the HW (e.g. PXP) and synchronize with the following drawing operations. This approach is thus useful only if you have few pixel to draw.
If you have an application case where you need to compose an image programmatically and none of the Embedded Wizard drawing functions works for you, the recommended approach would be to prepare the image within an Extern Bitmap as explained in my first answer of this thread. With this approach you can directly address the bitmap memory and flexibly set the pixel.
I hope, it helps you further.
Best regards
Paul Banach