What classes for the graphic editor to use?

Question

Qt

Purpose: a small editor for pixel art with tips for convenient preparation of graphics for devices: the scope of the selected line of devices (aspect ratio), the ability to change resolutions and see at what resolution the graphics begin to be distorted.
My level is not at all enough to write a program without help - I just know what should be in it.
From the software side, classes seem to be needed for such tasks:
1. Create a canvas for drawing, specify the resolution, aspect ratio.
Class: QGraphicsScene\QPixmap?
2. Upload an image jpg, png, bmp - the canvas will be automatically created according to the image parameters.
Class: QPixmap?
3. Work with the image: draw, erase, select the image, scale (manually and automatically - if you set the canvas to a different resolution), rotate.
Class: there are probably no classes here - implementation with your own algorithms and binding them to the mouse and keyboard handler.
4. Apply a "grid" over the canvas. Grid size - resolution size. The size can be changed - the grid will become denser / rarer.
Class: ?
5. Display frames on top of the canvas. Frame size - aspect ratio.
Class: QFrame?
6. Save png image, bitness, alpha.
Class: ?

Answer 1

My answer may seem strange, but try to create a topic with the same text here , the chances of getting advice from a good Qt graphics specialist will greatly increase.