I played a bit with your project.
Attached you find a kind of demonstrator project which shows what could be done with B4X.
On the graphic there is a crane, a building and three loads.
Cranes, buildings and loads are classes, and have physical dimensions in meter.
View attachment 157713
There are three management modes:
Crane: In this mode you can move the crane, or change the dimensions of a building.
Scale: You can move the graphic with the mouse or a finger.
Measure: Allows to measure a distance.
Crane:
The crane is simply shown with the boom, more graphics could be added.
The crane has three dots.
If you click on the pivot point of the boom, you can move the crane horizontally.
If you click on the top of the boom, you can move the top in both directions with limits for the length and the angle.
If you click on the hook, you can move it vertically.
View attachment 157715
If the hook is near a connection point of a load, a magenta point is displayed.
Click on this point:
View attachment 157716
It is displayed in green meaning that the hook is connected to the load.
And you can move it either on the top of the boom.
View attachment 157717
Or with the hook:
View attachment 157718
After moving the load, for example on the top of the building you can click on the green connection point to disconnect the hook:
View attachment 157719 View attachment 157720
The point is displayed in magenta showing the connection.
Now, if you move the boom, the load remains in its position.
View attachment 157721
Scale:
You can change the scale with the slider, or with the mouse wheel in B4J, the works independently of the mode selection.
You can move the graphic in both direction.
View attachment 157727
Measure:
When you click on the screen a cross is displayed.
And when you move the mouse a second cross is displayed and the coordinates, the length and the angle are displayed in the top left corner.
View attachment 157730 View attachment 157731
There are also three sliders which allow do dynamically move the crane.
The slider determines the speed, when you release it, the slider moves back to 0.
View attachment 157728
Not everything has been tested there might remain some bugs.
What is missing:
- graphic for the crane.
- zoom with the fingers in B4A and move the graphic with the right mouse button in B4J.
- the measuring method should be improved.
- not tested with B4i.
- other objects e.t.c.