I made a set of images of piano keyboard, all in two versions - one white and second with red color. I lined all keys pictures up next to each other, first white keys, then red over them. Now I would like to hide red ones, and they need to show only when it's clicked on the certain white key, so it's needed to visually show as if it were pressed. Then back to white when it's released.
I'm also interested doing it with my midi keyboard as well, so wonder how to achieve this with midi data? Thanks
How to achieve this depends on what Controll you use for showing the button.
If you use TImages then use OnMouseDown (http://docwiki.embarcadero.com/Libraries/XE7/en/Vcl.Controls.TControl.OnMouseDown) and OnMouseUp (http://docwiki.embarcadero.com/Libraries/XE7/en/Vcl.Controls.TControl.OnMouseUp) events.
In OnMouseDown you turn your Piano Key color to red.
In OnMouseUp you turn your Paino Key color to white.
If you decide for this approach you might also need to handle special case (user moving mouse away from key while mouse button bein pressed down).
You could achieve this with OnMouseLeave (http://docwiki.embarcadero.com/Libraries/XE7/en/Vcl.Controls.TControl.OnMouseLeave) event in which you check to see if your Piano Key is red and then change it to white.
As for general aproach for switching between pressed and unpressed key versions don't change their positions by brnging them to front or sending them back as this would screw up the clicking detections of your controlls (by default the topmost detects clicks).
Instead use one set of controls and change their image at runtime.
If you have any expirience with creating custom components you could quickly create one which will have two states and two images one for each state. So in the end you only switch between two states either with ckicks or with code.
If you don't have expirience with creating custom components please tell which components you use now and I can try making a custom version of that component with the above mentioned functionality for you.