Have macOS installer dmg show arrow to drag ChimeraX to Applications

[Tom Goddard]

At the ChimeraX microscopy tutorial I found another user running ChimeraX from the dmg, asking me why it has to verify the dmg every time they run ChimeraX.

We should have the dmg show the ChimeraX icon and an arrow to drag it to the Applications folder. This is a standard mac dmg install approach.

[Conrad Huang]

​https://stackoverflow.com/questions/8680132/creating-nice-dmg-installer-for-mac-os-x

describes some ways of doing this. I really don't have time for it and don't consider it very high priority, so someone else should pick it up.

[Tom Goddard]

The approach used by this Makefile seems reasonable.

​https://github.com/remko/fancy-dmg/blob/master/Makefile

Basically you make a template dmg image which has the icons and background arrow image positioned manually. Then you copy in the actual ChimeraX.app into a copy of the template and compress it to form the final dmg.

[Zach Pearson]

This will require modifying create_dmg in build_tools/macosx_package/notarize.py, which creates the dmg on the fly from a built ChimeraX.

From stackoverflow, the solution seems to be to create a template DMG, then make a copy of it and mount it. Then, copy the built application into the mounted DMG. Finally, unmount it compress it with hdiutil.

[Zach Pearson]

I installed the Python package dmgbuild on the Mac build machines and modified the build script to use it, then tested with a Mac Intel build. All of tomorrow's Mac builds should have the new format: an RBVI banner taken from our website, and a background that places an arrow with the text "Drag to Install" on top between ChimeraX and a symbolic link to /Applications.