transparent windows

[totaam]

Issue migrated from trac ticket # 1570

component: core | priority: major | resolution: fixed

2017-07-10 07:08:00: antoine created the issue

---

Transparency aka "alpha channel" tracker ticket.

Original tickets and important changesets:

• missing tray icons - forward notification area #77 tray icons
• disappearing tooltips #262 disappearing tooltips
• 32-bit visuals and transparent windows #279 32-bit visuals and transparent windows
• Systray icon transparency broken #280 Systray icon transparency broken
• opengl rendering improvements: handle plain RGB, scaling, transparency #385 opengl transparency (and more)
• webp artifacts with transparency #487 webp artifacts with transparency
• small tooltip windows have transparency issues #500 small tooltip windows have transparency issues
• detect lack of transparency support and disable it to save bandwidth #577 detect lack of transparency support and disable it to save bandwidth
• transparency forwarding is broken #892 transparency forwarding is broken
• transparency support is broken with pixmap backing #961 transparency support is broken with pixmap backing
• pixbuf backend does not support transparency with desktop scaling enabled #1145 pixbuf backend does not support transparency with desktop scaling enabled
• transparency with the native opengl backend on win32 #1682 transparency with the native opengl backend on win32
• transparency with the native opengl backend on macos #1794 transparency with the native opengl backend on macos

[totaam]

2017-07-10 07:35:41: antoine changed status from new to assigned

[totaam]

2017-07-10 07:35:41: antoine edited the issue description

[totaam]

2017-07-10 07:35:41: antoine commented

---

Fixes in r16262:

• skip compositing check with opengl backend on macos (though transparency still doesn't work..)
• enable transparency by default on macos as this seems to work with both cairo and pixmap backends
• remove override in pixmap backing, use the superclass default (ie: enabled on macos)
• add better error logging when initializing / enabling transparency, especially failures

This reverts an earlier changeset: r4934 "transparency does not work on OSX" - as it works with cairo and pixmap, the opengl case may be fixable.
If not, we should disable it in the backend - which will save some bandwidth.

[totaam]

2017-11-06 09:00:03: antoine commented

---

Hopefully this can be dealt with as part of #1569.

[totaam]

2017-11-11 15:16:05: antoine commented

---

r17373 enables transparency with GTK3, which works for the cairo backend (with opengl=off).

For opengl, r17375 passes the flag to the glcontext class so it can choose an appropriate visual.
Unfortunately, despite using the DwmEnableBlurBehindWindow (as directed here: [https://stackoverflow.com/a/4055059]), the window remains opaque on win32. See patch attached.

[totaam]

2017-11-11 15:16:30: antoine uploaded file win32-opengl-alpha.patch (2.6 KiB)

try to enable transparency with opengl

[totaam]

2017-11-12 07:17:39: antoine commented

---

r17385 uses non-opengl rendering if the window requires transparency, will follow up in #1682 for win32.

macos support is blocked by #1575

[totaam]

2018-03-28 15:14:47: antoine edited the issue description

[totaam]

2018-03-28 15:14:47: antoine commented

---

r18900 does the same as r17373 on macos: the cairo backend does handle transparency already just fine so let's use it, for opengl: #1794.

[totaam]

2019-09-21 13:16:09: antoine changed status from assigned to closed

[totaam]

2019-09-21 13:16:09: antoine set resolution to fixed

[totaam]

2019-09-21 13:16:09: antoine commented

---

Closing as this is now supported on all platforms, with all the backends, except for win32 + opengl: #1682