[Android Apps and Games] Chainfire:
Walkthrough video

GIF

Drivers

CF.lumen currently supports several driver backends to adjust the display: the original CF.lumen driver, the KCAL kernel driver, the PCC/RGB kernel driver, and the rootless (non-root) overlay. Driver selection will only be presented to you if multiple drivers are actually supported on your device.

Drivers: performance background

Software compositing is when your device takes the different surfaces on screen (the app's display, the status bar, the navigation bar, a popup window, these are all surfaces), draws them into a single buffer, then lets the hardware display this buffer. Virtually all modern devices can also do hardware compositing, where these different surfaces are presented to display hardware themselves, skipping one drawing step. It should be noted however, that hardware compositing only supports three surfaces (usually), so only the most basic scenes can be rendered this way. If more than the number of supported surfaces are displayed, the system falls back to software compositing automatically. Performance is slightly lower when this happens, but it happens all the time, and I doubt you've ever noticed it without looking for it.

One specific note about this is that "secure" content (DRM protected video rendering, for example) can only be hardware composited, as the software is not allowed to gain access to the surface. So if you are experiencing video disappearing, it's because the system has switched to software compositing. This can be due to CF.lumen's driver, a color overlay, or even just a system popup pushing the number of surfaces beyond the number of supported surfaces by the hardware compositor.

Drivers: CF.lumen

The CF.lumen driver requires software compositing, as it changes the colors displayed during the software compositing step. Of course, it lets the system go back to hardware compositing if it's not actively changing colors. This can slightly impact performance.

This driver changes colors on the surface content level, and can perform all sorts of calculus before deciding what to display. This usually gives it the highest possible image quality output. For example, in the color channel modes (red - night mode, green, blue, amber, salmon), the image is first converted to a luminance-based grayscale image, and then output in the selected color channels. This dramatically improves clarity and detail over only displaying the selected channels. Taking red mode as an example, this means that green and blue image content still shows up in a shade of red, whereas normally all colors devoid of a red component would show up as full black. Because of the surface-based manipulation, the invert filter may sometimes show unexpected results.

This driver affects both full-screen screenshots as well as app screenshots. Aside from normal screenshot/cast purposes, these are also used by the system for animations and in the recent task lists, and thus it may sometimes appear like a filter is applied twice during rotation or while browsing the tasks list.

Since v3.65 this driver comes in three different modes:

Drivers: CF.lumen: Compatibility mode

This driver mode should work on virtually all devices out there, however, on many firmwares it comes with an extra large performance penalty. Rendering quality is generally excellent, but various internal actions of Android itself (such as screen on, pattern unlock, app install, etc), as well as any app that triggers Android's accessibility options, may temporarily interfere with the rendering. This can cause a flash of the original colors being shown, instead of our manipulated colors.

Drivers: CF.lumen: Performance mode

This driver mode overrides Android's rendering system in a different way. While it doesn't work on all devices and firmwares, if it does work, it is often significantly faster than the compatibility mode. It also doesn't suffer from short flashes of the original colors being shown. This mode causes visible artifacts on some devices, though it isn't common.

Drivers: CF.lumen: Anti-flicker mode

This driver mode is a hybrid of compatibility and performance modes. It uses the same subsystem as performance mode, and thus it doesn't work on all devices and firmwares. This mode keeps the rendering from compatibility mode, but attempts to prevent the short flashes of the original colors being shown.

Drivers: KCAL

The KCAL driver is quickly becoming a popular kernel mod for Qualcomm devices. It allows color adjustments in the display hardware itself. There is no performance difference with this driver, but of course your kernel must support it. This is the fastest driver.

This driver changes colors on the display level, and is limited in the operations it can perform. It is fast, but the image quality can be less. In color temperature modes (probably your most used mode) there is no difference with the CF.lumen driver. In the color channel modes however, there is no luminance conversion. If you select for example the red mode, you will only see the red component of colors. Pure blue, pure green, or any color which is a mix of blue and green but not red, will appear black.

A gamma correction option is available for this driver. Some devices automatically gamma correct the values CF.lumen gives the kernel, the app needs to know about this, so it can take this into account in its calculations.

This driver affects neither full-screen screenshots nor app screenshots. It does not support the colorblind filter.

Drivers: PCC/RGB

This driver is very closely related to the KCAL driver, as they use the same hardware, so please read that section. Some kernels provide support for one but not the other. If both are supported, KCAL generally gives you a few more options than PCC/RGB, but there is no performance difference between the two.

This driver does not support the grayscale, invert or colorblind filters.

Drivers: rootless

The rootless fallback driver (for non-root users) uses a color overlay. This is an additional surface, causes at least one additional expensive full-screen rendering step, and is likely to throw your system into software compositing mode most of the time. This is the slowest (and ugliest) driver.

Image quality wise, it is no competition for the other drivers, but not everyone has root. Like the other screen color tint apps on the market (there are quite a few, and while CF.lumen is older than all of those, it is certainly not the best known or most popular one), a color overlay is used. Where the other drivers properly manipulate the displayed colors, this driver is more like putting a half-transparent colored sheet over a picture. While it somewhat does the job, it lowers contrast significantly.

On Android 6.0, various Android functions refuse to work when an overlay is present. This includes apps asking for permission, installing apps, etc. The app attempts to detect these situations and automatically turn off the filter. If you spot a situation where the filter is not automatically temporarily disabled, please let me know.

This driver affects only full-screen screenshots (but not full-screen animations), not app screenshots. It does not support the grayscale, invert, or colorblind filters.

Non-GApps firmwares

This app uses Maps for manual location setting, and Play for purchasing Pro. An increasing number of users do not have GApps, for privacy, security, and other concerns. If the app is installed on such a firmware, your location will be determined using the normal location API (without manual override, so your phone has to be able to determine your location). As I do not want to deprive anyone from the potential health benefits of sleeping better, the app operates in Pro mode if you do not have the Play store installed (PayPal'ing me beer money is always an option).

The APK is attached to this post for those not using Google Play (only).

Under no circumstances are you allowed to (re-)distribute this APK

(v2.00: 32, v2.05: 180, v2.10: 164, v2.16: 288, v2.25: 118, v2.40: 555, v2.50: 546, v2.60: 39, v2.61: 132, v2.66: 27, v2.71: 563, v2.74: 388, v2.75: 1042, v3.00: 4320; v3.65: 1376)