This commit is squashed from the following commits:
MAX7456 - Calculate buffer offset only once per string.
MAX7456 - Avoid duplicate addition by using second loop variable.
MAX7456 - Rename 'buff' to 'input' for clarity.
> There's two 'buffers', now the other variable names make more sense.
MAX7456 - Use consistent variable names.
> Use `text` instead of `s` and `input`.
Often the user doesn't realize that there are more menu items then displayed and the only way to tell was to try and move the selection to the bottom to see if another page appears.
This PR adds page up/down indicators if there are more menu items than those visible on the current display.
Uses the OSD arrow symbols when possible (for OSD supporting devices), otherwise the `^` (carat) and `V` are used for text-only represenatations.
To determine if the device was capable of displaying symbols the `displayPort` structure has a new `deviceType` set when it is initialized. There have been other times when knowing the type of device would have been useful so that's now supported. Then this is abstracted by a new `displaySupportsOsdSymbols()` function. Devices that support OSD are assumed to support the OSD symbols as the OSD element drawing code always uses them. For devices that don't support OSD function we have to presume the sybols aren't available.
Improves menu readability by changing the background from a transparent display of the camera image to a static opaque gray background.
The behavior is controlled with the `osd_menu_background` parameter which defaults to `TRANSPARENT` to preserve the previous behavior. Other opaque options are available:
```
osd_menu_background = TRANSPARENT
Allowed values: TRANSPARENT, BLACK, GRAY, LIGHT_GRAY
```
The background setting is available in the CMS OSD menu and the user can cycle through the various options with the display updating in real-time.
Currently only the onboard MAX7456-based OSD is supported, but the implementation adds `displayPort` support so it can easily be extended to other OSD devices if those manufacturers want to add support. Also can be extended to other background types (like colors, varying transparency, etc.) for future device support.
Makes use of the built-in MAX7456 feature to display all transparent pixels as "gray". The MAX7456 display area seems to be a few scan lines smaller than the actual camera video image so it's normal for some of the camera image to "leak" at the top/bottom of the display. The OSD display area can be adjusted up/down using the `vcd_v_offset` setting if desired.
- Add displayWriteFontCharacter() for font writing, removing all max7456
specific code.
- Add displayIsReady() for asynchronous display initialization
- Add displayBeginTransaction()/displayCommitTransaction() for display
transactions, which allow performing complex drawing operations without
flickering
- Add displayGetCanvas(), which retrieves the canvas associated with a
display (if it has it)
- Add canvas implementation for pixel based access for a display
- Add FrSkyOSD driver and displayPort driver
- Enable FrSkyOSD driver for targets with flash > 256
- Rename max7456_symbols.h to osd_symbols.h
Significantly reduces the time the OSD task spends drawing elements that are completely or mostly static. The larger the element the more time savings are realized. Currently implemented support for:
- Crosshairs
- Artificial Horizon Sidebars
- Craft name
- Display name
- Stick overlay
Since the static portions are only rendered once, the static elements add no processing time to the OSD task. As an example, enabling the above elements prior to these changes results in a total rendering time of 47us. After the enhancements they take only 6us (basically the rendering phase minimum overhead). So effectively 41us are removed from the OSD task.
Opens the possibility to add large mostly static elements with no additional overhead. An example would be a camera framing element that might draw a "box" around most of the screen. Previously this would add significant processing overhead to the OSD task, but now it will have no impact.
