ssd1306: Add function SetFlip and GetFlip

[notpop]

Implementation of the Flip Functions

Hello, I am new to contributing to OSS, so I apologize in advance if there are any mistakes.

What I did

I added a Flip functions to the ssd1306 driver.

Background

While playing with ssd1306, I wanted to flip the display, but I found that there was no method implemented for it. I had to directly execute commands within the application. Thus, I thought it would be helpful to implement this functionality in the driver itself.

Why I didn't extend SetRotation

Initially, I thought it would be best to integrate the flip functionality into SetRotation to align with the other existing implementations. However, I found that implementing 90° and 270° rotations is quite challenging. To help clarify my point, please refer to the images below:

• 0° image
• 90°? image
• 180° image
• 270°? image

From my current understanding, it seems that the ssd1306 hardware does not support these kinds of rotation features directly, so a more complex implementation would be required. However, I believe that even just implementing the flip functionality is useful, so I decided to start with this.

Thank you for your time and consideration.

[sago35]

Thank you for the PR.

It is true that the SSD1306 does not seem to have 90-degree or 270-degree rotation capabilities, so the Flip API seems appropriate.
The only potential issue might be that the default value has been changed.
Originally, it was set so that IsFlip == true. I also found out that the register settings when IsFlip == true differ from the initial values of the SSD1306. However, in terms of compatibility with tinygo.org/x/drivers, I think it would be better not to change this. What do you think? @deadprogram

[deadprogram]

I think we would be better off with SetRotation like other displays instead of adding another API. The implementation could return an error if you tried to set to a currently unsupported rotation for a particular display.

[notpop]

Thank you for your feedback. Based on your suggestions, I have revised the SetRotation function.

[deadprogram]

Thank you for making the changes @notpop looks good to me.

I changed the branch for this PR to dev as discussed here:
https://github.com/tinygo-org/drivers/blob/release/CONTRIBUTING.md#how-to-use-our-github-repository

@sago35 or anyone else have any comments before I squash/merge?

[sago35]

LGTM

[deadprogram]

Thank you @notpop and @sago35