Fix find element wrong coordinate

[KazuCocoa]

closes appium/appium#12209

@jlipps Can you give me a good example app for if (screenAR === shotAR) lines I can confirm?
I simply commented out for now. If we do not need this, I would like to remove them.

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will update https://github.com/appium/appium/blob/master/docs/en/advanced-concepts/image-elements.md later

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problem

find by image feature returns wrong coordinate in Android and iOS case.
test cases in below test section fails even it compares same image/element.

For Android

In here, Appium scales screenshot to window size. Then, Appium uses the scaled image as an input for compareImages.

e.g.
The screenshot is 1080x1920. The window size is 1080x1794. OpenCV compares a template image with the screenshot which is scaled from 1080x1920 to 1080x1794. Then Appium returns 1080x1794 based coordinations if it succeeds to find the template image. (But the returns coordinate should be 1080x1920 based one, since find_element :accessibility_id, xxxx returns rect based on 1080x1920 based size.

For iOS

iOS returns 750 × 1334 pixels screenshot evern the window size is width=375, height=667.
compareImages uses scaled screenshot from 750 × 1334 pixels to width=375, height=667. The ratio is 2.
Users should coordinate a template image scale if they would like to use 750 × 1334 pixels screenshot based image as the template image to fixt to width=375, height=667.

It means:
Cannot find proper image

el = @@driver.find_element :accessibility_id, 'Buttons' # find an element labelled 'buttons'
@driver.save_element_screenshot el, 'test_ios_button.png' # Save the element image

image_element = @driver.find_element_by_image 'test_ios_button.png' # Find image with the above element
image_element # raise no element found error because the input image is based on `750 × 1334 pixels` size

Then, users should do:

el = @@driver.find_element :accessibility_id, 'Buttons' # find an element labelled 'buttons'
@driver.save_element_screenshot el, 'test_ios_button.png' # Save the element image

# Need a process to scale `test_ios_button.png` down to fit to `width=375, height=667` size

image_element = @driver.find_element_by_image 'test_ios_button.png'
image_element # can find image

Implementation

• Get rid of here
  • @jlipps Do you have a good example for this implementation?
• Introduce fixScaleTemplateImage for iOS case to reduce user actions for an input image

test

https://github.com/appium/ruby_lib_core/pull/193/files is an example to make sure this PR works.
In the test, I ensured the below case for Android and iOS:

1. Find an element
2. Get the element screenshot
3. Find an element by image using step2 's partial image
4. Assert rect etc between step1 and step3

They worked after this PR.
(This includes landscape and portrait mode.)

[mykola-mokhnach]

scale might be destructed here

[mykola-mokhnach]

I mean const {xScale, yScale} = scale, so you don't have to always add scele. prefix

[mykola-mokhnach]

lets be consistent fixImageTemplateSize + fixImageTemplateScale %)

[mykola-mokhnach]

it might be better for the readability if you provide the default value for the argument if it is optional (scale=null)

[KazuCocoa]

I'm about to merge this in order to publish this via at beta.
I'll re-consider 4fb91b9 again if the beta has ratio issue.
(Perhaps, scaling width or hight base is pretty enough in many cases.)

[KazuCocoa]

Will consider different ratio case more (and create a PR)