#1797 Add checkbox to ribbon for user preference to compress images

[blewjy]

Fixes #1797

Outline of Solution
Previously, when using Crop to Shape, high resolution images will be compressed after the crop. This is because we were exporting the images at 96ppi. This PR bumps this up to 330ppi to maintain a certain amount of quality on the pictures.

Before:

After:

There is also a checkbox added to the main ribbon to allow users to decide if they would like images to be compressed. If this is checked, the image exporting resolution will be set back down to the original 96ppi.

Checkbox:

Note: this PR also affects other labs that use the same exporting and import method, including EffectsLab, thus the FT slides for EffectsLab had to be updated.

[ChesterSng]

Hi @blewjy, good job on solving the issue! Tested on PowerPoint 2016
Image now retain its resolution after Crop functions.

There is an issue when checking Compress Images:
Compress Image becomes unchecked after switching tabs

1. Check Compress Images
2. Go to any other ribbon tab i.e. Home
3. Go back to PowerPointLabs tab.
4. Compress Images is now unchecked.
   However, if you do Crop functions, the images are now lower resolution, which means even though it is unchecked, Compress Images is still active.

I think you need to add a getPressed parameter and a function to use ShouldCompressImages like in Maintain Tab Focus.

I also have a suggestion for the tooltip of Compress Images:

People might not understand the what functionalities it affects even though it states image-related functions, not sure if it is important to include a list of features that it will affect for better clarity.

Alternatively, maybe a ? icon can be added to beside the Compress Images option so people who click it can get a more detailed explanation of the option:

[blewjy]

Hey @ChesterSng, thanks for your review!

I think you need to add a getPressed parameter and a function to use ShouldCompressImages like in Maintain Tab Focus.

You're right about this, adding the function solved that issue.

People might not understand the what functionalities it affects even though it states image-related functions, not sure if it is important to include a list of features that it will affect for better clarity.
Alternatively, maybe a ? icon can be added to beside the Compress Images option so people
who click it can get a more detailed explanation of the option:

To keep it consistent with the other buttons, I decided to add more detail to the tooltip instead. I listed out the features that were affected by this compress image setting.

[ChesterSng]

Hi @blewjy, previous bug is fixed! Code LGTM

[leeyh20]

Was it tested on 2016?

[ChesterSng]

@leeyh20 Yup tested!

[leeyh20]

LGTM except for one part!

[leeyh20]

it will be better if these ratio values will be stored in GraphicsUtil as a constant so that if anyone wants to find these values then they will directly go to GraphicsUtil, not Ribbon1.

[blewjy]

Done! moved them into GraphicsUtil

[YuPeiHenry]

Tested and working on PPT2010.

[leeyh20]

Sorry just one last thing!

[leeyh20]

I realised that these variables are lower-case while the above const float is upper-case for the first letter, could you standardise them according to https://github.com/oss-generic/process/blob/master/codingStandards/CodingStandard-CSharp.adoc ?

[blewjy]

Done! Changed to camel case for private variabels.