Synfig: Allow to set default canvas background

[wstaelens]

Synfig version & platform:
Synfig 1.2.2 - Windows 10 x64 Pro

Issue description:

It would be great to let us set a default background in the Canvas Properties.
Now you see by default a transparent checker background, and when previewing/rendering it is set to gray.

allow us to set a default "world" or "scene" background as in Blender.

[morevnaproject]

You can simply drag-n-drop any image file to Synfig workarea from file manager and then place it below all layers.

[wstaelens]

Yes I know, but this feels like a "hack" and clutters up the workspace layers.
Just setting a default background color for the canvas in the properties would be great. If you still want to use a background image or rectangle you would just set it as transparent...

[BobSynfig]

Hi,
I added some options for backgrounds:
Selection of Preview Background Color (Render page)

Add automatically a default background layer on new animation (Document page)

• None
• Solid Color
• Image - Scale to fit canvas depend on the option in Editing page

These layers will be named "Background"

Cheers :)

[Jose-Moreno]

@BobSynfig Hey that's awesome! Every contribution counts. I wish I knew how to properly develop software with C++ to help as well, but it's great to see more people adding more "quality-of-life" options :slightly_smiling_face:

[morevnaproject]

@BobSynfig Thank you very much for this improvement, I really like the solution!

690 is merged now.