Take Alpha into account when doing Color Blending

[Pixaurora]

Is your feature request related to a problem? Please describe.
When using any of the blend modes, alpha is ignored and set to 1.0 when the color is returned.

Describe the solution you'd like
It would be nice to be able to have the blend modes apply "less intensely" if the opacity of the source color is lower, i.e. when using Normal, if the source's opacity is 0, the backdrop's color would be unchanged.

After dwelling on this for a bit, I think an acceptable solution could be to use Color::mix_with on the source color, mixing with the backdrop color with the weight being based on the differences between their alpha channels (i.e. source alpha - backdrop alpha). I'm open to different ideas though!

[JiatLn]

thank you for your issue! I fixed it in v0.3.8

[Pixaurora]

Thank you!