Specifies whether to protect the alpha channel during drawing. You can also set the value.
Default is false.
In Kirikiri 2.23 beta 1 and earlier, each drawing method had a parameter called "hda" that performed the same action as this property, but it was separated into a property starting from 2.23 beta 2.
In some drawing operations, when the Layer.face property is dfOpaque, you can use this property to specify whether to preserve the image's alpha channel (mask image). For many methods, setting this property to false allows for faster drawing. If Layer.type is neither ltAlpha nor ltAddAlpha, the image's alpha channel is not used, so setting this property to false is not a problem. However, if this property is false, the alpha channel will be destroyed.