Add IconSet, FaceSet to style package

style/faceset.go

@@ -0,0 +1,13 @@
+package style
+
+import "golang.org/x/image/font"
+import "git.tebibyte.media/tomo/tomo"
+
+// FaceSet holds a set of font faces.
+type FaceSet interface {
+	// Face returns the font face which most closely matches the given
+	// tomo.Face. The face must be closed when it is done being used. If no
+	// suitable face could be found, This behavior must return a fallback
+	// face (such as basicfont.Face7x13) instead of nil.
+	Face (tomo.Face) font.Face
+}

style/iconset.go

@@ -0,0 +1,28 @@
+package style
+
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/data"
+import "git.tebibyte.media/tomo/tomo/canvas"
+
+// IconSet holds a set of icon textures.
+type IconSet interface {
+	// A word on textures:
+	//
+	// Because textures can be linked to some resource that is outside of
+	// the control of Go's garbage collector, methods of IconSet must not
+	// allocate new copies of a texture each time they are called. It is
+	// fine to lazily load textures and save them for later use, but the
+	// same texture must never be allocated multiple times as this could
+	// cause a memory leak.
+	//
+	// As such, textures returned by these methods must be protected.
+	
+	// Icon returns a texture of the corresponding icon ID. If there is no
+	// suitable option, it should return nil.
+	Icon (tomo.Icon, tomo.IconSize) canvas.Texture
+
+	// MimeIcon returns a texture of an icon corresponding to a MIME type.
+	// If there is no suitable specific option, it should return a more
+	// generic icon or a plain file icon.
+	MimeIcon (data.Mime, tomo.IconSize) canvas.Texture
+}