Revise console interface

src/gopheros/device/video/console/device.go

@@ -0,0 +1,45 @@
+package console
+
+import "image/color"
+
+// ScrollDir defines a scroll direction.
+type ScrollDir uint8
+
+// The supported list of scroll directions for the console Scroll() calls.
+const (
+	Up ScrollDir = iota
+	Down
+)
+
+// The Device interface is implemented by objects that can function as system
+// consoles.
+type Device interface {
+	// Dimensions returns the width and height of the console in characters.
+	Dimensions() (uint16, uint16)
+
+	// DefaultColors returns the default foreground and background colors
+	// used by this console.
+	DefaultColors() (fg, bg uint8)
+
+	// Fill sets the contents of the specified rectangular region to the
+	// requested color. Both x and y coordinates are 1-based (top-left
+	// corner has coordinates 1,1).
+	Fill(x, y, width, height uint16, fg, bg uint8)
+
+	// Scroll the console contents to the specified direction. The caller
+	// is responsible for updating (e.g. clear or replace) the contents of
+	// the region that was scrolled.
+	Scroll(dir ScrollDir, lines uint16)
+
+	// Write a char to the specified location. Both x and y coordinates are
+	// 1-based (top-left corner has coordinates 1,1).
+	Write(ch byte, fg, bg uint8, x, y uint16)
+
+	// Palette returns the active color palette for this console.
+	Palette() color.Palette
+
+	// SetPaletteColor updates the color definition for the specified
+	// palette index. Passing a color index greated than the number of
+	// supported colors should be a no-op.
+	SetPaletteColor(uint8, color.RGBA)
+}