doodle/render/interface.go

105 lines
2.1 KiB
Go
Raw Normal View History

package render
import (
"fmt"
"git.kirsle.net/apps/doodle/events"
)
// Engine is the interface for the rendering engine, keeping SDL-specific stuff
// far away from the core of Doodle.
type Engine interface {
Setup() error
// Poll for events like keypresses and mouse clicks.
Poll() (*events.State, error)
GetTicks() uint32
// Draw presents the current state to the screen.
Draw() error
// Clear the full canvas and set this color.
Clear(Color)
DrawPoint(Color, Point)
DrawLine(Color, Point, Point)
DrawRect(Color, Rect)
DrawText(Text, Rect) error
// Delay for a moment using the render engine's delay method,
// implemented by sdl.Delay(uint32)
Delay(uint32)
// Tasks that the Setup function should defer until tear-down.
Teardown()
Loop() error // maybe?
}
// Color holds an RGBA color value.
type Color struct {
Red uint8
Green uint8
Blue uint8
Alpha uint8
}
func (c Color) String() string {
return fmt.Sprintf(
"Color<#%02x%02x%02x>",
c.Red, c.Green, c.Blue,
)
}
// Point holds an X,Y coordinate value.
type Point struct {
X int32
Y int32
}
func (p Point) String() string {
return fmt.Sprintf("Point<%d,%d>", p.X, p.Y)
}
// Rect has a coordinate and a width and height.
type Rect struct {
X int32
Y int32
W int32
H int32
}
func (r Rect) String() string {
return fmt.Sprintf("Rect<%d,%d,%d,%d>",
r.X, r.Y, r.W, r.H,
)
}
// Text holds information for drawing text.
type Text struct {
Text string
Size int
Color Color
Stroke Color // Stroke color (if not zero)
Shadow Color // Drop shadow color (if not zero)
}
func (t Text) String() string {
return fmt.Sprintf("Text<%s>", t.Text)
}
// Common color names.
var (
Invisible = Color{}
White = Color{255, 255, 255, 255}
Grey = Color{153, 153, 153, 255}
Black = Color{0, 0, 0, 255}
SkyBlue = Color{0, 153, 255, 255}
Blue = Color{0, 0, 255, 255}
Red = Color{255, 0, 0, 255}
Green = Color{0, 255, 0, 255}
Cyan = Color{0, 255, 255, 255}
Yellow = Color{255, 255, 0, 255}
Magenta = Color{255, 0, 255, 255}
Pink = Color{255, 153, 255, 255}
)