render/canvas/canvas.go

38 líneas
719 B
Go

package canvas
import (
"syscall/js"
)
// Canvas represents an HTML5 Canvas object.
type Canvas struct {
Value js.Value
ctx2d js.Value
}
// GetCanvas gets an HTML5 Canvas object from the DOM.
func GetCanvas(id string) Canvas {
canvasEl := js.Global().Get("document").Call("getElementById", id)
canvas2d := canvasEl.Call("getContext", "2d")
c := Canvas{
Value: canvasEl,
ctx2d: canvas2d,
}
canvasEl.Set("width", c.ClientW())
canvasEl.Set("height", c.ClientH())
return c
}
// ClientW returns the client width.
func (c Canvas) ClientW() int {
return c.Value.Get("clientWidth").Int()
}
// ClientH returns the client height.
func (c Canvas) ClientH() int {
return c.Value.Get("clientHeight").Int()
}