A rendering engine library for Go supporting both SDL2 and WebAssembly (HTML Canvas) targets.
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package canvas
import (
"syscall/js"
"git.kirsle.net/apps/doodle/lib/render"
)
// Methods here implement the drawing functions of the render.Engine
// Clear the canvas to a certain color.
func (e *Engine) Clear(color render.Color) {
e.canvas.ctx2d.Set("fillStyle", color.ToHex())
e.canvas.ctx2d.Call("fillRect", 0, 0, e.width, e.height)
}
// SetTitle sets the window title.
func (e *Engine) SetTitle(title string) {
js.Global().Get("document").Set("title", title)
}
// DrawPoint draws a pixel.
func (e *Engine) DrawPoint(color render.Color, point render.Point) {
e.canvas.ctx2d.Set("fillStyle", color.ToHex())
e.canvas.ctx2d.Call("fillRect",
int(point.X),
int(point.Y),
1,
1,
)
}
// DrawLine draws a line between two points.
func (e *Engine) DrawLine(color render.Color, a, b render.Point) {
e.canvas.ctx2d.Set("fillStyle", color.ToHex())
for pt := range render.IterLine2(a, b) {
e.canvas.ctx2d.Call("fillRect",
int(pt.X),
int(pt.Y),
1,
1,
)
}
}
// DrawRect draws a rectangle.
func (e *Engine) DrawRect(color render.Color, rect render.Rect) {
e.canvas.ctx2d.Set("strokeStyle", color.ToHex())
e.canvas.ctx2d.Call("strokeRect",
int(rect.X),
int(rect.Y),
int(rect.W),
int(rect.H),
)
}
// DrawBox draws a filled rectangle.
func (e *Engine) DrawBox(color render.Color, rect render.Rect) {
e.canvas.ctx2d.Set("fillStyle", color.ToHex())
e.canvas.ctx2d.Call("fillRect",
int(rect.X),
int(rect.Y),
int(rect.W),
int(rect.H),
)
}