render/canvas/engine.go
Noah Petherbridge 03b4441eaa WASM Event Queue
* Refactor the event system in the WASM render engine to serialize the
  async JavaScript events into a channel, so that queued events are read
  off serially in the main loop similar to SDL. This fixes keyboard
  input issues, altho if you type really fast some input keys get lost.
2019-06-26 20:33:24 -07:00

85 lines
1.7 KiB
Go

package canvas
import (
"time"
"git.kirsle.net/apps/doodle/lib/events"
"git.kirsle.net/apps/doodle/lib/render"
)
// Engine implements a rendering engine targeting an HTML canvas for
// WebAssembly targets.
type Engine struct {
canvas Canvas
startTime time.Time
width int
height int
ticks uint32
// Private fields.
events *events.State
running bool
// Event channel. WASM subscribes to events asynchronously using the
// JavaScript APIs, whereas SDL2 polls the event queue which orders them
// all up for processing. This channel will order and queue the events.
queue chan Event
}
// New creates the Canvas Engine.
func New(canvasID string) (*Engine, error) {
canvas := GetCanvas(canvasID)
engine := &Engine{
canvas: canvas,
startTime: time.Now(),
events: events.New(),
width: canvas.ClientW(),
height: canvas.ClientH(),
queue: make(chan Event, 1024),
}
return engine, nil
}
// WindowSize returns the size of the canvas window.
func (e *Engine) WindowSize() (w, h int) {
return e.canvas.ClientW(), e.canvas.ClientH()
}
// GetTicks returns the number of milliseconds since the engine started.
func (e *Engine) GetTicks() uint32 {
ms := time.Since(e.startTime) * time.Millisecond
return uint32(ms)
}
// TO BE IMPLEMENTED...
func (e *Engine) Setup() error {
return nil
}
func (e *Engine) Present() error {
return nil
}
func (e *Engine) NewBitmap(filename string) (render.Texturer, error) {
return nil, nil
}
func (e *Engine) Copy(t render.Texturer, src, dist render.Rect) {
}
// Delay for a moment.
func (e *Engine) Delay(delay uint32) {
time.Sleep(time.Duration(delay) * time.Millisecond)
}
// Teardown tasks.
func (e *Engine) Teardown() {}
func (e *Engine) Loop() error {
return nil
}