Noah Petherbridge
4d08bf1d85
* Switch from otto to goja for JavaScript engine. * goja supports many ES6 syntax features like arrow functions, const/let, for-of with more coming soon. * Same great features as otto, more modern environment for doodads!
137 lines
3.3 KiB
Go
137 lines
3.3 KiB
Go
package uix
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import (
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"errors"
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"fmt"
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"reflect"
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"time"
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"git.kirsle.net/apps/doodle/pkg/log"
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"github.com/dop251/goja"
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)
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// Animation holds a named animation for a doodad script.
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type Animation struct {
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Name string
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Interval time.Duration
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Layers []int
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// runtime state variables
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activeLayer int
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nextFrameAt time.Time
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}
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/*
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TickAnimation advances an animation forward.
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This method is called by canvas.Loop() only when the actor is currently
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`animating` and their current animation's nextFrameAt has been reached by the
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current time.Now().
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Returns true when the animation has finished and false if there is still more
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frames left to animate.
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*/
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func (a *Actor) TickAnimation(an *Animation) bool {
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an.activeLayer++
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if an.activeLayer < len(an.Layers) {
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a.ShowLayer(an.Layers[an.activeLayer])
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} else if an.activeLayer >= len(an.Layers) {
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// final layer has been shown for 2 ticks, return that the animation has
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// been concluded.
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return true
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}
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// Schedule the next frame of animation.
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an.nextFrameAt = time.Now().Add(an.Interval)
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return false
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}
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// AddAnimation installs a new animation into the scripting engine for this actor.
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//
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// The layers can be an array of string names or integer indexes.
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func (a *Actor) AddAnimation(name string, interval int64, layers []interface{}) error {
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if len(layers) == 0 {
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return errors.New("no named layers given to AddAnimation()")
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}
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// Find all the layers by name.
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var indexes []int
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for _, name := range layers {
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switch v := name.(type) {
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case string:
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var found bool
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for i, layer := range a.Doodad().Layers {
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if layer.Name == v {
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indexes = append(indexes, i)
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found = true
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break
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}
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}
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if !found {
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return fmt.Errorf("layer named '%s' not found in doodad", v)
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}
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case int64:
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// TODO: I want to find out if this is ever not an int64 coming from
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// JavaScript.
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if reflect.TypeOf(v).String() != "int64" {
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log.Error("AddAnimation: expected an int64 from JavaScript but got a %s", reflect.TypeOf(v))
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}
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iv := int(v)
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if iv < len(a.Doodad().Layers) {
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indexes = append(indexes, iv)
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} else {
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return fmt.Errorf("layer numbered '%d' is out of bounds", iv)
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}
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default:
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return fmt.Errorf(
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"invalid type for layer '%+v': should be a string (named layer) "+
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"or int (indexed layer) but was a %s", v, reflect.TypeOf(name))
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}
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}
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a.animations[name] = &Animation{
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Name: name,
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Interval: time.Duration(interval) * time.Millisecond,
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Layers: indexes,
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}
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return nil
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}
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// PlayAnimation starts an animation and then calls a JavaScript function when
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// the last frame has played out. Set a null function to ignore the callback.
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func (a *Actor) PlayAnimation(name string, callback goja.Value) error {
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anim, ok := a.animations[name]
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if !ok {
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return fmt.Errorf("animation named '%s' not found", name)
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}
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a.activeAnimation = anim
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a.animationCallback = callback
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// Show the first layer.
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anim.activeLayer = 0
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anim.nextFrameAt = time.Now().Add(anim.Interval)
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a.ShowLayer(anim.Layers[0])
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return nil
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}
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// IsAnimating returns if the current actor is playing an animation.
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func (a *Actor) IsAnimating() bool {
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return a.activeAnimation != nil
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}
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// StopAnimation stops any current animations.
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func (a *Actor) StopAnimation() {
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if a.activeAnimation == nil {
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return
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}
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a.activeAnimation = nil
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a.animationCallback = goja.Null()
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}
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