Merge pull request #1 from svera/separate-bounded-animation

Separate bounded animation

animation/animation.go

@@ -1,29 +1,34 @@
 package animation
 
 import (
+	"encoding/json"
 	"fmt"
+	"io"
 
 	"github.com/faiface/pixel"
+	"github.com/svera/quarter"
+)
+
+// Returned errors
+const (
+	ErrorVersionNotSupported = "Version \"%s\" not supported"
+	ErrorNoAnims             = "File must have at least one animation declared, none found"
 )
 
 // AnimFile defines the structure of a disk file containing information about animations
 type AnimFile struct {
 	Version string
 	Sheet   string
-	Anims   []struct {
-		AnimData
+	Anims   map[string]struct {
+		Frames   int
+		Cycle    string
+		Duration float64
+		YOffset  float64 `json:"y_offset"`
+		Width    float64
+		Height   float64
 	}
 }
 
-type AnimData struct {
-	Frames   int
-	Cycle    string
-	Duration float64
-	YOffset  float64 `json:"y_offset"`
-	Width    float64
-	Height   float64
-}
-
 // Animation types of cycles
 const (
 	SingleReverse = iota - 2
@@ -34,7 +39,7 @@ const (
 
 // Returned errors
 const (
-	ErrorAnimationDoesNotExist = "Animation %d does not exist"
+	ErrorAnimationDoesNotExist = "Animation '%s' does not exist"
 )
 
 // To convert string values used in sprite definition file to integer values used internally
@@ -48,8 +53,8 @@ type sequence struct {
 
 // Animation implements an animated sprite
 type Animation struct {
-	anims              []*sequence
-	currentAnimID      int
+	anims              map[string]*sequence
+	currentAnimID      string
 	currentFrameNumber int
 	elapsed            float64
 	Position           pixel.Vec
@@ -59,16 +64,45 @@ type Animation struct {
 // NewAnimation returns a new Sprite instance to be drawn at position x, y
 func NewAnimation(pos pixel.Vec, numberAnims int) *Animation {
 	return &Animation{
-		anims:    make([]*sequence, numberAnims),
+		anims:    make(map[string]*sequence, numberAnims),
 		Position: pos,
 		Dir:      1,
 	}
 }
 
+func Deserialize(r io.Reader, pos pixel.Vec) (*Animation, error) {
+	data := &AnimFile{}
+	err := json.NewDecoder(r).Decode(data)
+
+	if err != nil {
+		return nil, err
+	}
+
+	anim := NewAnimation(pos, len(data.Anims))
+
+	if data.Version != "1" {
+		return anim, fmt.Errorf(ErrorVersionNotSupported, data.Version)
+	}
+
+	pic, err := quarter.LoadPicture(data.Sheet)
+	if err != nil {
+		return anim, err
+	}
+
+	if len(data.Anims) == 0 {
+		return nil, fmt.Errorf(ErrorNoAnims)
+	}
+
+	for i, an := range data.Anims {
+		anim.AddAnim(i, pic, an.YOffset, an.Width, an.Height, an.Frames, an.Duration, an.Cycle)
+	}
+	return anim, nil
+}
+
 // AddAnim adds a new animation to the Sprite, identified with ID,
 // whose frames are taken from pic from left to right, starting from X = 0
 // duration defines how many seconds should it take for the animation to complete a cycle
-func (a *Animation) AddAnim(idx int, pic pixel.Picture, yOffset, width, height float64, numberFrames int, duration float64, cycle string) {
+func (a *Animation) AddAnim(idx string, pic pixel.Picture, yOffset, width, height float64, numberFrames int, duration float64, cycle string) {
 	a.anims[idx] = &sequence{
 		timePerFrame: duration / float64(numberFrames),
 	}
@@ -81,8 +115,8 @@ func (a *Animation) AddAnim(idx int, pic pixel.Picture, yOffset, width, height f
 }
 
 // SetCurrentAnim defines which animation to play
-func (a *Animation) SetCurrentAnim(ID int) error {
-	if ID < 0 || ID > len(a.anims)-1 {
+func (a *Animation) SetCurrentAnim(ID string) error {
+	if _, ok := a.anims[ID]; !ok {
 		return fmt.Errorf(ErrorAnimationDoesNotExist, ID)
 	}
 	if ID != a.currentAnimID {
@@ -97,7 +131,7 @@ func (a *Animation) SetCurrentAnim(ID int) error {
 }
 
 // CurrentAnim returns the current animation index
-func (a *Animation) CurrentAnim() int {
+func (a *Animation) CurrentAnim() string {
 	return a.currentAnimID
 }
 
@@ -106,13 +140,13 @@ func (a *Animation) Draw(target pixel.Target, dt float64) {
 	m := pixel.IM.ScaledXY(pixel.ZV, pixel.V(a.Dir, 1)).Moved(a.Position)
 	a.anims[a.currentAnimID].frames[a.currentFrameNumber].Draw(target, m)
 	a.elapsed += dt
-	if idx := a.nextFrameIndex(dt); idx != a.currentFrameNumber {
+	if idx := a.nextFrameIndex(); idx != a.currentFrameNumber {
 		a.elapsed = 0
 		a.currentFrameNumber = idx
 	}
 }
 
-func (a *Animation) nextFrameIndex(dt float64) int {
+func (a *Animation) nextFrameIndex() int {
 	if a.elapsed <= a.anims[a.currentAnimID].timePerFrame {
 		return a.currentFrameNumber
 	}
@@ -146,3 +180,7 @@ func (a *Animation) lastFrame() int {
 func (a *Animation) isLastFrame(number int) bool {
 	return len(a.anims[a.currentAnimID].frames)-1 == number
 }
+
+func (a *Animation) CurrentFrameNumber() int {
+	return a.currentFrameNumber
+}

animation/animation_test.go

@@ -11,10 +11,10 @@ import (
 func TestSetCurrentAnim(t *testing.T) {
 	var testValues = []struct {
 		testName      string
-		ID            int
+		ID            string
 		expectedError string
 	}{
-		{"Animation ID below 0 does not exist", -1, fmt.Sprintf(animation.ErrorAnimationDoesNotExist, -1)},
+		{"Inexistent Animation ID throws an error", "NonExistentID", fmt.Sprintf(animation.ErrorAnimationDoesNotExist, "NonExistentID")},
 	}
 	for _, tt := range testValues {
 		t.Run(tt.testName, func(t *testing.T) {