Adds time delta subtration to cut

Author: Ciro S. Costa

editor/cut.go

@@ -1,6 +1,8 @@
 package editor
 
 import (
+	"math"
+
 	"github.com/cirocosta/asciinema-edit/cast"
 	"github.com/pkg/errors"
 )
@@ -64,6 +66,14 @@ func Cut(c *cast.Cast, from, to float64) (err error) {
 		return
 	}
 
+	if toIdx+1 < len(c.EventStream) {
+		delta := c.EventStream[toIdx+1].Time - c.EventStream[fromIdx].Time
+		for _, remainingElem := range c.EventStream[toIdx+1:] {
+			remainingElem.Time -= delta
+			remainingElem.Time = math.Round(remainingElem.Time*1000) / 1000
+		}
+	}
+
 	c.EventStream = append(
 		c.EventStream[:fromIdx],
 		c.EventStream[toIdx+1:]...)

editor/cut_test.go

@@ -8,25 +8,6 @@ import (
 	"github.com/cirocosta/asciinema-edit/editor"
 )
 
-var (
-	event1 = &cast.Event{
-		Time: 1,
-		Data: "event1",
-	}
-	event1_2 = &cast.Event{
-		Time: 1.2,
-		Data: "event1_2",
-	}
-	event1_6 = &cast.Event{
-		Time: 1.6,
-		Data: "event1_6",
-	}
-	event2 = &cast.Event{
-		Time: 2,
-		Data: "event2",
-	}
-)
-
 var _ = Describe("Cut", func() {
 	Context("with nil cast", func() {
 		It("fails", func() {
@@ -48,12 +29,30 @@ var _ = Describe("Cut", func() {
 
 	Context("with non-empty event stream", func() {
 		var (
-			err                   error
-			data                  *cast.Cast
-			initialNumberOfEvents int
+			err                                error
+			data                               *cast.Cast
+			initialNumberOfEvents              int
+			event1, event1_2, event1_6, event2 *cast.Event
 		)
 
 		BeforeEach(func() {
+			event1 = &cast.Event{
+				Time: 1,
+				Data: "event1",
+			}
+			event1_2 = &cast.Event{
+				Time: 1.2,
+				Data: "event1_2",
+			}
+			event1_6 = &cast.Event{
+				Time: 1.6,
+				Data: "event1_6",
+			}
+			event2 = &cast.Event{
+				Time: 2,
+				Data: "event2",
+			}
+
 			data = &cast.Cast{
 				EventStream: []*cast.Event{
 					event1,
@@ -71,19 +70,52 @@ var _ = Describe("Cut", func() {
 			Expect(err).ToNot(Succeed())
 		})
 
-		It("cuts single frame if `from` == `to`", func() {
-			err = editor.Cut(data, 1.2, 1.2)
-			Expect(err).To(Succeed())
-
-			Expect(data.EventStream).To(ContainElement(event1))
-			Expect(data.EventStream).ToNot(ContainElement(event1_2))
-			Expect(data.EventStream).To(ContainElement(event1_6))
-			Expect(data.EventStream).To(ContainElement(event2))
+		Context("cutting a single frame when `from` == `to`", func() {
+			JustBeforeEach(func() {
+				err = editor.Cut(data, 1.2, 1.2)
+				Expect(err).To(Succeed())
+			})
+
+			It("removes the frame", func() {
+				Expect(data.EventStream).To(ContainElement(event1))
+				Expect(data.EventStream).ToNot(ContainElement(event1_2))
+				Expect(data.EventStream).To(ContainElement(event1_6))
+				Expect(data.EventStream).To(ContainElement(event2))
+
+				Expect(len(data.EventStream)).
+					To(Equal(initialNumberOfEvents - 1))
+			})
+
+			It("adjusts the remaining time stamps", func() {
+				Expect(event1.Time).To(Equal(float64(1)))
+				Expect(event1_6.Time).To(Equal(float64(1.2)))
+				Expect(event2.Time).To(Equal(float64(1.6)))
+			})
+		})
 
-			Expect(len(data.EventStream)).To(Equal(initialNumberOfEvents - 1))
+		Context("cutting range without bounds included", func() {
+			JustBeforeEach(func() {
+				err = editor.Cut(data, 1.2, 1.6)
+				Expect(err).To(Succeed())
+			})
+
+			It("removes the frame", func() {
+				Expect(data.EventStream).To(ContainElement(event1))
+				Expect(data.EventStream).ToNot(ContainElement(event1_2))
+				Expect(data.EventStream).ToNot(ContainElement(event1_6))
+				Expect(data.EventStream).To(ContainElement(event2))
+
+				Expect(len(data.EventStream)).
+					To(Equal(initialNumberOfEvents - 2))
+			})
+
+			It("adjusts the remaining time stamps", func() {
+				Expect(event1.Time).To(Equal(float64(1)))
+				Expect(event2.Time).To(Equal(float64(1.2)))
+			})
 		})
 
-		It("cuts frames in range", func() {
+		It("cuts frames in range containing last element", func() {
 			err = editor.Cut(data, 1.2, 2)
 			Expect(err).To(Succeed())
 
@@ -92,7 +124,8 @@ var _ = Describe("Cut", func() {
 			Expect(data.EventStream).ToNot(ContainElement(event1_6))
 			Expect(data.EventStream).ToNot(ContainElement(event2))
 
-			Expect(len(data.EventStream)).To(Equal(initialNumberOfEvents - 3))
+			Expect(len(data.EventStream)).
+				To(Equal(initialNumberOfEvents - 3))
 		})
 	})
 })

editor/quantize.go

@@ -0,0 +1,11 @@
+package editor
+
+// Quantize constraints a set of inputs that lie in a range to a single
+// value that corresponds to the lower bound of such range.
+//
+// 1. capture all delays
+// 2. for each delay, check if the delay fits in the quantization
+//    range.
+// 3. if it fits, reduce the delay to the maximum allowed (floor of
+//    the quantization range).
+// 4. adjust the rest of the event stream.