[RSDK-9513] Add VideoSourceFromCamera helper in stream camera utils (#…

…4625)

robot/web/stream/camera/camera.go

@@ -1,7 +1,12 @@
-// Package camera provides functions for looking up a camera from a robot using a stream
+// Package camera provides utilities for working with camera resources in the context of streaming.
 package camera
 
 import (
+	"context"
+	"image"
+
+	"github.com/pion/mediadevices/pkg/prop"
+
 	"go.viam.com/rdk/components/camera"
 	"go.viam.com/rdk/gostream"
 	"go.viam.com/rdk/resource"
@@ -19,3 +24,22 @@ func Camera(robot robot.Robot, stream gostream.Stream) (camera.Camera, error) {
 	}
 	return cam, nil
 }
+
+// VideoSourceFromCamera converts a camera resource into a gostream VideoSource.
+// This is useful for streaming video from a camera resource.
+func VideoSourceFromCamera(ctx context.Context, cam camera.Camera) gostream.VideoSource {
+	reader := gostream.VideoReaderFunc(func(ctx context.Context) (image.Image, func(), error) {
+		img, err := camera.DecodeImageFromCamera(ctx, "", nil, cam)
+		if err != nil {
+			return nil, func() {}, err
+		}
+		return img, func() {}, nil
+	})
+
+	img, err := camera.DecodeImageFromCamera(ctx, "", nil, cam)
+	if err == nil {
+		return gostream.NewVideoSource(reader, prop.Video{Width: img.Bounds().Dx(), Height: img.Bounds().Dy()})
+	}
+	// Okay to return empty prop because processInputFrames will tick and set them
+	return gostream.NewVideoSource(reader, prop.Video{})
+}

robot/web/stream/camera/camera_test.go

@@ -0,0 +1,37 @@
+package camera_test
+
+import (
+	"context"
+	"image"
+	"testing"
+
+	"go.viam.com/test"
+
+	"go.viam.com/rdk/components/camera"
+	"go.viam.com/rdk/rimage"
+	camerautils "go.viam.com/rdk/robot/web/stream/camera"
+	"go.viam.com/rdk/testutils/inject"
+	"go.viam.com/rdk/utils"
+)
+
+func TestVideoSourceFromCamera(t *testing.T) {
+	sourceImg := image.NewRGBA(image.Rect(0, 0, 3, 3))
+	cam := &inject.Camera{
+		ImageFunc: func(ctx context.Context, mimeType string, extra map[string]interface{}) ([]byte, camera.ImageMetadata, error) {
+			imgBytes, err := rimage.EncodeImage(ctx, sourceImg, utils.MimeTypePNG)
+			test.That(t, err, test.ShouldBeNil)
+			return imgBytes, camera.ImageMetadata{MimeType: utils.MimeTypePNG}, nil
+		},
+	}
+	vs := camerautils.VideoSourceFromCamera(context.Background(), cam)
+
+	stream, err := vs.Stream(context.Background())
+	test.That(t, err, test.ShouldBeNil)
+
+	img, _, err := stream.Next(context.Background())
+	test.That(t, err, test.ShouldBeNil)
+
+	diffVal, _, err := rimage.CompareImages(img, sourceImg)
+	test.That(t, err, test.ShouldBeNil)
+	test.That(t, diffVal, test.ShouldEqual, 0)
+}