wasm: check for error condition in image method

facemask/canvas.go

@@ -3,6 +3,7 @@ package facemask
 import (
 	"fmt"
 	"image"
+	"image/draw"
 	"math"
 	"sync"
 	"syscall/js"
@@ -147,9 +148,10 @@ func (c *Canvas) Render() error {
 	var data = make([]byte, width*height*4)
 	c.done = make(chan struct{})
 
-	img := pixels.LoadImage("/images/surgical-mask.png")
-	mask = js.Global().Call("eval", "new Image()")
-	mask.Set("src", "data:image/png;base64,"+img)
+	if img, err := pixels.LoadImage("/images/surgical-mask.png"); err != nil {
+		mask = js.Global().Call("eval", "new Image()")
+		mask.Set("src", "data:image/png;base64,"+img)
+	}
 
 	maskWidth = js.ValueOf(mask.Get("naturalWidth")).Int()
 	maskHeight = js.ValueOf(mask.Get("naturalHeight")).Int()
@@ -174,8 +176,7 @@ func (c *Canvas) Render() error {
 			uint8Arr := js.Global().Get("Uint8Array").New(rgba)
 			js.CopyBytesToGo(data, uint8Arr)
 
-			dx, dy := c.windowSize.width, c.windowSize.height
-			gray := pixels.RgbaToGrayscale(data, dx, dy)
+			gray := pixels.RgbaToGrayscale(data, width, height)
 
 			// Reset the data slice to its default values to avoid unnecessary memory allocation.
 			// Otherwise, the GC won't clean up the memory address allocated by this slice
@@ -264,16 +265,20 @@ func (c *Canvas) StartWebcam() (*Canvas, error) {
 }
 
 // triangulate triangulates the image passed as pixel data
-func (c *Canvas) triangulate(data []uint8, dets []int) ([]uint8, error) {
+func (c *Canvas) triangulate(data []uint8, size image.Rectangle) ([]uint8, error) {
 	// Converts the buffer array to an image.
-	img := pixels.PixToImage(data, int(float64(dets[2])))
+	img := pixels.PixToImage(data, size)
 
 	// Call the face triangulation algorithm.
 	res, _, _, err := c.triangle.Draw(img, *c.processor, func() {})
 	if err != nil {
 		return nil, err
 	}
-	return pixels.ImgToPix(res), nil
+
+	dst := image.NewNRGBA(res.Bounds())
+	draw.Draw(dst, res.Bounds(), res, image.Point{}, draw.Over)
+
+	return pixels.ImgToPix(dst), nil
 }
 
 // drawDetection draws the detected faces and eyes.
@@ -338,7 +343,8 @@ func (c *Canvas) drawDetection(data []uint8, dets [][]int) error {
 
 					// Triangulate the facemask part.
 					c.lock.Lock()
-					triangle, err := c.triangulate(imgData, det)
+					rect := image.Rect(0, 0, scale, scale)
+					triangle, err := c.triangulate(imgData, rect)
 					if err != nil {
 						return err
 					}

masquerade/canvas.go

@@ -102,7 +102,11 @@ func (c *Canvas) Render() {
 	c.done = make(chan struct{})
 
 	for i, file := range sunglasses {
-		img := pixels.LoadImage(file)
+		img, err := pixels.LoadImage(file)
+		if err != nil {
+			c.Alert(err)
+			return
+		}
 		eyemasks[i] = js.Global().Call("eval", "new Image()")
 		eyemasks[i].Set("src", "data:image/png;base64,"+img)
 	}
@@ -110,7 +114,11 @@ func (c *Canvas) Render() {
 	eyeMaskHeight = js.ValueOf(eyemasks[0].Get("naturalHeight")).Int()
 
 	for i, file := range masks {
-		img := pixels.LoadImage(file)
+		img, err := pixels.LoadImage(file)
+		if err != nil {
+			c.Alert(err)
+			return
+		}
 		mouthmasks[i] = js.Global().Call("eval", "new Image()")
 		mouthmasks[i].Set("src", "data:image/png;base64,"+img)
 	}

pixels/image.go

@@ -6,7 +6,6 @@ import (
 	"image"
 	"image/color"
 	"io/ioutil"
-	"log"
 	"math"
 	"net/http"
 	"net/url"
@@ -105,11 +104,11 @@ func RgbaToGrayscale(data []uint8, dx, dy int) []uint8 {
 }
 
 // LoadImage load the source image and encodes it to base64 format.
-func LoadImage(path string) string {
+func LoadImage(path string) (string, error) {
 	href := js.Global().Get("location").Get("href")
 	u, err := url.Parse(href.String())
 	if err != nil {
-		log.Fatal(err)
+		return "", err
 	}
 
 	u.Path = path
@@ -117,14 +116,14 @@ func LoadImage(path string) string {
 
 	resp, err := http.Get(u.String())
 	if err != nil {
-		log.Fatal(err)
+		return "", err
 	}
 	defer resp.Body.Close()
 
 	b, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		log.Fatal(err)
+		return "", err
 	}
 
-	return base64.StdEncoding.EncodeToString(b)
+	return base64.StdEncoding.EncodeToString(b), nil
 }

triangulate/canvas.go

@@ -378,6 +378,7 @@ func (c *Canvas) triangulate(data []uint8, size image.Rectangle) ([]uint8, error
 
 	dst := image.NewNRGBA(triangled.Bounds())
 	draw.Draw(dst, triangled.Bounds(), triangled, image.Point{}, draw.Over)
+
 	return pixels.ImgToPix(dst), nil
 }