capture screenshot with parameters

.gitignore

@@ -1,4 +1,6 @@
+img/
 bin
+.DS_STORE
 
 # Ignore everything in vendor/, except for *.go files,
 # LICENSE and COPYING. Ignore Go tests.

example/go/main.go

@@ -7,16 +7,24 @@ import (
 	"log"
 	"net/http"
 	"net/url"
+	"os"
 
 	"github.com/pressly/screenshot/rpc/screenshot"
 )
 
+var (
+	flags = flag.NewFlagSet("screenshot", flag.ExitOnError)
+
+	// Logging options
+	window = flags.String("window", "800x600", "{width}x{height}")
+)
+
 func main() {
-	flag.Parse()
+	flags.Parse(os.Args[1:])
 
-	args := flag.Args()
-	if len(args) != 2 {
-		log.Fatalln("./example URL OUTPUT-FILE")
+	args := flags.Args()
+	if len(args) < 2 {
+		log.Fatalln("./example URL OUTPUT-FILE -window={width}x{height}")
 	}
 	urlLink, filename := args[0], args[1]
 
@@ -27,7 +35,7 @@ func main() {
 
 	client := screenshot.NewScreenshotJSONClient("http://localhost:6666", &http.Client{})
 
-	resp, err := client.Image(context.Background(), &screenshot.RequestImage{Url: u.String()})
+	resp, err := client.Image(context.Background(), &screenshot.RequestImage{Url: u.String(), Window: *window})
 	if err != nil {
 		log.Fatal(err)
 	}

go.mod

@@ -1,6 +1,7 @@
 module github.com/pressly/screenshot
 
 require (
+	github.com/chromedp/cdproto v0.0.0-20181103000133-6fb67cb3bc62 // indirect
 	github.com/chromedp/chromedp v0.1.2
 	github.com/golang/protobuf v1.2.0
 	github.com/pkg/errors v0.8.0

go.sum

@@ -1,5 +1,7 @@
 github.com/chromedp/cdproto v0.0.0-20180713053126-e314dc107013 h1:8nmuTwCseJcww39MvVHI59223+PxSzn6g3cl8ChF0/4=
 github.com/chromedp/cdproto v0.0.0-20180713053126-e314dc107013/go.mod h1:C2GPAraqdt1KfZU7aSmx1XUgarNq/3JmxevQkmCjOVs=
+github.com/chromedp/cdproto v0.0.0-20181103000133-6fb67cb3bc62 h1:Ccuq1Cp3Z0z2vXDC2fKTrWy6yRZrM626WEdrB+tSUew=
+github.com/chromedp/cdproto v0.0.0-20181103000133-6fb67cb3bc62/go.mod h1:NcHZYATbiYX27TBzC98mmdw6oG1CGTiRXN+qGlkIzXs=
 github.com/chromedp/chromedp v0.1.2 h1:qB/dpbbbOPGkKyZU2gKB49jp+ZvY9C3rPUfYELLz+6g=
 github.com/chromedp/chromedp v0.1.2/go.mod h1:83UDY5CKmHrvKLQ6vVU+LVFUcfjOSPNufx8XFWLUYlQ=
 github.com/disintegration/imaging v1.4.2 h1:BSVxoYQ2NfLdvIGCDD8GHgBV5K0FCEsc0d/6FxQII3I=

lib/headless/headless.go

@@ -1,11 +1,10 @@
 package headless
 
 import (
-	"bytes"
 	"context"
-	"io"
 	"log"
 
+	"github.com/chromedp/cdproto/page"
 	"github.com/chromedp/chromedp"
 	"github.com/pkg/errors"
 )
@@ -35,19 +34,31 @@ func (c *Chrome) Close() {
 	}
 }
 
-func (c *Chrome) NewImage(ctx context.Context, addr string) (io.Reader, error) {
+func (c *Chrome) NewImage(ctx context.Context, addr string, x, y, width, height float64) ([]byte, error) {
 	// run task list
+
 	var buf []byte
 	err := c.Run(ctx,
 		chromedp.Tasks{
 			chromedp.Navigate(addr),
 			chromedp.WaitReady("body"),
-			chromedp.CaptureScreenshot(&buf)},
-	)
+			chromedp.CaptureScreenshot(&buf),
+		})
+	if err != nil {
+		return nil, err
+	}
 
+	currentTarget := c.GetHandlerByIndex(0)
+	image, err := page.CaptureScreenshot().WithClip(&page.Viewport{
+		X:      x,
+		Y:      y,
+		Width:  width,
+		Height: height,
+		Scale:  1.0,
+	}).Do(ctx, currentTarget)
 	if err != nil {
 		return nil, err
 	}
 
-	return bytes.NewReader(buf), nil
+	return image, nil
 }

rpc/screenshot/service.proto

@@ -6,13 +6,14 @@ option go_package = "screenshot";
 service Screenshot {
     // Image takes a URL and produces a screenshot of that page.
     rpc Image(RequestImage) returns (Resp);
-
-    // Image takes a URL and produces a screenshot of that page.
-    // rpc PDF(RequestImage) returns (Resp);
 }
 
 message RequestImage {
     string url = 1;
+    string window = 2;
+    float x = 3;
+    float y = 4;
+    string crop = 5;
 }
 
 message Resp {