Image jumps

[stuartmscott]

Describe the bug:

Similar to #1266, but for ImageFillOriginal

Example code:

Run the below with any jpeg image as go run main.go /path/to/image.jpg

package main

import (
	"bytes"
	"fyne.io/fyne"
	"fyne.io/fyne/app"
	"fyne.io/fyne/canvas"
	"fyne.io/fyne/widget"
	"image/jpeg"
	"io/ioutil"
	"log"
	"os"
)

func main() {
	// Create Fyne App
	a := app.New()

	// Create Fyne Window
	w := a.NewWindow("Image Jump")

	// Create image to hold image
	img := &canvas.Image{
		FillMode: canvas.ImageFillOriginal,
	}
	scroller := widget.NewScrollContainer(img)

	// Create goroutine to load file contents and update image
	go func() {
		data, err := ioutil.ReadFile(os.Args[1])
		if err != nil {
			log.Println("Error:", err)
			return
		}
		i, err := jpeg.Decode(bytes.NewReader(data))
		if err != nil {
			log.Println("Error:", err)
			return
		}
		img.Image = i
		img.Refresh()
		scroller.Refresh()
	}()

	// Add scroller to window
	w.SetContent(scroller)

	w.Resize(fyne.NewSize(480, 600))
	w.ShowAndRun()
}

[andydotxyz]

On develop :)