在图片框中显示图像字符串数据。

Question

I've to display a image in a picture box in VisualWebGui. I've image in string format.

string ImageString_P;
FileStream fs_P = new FileStream(LocalDirectory + "Page_2.tif", FileMode.Open, FileAccess.Read);

byte[] picbyte_P = new byte[fs_P.Length];
fs_P.Read(picbyte_P, 0, Convert.ToInt32(fs_P.Length));
ImageString_P = Convert.ToBase64String(picbyte_P);

Now, how can I display this image(ImageString_P) in the picture box. Should I create the image of this string data or can I directly display this data in the PictureBox?

If I'll create the image in a path(suppose “c:\\xyz.jpg”) . How it (xyz.jpg) will be displayed in the picturebox.

Answer 1

Visual WebGui is a web application and as such it basically needs to let the browser specifically request any graphics data that should be rendered, which is fundamentally different from that of desktop applications, where you can simply assign the graphics data itself to the image property of a PictureBox.

If you study how a webpage with a PictureBox is rendered to the browser in Visual WebGui, you will see that the PictureBox is rendered as an img tag with the source being set to an Url, which is responsible for serving the image to the browser. When the browser sees that Url on the img tag, it issues another request to the server for the contents of that Url. This "secondary" request is called a gateway request in Visual WebGui.

To serve the graphics to the browser, you need some kind of Gateway in your Visual WebGui application. There are a few types of predefined gateways in Visual WebGui, like for Images (ImageResourceHandle) and icons (IconResourceHandle), but in this case you have a dynamically generated image, so you will need to define your own gateway to serve the graphics contents.... or you can write the image data to, say, Resources\\Images folder of your application and then use an ImageResourceHandle to reference it.

Defining your own gateways in Visual WebGui is very simple, and you can see quite a few examples here .

Hope this helps, Palli

Answer 2

You can do like this:

string ImageString_P;
FileStream fs_P = new FileStream(LocalDirectory + "Page_2.tif", FileMode.Open, FileAccess.Read);

byte[] picbyte_P = new byte[fs_P.Length];
this.picMyPicture.Image = new DynamicStreamResourceHandle(contentBitmap, "image/jpeg");

and it should render fine.