Hi,

What is the recipe for loading images into a grid column that is bound to a dataset.

The grid column ControlType is set to ctImage and is bound to a dataset column called "Status".
Should this "Status" column be of type string and contain a URL to where the images are located?

// Thom

Switched to column ControlType = ctIcon instead.

// Thom

But I am still interested in what happens when ctImage is used.

I see that this is sent to server "GET /databases/images/MyImage.png".
But what is the correct response that the server needs to send back?

// Thom

On 10/9/2016 2:52 PM, thomh wrote:
> What is the recipe for loading images into a grid column that is bound to a dataset.
>
> The grid column ControlType is set to ctImage and is bound to a dataset column called "Status".
> Should this "Status" column be of type string and contain a URL to where the images are located?


Yes - that's all you need to do (can be relative URL which it is for below).

For example if you look at the "databound" example then it includes a
customer table with photo in the ContactPhoto field.

Dropping a grid, linking it to Customers dataset and then configuring a
column for ContactPhoto with column type ctImage shows the photo in the
grid cell. I do recommend increasing the rowheight in this case to see
actual image properly.

Looking at the communications underneath the original dataset JSON
returns all rows and ContactPhoto for first record is :
?method=load&database=ExampleData&dataset=Customer&column=ContactPhoto&row=ADF

and then new request goes out for

http://<ip and
port>/databases?method=load&database=ExampleData&dataset=Customer&column=ContactPhoto&row=ADF


and response to that is the actual png image (raw data).

Grid actually will fetch new images only as you scroll them into visible
area so as you scroll additional images are loaded.

Raul

Thanks, Raul.

What is the proper reponse to send back to client?

I am returning a PNG file and send back this response
(from a RealThinClient coded sever):

Server.Response['Cache-Control'] := 'no-cache';
Server.Response['Content-Type'] := 'image/png';
Server.Response.Status(200, 'OK');

However, the image does not show up in the databound image control.

// Thom

On 10/11/2016 4:33 PM, thomh wrote:
> What is the proper reponse to send back to client?
>
> I am returning a PNG file and send back this response
> (from a RealThinClient coded sever):
>
> Server.Response['Cache-Control'] := 'no-cache';
> Server.Response['Content-Type'] := 'image/png';
> Server.Response.Status(200, 'OK');
>
> However, the image does not show up in the databound image control.


That looks OK to me - i suggest you use the browser debug tools to see
what's going on exactly underneath.  (it's usually F12 and then look for
network tab).

For comparison this is what the result headers looks like for databound
example image using EWB IDE and chrome:

HTTP/1.1 200
Date: Tue, 11 Oct 2016 21:18:13 GMT
From:
Server: Internal Web Server
Connection: Keep-Alive
Cache-Control: no-cache
Content-Type: image/png
Content-Length: 53399

Raul

Thom:

Here is what I do...


             EWBGetGraphic(Request);  // see below
             
             Response.ContentType := Request.Info.asString['contenttype'];
             Response.HeaderText := Response.HeaderText + RtcString(GetGenericHeader);  // see below
             WriteEx(Request.Info.asByteArray['img']);


function TdmRTCProviders.GetGenericHeader: string;
begin
 result := 'Access-Control-Allow-Origin: *' + #13#10 +
           'Cache-Control: must-revalidate, post-check=0, pre-check=0' + #13#10 +
           'Cache-Control: no-cache, no-store' + #13#10;
end;


// IMPORTANT BITS OF EWBGETGRAPHIC
// tbX is database table.  The graphic is in a Blob and the Content Type is in a Field

// so I store the Content Type 'image/png' in Request.Info['contenttype']  
// then the Graphic is read from a Blob Field and put into a TRTCByteArray
//     Request.Info.asByteArray['img']
// Then the Header is filled in, content type and use WriteEX to send the graphic to the browser.


Passed into the procedure:   Request: TRtcServerRequest

var
 buffer : RtcByteArray;

 Request.Info['contenttype'] := tbX.FieldByName(sField + '_ContentType').Asstring;
 buffer := Request.Info.NewByteArray('img',TBlobField(tbX.FieldByName(sField)).BlobSize);
 Move(TBlobField(tbX.FieldByName(sField)).Value[0], buffer[0], TBlobField(tbX.FieldByName(sField)).BlobSize);


Walter