display image blob in grid

[Steve Wood]

I am creating an image blob in a function called from a grid OnGridInitialize event. I want to display that image in a grid without saving the image file to disk or a table record. Any thoughts?

If that doesn't work, I'd like the grid to display a jpg file that has been saved to the session folder.

[mheller]

Re: display image blob in grid

Do you want to display this in grid rows or in a linked content section?

[Steve Wood]

Re: display image blob in grid

It is a single-record, add-only grid patterned after a Dialog component, with no linked content.

Now that I think of it, I probably can't deal directly with the blob since it cannot be converted to a normal string. It will probably have to be saved on disk as a normal image and then referenced in the grid by refreshing the grid, or just the image somehow. I just don't want the image to be saved to a table or to the webroot.

If saved to disk, it must go to the session folder so it can automatically be removed when the session expires.

Background, if necessary: The function that creates the image is compiled in an AEX defined in the "xbasic .aex files" property of the grid, and called both from an event and also from a button defined in the grid. The function part is working perfectly. The generated image starts out as a blob, then is or can be saved to disk.

[Steve Wood]

Re: display image blob in grid

Martin, you sounded hopeful, do you have anything? I haven't got it solved yet.

[jdrake]

Re: display image blob in grid

I believe you can do this using a modified form of the simplechartlite example.

http://wiki.alphasoftware.com/Placin...+on+a+Web+Page


If you were to use an a5w page to generate the blob you can then pass it easily through html.

ex: <img src="http://myserver/genImage.a5w"></img>

[Lenny Forziati]

Re: display image blob in grid

Steve, you can serve the JPEG from the table without creating a file anywhere on disk using a technique similar to serving a file from outside the webroot.

First, have the IMG tag refer to an A5W page instead of a .jpg file. The browser doesn't care about the file extension, it relies on the MIME type sent back as a response.

Then, in your A5W you need code to retrieve the blob from your table, set the appropriate MIME type, and simply output the blob back to the browser.

[jdrake]

Re: display image blob in grid

Let me simplify it a little.

I have a file called test.a5w with the code:

<%a5

DIM myPicture as B

myPicture = file.to_blob("d:\myPic.png")


Response.mime_type = "image/png"
? myPicture

%>

I then have a second file test2.a5w (could easily be a grid).

<img src="test.a5w"></img>

Since you said you already had the blob in your own variable then you can ignore my loading of a picture into a blob variable.

The key here is the file extensions don't mean anything to a browser, its all in the "mime_type". Therefore, even though your image source is an a5w, your browser knows that is really an image/png.

This leads to other tremendous possibilities such as streaming a pdf on demand without having to save it as a file on the server.

~~Edit~~
I guess Lenny beat me to the punch.

[envisionsolutions]

Re: display image blob in grid

I have this code in the body of get_logo.a5w
<%a5

DIM mypicture as B

mypicture = file.to_blob("C:\A5Webroot\images\pic.jpg")


Response.mime_type = "image/jpg"
? mypicture

%>

I have a second page with this in it:

<img src="get_avatar.a5w"></img>

The image does not display, am I doing something wrong here?

[omagarc]

Re: display image blob in grid

I have this code in the body of get_logo.a5w
<%a5

DIM mypicture as B

mypicture = file.to_blob("C:\A5Webroot\images\pic.jpg")


Response.mime_type = "image/jpg"
? mypicture

%>

I have a second page with this in it:

<img src="get_avatar.a5w"></img>

The image does not display, am I doing something wrong here?

your not using the same page. you show get_logo.a5w but calling get_avatar.a5w

[jon.warner]

Re: display image blob in grid

I have this code in the body of get_logo.a5w
<%a5

DIM mypicture as B

mypicture = file.to_blob("C:\A5Webroot\images\pic.jpg")


Response.mime_type = "image/jpg"
? mypicture

%>

I have a second page with this in it:

<img src="get_avatar.a5w"></img>

The image does not display, am I doing something wrong here?

Josh,

Did you ever get anywhere with this? I'm trying to do the same thing. The instructions in this thread seem completely straightforward...but still no luck.

Jon

[envisionsolutions]

Re: display image blob in grid

With the help of another A5 developer(Mauricio) I was able to make it work. You may not be trying to do exactly what I was attempting but here goes. I wanted to set the image of each user as a session variable so that I could display it wherever I needed to within the web app. I have a codepage.a5w that I use to collect the session variables and then it redirects to the ultimate destination which is my TabbedUI. I have a user table with a character field that I named linked_image where the path and name of the image is stored. My suggestion is to create an images folder inside of your A5WebRoot. Make sure that in your linked_image field that the path looks something like this. images\user1.pic

Add this code to whichever page you are using to collect/set your session variables(mine is located in my codepage.a5w:

<%A5
session.techpic = sql_lookup("::name::Your_Connection_String", "your_table", "id = '" + session.__protected__ulink + "'", "(linked_image)")
%>

Now to display the image:
<%A5
?"<img src=\"" + session.techpic + "\" />"
%>

[jon.warner]

Re: display image blob in grid

With the help of another A5 developer(Mauricio) I was able to make it work. You may not be trying to do exactly what I was attempting but here goes. I wanted to set the image of each user as a session variable so that I could display it wherever I needed to within the web app. I have a codepage.a5w that I use to collect the session variables and then it redirects to the ultimate destination which is my TabbedUI. I have a user table with a character field that I named linked_image where the path and name of the image is stored. My suggestion is to create an images folder inside of your A5WebRoot. Make sure that in your linked_image field that the path looks something like this. images\user1.pic

Add this code to whichever page you are using to collect/set your session variables(mine is located in my codepage.a5w:

<%A5
session.techpic = sql_lookup("::name::Your_Connection_String", "your_table", "id = '" + session.__protected__ulink + "'", "(linked_image)")
%>

Now to display the image:
<%A5
?"<img src=\"" + session.techpic + "\" />"
%>

Actually, after several frustrating hours...it appears to be working. Just realized the ONLY thing to be on the page that calls the image blob is the code block. Considering I set the MIME type to image/jpeg, it makes sense that HTML tags would cause problems.

I agree that having images under the webroot makes for easier access, but the images are sensitive (some confidential). So, easy access is a problem.

What I'm attempting to do -- though I haven't tried it yet (fingers crossed) -- is use this to render images on reports, using the printHTML function. We'll see how it goes.

Thanks for your reply.

Jon