Listview – How to Add an Image to ListView in Delphi Not Showing

bitmapdelphilistview

I have a listview in a Multi-device form using Delphi 12.
I'm trying to add a image, but the image is not showing just a blank space.
I don't know if it's the way I download the Image or do I have to convert it?
I spend the whole day trying everything, look at all examples, but all of them had the images in a table or in a imagelist. I know I'm loading the Image twice since I want to check for nil.

Here is the code:

var
jsa: TJSONArray;
jso : TJsonObject;
i: Integer;
Name: String;
LItem: TListViewItem;
begin

if Length(S) > 10 then
   begin
      jso := TJSonObject.ParseJSONValue(S) as TJsonObject;
      if jso <> nil then
         Try
            jsa := jso.GetValue('results') as TJSONArray;
            if Jsa.Count > 0 then
               begin
                  for I := 0 to jsa.Count-1 do
                     begin                             
                         LItem := ListView1.Items.Add;
                         if GetImageFromURL(jsa[i].GetValue<string>('image')) <> nil then
                            LItem.Bitmap := GetImageFromURL(jsa[i].GetValue<string>('image'));
                         LItem.Detail := jsa[i].GetValue<string>('text');
                         LItem.Text := jsa[i].GetValue<string>('expire');
                     end;
               end;
        Finally
             jso.Free;
        End;

   end;

Here is the function that gets the image from a webserver.

function TPromoForm.GetImageFromURL(const S: String): TBitmap;
var
   ms       : TMemoryStream;
   httpCli  : TNetHTTPClient;
   resp     : IHTTPResponse;
   url      : String;
   Image: TBitmap;
begin
result := nil;
httpCli := TNetHTTPClient.Create(nil);
try
    httpCli.UserAgent := 'Mozilla/5.0 (Windows NT 10.0; WOW64; rv:44.0) Gecko/20100101 Firefox/44.0';
    ms := TMemoryStream.Create();
    Image  := TBitmap.Create;
    Image := nil;
    try
        url  := S;
        resp := httpCli.Get(url, ms);
        if resp.StatusCode <> 200 then
           Showmessage(Format('HTTP Error=%d %s', [resp.StatusCode, resp.StatusText]))
        else
          begin
            try
              Image  := TBitmap.Create;
              ms.Position := 0;
              Image.LoadFromStream(ms);
              result := Image;
            finally
              Image.Free;
            end;
          end;
    finally
        ms.Free;
    end;
finally
    httpCli.Free;
end;
end;

The image is a jpg.
Thanks for any help.
Kim

Best Answer

You are Free'ing the TBitmap object before you exit from GetImageFromURL(), thus you are assigning an invalid object to the TListViewItem.Bitmap.

You need to either:

  • Get rid of Image.Free inside of GetImageFromURL() and let it return the object to the caller, who will then have to Free it after using it.

  • Have the caller pass in a valid TBitmap object, such as the TListViewItem.Bitmap, for GetImageFromURL() to fill in.

Related Question