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Programming => Databases => Topic started by: hamacker on November 25, 2021, 05:02:45 pm

Title: DBGRID not responsive when I load pics from db into column cells
Post by: hamacker on November 25, 2021, 05:02:45 pm

Hi guys,
I have a DBGrid that show me a table with blob images where only '.jpg' and '.bmp' in 1024x1024px are acceptable.
The images are faces pictures stretched to 64x64 in dbgrid cell, my problem is that my code bellow is fast to show in dbgrid, but not responsive to navigate when I click or move up/down, need to wait each move.
The code is:

Code: Pascal  [Select][+][-]

1. var
2.   db_tmpfoto:TDBImage;
3.   fixRect : TRect;
4.   bmpWidth : integer;
5. begin
6.   if Sender is TDBGrid then
7.   begin
8.     fixRect := Rect;
9.     with TDBGrid(Sender) do
10.     begin
11.       (...)
12.       fixRect := Rect;
13.       if Column.Index=0 then  // pic in column index 0
14.       begin
15.         Canvas.FillRect(Rect);
16.         db_tmpfoto:=TDBImage.Create(nil);
17.         try
18.           db_tmpfoto.Datasource:=DS_Qry_Pesqusia;
19.           db_tmpfoto.DataField:='foto';
20.           bmpWidth := (Rect.Bottom - Rect.Top);
21.           fixRect.Right := Rect.Left + bmpWidth;
22.           Canvas.StretchDraw(fixRect,db_tmpfoto.Picture.Bitmap);
23.         finally
24.           db_tmpfoto.free;
25.         end;
26.       end;
27.     end;
28.   end;

It´s load well but so, so slow to navigate, it´s not responsive then I try other method(winner method in my opnion), load all images from db into imagelist and draw in oncolumndrawcell:

Code: Pascal  [Select][+][-]

1. var
2.   MyEffect:TGraphicsDrawEffect; // units   ImgList, GraphType
3. begin
4.   if Sender is TDBGrid then
5.   begin
6.     with TDBGrid(Sender) do
7.     begin
8.       MyEffect:=gdeShadowed;
9.       if gdRowHighlight in State then
10.       begin
11.         MyEffect:=gdeHighlighted;
12.       end;
13.       if Column.Index=0 then  // foto na coluna 0
14.       begin
15.         Canvas.FillRect(Rect); // limpando a celula com rect vazio
16.         i:=dmPrincipal.Colaboradores_Pics.IndexOf(Datasource.Dataset.Fieldbyname('nome_completo').AsString);
17.         if (i>=0) and (i<=Pred(dmPrincipal.imgList_Colaboradores.Count)) then
18.         begin
19.           dmPrincipal.imgList_Colaboradores.Draw(
20.               Canvas,
21.               Rect.CenterPoint.x-(dmPrincipal.imgList_EP.Width div 2),
22.               Rect.CenterPoint.y-(dmPrincipal.imgList_EP.Height div 2),
23.               i, // imageindex
24.               MyEffect);  // gdeHighlighted ou gdeShadowed
25.  
26.         end;
27.       end;
28.           (...)

It´s responsive, it´s fast but I need to wait all images want be loaded before into imagelist using threads.
Before considering method using Imagelist a winner, please, there is a good and fast method to load jpg into a dbgrid cell?

Any help will be wellcome.