Draw the DBGrid (replacement image from the resource) - delphi

Question

I need your help. Draw method the DBGrid. I have table DBGrid.
How? To my method "DrawDBGrid", add my method "LoadDefaultImage"
If there is no file path (image), a replacement image from the resource will be displayed.
My "LoadDefaultImage"
procedure LoadDefaultImage(AImage: TImage; aPngName: string);
var
lImage: TPngImage;
begin
lImage := TPngImage.Create();
try
lImage.LoadFromResourceName(hInstance, aPngName);
AImage.picture.Graphic := lImage;
finally
lImage.Free();
end;
end;
Call the method
LoadDefaultImage(AImage, 'No image');
My "DrawDBGrid"
procedure DrawDBGrid(aDBGrid: TDBGrid; aGraphicFieldName: string; Column: TColumn; State: TGridDrawState; Sender: TObject;
const Rect: TRect; DataCol: Integer);
var
lRect: TRect;
lImage: TJPEGImage;
lPicturePath: string;
lDataset: TclientDataSet;
lIsFile: Boolean;
begin
lDataset := TclientDataSet(aDBGrid.DataSource.DataSet);
lPicturePath := extractfilepath(paramstr(0)) + lDataset.FieldByName(aGraphicFieldName).AsString;
lIsFile := fileexists(lPicturePath);
if (Column.Field.FieldName <> aGraphicFieldName) or (not lIsFile) then
begin
if (gdSelected in State) and (TDBGrid(Sender).Focused) then
TDBGrid(Sender).canvas.Brush.color := $E8E3A8
else
TDBGrid(Sender).canvas.Brush.color := clWhite;
aDBGrid.DefaultDrawColumnCell(Rect, DataCol, Column, State);
end
else
begin
lRect.left := Rect.left + 1;
lRect.Top := Rect.Top + 1;
lRect.Right := Rect.Right - 1;
lRect.Bottom := Rect.Bottom - 1;
lImage := TJPEGImage.Create;
try
try
lImage.LoadFromFile(extractfilepath(paramstr(0)) + lDataset.FieldByName(aGraphicFieldName).AsString);
aDBGrid.canvas.StretchDraw(lRect, lImage);
except
on e: exception do
begin
raise exception.Create('Błąd wyświetlania pliku ' + lDataset.FieldByName(aGraphicFieldName)
.AsString + ''#13'' + ''#10'' + e.Message);
end;
end;
finally
lImage.Free;
end;
end;
end;

Answer 1

If the DrawDBGrid is a standalone procedure called from the rendering event, you can modify it for passing a pre-loaded default image like so:
procedure DrawDBGrid(aDBGrid: TDBGrid; aGraphicFieldName: string; Column: TColumn; State: TGridDrawState; Sender: TObject;
const Rect: TRect; DataCol: Integer; DefaultImage: TPngImage);
Then inside it you can do this:
...
lIsFile := FileExists(lPicturePath);
// if not the desired column
if (Column.Field.FieldName <> aGraphicFieldName) then
begin
if (gdSelected in State) and (TDBGrid(Sender).Focused) then
TDBGrid(Sender).canvas.Brush.color := $E8E3A8
else
TDBGrid(Sender).canvas.Brush.color := clWhite;
aDBGrid.DefaultDrawColumnCell(Rect, DataCol, Column, State);
end
else // the right column
begin
// if the file was not found, draw the default image that was passed
if not lIsFile then
begin
aDBGrid.canvas.Draw(Rect, DefaultImage);
end
else
begin
lRect.left := Rect.left + 1;
lRect.Top := Rect.Top + 1;
lRect.Right := Rect.Right - 1;
lRect.Bottom := Rect.Bottom - 1;
lImage := TJPEGImage.Create;
try
try
lImage.LoadFromFile(extractfilepath(paramstr(0)) + lDataset.FieldByName(aGraphicFieldName).AsString);
aDBGrid.canvas.StretchDraw(lRect, lImage);
except
on e: exception do
begin
raise exception.Create('Błąd wyświetlania pliku ' + lDataset.FieldByName(aGraphicFieldName)
.AsString + ''#13'' + ''#10'' + e.Message);
end;
end;
finally
lImage.Free;
end;
end;
...
The last piece of Lego here is that you'll pre-load the default image, for instance when the form is created and keep it stored e.g. as a private field of type TPngImage in the form class and pass it into your standalone procedure.