Title: Painting images in DBGrid columns
Question: How to paint images in a DBGrid
Answer:
Painting images in DBGrid columns
1.Create new application. Add a DBGrid to your form. Rename the DBGrid too grdBase. Add a datasource too your DBGrid. On your DBGrids properties, extend the Options property and set the dgEditing property too false. This will stop the user from double clicking on the column on which we painted our image, and seeing the actual columns value. Double click on the DBGrids OnDrawColumnCell event, delphi will generate the following code for you.
procedure YourFormName.grdBaseDrawColumnCell(Sender: TObject;
const Rect: TRect; DataCol: Integer; Column: TColumn;
State: TGridDrawState);
begin
inherited; //Depending if you inherited from another form or not.
end;
2.Add an image component too your form, set the AutoSize property to true. Load a picture into the image component, I recommend a 16x16 sized bitmap. Rename the image component to imgNo, add another image component too your form, again AutoSize property to true, and rename it too imgYes. Yes naming conventions are important remember that.
3.Now lets get to the fun.
In your previously generated procedure do the following
if not Datamodule.Query.FieldByName('AutoKeyField').IsNull then //3.1
if Column.FieldName = 'ColumnName' then //3.2
begin
grdBase.Canvas.FillRect(Rect); //3.3
case Datamodule.Query.FieldByName('FieldName').AsInteger of //3.4
ACTIVE:grdBase.Canvas.Draw(Rect.Left,Rect.Top,imgYes.Picture.Bitmap);
NOTACT:grdBase.Canvas.Draw(Rect.Left,Rect.Top,imgNo.Picture.Bitmap);
end;
end;
3.1 First check if the datasource is empty
3.2 Get the column in which we are going to paint, Remember this
Column name is case sensitive.
3.3 Fills the selected columns region.
3.4 My field that I want to paint is an integer field therefore I used a case
statement with constant values, handling the different values.
Your finished procedure should look similar too this
procedure YourFormName.grdBaseDrawColumnCell(Sender: TObject;
const Rect: TRect; DataCol: Integer; Column: TColumn;
State: TGridDrawState);
begin
inherited; //Depending if you inherited from another form or not.
if not Datamodule.Query.FieldByName('AutoKeyField').IsNull then //3.1
if Column.FieldName = 'ColumnName' then //3.2
begin
grdBase.Canvas.FillRect(Rect);//3.3
case Datamodule.Query.FieldByName('FieldName').AsInteger of //3.4
ACTIVE:grdBase.Canvas.Draw(Rect.Left,Rect.Top,imgYes.Picture.Bitmap);
NOTACT:grdBase.Canvas.Draw(Rect.Left,Rect.Top,imgNo.Picture.Bitmap);
end;
end;
end;
By Dewald Marais