PopupMenu-With-Different-Item-Heights-and-Custom-Graphics-in-Delphi-Applications


            Title: PopupMenu With Different Item Heights (and Custom Graphics) in Delphi Applications
A popup menu appears when the user clicks on a control with the right mouse button.
Popup Menu wih Images
Drop a TPopupMenu (name "PopupMenu1") on a form. Assign it 3 menu items: popItem1, PopItem2 and popItem3. Drop a TImageList (name "ImageList1"), populate it with 3 bitmaps.
Use ImageList1 for the PopupMenu1's Images property.
When a popup menu is shown, the image appears next to the menu item caption. By design, all items are of the same height.
Menu Items with Custom Height
If you need to have different height for some of the menu items, you must turn to owner drawing.
Let's say we want to have a larger height for the second menu item "popItem2", and draw some custom graphics for it.
When OwnerDraw for the TPopupMenu is true, each menu item will receive an OnMeasureItem and an OnDrawItem event when they need to be rendered on screen.
Here's what to do:
Set OwnerDraw to True for the Popup Menu.
To apply owner drawing for the second menu item, handle the OnMeasureItem and AdvancedDrawItem events
The OnMeasureItem event is used to set the height (and width) of the menu item. The OnAdvancedDrawItem occurs when an owner-draw menu needs to be drawn.
Here's the implementation for those two events, for the "popItem2":
 //draw graphics item
 procedure TMainForm.popItem2AdvancedDrawItem(
 Sender: TObject; ACanvas: TCanvas;
 ARect: TRect; State: TOwnerDrawState) ;
 begin
 ACanvas.FillRect(ARect) ;
 
 //draw text
 ACanvas.Font.Style := [fsBold];
 ACanvas.TextRect(ARect,24 + ARect.Left, 4 + ARect.Top,'Picture in PopupMenu!') ;
 
 //shrink rect
 InflateRect(ARect,-5,-5) ;
 //move it "down"
 ARect.Top := ARect.Top + 20;
 //draw image
 ACanvas.StretchDraw(ARect, Image1.Picture.Graphic) ;
 end;
 
 //set the item height
 procedure TMainForm.popItem2MeasureItem(
 Sender: TObject; ACanvas: TCanvas;
 var Width, Height: Integer) ;
 begin
 //set to desired height
 Height := 100;
 end;
 
Note: in the above code, a TImage (name "Image1") is used to supply the graphics to be drawn for the menu item.
If you want to use an image contained in the ImageList, you can use the next code for the OnAdvancedDrawItem event:
 //draw graphics item
 procedure TMainForm.popItem2AdvancedDrawItem(
 Sender: TObject; ACanvas: TCanvas;
 ARect: TRect; State: TOwnerDrawState) ;
 var
 bitmap : TBitmap;
 begin
 ACanvas.FillRect(ARect) ;
 
 //draw text
 ACanvas.Font.Style := [fsBold];
 ACanvas.TextRect(ARect,24 + ARect.Left, 4 + ARect.Top,'Picture in PopupMenu!') ;
 
 //draw graphics from the imagelist
 bitmap := TBitmap.Create;
 try
 ImageList1.GetBitmap(popItem2.ImageIndex,bitmap) ;
 InflateRect(ARect,-5,-5) ;
 ACanvas.StretchDraw(ARect, bitmap) ;
 finally
 bitmap.Free;
 end;
 end;
 
In the above code, the GetBitmap of the TImageList is used to draw the graphics contained in the image list.
Graphic Delphi
