Tuesday, 5 December 2017

Delphi interesting skinning issue with .NET COM wrapper

I've come across an interesting issue with skinning and invoking a .NET Windows form and messagebox. I have a test Delphi application that is skinned using either Alpha Skins or setting the custom styles, I then invoke a .NET wrapper DLL developed in Visual Studio 2015 (COM interop)  and call the method to show a Windows form, this does not get skinned. However on the Windows form there is a button that shows a Windows messagebox, this does get skinned, see image below.


It would be nice if the Windows form also was skinned to match the Delphi application and it seems strange that the Windows messagebox which is invoked by the Windows form is skinned.

Thursday, 21 September 2017

TObjectList vs TObjectDictionary

When I need to store a list of objects I usually use a TObjectList (Generics.Collections), but I was speaking to another developer who uses TObjectDictionary to store a list of objects. I searched the net for when to use a TObjectDictionary instead of a TObjectList and vice-versa, but could not find any definitive answers. I decided to write a little test app to understand the difference, this simply did the following:

  • Created 1 million objects for each list and added them to the list.
  • Cleared the list of the 1 million objects.
  • Populated the list with 1 million newly created objects.
  • Found 100 objects in the list.
Below are the results, time is in ms:


ObjectList Clear - 47
ObjectList Populate - 344
ObjectList Find - 78
ObjectList Find - 78
ObjectList Find - 78
ObjectList Find - 79

ObjectDictionary Clear - 265
ObjectDictionary Populate - 579
ObjectDictionary Find - 0
ObjectDictionary Find - 0
ObjectDictionary Find - 0
ObjectDictionary Find - 0

As you can see the TObjectDictionary was slower to clear and populate the list, but was faster finding the 100 objects. This is most likely due to the TObjectDictionary being derived from TDictionary which is a hash table and is optimised for lookups.

So, generally from these results I am happy sticking with TObjectList, but if I need to store a lot of objects and also need to find a lot of objects then using a TObjectDictionary is a better choice. 

Tuesday, 25 July 2017

Windows 10 Notification

Here is a quick and simple example of a notification procedure. On a form I added a 'TNotificationCenter' component from the 'System' tool palette.

procedure TForm.DoNotification(aName, aTitle, aBody: string);
var
    appNotification: TNotification;
begin
    appNotification := NotificationCenter1.CreateNotification;
    try
        appNotification.Name := aName;
        appNotification.Title := aTitle;
        appNotification.AlertBody := aBody;
        NotificationCenter1.PresentNotification(appNotification);
    finally
        appNotification.Free;
    end;
end;

procedure TForm.ShowTestNotification;
begin
    DoNotification('Test Name', 'Test Title', 'This is an example');
end;

There is an event in the NotificationCenter component called 'OnReceiveLocalNotification', which is useful if you want to display a notification and when a user clicks on the notification the software performs an operation. 

I did this example in Delphi XE10 Berlin, it is a very limited example due to Delphi being very limited with what can be done with Windows Notifications. Looking at the documentation you can do more with iOS, I am not sure why they have made it so limited. I have briefly looked at some C# examples and you can do more with notifications like custom sounds, icons, images and actions. 

One thing I have noticed is that when I run this example the notification is shown and then when it goes away it is automatically removed from the action centre. One thing I would require is that if the user does not acknowledge the notification, it should stay in the Action Centre list. For me it would be really useful to have the following:
  • Custom image.
  • Custom sound.
  • FireDate to work in Windows 10.
  • Option for the notification to stay in the Action Centre.

I would like to see Embarcadero expand on what these notifications can do, obviously they are limited to what the OS can do. If they could persist in the Action Centre until clicked then I can think of multiple uses for notifications.  

Monday, 24 July 2017

XE10 Berlin fix for issue when opening older project

I recently had an issue with a project that had been updated from XE to XE10. The issue was when opening the project it could not find some components on the main form (3rd party), however the correct packages are installed and if I started a new project I could add the components from the tool palette without any issues.

One work-around I found was having adding these components to another project, then when I opened Delphi XE10 I opened this project and then closed it before opening the project that had problems with the components, and it all worked fine.

In the end the solution I found was the following:

  1. In the package itself, find the unit with the 'Register' procedure.
  2. Check 'DesignInf' is in the uses clause.
  3. At the top of the 'Register' procedure add 'ForceDemandLoadState(dlDisable);' 
  4. Install the package again.
What this does is disables the IDE from using the smart loading of installed packages, this means when the IDE starts it always loads the installed packages.

Thursday, 20 July 2017

How to create GUID at runtime

To create a GUID (Globally Unique Identifier) at runtime I have two different ways of doing this.

First Method
Add ComObj unit to the uses clause, if not already there, then to create the GUID as a string just do the following:
FThisID := CreateClassID;

Second Method
This method you need the SysUtils in the uses clause. The do something like the following:
var
  newGUID: TGUID;
begin
  SysUtils.CreateGUID(newGUID);
  FThisID := GUIDToString(newGUID); 
end;

Friday, 2 June 2017

How to dock a form to a panel programmatically

This is a quick solution to a question I had on how to have a form that is set so it can dock into another form's panel. I have a main form with a panel on the right with the 'Docksite' property set to true. I have another form with the 'DragKind' property set to dkDock and the 'DragMode' set to dmAutomatic. I create the docking form at runtime and wanted it so that by default it was docked into the right panel. The quick solution that I found hard to find on the net is after I create the form do the following:

DockingForm.ManualDock(PanelRight);
DockingForm.Show;

Thursday, 25 May 2017

Frame Inheritance - TabOrder: Property does not exist - Issue Fixed

I've been working on an application recently and it has a few frames (TFrame), I noticed that there were common properties and methods to all the frames, so I decided that they should derive from a base class. I created the base frame class and then in code derived the other frames from the base frame. It all seemed to work fine a build and ran OK, however after closing the project and then coming back to it a few days later, when I tried to open a frame I received an error stating the TabOrder property does not exist, I ignored it and received more property does not exist errors (I did not save any changes). The solution to this problem was simple, in the .dfm file at the top was:

object TestFrame: TTestFrame 

This needed to be changed to:

inherited TestFrame: TTestFrame

The ideal way to do this is at design time when designing the structure of the application, if there is an abstract or concrete frame class then this should be added to the repository so when a developer needs to create a new frame, they can simply inherit the frame from the one in the repository.

This is a very similar problem to inheriting datamodules, I've also had to do something similar.