on a form I need a first set of UI controls at process start, later I only need a second set of components. I put the set for process set #1 on a first panel , after finish process step #1 I start to hide panel #1, is ther any better way from UI design guide lines ?
I would use Frames instead of Panels. You can design Frames at design-time just like Forms, and then create instances of your Frames at run-time as needed. So create your first Frame (you can even place it on the Form at design-time) and then at run-time, when ready you can destroy the first Frame instance and create an instance of the second Frame.
Using panels like you describe is a very common and very respectable way to proceed. Nothing wrong with doing it that way.
Another often used idiom is a page control with hidden tabs. So, make a page control. Add two tab sheets. Set TabVisible to False for both tab sheets. Then at run time set the ActivePage property of the page control to specify which page is shown to the user.
The page control approach is really rather similar to using panels. It's perhaps marginally easier to work with at design time, but much comes down to personal preference.
Related
I am running Lazarus 0.9.30.2.
I have a TForm on which there is a TPageControl. Within the TPageControl there is a series of TTabSheets. At runtime the order of the TTabSheets differs from design time (see picture).
The order in design time is what I want to see at runtime, at least for the very first time the form is displayed. Why does the order change at run time and is there a way to control this?
#TLama is correct that this is related to way the Windows tab control behaves when in multi-line view. The behaviour you are observing is related to the way selection is handled for multi-line tabs. When you select a tab it is always shown in the bottom row because the visual cue to indicate which tab is selected can only really work for tabs in the bottom row.
Given that constraint the control simply has to rearrange rows of tabs as you modify the selected tab. It's astoundingly confusing for the user. Good UI design never has UI elements changing position like this.
Clearly what is happening here is that the rearrangement is happening at runtime when the form is first shown and for whatever reason this is resulting in a different arrangement from the design time arrangement. Given that the user can arrange the rows in any order just by selecting them I'm not sure you should worry about what order the rows appear in.
If you are dead set on forcing a particular arrangement when the form first shows you can add code like this to a OnCreate handler for the form:
PageControl1.ActivePage := TabSheet9;
PageControl1.ActivePage := TabSheet5;
PageControl1.ActivePage := TabSheet1;
Best practise for UI design is to avoid multi-line tab controls and I urge you to attempt to re-design your UI that way.
In this article there is an explanation of how to use TFrames as an alternative to TTabSheets in a Delphi PageControl.
I've been pondering a similar exercise, which the above doesn't seem to provide the solution for, and for which my solution seems to be overly complicated.
The requirement is for a tabbed interface, where each tab can be one of a number of different designs. Each design is implemented as a TFrame.
Due to the nature of the application being designed, we may have multiple copies of any frame open at any particular moment (with the content of each tab differing, but not the design) so that the user can compare the details of 2/3 different items at the same time.
For example in one session we may have 3 tabs open, all of Frame design A.
On another occasion we may have 3 tabs open each of Frame A, B and C.
The design needs to be flexible enough that we can add Frames to the design on request.
At the moment the solution that I have is to have separate TLists managing each type of Frame that we have open, with perhaps a master TList to keep track of the tabs that are open. As I said, over complicated.
Does anyone have a suggestion of how this could be handled more simply?
I'd probably leave out the master TList of frame instances.
If you need them you'll be able to get them by interrogating the TPageControl directly or through each of your individual TLists for each frame type.
Apart from that your approach sounds reasonable.
I have an application that manages frames on a single panel with my own menu control to control which frame is visible. When I need to make a frame visible I simple set visible:=false for every frame on the panel except for the one that I want. I am in control of what goes onto the panel so I know that at the very least each control is a Tframe and I can get to each frame by iterating over the Panel's Controls property. I then use interfaces to communicate between my main form and my frames.
Now if you want to use a standard windows tabbed interface you could still use the page control as you have suggested, you know that each TtabSheet has a single Tframe on it and you can check it's type and work with it as required. I don't see why you'd need a Tlist because if you really need to get at the "list of Tframes" you could build it dyamically anyway by iterating over the TtabSheets in the page control.
An alternative which would work similarly to my first approach, but gets you nice Windows tabs, would be to use a TtabControl instead of a TpageControl. With the TtabControl you basically just get a Tstrings instance (in the Tabs property) which represents all of the tabs. Since it's a Tstrings you can associate an object (ie your Tframe) with each item and hence each tab. When you click a tab you hide everything and show the correct Tframe. You also have your list because it's attached to the TtabControl via the Tabs property. You just have to handle the visibility of the frames yourself.
We use a TPageControl and create runtime a TTabSheet descendant, which has a new property for our own TFrame (we do not need to scan through .Controls or .Components to search our frame each time).
I have a tPageControl on a form, and have made a nice 'welcome page' as a new ttabsheet at design time for the user to start off with. However, if the user closes this tab, I would like the option to bring it back, as it was in originally (much like the welcome page in the Delphi IDE). This seems like a simple problem...
When the tab closes, the original sheet is freed and set nil. I tried creating the sheet again by name (e.g. tabsheet1 := ttabsheet.create) and assigning it to the pagecontrol, but none of the original components from the sheet are there anymore...
I know designing the welcome page as a separate form, creating it when I need it and slapping it into a new tabsheet would work... but I was just wondering if there was a way to do it with the design time tabsheet.
Thanks all!
Rusty
As Serg mentioned, you can just set the tabsheet's TabVisible property to false when you want to hide the page. The page control will switch to the next tab if it needs to, the tab will disappear, and the user won't be able to switch back to it until you change TabVisible back.
Re-creating the design-time tab sheet will be quite a challenge because all the information describing its layout is embedded in the DFM resource for your form. It's not like there a separate resource for each tab, so you'd need to read the resource, extract the portion relevant to the tab, and then get ReadComponent to build a new instance; nothing in Delphi is designed to make that very easy, so you should consider other options.
The easiest solution would probably be to design your welcome page on a frame; I've found frames to be a little more cooperative than full-fledged forms when it comes to re-parenting them.
Another option is to create the entire tab in code. GExperts has a tool to make that pretty easy. Select the tab sheet, and then choose DExperts's "components to code" command. That places some code on the clipboard, and you can paste it into a function in your program. The code will contain everything required to re-create the selected components in code instead of building them from the DFM resource. Then, you can use that function to not only re-create the tab after it's been closed, but to create the tab in the first place. That way, you can be assured that you're creating the same thing both times.
The reason your attempt at re-creating the tab didn't work is that the name of the variable used to hold a reference to the form doesn't really define anything. All you did was create a brand new TTabSheet. The fact that you stored a reference to it in the same variable that used to hold a reference to the old tab is irrelevant. (But please feel free to give that variable a more meaningful name; all "TabSheet1" says is that it's the first tab you put on your form, way back when you first started working on this project.)
Rob's right about what's going on, and about using frames to fix it. Bit if you want a simpler solution, you could try just making the tab invisible whan the user closes it, instead of freeing it.
Thank you all for your comments and suggestions. A couple notes :
I tried the GEExperts option (pretty nice, I havent used this one before!) : however, it did not preserve many design time settings (font size and color for example)...also there were components with glyphs that didnt get saved....
Changing the visibility of the tabsheet doesnt seem to work either; the pagecontrol doesn't seem to know what to display, even after calling .Refresh ...it shows whatever is underneath your window.
Anyhow, I might investigate the frames option, but likely will just move the components to a new form and call it when needed...
Thanks again!
yesterday I've started discussion on "MDI vs tabbed interface". I've asked whether should I continue developing my app as MDI-based, or should I embed the child forms into tab sheets.
Someone pointed that I should use TFrames instead... My question is: why?
What are pros of using TFrames when embedding the form over TFrame? So far I don't know any, switching would only require me to rewrite some parts of code...
(I'm not going to use embedding at design time anyway!)
Thanks in advance
Answering the comment to provide a reason why to use frames:
I would consider frames to be building blocks of the GUI, with design time combination of existing components to more advanced components. Before Delphi 5 one would have used a TCustomPanel descendant with child controls and registered this as the new component, ready to be dropped onto a form. Frames allow for the same thing with less hassle.
They allow you to concentrate on developing exactly the functionality you need, and nothing more. Done right you can then embed them into tab control sheets, into modal or modeless dialogs, into MDI child frames and into standard frames. You can even add several of them into one form - something one would probably not do with embedded forms. The point is that for maximum reusability a layered approach is often necessary, and frames help with that.
A frame is fit for embedding from the go. A form has to be adapted to not show a caption bar and border, normally one would override the CreateParams() and adjust the window style accordingly. There are a lot more form properties in the inspector that just don't make sense for an embedded form. IMHO one should use the most basic and generic entity that suffices. A form just is much more than a control container for embedding.
OTOH I don't know of any disadvantage of embedding a frame that embedding a form wouldn't have.
Edit:
There's a comment regarding events like OnCreate or OnShow that frames don't have. Actually, I'd consider that another advantage of frames, as event handlers don't have parameters, so a lot of stuff gets hard-coded in forms, necessarily.
Consider the case of per-user settings: in OnCreate there's not much information available, so one invariably ends up using a constant or the name of the form for the INI file section, making it very hard or even impossible to reuse the form or to create several instances of it. With frames on the other hand a method LoadSettings is the obvious way to do it, and it can carry the necessary parameters. That way control is returned to where it belongs, to the container of the embedded frame / form. Reusability is only possible if the behaviour can be adjusted from the outside.
For contained objects that are not components and need to be lifetime-managed, there are for example AfterConstruction and BeforeDestruction.
Maybe you will find some answers in this thread: gui-design-multiple-forms-vs-simulated-mdi-tabs-vs-pagecontrol
Frame use the fastest load and without delay when creating the frame.
But the frame should be has a parent to embedded it. Disadvantage with no onCreate or onShow event has been triggered. but you can call with message for trigger onShow event like this one :
put on private section of frame:
procedure CMShowingChanged(var M: TMessage); message CM_SHOWINGCHANGED;
and then create the code like this :
procedure TFrame1.CMShowingChanged(var M: TMessage);
begin
inherited;
if Showing then
begin
// .... put your code for onShowing is triggered
end
else
begin
// .... put your code for onHiding is triggered
end;
end;
Hope can helping you to consider embedded frame for GUI.
You may consider combined with PageControl to control your frame opening.
Manz
I had same decision few years ago for one of our applications, we wanted to make it looks embedded forms, first I used the Frames and I wrote a class to manage it.
Later I found TLMDDisplayForm component from LMDTools, which making embedding forms inside it very easy task, it reduced the code used and we have more features.
one of main goals that we changed from frames to Forms was missing some events of TForm like: OnCreate, OnShow, OnActive which we use for some tasks in our applications, beside missing some properties such as: ActiveControl and other things I don't remember.
If you would like to go with Forms, I suggest you to use LMDTools which make the task easier for you, beside the basic version is free :-)
For dynamically inserted forms/frames I personally prefer to use embedded forms over frames. Several versions back when one would edit a frame which was set to alClient, the frame would resize between edits and any controls which were aligned specific to the right of the frame would change position. When using embedded forms this didn't happen so I made the switch. I believe this issue is now fixed with later versions of Delphi.
I strongly agree with the points Mghie made earlier regarding the inability to pass information to the embedded form through notification events. To solve this I generally implement a series of interfaces in each embedded form for communication. This really simplifies the code, and allows for more generic implementations where you have a single "container" that will be dealing with many different types of embedded forms/frames. A few examples of this are available on my blog as part of the wizard framework I designed.
I think both should be used. For example, I have a "standard" frame that has a dbnavigator, dbgrid and datasource components which is very handy for the typical data browsing. Instead of inserting such components every time, I insert a frame that also has the ability to export its data (with JVCL :D) to several formats...but I know what I want to display at design time, so I suggest a very easy rule: if it is known at design time, use frames, otherwise use embedded forms.
However, keep in mind that forms were not designed to be embedded. Using them like so, its unnatural (as a vampire states when she buries her 80 old year daughter and she looked like 30 :D). The embedded form knows little about the one that owns it and can also (logically) assume that is not embedded.
Complementing that, a frame is a component, and so, when embedded (owned by) in a form, the form knows about it and the frame knows about the form (can use its methods and properties. An embedded one can also do that but requires extra coding)
Perhaps Embarcadero could give us a hand by creating a TEmbeddableForm or an interface for such purposes
Regards,
Alvaro Castiello
Frames are good when you want to repeat a "sub-form" multiple times in a form. I'd not use them for tabbed interfacing, as the embedded form is a better solution for MDI/Tabbed interface use.
In our primary application, we have a form that will allow us to do cross tab analysis of data in four different ways. Presently, each analysis appears in its own page of a PageControl on the screen. Now, upper management would like us to add in a historical aspect to the form, which in other areas we would use a PageControl to do, but nesting two of them seems like a bad idea to display the periods and analyses tabs stacked on top of each other. Does anyone have any suggestions as to how we could re-work this to look decent and work well? Thanks.
What about using the TTabset control along the bottom of the form to allow switching between the historical periods and the current data? I would also make sure that there was a visual difference in how the data is presented for historical vs current data. Like use an off grey cell background for historical data.
Use an small (horizontal) TTabSet with a vertical one.
See here (you can click on the picture to zoom). The TTabSet is shipped OOTB with Delphi. The vertical one can be written very easily if your requirements are low. If you want, I can share the code. But if you want a better vertical tab set then you can spend more time on writing or get one which is ready made from Torry or somewhere else.
HTH.
IMHO, you can use frames for each analysis result page, then you can use either PageControl or TabSet or any other visual control for loading and showing the appropriate frame.
Since frames are totally independent from the visual control you use to select proper period and analysis, you won't be restricted to tab-based controls; for example you can have a tabset for analysis selection, and a treeview for period selection.
Frames have some additional benefits here too:
First of all, their code is kept in
separate units and this will increase
code readability.
Second, you can design a base frame
and put all the controls and codes
which all these 4 analysis share into
that base frame, and in this way have
a better code reuse.
Third, you can either drop each frame
on your main form and make them load
just like before, or you can define a
container control (e.g a panel), and
based on user's selection load one of
the frames into the container control
dynamically, so reduce initial load
time of your application, and
probably reduce the overall system
resource consumption.