I have a project where I try to share form files between Delphi and Lazarus. This actually works well excep with GroupBox there "top" values is caluculated against two different "tops". This menas that in Lazarus the controls are moved about 20-30 pixels too far down the TGroupBox.
Anyhow, assuming I design in Delphi, and I make a descendant TGroupBox. IO could Add a property called "fixiffromdelphi" (or something like that) and then add some code which ensures the child controls get placed correctly.
Ideally, this should happen under streamning, but I am not sure how to go about it. Is there anyway the parent (GroupBox) can access the subcontrols while the form streams in the dfm/lfm? And through that override e.g. top value?
Related
I have a container control (TLayout or TPanel or TScrollbox, etc.) which can have several other nested controls inside. Is there a way in Firemonkey to know when the container becomes "active"? I mean for example:
when any of its children get focus or
user clicks any of its non-focus controls
I am asking for a kind of event-bubble. OnClick would be enough so when user clicks any nested control, the parent container is notified. Control's HitTest property would be a solution but if I set that property to False (to let the parent manages the onlick) on a TEdit, it becomes useless obviously (I can't type on it)
Edit:
A simple layout example:
Drop a TScrollBox in a form
Drop a TPanel in form and put it as child of the TScrollBox
Drop a TEdit in form an put it as child of TPanel
Ok, I can simply do a sort of Parent.Parent.Click after receive the OnClick on TEdit but imagine now several TScrollBoxes, with different level of nesting using TPanels with a bunch of different controls inside. It doesn't make sense neither adding the onclick code for each control in the tree, nor change the hierarchy of Parent.Parent.Click every time I redesign the layout adding an intermediate parent control.
Is there any way to do this in Firemonkey (either for Windows or MacOS)?
PS: I'm using Delphi 10.2.3 (Tokyo)
I've been searching the whole internet for an answer but I cant find one.
What I want to do is to create a component that I, in design time, can add components to, move them around, right click on them to pop up a menu, change their properties, etc etc.
Like, for instance, I drop my component "A" (which is based on TImage32 from the Graphics32 library), and then I want to be able to drop a component "B" (which is based on TBitmap32) in to A, but since B is not inherited from a standard VCL like TPanel I dont know how to make a design time component.
What you are searching for is the ability to create a parent/child relationship. The parent acts as a container and the child is contained within the bounds of the container. A TPanel is a classic example of a container. Any visual component can be a child.
In terms of ancestry the parent must be derived from TWinControl and the child must be derived from TControl. In practice you seldom derive from these classes directly, rather from one of their descendents. The other factor, if I recall correctly, is that the parent control must include csAcceptsControls in its ControlStyle.
Now, TImage32 does indeed derive from TWinControl and so it can act as a container. However, I am not sure whether or not csAcceptsControls is included in the ControlStyle for TImage32.
I'm really not familiar with TImage32 and don't know whether or not it can act as a parent. I have a suspicion that it is not designed to act as a container. If that is the case then you can add csAcceptsControls to the ControlStyle in the constructor of your derived class and have the control act as a parent.
I suspect that if TImage32 does not include csAcceptsControls then this is by design and the image control is not expected to act as a parent.
Apparently TImage32, unlike the VCL TImage, is indeed capable of acting as a parent to other controls.
As for the other control in your question, TBitmap32 is not derived from TControl and cannot be a child control.
I have a number of forms that 'host' other forms using ChildForm.Parent := HostForm and ChildForm.Align = alClient etc. Some child forms are host themselves for another child form. Under Windows 7, the alignment is fine but Windows XP sometimes leaves the child form visible but not client aligned. Touch the outer window frame to resize it by one pixel and it all springs aligned correctly. Is there a command I can send to the host form to ensure that the alignment has taken place properly?
You might want to take look at Realign method. Look also at AlignControls and ArrangeControl to manually align the child control. Consider also using Frames instead of Forms if it is possible - they are designed for the job you described (but on the other hand have a number of inconveniences - for example lack of OnCreate event).
Best regards -- Spook.
I also had this problem a few times and it seems it is often caused by faulty controls on the child form.
How to avoid issues when embedding a TForm in another TForm?
Before Delphi 2006 (I think) introduced the TFlowPanel and TGridPanel, I did a control that was similar in concept. It still does a couple of things those controls do not do, and when upgrading my code to Delphi 2009, I decided to add a couple of enhancements to that as well.
Right now, the order of the child controls is determined by their creation order. The FlowPanel and GridPanel show a better way with ControlIndex and other filtered properties, but I was wondering if there is a way to handle drag and drop reordering in design-time? As far as I can tell, dragging an edit control and dropping it onto my panel doesn't call anything that I can access at design-time.
I was half-fantasising about a way to either detect the drop operation directly, or to perhaps detect when a control is moved so I can determine where it should go.
Any ideas?
Update:
OK, got it working. The container control was already overriding AlignControls to manage the placement of the controls. When you drag the nested control and drop it, AlignControls is again called. I then compared the new coordinates of the control with the other controls in the list and moved it to the appropriate position.
There were a couple of problems that I had to work through (mostly related to the many calls to AlignControls) but the basic concept is simple enough. Thanks to all the commenters for all the help.
You can't drag a control that's already on the form and drop it onto your panel. Dragging is only for moving a control, not for changing its parent. To change the parent, cut and paste.
If the control is already on your panel, and you want to move it to another position on your panel, then the panel can control the layout by overriding the TWinControl.AlignControls method. When a control is moved, its SetBounds method is called, and among the things tha happens is that it calls AlignControl(Self) on its parent window. That calls AlignControls. Look in Controls.pas, and you'll see that that's a complicated method, but it's what is responsible for the layout of the children on a control, and that's exactly what you're planning to change.
Perhaps some of these suggestions might help.
You can re-parent a control in the designer without having to do cut-and-paste. View the structure pane, and simply drag the visual control to the node of another parent in the structure pane. If you have things in a flowpanel, drag everything out of the flow panel and drag them back in the order that you want them to be.
(You can re-parent ANY visual control this way, without changing anything other than its parent. I highly recommend doing it this way.)
You can view the form as text, and move the declaration order around in there -- but obviously you'll need to be careful when editing the "resource" file directly.
You can set tab order in the designer, so you could make a different control based on tab order that works as you want. You can right click on the form and change the creation order of the non-visual controls, but that doesn't work with visual controls.
Have you tried to write an "OnDragDrop" event for your grid component, where you check if your component is in design mode?
I haven't written such a component yet, but I don't see why the event shouldn't trigger.
I'm looking after a way to AlphaBlend a child form, if possible using layered windows as there will be interactive controls behind it.
The problem is I have a component in a regular TForm that paints multiple visual layers (drawings, pictures...). At some point I need to instantiate an editor control on this form (in-place), this control will involve a variety of standard input controls outside of my control (edit box, check box, etc.), however I would like to overlay the layers in front of the layer being edited using alpha blending (and WS_EX_TRANSPARENT to make it click-through).
I first thought of using child forms for that (borderless TForms parented to the component), and that works alright, up to the point where the AlphaBlended TForm isn't alphablended at all, but turns opaque as soon as parented...
I then tried to unparent the alphablended form, set it to fsStayOnTop, and by reacting to the relevant events, keep it in front of the component on screen, that works, but that isn't a truly satisfying solution: the alphablended StayOnTop form is also in front of other modal and modeless forms of the application, should the user decide to move them in front of the component...
So, any other ideas on a way to have a child form be alphablended? (or behave like it is)
According to MSDN you are out of luck, as WS_EX_LAYERED cannot be used for child windows.
Maybe you could hide all editor forms when your form / application loses focus, that would at least keep them from being on top of other windows. Still, it's unsatisfactory...