My goal is to create a simple forms editor like the one that we find on Delphi IDE.
Right now the user can select and add the components making it parent of a TPanel that is the holder of the form. For simplicity, please consider also TPanel as the visual components added to the form.
I have 2 missing parts I want to find out ideas/code to help complete:
1 - how to move the created visual component? The same effect that in IDE for moving the visual component, for example Tpanel, around, chaning its top and left position
2 - how to draw that hooks for the component with focus on the form editor
3 - how to resize using the hooks
I only want the part related to handle the visual part. I am not generating DFM or anything like that.
Simply put your moving code needs to do this:
When the mouse goes down, check if the mouse position is over a control that can be dragged. If so, then set a variable named FDragControl to refer to that control. This code lives in an OnMouseDown event handler.
When the mouse moves, if FDragControl is not nil, move the control. This code lives in an OnMouseMove event handler.
When the mouse goes up, set FDragControl to nil.
That's pretty much all there is to it. The main nuance is that you must also remember the X, Y values of the mouse when the drag commenced. So in your OnMouseDown handler you write:
FStartMousePos := Point(X, Y);
FStartDragControlPos := Point(FDragControl.Left, FDragControl.Top);
And then in the OnMouseMove your position code reads:
FDragControl.Left := FStartDragControlPos.X + (X-FStartX);
FDragControl.Top := FStartDragControlPos.Y + (Y-FStartY);
You will also need to capture the mouse when you start dragging.
The resizing code is similar. Again, you need to decide in the OnMouseDown that you are resizing rather than dragging, but the code still involves handling mouse down, move and up events.
As for painting, you need to force a repaint whenever one of your event handlers changes a property that will influence the visual appearance of your form. You can use the value of FDragControl to decide whether or not to use special drawing of your control and indicate that it is being dragged. And likewise for resizing.
I've not coded up a full working implementation since your question is high level and conceptual. The implementation is down to you.
// I have made this an answer as I have just read your latest update which really should have been made as an edit to your original question but, anyway.
You can download the Cindy Components Pack and use the cyResizer Component which will do pretty much everything you need and is very customisable as well.
You can download it from here: http://sourceforge.net/projects/tcycomponents/
Searching more for an answer I could find these articles:
How to Move and Resize Controls at Run Time
http://delphi.about.com/library/weekly/aa102505a.htm
How to Add Size Handles to Controls being Resized at Run-Time
http://delphi.about.com/library/weekly/aa110105a.htm
Pretty much with all the information to complete this task with source code example.
These articles show how to implement and use a TMover class. I have done it and work correctly.
I have also downloaded the TcyComponents Pack and used the TcyResizer. It is a full featured form editor with pretty much everything that is required for a Delphi like forms editor. I recommend. It comes with source code and works fine with XE2 version.
Related
I have done some FireMonkey stuff in XE2, in this case I'm having troubles with a customized TListBox.
In XE2 I built this customized TListBox by removing it's background and surrounding rectangle (basically I only need the 'grouping of child items' functionality provided by TListBox. This was simple, drop a TListBox, hit 'edit custom style', select the background rectangle, edit the fill and the stroke and you're golden.
Now we're moving to XE5 and I cannot reproduce the same behavior. Using the style book editor I can see the background (which is now TStyleObject and not TRectangle), but I cannot make the changes I could make before. I see tutorials on how to add stuff to a TListBox, but not on how to take default behavior away.
Can someone explain how to achieve this specific behavior, or point me towards a good tutorial?
Try changing the StyleLookup property of the list box to transparentlistboxstyle
To thwart the nit-pickers, let me start with, I searched here with this and could not find an answer, and yes, also I did scroll through the "Similar questions."...
Adding shortcuts to a TForm
I want to drag and drop some shortcuts from the Desktop to a TForm in my application. I am using Anders Melander's brilliant Drag Drop Suite (DDS).
I tried putting a TImage on the form but the DDS does not drop to an Image so I added a TPanel with a TImage on it. I could then drop on the panel and assign the image to the TImage.Picture. Problem was the Panel has no Transparent Property so the shortcut on the form looks clunky with the visible Panel behind it.
I need to be able to drop to the TImage or make the underlying TPanel transparent.
Can anyone help with code-snippets for either of those options, or better yet, a method of dropping a Shortcut directly on to my Form.
Thanks
Coincidentally I needed to make a TWinControl (the base for every visible control with a window handle, including TPanel) transparent. I found numerous results and applied them to this answer.
It's been a while since I implemented drag and drop, but I assume you call some API and pass it the handle of the panel? That answers the question why you can't use TImage. TImage is a graphic control, a control without a handle, that relies on its parent for recieving messages and drawing itself.
It should be possible to use the form, though, since that has a handle too.
If the TImage is directly on the TForm, then let the TForm handle the drop, no TPanel needed. OLE Drag&Drop operations (which Ander's components implement) provide coordinates where dragging and dropping occurs. The TForm should be able to detect when a drag is over the area occupied by the TImage and what type of data is being dragged, and only allow dropping of supported types within that area, extracting the dropped data and updating the TImageas needed, and denying anything else that does not match that criteria.
My issue is with the thing Delphi progies scare to death - Rich Edit in Windows (XP and pre-XP versions).
Situation:
I have added EM_AUTOURLDETECTION in OnCreate of form. Target -> RichEdit1. Then, I have form, that is "collapsed" after showing form. RichEdit Control is sattic, visible and enabled, but it is "hidden" because form window is collapsed.
I can expand and collapse form, using Button1 and changing forms Constraints and Size properties.
After first time I expand form, the URL inside RichEdit1 control is highlighted. But, after second, third, fourth, etc... times I collapse and expand form, the RichEdit1 Control does not highlight URL anymore.
I have tried EM_SETTEXTMODE messages, also WM_UPDATEUISTATE, also basic WM_TEXT message -> no luck. It sems like this merssage really works ( enables detection ) while sending keyboard strokes ( virtual keycodes ), but not when text has been modified.
Also - I am thinking to rewrite code to make RichEdit Control dynamic. Would this fix the problem?
Maybe solution is to override OnPaint / OnDraw method to avoid highlight ( formatting ) losing when collapsing or expanding form?
Weird is that my Embarcadero Documentation says this function must work in any moment text has been modified. Why it does not work?
Any help appreciated. I am making this Community Wiki because this is common problem and togewther we cam find solution, right? :)
Also - follow-ups and related Question:
Override OnPaint
How to autodetect urls in RichEdit 2.0?
http://www.vbforums.com/archive/index.php/t-59959.html
I am not sure but is the window of the richedit recreated when geing from hide to show? If this is the case you might create your own derived TRichEdit class, override the function that creates the WIndows Handle (TWinControl.CreateHandle) and add EM_AUTOURLDETECTION there.
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.
In Delphi, I've added a Scrollbar component (oriented vertical) to the right side of my form.
I've added a Scrollbar OnChange event so I can change the view of the form and the position of the scrollbar thumb when the user clicks on the UpArrow or DownArrow button with his mouse, and this works fine.
But the OnChange event only seems to get triggered when the mouse button is initially pressed on the arrow.
I notice all scrollbar controls repeat the command and continue scrolling while the mouse remains pressed on the arrow, and I'd like to implement this behavior.
So how can I easily detect if the user has not moved the mouse and continues to press the mouse button while the mouse remains over the arrow?
Conclusion. Somehow something in the scrollbar in my project got corrupted. After I deleted the ScrollBar, and added it again, the problem vanished.
This is one of those tricky ones that took me a lot of time to solve. Thanks for your help. I'm closing this question.
Use the OnScroll event.
The following code adds 'xxx' to a memo as long as the mouse is held down on the scrollbar arrow button. Tested with Delphi 6.
procedure TForm1.ScrollBar1Scroll(Sender: TObject; ScrollCode: TScrollCode;
var ScrollPos: Integer);
begin
Memo1.Lines.Add( 'xxx' );
end;
The usual way to handle auto-repeating is to enable a TTimer and check in the OnTimer() event handler whether the action needs to be performed again, and to deactivate the timer if not. If you need sample code, I seem to remember that the SynEdit control used a similar technique for autoscrolling in drag and drop operations.
If a component does not encapsulate the behaviour you are looking for and you can't easily simulate the behaviour with the methods available you should really subclass the closest component that does most of what you need and add the behaviours that are missing.
I know that some extra work is involved but it really is the better way to go. Now with Delphi, I seem to recall that subclassed components needed a bit of extra work as well to be able to be used from the IDE for form design, maybe this has changed since version 7.