I have a tree control that implements drag and drop. I use an overridden OnStartDrag() to get my own TDragObjectEx that shows an image while dragging. This works perfectly within the tree control, but as soon as I leave the tree control the image disappears. The cursor stays though.
I tried implementing OnDragOver, to reset the image but that does not appear to work.
Any hints on this? I am using C++ builder 2010, but delphi would do the same thing.
Update:
Found setting csDisplayDragImage on each control in the form controls, and in form itself solves this issue. Is there some automated way to have csDisplayDragImage set in an entire form rather than have to set it manually in Create for each item?
void __fastcall TForm1::FormCreate(TObject *Sender)
{
ControlStyle << csDisplayDragImage;
RMU->ControlStyle << csDisplayDragImage;
Button1->ControlStyle << csDisplayDragImage;
}
If I remember correct, you have to include the [csDisplayDragImage] flag in the "ControlStyle" of controls of which you want drag images to be seen when sth. is being dragged over them..
Update: setting "AlwaysShowDragImages" of the DragObject causes the drag image to be displayed all across the desktop.
Evidently, each control that's going to display the drag image needs to have the csDisplayDragImage control style set. You can add that flag to a control and all its chilren with a simple function:
void AddDisplayDragImageStyle(TControl* ctl)
{
ctl->ControlStyle << csDisplayDragImage;
TWinControl* win = dynamic_cast<TWinControl*>(ctl);
if (win)
for (int i = 0; i < win->ControlCount; ++i)
AddDisplayDragImageStyle(win->Controls[i]);
}
Have the form call that on itself: AddDisplayDragImageStyle(this).
Related
I am trying to make an image picker component in LibreOffice.
I have a dialog that is dynamically filled with images. When the user clicks on one images, it should be selected and the dialog should be closed.
The problem is that the number of images is variable. So I need to enable scrolling in the dialog (so that the user can navigate through all images).
There seems to be some properties on the dialog object (Scrollbars, Scroll width, Scroll height, etc)
However, I cannot find a way to use them anywhere.
Any ideas?
The scrollbar is one of the Controls available through the dialog box editor. That is the easier way to put a ScrollBar on a dialog box. Just insert it like any other control. There is a harder way via DialogModel.addControl but that seems non-essential to answering this question.
If you add a scrollbar to the dialog box and run the dialog box, you will find it does nothing by default. The functionality (apparently) must be written into a macro. The appropriate triggering event is the While Adjusting event on the ScrollBar object, although it does not trigger the macro simply with the "Test Mode" function in the dialog editor. Running the dialog box through a macro triggers the While Adjusting event when the scroll arrows are triggered, when the slider area is clicked to move the slider, and when the slider itself is dragged. The Object variable returned by the scrollbar event contains a property .Value which is an absolute value between 0 and the EventObject.Model.ScrollValueMax, which allows you to manipulate the other objects on the page manually based on the position of the slider.
Yes, that's right, manipulate objects manually. The sole example I found, from the LibreOffice 4.5 SDK, does precisely this. Of course, it is not as bad as it sounds, because one can iterate through all of the objects on the page by reading the array Dialog.getControls(). In any event, the secret sauce of the example provided in the SDK is to define Static variables to save the initial positions of all of the objects you manipulate with the scrollbar and then simply index those initial positions based on a ratio derived from the scrollbar Value divided by the ScrollValueMax.
Here is a very simple working example of how to scroll. This requires a saved Dialog1 in the Standard library of your document, which contains an object ScrollBar1 (a vertical scrollbar) and Label1 anywhere in the dialog. The ScrollBar1 must be configured to execute the macro ScrBar subroutine (below) on the While Adjusting event. Open the dialog by executing the OpenDialog macro and the scrollbar will move the Label1 control up and down in proportion to the page.
Sub OpenDialog
DialogLibraries.LoadLibrary("Standard")
oVariable = DialogLibraries.Standard.Dialog1
oDialog1 = CreateUnoDialog( oVariable )
oDialog1.Execute()
End Sub
Sub ScrBar (oEventObj As Object)
Static bInit As Boolean
Static PositionLbl1Y0 As Long
oSrc = oEventObj.Source
oSrcModel = oSrc.Model
scrollRatio = oEventObj.Value / oSrcModel.ScrollValueMax
oContx = oSrc.Context
oContxModl = oContx.Model
oLbl1 = oContx.getControl("Label1")
oLbl1Model = oLbl1.Model
REM on initialization remember the position of the label
If bInit = False Then
bInit = True
PositionLbl1Y0 = oLbl1Model.PositionY
End If
oLbl1Model.PositionY = PositionLbl1Y0 - (scrollRatio * oContx.Size.Height)
End Sub
The example provided by the SDK does not run on my setup, but the principles are sound.
There appears to be a second improvised method closer to the functionality one might expect. This method uses the DialogModel.scrollTop property. The property appears to iterate the entire box up or down as a scroll based on the user input. There are two problems using this methodology, however. First, unless you put the scrollbar somewhere else, the scroll bar will scroll away along with the rest of the page. You will need to adjust the location of the scrollbar precisely to compensate for/negate the scrolling of the entire page. In the example below I tried but did not perfect this. Second, the property seems to miss inputs with frequency and easily goes out of alignment/ enters a maladjusted state. Perhaps you can overcome these limitations. Here is the example, relying on the same setup described above.
Sub ScrBar (oEventObj As Object)
Static scrollPos
oSrc = oEventObj.Source
oSrcModel = oSrc.Model
scrollRatio = oEventObj.Value / oSrcModel.ScrollValueMax
If IsEmpty(scrollPos) = False Then
scrollDiff = oEventObj.Value - scrollPos
Else
scrollDiff = oEventObj.Value
End If
scrollPos = oEventObj.Value
oContx = oSrc.Context
oContxModl = oContx.Model
oContxModl.scrollTop = scrollDiff * -1
oSrcModel.PositionY=(scrollRatio * oContx.Size.Height/5) * -1
End Sub
This (sort of) will scroll the contents of the entire dialog box, within limits and with the caveats noted above.
I have a TFrame on which some TEdits are placed. These edits are
boxes for serial key input, as I'm trying to setup a user experience
where input focus jumps from one edit box to the next, when a certain amount of
characters been entered in each. That is, user do not need to press tab
or click on the next edit in order to advance.
I found an example in the C++ Builder HowTo book (great book) on how to
"simulate" enter press to behave like a tab press in edits and was
trying to employ the same technique. However, something in my app don't
work as in that example.
In the frames KeyPress event, I have the code
void __fastcall TAboutFrame::Edit1KeyPress(TObject *Sender,
System::WideChar &Key)
{
TEdit* theEdit = dynamic_cast<TEdit*>(Sender);
if(!theEdit)
{
return;
}
if(theEdit->Text.Length() >= 6)
{
//jump to next edit
Perform(WM_NEXTDLGCTL, 0, 0);
...
But the 'jump' to next control does not occur.
The main Form, the frames parent, do have key preview == true and I can
set a breakpoint to see that the Perform call is indeed executed.
The tab orders on the edits are 1,2,3,4,5.
I wonder if this has todo with TFrames messaging or?
If the controls you are using descend from TWinControl (Which they should if you are using stock VCL controls), You can also use TWinControl->SetFocus() to explicitly set the focus to the desired control.
i wanna make a windows database application with c++ builder. The idea is to have a static menu of 6 icons at the top (i need this to be constant in every screen) while the rest of the screen will host all user interactions and data regarding with the selected menu item. I have a litte experiece with SDI apps and as far as i know there is no way the whole application to be in a single screen / form. Should i build this like an MDI app or is there any other way to maintain a fixed icon based menu at top while the rest screen data to change for every different menu item? I dont want to be in a single window with no overlaping forms while user navigates through the application.
Although an MDI application is definitely possible, the interaction between the different forms sometimes is a little cumbersome. A tabbed page is easier to handle since everything then resides within the same TForm class.
If you want to change the appearance of the individual tabs you can overload the 'PageControlDrawTab' Just add an event handler, get a handle to the Canvas of the tab itself and you are free to draw is as you want. See the example below:
void __fastcall TMainForm::PageControlDrawTab(TCustomTabControl *Control,
int TabIndex, const TRect &Rect, bool Active)
{
/* OnDraw handler to change the appearance of the Tabs.
Change it to blue text on white background.
*/
String s;
TRect r;
TTabControl * tTab = (TTabControl *)Control; // Get a pointer to the tab itself
s = tTab->Tabs->Strings[TabIndex]; // Retrieve the text of this tab
Control->Canvas->Brush->Color = clWhite; // Use the Canvas to draw
Control->Canvas->Font->Color = clBlue; // .. whatever you like
Control->Canvas->FillRect(Rect);
Control->Canvas->TextRect(Rect,Rect.Left+4,Rect.Top+2,s);
}
You will probably have to do it in a MDI format. I do not know of any way to share the menu across forms. The other option you could use though is to use a page control and have all the other "forms" live in a tab so the menu is the same all the time. The menu items could respond differently if you would like them to when the user is on a different tab, or they could do the same thing no matter what tab you are on. Sorry this is the form of an answer, I don't have comment rights yet.
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.
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.