I am starting to learn Delphi. So I decided to write an application like MS Excel from scratch. In a new Form1, I did put a TPageControl component containing only 1 page. In that page, I did put a TAdvStringGrid and a TPanel with some buttons (button1, button2) and a Popup1 menu for defining some actions on the grid, like copy cell, copy row, delete row, etc. For that StringGrid, also, I have defined some properties, like colors, fonts, etc. I added a toolbar with a button to the main form, in order to add more pages to the PageControl. The OnClick method of that button defines two actions:
1) to add a new Page2 to the PageControl, and
2) to add a new StringGrid In the new created Page2 .
That new (runtime defined) StringGrid created in a new Page of a Tpagecontrol should inherite (get, copy, clone, duplicate) the properties and methods of the StringGrid parent already defined in the first page at design time, and should be able to call the PopUp1 menu just like the StringGrid parent. How we do this?
At the beginning, I thought I just should copy the StringGrid properties using assing(), but when using this approach, the popup menu does not pop up when right mouse clicking on the new StringGrid... and the buttons (button1 and button2) of Form1 only work with the first StringGrid but not with the new added one. I did read somewhere that in order to solve this problem, I could duplicate the StringGrid component by using the write and read TMemoryStream (save the parent stringgrid into a memorystream, create a new stringgrid and then read that memorystream into the new created stringgrid), so I did, but when the program executes this component cloning method, I get a runtime error. :-(
I did carefully chech the Help. Nothing found on that topic. Seems there is not any Delphi component library or third party components that cope with this kind of task. Can anybody help, please? :o)
I would use an tabcontrol instead of an pagecontrol. That way, you would end up with multiple tabs but only one page and grid. I would then make some kind of data structure to keep all my cell information in, and render this structure to the grid. This way, I can have multiple structures, and let the active tab decide which structure to render. You will also end up with a looser coupling between your gui and your logic, making it easier change things later. E.g. if you need to bring in some values form a different spreadsheet into a cell in the current spreadsheet, you can load up a structure and pick out the wanted values. No need to make any gui for the second spreadsheet at all.
For a 3.party component, I will recommend TMS FlexCell and TAdvSpreadGrid. That will give you most of what you need.
A tricky choice for a learner :) however you do not need to start streaming things.
Look up the assign() procedure for TPersistent this is the routine you need to copy parts of the grid easily. For example
for i := 0 to StringGrid1.RowCount - 1 do
StringGrid2.Rows[i].Assign(StringGrid1.Rows[i]);
for an easy start differentiate your grids with the Tag property(StringGrid1.Tag := 1, StringGrid2.Tag := 2 Etc.
The popup menu is pretty simple too:
StringGrid2.popupmenu := stringGrid1.popupMenu But then then you must decide in the Popup Routine Which Grid is "Active" some thing l like
Tform1.popupMenuItem1Click(Sender: TObject)
if Sender is TStringGrid then
Case TStrigngGrid(Sender).Tag of
1: // Grid 1
2: // Grid 2
You can use the same simple logic with the buttons.
As neftali mentioned the best thing would be to put the created grids in an ObjectList.
You would then end up with the slightly more complex but expandabe:
Tform1.popupMenuItem1Click(Sender: TObject)
var AGrid: TStringGrid;
if Sender is TStringGrid then
AGrid := MyListOfStringGrids[MyListOfStringGrids.IndexOf(Sender)];
DoMenuItem1Stuff(AGrid);
Have fun
"...and the buttons (button1 and button2) of Form1 only work with the first StringGrid but not with the new added one. I did read somewhere that in order to solve this problem..."
There is no generic method for solving this. Delphi offers different tools to solve it.
You can create a list of Objects (TObjectList) that containts all the StringGrid; At Button1 Click event you must search what is the grid that you are using at this moment. For example (BIS for the other buttons):
var
index:integer;
sg:TStringGrid;
begin
...
// search the active page
index := pageControl.ActivePageIndex; //0, 1, 2,...
// USe this for search the StringGrid
sg := TStringGrid(OList.Objects[index]);
// the code that you have at the event bus woking with sg
// not stringgrid1, stringgrid2,...
...
sg.Color :=
...
If you don't want use ObjectList, there are alternatives. You can use Tag property for all StringGrids. Assign 0, 1, 2, 3,...
Extract the index (active page) and search the TStringGrid that have the property Tag with the same value. You can do this with FindComponent. The first methos is better. ;-)
Regards.
P.D: Excuse for my bad english.
Dear all, I am trying to learn Delphi
The Delphi style is to find/create/buy a component that does the job and use them in the design-time. You could try making a custom component based on a grid or use TFrame. See links from Custom Component Development and help files that comes with Delphi.
If you really need to clone the control dynamically, here's an example I found that uses stream.ReadComponent.
Related
I have a mainForm with a DBGrid and I have a second form with a CheckListBox that shows all of the DBGrid columns for the user to choose. I need to reference in Form2 the DBGrid that I have in MainForm.
I would like this second form to handle all of the procedures connected to the dbdgrid columns , so that I can reuse it easily.
That was the idea, but I dod'nt find the way to pass the DBGrid reference.
Is it possible ?
Answering the question you asked, on your Form2, define a property
TForm2
[...]
private
FGrid : TDBGrid
public
property Grid : TDBGrid read FGrid write FGrid;
Then, after you've created an instance of TForm2, just do
Form2.Grid := MainForm.DBGrid1;
Then, on Form2, you can do anything valid you like to change Grid and the changes will be made to MainForm.DBGrid1.
Is it possible?
The question should rather be Is there a better way to achieve what I want?
Would it be maintainable if Form2 worked basically with a control from a different form? What if other forms would also need to hold references to components on other forms?
How hard would it be in a year to find a bug if controls are used over different forms?
Would such a solution match to the SOLID principles?
Answering these questions should help you to look for a different approach.
You should consider to separate UI and business logic. A TDBGrid seems to be a convenient way to get data from a database into your application but it violates the Single Responsibility Principle since it loads and displays data at the same time. Don't use it as a basic data provider inside your application. Perform the SQL queries from a deeper UI independant layer of your software. Store the results in containers and display them in all the ways you want in your different forms.
I have a form with a dbgrid and a second form with dbedits. My form with the dbgrid has a double click event(code below is the event) the dbedits on the second form has a data source that is connected to the first form's CDS and when I compile and run the program and open the form with db grid I can double click any record and it is display in the dbedits on the second form, but if I close the forms and reopen the form the only record that will display in the second form dbedits is the first record in the table. I have to open and close CDS and that is not working. what else would I need to do to correct this problem.
procedure TFRM_ADMIN.DBGrid1DblClick(Sender: TObject);
BEGIN
frm_LEADDETAILADMINLEAD := tfrm_LEADDETAILADMINLEAD.Create(FRM_ADMIN);
frm_LEADDETAILADMINLEAD.SHOW;
END;
The site will not allow me to add the dmf text. It is to large. I am using sqlconnection, sqlquery, data set provider, client data set, data source set up if this helps any.
This is a very wild quess, but I suspect the following at play:
You use the public variables for the forms that the IDE automatically has added to each unit.
You create FRM_ADMIN the way you create frm_LEADDETAILADMINLEAD, something like:
FRM_ADMIN := TFRM_ADMIN.Create(MainForm);
FRM_ADMIN.Show;
You don't close this form, but hide it (the default close action of a form).
The second time you create your second form, the designtime set DataSet property of the DataSource of your second form is automatically resolved to the ClientDataSet on the first instance of the first form.
So in the second run you are editing the record that was selected in the first run.
Solution and recommendations:
Destroy forms (set Action := caFree) in the OnClose event.
Do not use the public variables, remove them. Keep you form reference in a separate private field, unique to each instance.
Assign DataSource and/or DataSet properties at runtime explicitly.
Use DataModules.
Further reading:
Binding a second instance of a form to a second instance of a data module?
Will there be any detrimental effects if I accidentally remove something from a forms uses list which a control is referencing?
Separate DataSet instances using DataModules.
Show message when Tform2 is created?
Everyone probably knows what I mean, but to clarify the control would need to:
Fire an event when user edits the text. The event would provide a SuggestionList: TStrings which you could fill with matches/suggestions.
if the SuggestionList is not empty a drop down should appear.
Unlike combo, the control should not attempt to automatically select/auto complete or otherwise affect the editing.
So, is there a Delphi edit/combo control that works like that ?
Use the autocompletion feature built in to all Windows edit controls.
First, fill your TStrings object however you want. Then use GetOleStrings to create a TStringsAdapter to wrap it. (The adapter does not claim ownership of the TStrings object, so you must make sure you don't destroy it while the adapter is still live.) The adapter gives you an IStrings interface, which you'll need because the autocompletion feature requires an IEnumString interface to provide the completion matches. Call _NewEnum for that.
Next, call CoCreateInstance to create an IAutoComplete object. Call its Init method to associate it with the window handle of your edit control. If you're using a combo box, then send it a cbem_GetEditControl message to find the underlying edit window.
You can stop at that point and autocompletion should work automatically. You can disable autocompletion if you want, or you can set any number of autocompletion options.
You say you don't want autocompletion, but in the OS terminology, I think what you really don't want is called auto append, where the remainder of the string is entered into the edit box automatically as the user types, but selected so that further typing will overwrite it, and the user needs to delete the excess text if the desired value is shorter than one of the matches.
There is also auto suggest, which displays a drop-down list of suggestions.
You can enable either or both options. You don't need to filter the list of suggestions yourself; the autocomplete object filters the IEnumString list by itself.
You can use standard TComboBox and faststrings library (for stringMatches() function).
procedure TForm1.cbChange(Sender: TObject);
var
s:Integer;
tmpstr:string;
begin
//suggestions: tstringlist
cb.AutoComplete:=false;
tmpstr:=cb.Text;
cb.Items.Clear;
for s:=0 to suggestions.Count - 1 do
if StringMatches(suggestions[s],cb.Text+'*') then
cb.Items.Add(suggestions[s]);
cb.DroppedDown:=(cb.Items.Count<>0) and (Length(cb.Text)<>0);
cb.Text:=tmpstr;
cb.SelStart:=Length(cb.Text)
end;
If you just want to show a file or url list:
SHAutoComplete(GetWindow(eb_MyComboBox->Handle, GW_CHILD), SHACF_AUTOSUGGEST_FORCE_ON | SHACF_FILESYS_DIRS);
I first implemented this feature like Rob described it in his answer. Later I saw that TComboBoxEx has the property AutoCompleteOptions where I set acoAutoSuggest to True and acoAutoAppend to False. The ComboBox now filters its item list when doing some entry and shows the matching items.
I'm using RAD Studio 10 Seattle and XE2 but don't know if this feature is available in older versions.
To the last bit of your question: "So, is there a Delphi edit/combo control that works like that ?":
A bit late to the party but yes, I have written a free and open source component that implements the Google Place Autocomplete and Google Place Details API's:
It does inherit from the standard TComboBox but you can modify the code to work with any TEdit
https://carbonsoft.co.za/components/
or
https://github.com/RynoCoetzee/TRCGPlaceAutoCompleteCombo
I have many "master/detail" forms in my application. A TDBGrid where each row shows a few core values of the item. Below the grid is usually a "Detail area" that shows the complete information of the item that is currently selected in the grid.
Currently I am listening to the "AfterScroll"-event of the TADOQuery behind the grid, but it seems to give me too many events.
Is AfterScroll the correct event for this? How are you doing this?
The "standard" way (in a data-aware environment) would be to not control that using GUI controls, but rather using the data components.
Most of the table data sets provide MasterSource (linked to an appropriate TDataSource component), and MasterFields properties.
You use these to link your datasets in a master-detail relationship.
Then your detail grid (or other data-aware controls) only needs to concern itself with linking to the correct dataset.
EDIT
Other kinds of datasets (e.g. TQuery, TADOQuery) sometimes provide DataSource to be used for a similar purpose. From Delphi 5 help: "Set DataSource to automatically fill parameters in a query with fields values from another dataset."
However, there are quite a few more complications (as will be observed reading the help). So it may be advisable to use TTable or TADOTable for the detail dataset instead.
I'm not aware if there's any 'standard' way but IMO AfterScroll is fine. Use a timer to prevent updating controls in quick succession, for instance while scrolling the grid. An example:
procedure TSomeForm.DataSetAfterScroll(DataSet: TDataSet);
begin
if not DataSet.ControlsDisabled then begin
if ScrollTimer.Enabled then
ScrollTimer.Enabled := False;
ScrollTimer.Enabled := True;
end;
end;
procedure TSomeForm.ScrollTimerTimer(Sender: TObject);
begin
ScrollTimer.Enabled := False;
UpdateGUI;
end;
I think you'll find an interval of 250-300 ms pleasant.
We are creating a component and want to mimic the concept behind Designer.GetComponentNames, where as we give can obtain a list of the available components on the form or any form in the uses. We haven't been able to get to the root of GetComponentNames. Any input would be much appreciated.
LE: Actually I take that back. I need this from the design time aspect.
Runtime? You have the Vcl.Forms.TScreen.Forms array for all the displayed forms, and you have Vcl.Forms.Application.Components containing all your forms IIRC. Then, each form has a Components array.
If I understand the first part of your question, you want to get a list of components owned by a form (by name) at designtime.
As background, I have a non-visual component (Call it TColorEdits.) that manages the colors of selected TWinControls on a form at runtime. This component has a TStrings property that contains the names of selected TWinControls on the form. The names of TWinControls to be managed may be selected at designtime using a dialog (dlgEditColors) that contains a couple listboxes, one of which is named DstList and shows all TWinControls available for management by TColorEdits.
So, here is some (simplified) code I use to get the names of TWinControls on a form at designtime and load the TWinControl names into DstList.
{ Load names of TWinControls owned by a form into TListBox DstList }
for i := 0 to TColorEdits(GetComponent(0)).Owner.ComponentCount - 1 do
if ((TColorEdits(GetComponent(0)).Owner.Components[i] is TWinControl) then
dlgEditColors.DstList.Items.Add(TColorEdits(GetComponent(0)).Owner.Components[i].Name);
You should be able to adjust the above code as part of a custom property editor for your component. Hope this helps with the first part of your question.