Как сделать калькулятор в Delphi?

Delphi - объектно-ориентированный язык программирования, разработанный компанией Borland в 1995 году. Он основан на языке программирования Pascal, но имеет более расширенные возможности и добавлены новые функции.

Как Delphi реализует многоплатформенную разработку?

Delphi является интегрированной средой разработки (IDE), которая позволяет разрабатывать программное обеспечение для различных платформ, включая Windows, macOS, Android и iOS. Delphi достигает многоплатформенности с помощью...

Копирование и вставка данных своего формата из буфера обмена

Советы » Буфер обмена » Копирование и вставка данных своего формата из буфера обмена

// The TClipboard provides easy clipboard access. But what if you 
// want to add (several) custom defined items to the clipboard? 

// For all actions is the unit Clipboard required. 

Clipboard; // First you have to register your own ClipBoard format // Zuerst registrieren wir unser eigenes ClipBoard Format const

MyClipboardFormatStr = 'MyData'; var

MyClpFormat: integer; MyClpFormat := RegisterClipboardFormat(MyClipboardFormatStr); { The variable SLMClpFormat will contain a unique format handle for your own clipboard format. Die Variable SLMClpFormat enthalt ein einzigartiges Format Handle fur unser ClipBoard Format. } procedure


p: Pointer; increment: Integer); begin

p := PChar(p) + Increment; end

; // Say you have a data record defined as: // Definiere zuerst etwa einen solchen Daten Record: type

PMyDataRec = ^TMyDataRec; TMyDataRec = record

Name: string

[50]; Value: Integer; end

; { Furthermore let's say the data records are stored in a Listbox and shall be copied to a list box. Angenommen, die Daten Records sind in einer ListBox gespeichert und sollen in eine ListBox kopiert werden. } // Copy like this: procedure

TForm1.CopyItems; var

i: integer; dh: THandle; ic: integer; p: Pointer; pi: pInteger; begin

// get number of items to be copied // Die Anzahl zu kopierenden Items ic := List1.SelCount; dh := GlobalAlloc(GMEM_FIXED or

GMEM_ZEROINIT, (SizeOf(TMyDataRec) * ic) + SizeOf(Integer)); { allocate memory for all items plus for a integer variable giving you the number of copied items } p := GlobalLock(dh); { Lock the allocated memory } pi := pInteger(p); pi^ := ic; { write number of items to allocated memory } IncPointer(p, SizeOf(Integer)); { increment the pointer behind the written data } // You don't have to create an instance of clipboard, this is done automatically for

i := 1 to

List1.Items.Count do

{ check all items if they are selected } begin


List1.Items[i - 1].Selected then


{ This one is selected -> copy it o the clipboard } PMyDataRec(p)^ := PMyDataRec(List1.Items[i - 1].Data)^; { of course data must point to a TMyDataRec } IncPointer(p, SizeOf(TMyDataRec)); { increment the pointer behind the written data } end

; end

; // You have now filled the allocated memory with all items that shall be copied. // Now you can put them to the clipboard Clipboard.Open; { Open the clipboard will prevent overwriting of so far copied items } Clipboard.Clear; { Clear the clipboard first } Clipboard.SetAsHandle(MyClpFormat, Dh); { Copy to clipboard } Clipboard.Close; { finally close the clipboard } GlobalUnlock(dh); { and unlock the allocate memory. But don't free it, it will be used by the clipboard } if

ic = 0 then

GlobalFree(dh); { You can free it if you haven't copied anything } end

; // Check first if your items are still available before pasting them from the clipbard if

Clipboard.HasFormat(MyClpFormat) then


Form1.Paste1.Enabled := True; { Yes, they are still available } end

; // And this is, how you paste them after Paste1 is clicked procedure

TMDIForm.Paste1Click(Sender: TObject); var

dh: THandle; pdr: PSLMDataRec; i, ic: integer; p: Pointer; pi: pInteger; li: TListItem; begin


Clipboard.HasFormat(MyClpFormat) then

// We have already checked, but maybe another application has overwritten the // clipboard in between.... begin

ClipBoard.Open; { First open the clipboard again } dh := Clipboard.GetAsHandle(MyClpFormat); { Catch the handle to the stored items } p := GlobalLock(dh); { and lock it } pi := pInteger(p); { The first item is an integer giving the number of items } ic := pi^; { so get the number of items } IncPointer(p, SizeOf(Integer)); { increment the pointer behind the read data } for

i := 1 to

ic do

{ get all copied items one after another } begin

li := List1.Items.Add; { first create a new listbox item } pdr := New(PMyDataRec); { Then create a new pointer to a TMyDataRec } pdr^ := PMyDataRec(p)^; { and fill it with data from the clipboard } IncPointer(p, SizeOf(TSLMDataRec)); { increment the pointer behind the written data } li.Data := pdr; { Set the data pointer of the list item to the new record } LI.Caption := pdr^.Name; { Let the item display the record field "Name" } // You can of course add more record fields if the item has subitems: LI.SubItems.Add(IntToStr(Value)); end

; { All data retrieved from clipboard } Clipboard.Close; { Close it } GlobalUnlock(dh); { and unlock the pointer, but don't free it. This will be done by the clipboard itself, if necessary } end

; end


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