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| - | Wikipedia:
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| - | In computer graphical user interfaces, drag-and-drop is the action of (or support for the action of) clicking on a virtual object and dragging it to a different location or onto another virtual object. In general, it can be used to invoke many kinds of actions, or create various types of associations between two abstract objects.
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| - | Drag and drop functionality is one of the most visible aspects of the graphical user interface.
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| - | Drag and drop operation enables you to do complex things intuitively.
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| - | In drag and drop we basically drag some data from a data source to a data target.
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| - | So we must have:
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| - | * Data object
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| - | * Data source
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| - | * Data target
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| - | For drag & drop of text, wxWidgets has a predefined <b>wxTextDropTarget</b> class.
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| - | In the following example, we drag and drop file names from the upper list control to the bottom one.
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| - | <source lang="cpp">
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| - | #include <wx/wx.h>
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| - | #include <wx/dnd.h>
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| - | class TextDrop : public wxFrame
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| - | {
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| - | public:
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| - | TextDrop(const wxString& title);
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| - | void OnSelect(wxCommandEvent& event);
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| - | void OnDragInit(wxListEvent& event);
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| - | wxGenericDirCtrl *m_gdir;
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| - | wxListCtrl *m_lc1;
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| - | wxListCtrl *m_lc2;
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| - | };
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| - | class MyTextDropTarget : public wxTextDropTarget
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| - | {
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| - | public:
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| - | MyTextDropTarget(wxListCtrl *owner);
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| - | virtual bool OnDropText(wxCoord x, wxCoord y,
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| - | const wxString& data);
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| - | wxListCtrl *m_owner;
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| - | };
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| - | </source>
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| - | <source lang="cpp">
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| - | #include "textdrop.h"
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| - | #include <wx/treectrl.h>
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| - | #include <wx/dirctrl.h>
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| - | #include <wx/dir.h>
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| - | #include <wx/splitter.h>
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| - | TextDrop::TextDrop(const wxString& title)
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| - | : wxFrame(NULL, wxID_ANY, title, wxDefaultPosition, wxSize(300, 200))
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| - | {
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| - | wxSplitterWindow *spl1 = new wxSplitterWindow(this, -1);
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| - | wxSplitterWindow *spl2 = new wxSplitterWindow(spl1, -1);
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| - | m_gdir = new wxGenericDirCtrl(spl1, -1, wxT("/home/"),
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| - | wxPoint(-1, -1), wxSize(-1, -1), wxDIRCTRL_DIR_ONLY);
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| - | m_lc1 = new wxListCtrl(spl2, -1, wxPoint(-1, -1),
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| - | wxSize(-1, -1), wxLC_LIST);
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| - | m_lc2 = new wxListCtrl(spl2, -1, wxPoint(-1, -1),
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| - | wxSize(-1, -1), wxLC_LIST);
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| - | MyTextDropTarget *mdt = new MyTextDropTarget(m_lc2);
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| - | m_lc2->SetDropTarget(mdt);
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| - | Connect(m_lc1->GetId(), wxEVT_COMMAND_LIST_BEGIN_DRAG,
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| - | wxListEventHandler(TextDrop::OnDragInit));
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| - | wxTreeCtrl *tree = m_gdir->GetTreeCtrl();
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| - | spl2->SplitHorizontally(m_lc1, m_lc2);
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| - | spl1->SplitVertically(m_gdir, spl2);
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| - | Connect(tree->GetId(), wxEVT_COMMAND_TREE_SEL_CHANGED,
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| - | wxCommandEventHandler(TextDrop::OnSelect));
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| - | Center();
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| - | }
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| - | MyTextDropTarget::MyTextDropTarget(wxListCtrl *owner)
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| - | {
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| - | m_owner = owner;
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| - | }
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| - | bool MyTextDropTarget::OnDropText(wxCoord x, wxCoord y,
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| - | const wxString& data)
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| - | {
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| - | m_owner->InsertItem(0, data);
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| - | return true;
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| - | }
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| - | void TextDrop::OnSelect(wxCommandEvent& event)
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| - | {
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| - | wxString filename;
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| - | wxString path = m_gdir->GetPath();
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| - | wxDir dir(path);
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| - | bool cont = dir.GetFirst(&filename, wxEmptyString, wxDIR_FILES);
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| - | int i = 0;
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| - | m_lc1->ClearAll();
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| - | m_lc2->ClearAll();
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| - | while ( cont )
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| - | {
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| - | m_lc1->InsertItem(i, filename);
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| - | cont = dir.GetNext(&filename);
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| - | i++;
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| - | }
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| - | }
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| - | void TextDrop::OnDragInit(wxListEvent& event)
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| - | {
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| - | wxString text = m_lc1->GetItemText(event.GetIndex());
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| - | wxTextDataObject tdo(text);
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| - | wxDropSource tds(tdo, m_lc1);
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| - | tds.DoDragDrop(wxDrag_CopyOnly);
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| - | }
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| - | </source>
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| - |
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| - | <source lang="cpp">
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| - | #include <wx/wx.h>
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| - | class MyApp : public wxApp
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| - | {
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| - | public:
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| - | virtual bool OnInit();
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| - | };
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| - | </source>
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| - | <source lang="cpp">
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| - | #include "main.h"
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| - | #include "textdrop.h"
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| - | IMPLEMENT_APP(MyApp)
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| - | bool MyApp::OnInit()
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| - | {
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| - | TextDrop *td = new TextDrop(wxT("TextDrop"));
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| - | td->Show(true);
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| - | return true;
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| - | }
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| - | </source>
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| - | In our example, we have a window separated into three parts. This is done by the <i>wxSplitterWindow</i> widget.
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| - | In the left part of the window, we have a generic directory control. We display all directories available under our filesystem. In the right part there are two windows. The first displays all files under a selected directory.
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| - | The second one is used for dragging the files.
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| - | <source lang="cpp">
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| - | MyTextDropTarget *mdt = new MyTextDropTarget(m_lc2);
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| - | m_lc2->SetDropTarget(mdt);
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| - | </source>
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| - | Here we define a text drop target.
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| - | <source lang="cpp">
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| - | wxString text = m_lc1->GetItemText(event.GetIndex());
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| - | wxTextDataObject tdo(text);
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| - | wxDropSource tds(tdo, m_lc1);
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| - | tds.DoDragDrop(wxDrag_CopyOnly);
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| - | </source>
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| - | In the <i>OnDragInit()</i> method, we define a text data object and a drop source object. We call the <i>DoDragDrop()</i> method. The <i>wxDrag_CopyOnly</i> constant allows only copying of data.
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| - | <source lang="cpp">
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| - | bool MyTextDropTarget::OnDropText(wxCoord x, wxCoord y,
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| - | const wxString& data)
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| - | {
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| - | m_owner->InsertItem(0, data);
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| - | return true;
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| - | }
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| - | </source>
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| - | During the dropping operation, we insert the text data into the list control.
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| - | [[image: wxwidgets_faq_textdrop.jpg | center]]
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| - | [[Категория:WxWidgets]]
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