您好……
我在 .net 框架中使用 Visual c++，我需要能够在运行时移动一个按钮，以便我用鼠标按住它，然后将它留在想要的位置，换句话说，拖放按钮。
我不需要将它拖放到另一个容器中，而是在同一个容器中，例如按钮的父级是panel1，我想将按钮移动到panel1中。
需要提及的重要一点是，我希望能够在按钮移动时而不是之后执行代码，例如，在每次更改按钮后输出按钮的位置。
希望这可以使想法清晰，有什么方法可以实现吗？
提前致谢:)
【问题讨论】：
标签： .net visual-c++ drag-and-drop
我假设您使用的是托管 C++/CLI，或者您只是使用 Visual C++。
对于您需要同时运行代码的部分，您可能需要一个额外的线程来让该代码在后台运行。请参阅 ::CreateThread 文档。
在我看来，如果它是 CDialog 的成员，您必须手动处理按钮拖动。甚至不允许按钮离开面板的代码（顺便说一句，“面板”是什么意思？它是一个组框吗？）。请参阅文档
不要忘记将此行添加到您的消息映射中
ON_WM_MOUSEMOVE()
ON_WM_LBUTTONDOWN()
ON_WM_LBUTTONUP()
【讨论】：
namespace Project1 {
using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System::Data;
using namespace System::Drawing;
using namespace System::Collections::Generic;
using namespace System::IO;
using namespace System::Text;
/// <summary>
/// Summary for MyForm
/// </summary>
public ref class MyForm : public System::Windows::Forms::Form
{
private:
static int m_textBoxCounter = 1;
static int m_newButtoncounter = 1;
static int s_btn_x_cord = 3;
static int s_btn_y_cord = 3;
static int s_tbox_x_cord = 335;
static int s_tbox_y_cord = 3;
static int m_TabIndexer = 5;
static int m_x_cord = 0;
static int m_y_cord = 0;
bool isDragging = false;
static int oldX, oldY;
static int top, left;
Int32 indexOfItemUnderMouseToDrag;
Int32 indexOfItemUnderMouseToDrop;
System::Drawing::Rectangle dragBoxFromMouseDown;
Point screenOffset;
System::Windows::Forms::Cursor^ MyNoDropCursor;
System::Windows::Forms::Cursor^ MyNormalCursor;
public:
MyForm(void)
{
InitializeComponent();
//
//TODO: Add the constructor code here
//
}
protected:
/// <summary>
/// Clean up any resources being used.
/// </summary>
~MyForm()
{
if (components)
{
delete components;
}
}
private: System::Windows::Forms::SplitContainer^ splitContainer1;
private: System::Windows::Forms::Label^ label1;
private: System::Windows::Forms::Button^ button1;
private: System::Windows::Forms::Button^ button2;
private: System::Windows::Forms::SaveFileDialog^ saveFileDialog1;
private:
/// <summary>
/// Required designer variable.
/// </summary>
System::ComponentModel::Container ^components;
#pragma region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
void InitializeComponent(void)
{
System::ComponentModel::ComponentResourceManager^ resources = (gcnew
System::ComponentModel::ComponentResourceManager(MyForm::typeid));
this->splitContainer1 = (gcnew System::Windows::Forms::SplitContainer());
this->label1 = (gcnew System::Windows::Forms::Label());
this->button1 = (gcnew System::Windows::Forms::Button());
this->button2 = (gcnew System::Windows::Forms::Button());
this->saveFileDialog1 = (gcnew System::Windows::Forms::SaveFileDialog());
(cli::safe_cast<System::ComponentModel::ISupportInitialize^>
(this>splitContainer1))->BeginInit();
this->splitContainer1->Panel1->SuspendLayout();
this->splitContainer1->SuspendLayout();
this->SuspendLayout();
//
// splitContainer1
//
this->splitContainer1->IsSplitterFixed = true;
this->splitContainer1->Location = System::Drawing::Point(11, 11);
this->splitContainer1->Margin = System::Windows::Forms::Padding(2);
this->splitContainer1->Name = L"splitContainer1";
//
// splitContainer1.Panel1
//
this->splitContainer1->Panel1->BackColor = System::Drawing::Color::White;
this->splitContainer1->Panel1->Controls->Add(this->label1);
this->splitContainer1->Panel1->Controls->Add(this->button1);
this->splitContainer1->Panel1->Controls->Add(this->button2);
//
// splitContainer1.Panel2
//
this->splitContainer1->Panel2->AllowDrop = true;
this->splitContainer1->Panel2->AutoScroll = true;
this->splitContainer1->Panel2->BackColor =
System::Drawing::Color::Transparent;
this->splitContainer1->Panel2->Padding =
System::Windows::Forms::Padding(2, 1, 2, 1);
this->splitContainer1->Panel2->DragDrop +=
gcnew System::Windows::Forms::DragEventHandler(this, &MyForm::Panel2_DragDrop);
this->splitContainer1->Panel2->DragEnter +=
gcnew System::Windows::Forms::DragEventHandler(this, &MyForm::Panel2_DragEnter);
this->splitContainer1->Panel2->DragOver +=
gcnew System::Windows::Forms::DragEventHandler(this, &MyForm::Panel2_DragOver);
this->splitContainer1->Panel2->DragLeave +=
gcnew System::EventHandler(this, &MyForm::Panel2_DragLeave);
this->splitContainer1->Panel2->MouseUp +=
gcnew System::Windows::Forms::MouseEventHandler(this,
&MyForm::splitContainer1_Panel2_MouseUP);
this->splitContainer1->Size = System::Drawing::Size(634, 443);
this->splitContainer1->SplitterDistance = 129;
this->splitContainer1->SplitterWidth = 3;
this->splitContainer1->TabIndex = 0;
//
// label1
//
this->label1->Location = System::Drawing::Point(3, 410);
this->label1->Name = L"label1";
this->label1->Size = System::Drawing::Size(292, 23);
this->label1->TabIndex = 4;
//
// button1
//
this->button1->AutoEllipsis = true;
this->button1->Cursor = System::Windows::Forms::Cursors::Default;
this->button1->DialogResult = System::Windows::Forms::DialogResult::Cancel;
this->button1->Location = System::Drawing::Point(17, 110);
this->button1->Margin = System::Windows::Forms::Padding(2);
this->button1->Name = L"button1";
this->button1->Size = System::Drawing::Size(98, 19);
this->button1->TabIndex = 0;
this->button1->Text = L"Add Button";
this->button1->UseVisualStyleBackColor = true;
this->button1->DragEnter +=
gcnew System::Windows::Forms::DragEventHandler(this, &MyForm::button_DragEnter);
this->button1->MouseDown +=
gcnew System::Windows::Forms::MouseEventHandler(this, &MyForm::button_MouseDown);
this->button1->MouseMove += gcnew
System::Windows::Forms::MouseEventHandler(this, &MyForm::button_MouseMove);
this->button1->MouseUp +=
gcnew System::Windows::Forms::MouseEventHandler(this, &MyForm::button_MouseUp);
//
// button2
//
this->button2->AutoEllipsis = true;
this->button2->Cursor = System::Windows::Forms::Cursors::Default;
this->button2->Location = System::Drawing::Point(17, 296);
this->button2->Margin = System::Windows::Forms::Padding(2);
this->button2->Name = L"button2";
this->button2->Size = System::Drawing::Size(98, 19);
this->button2->TabIndex = 1;
this->button2->Text = L"Add TextBox";
this->button2->UseVisualStyleBackColor = true;
this->button2->DragEnter += gcnew
System::Windows::Forms::DragEventHandler(this, &MyForm::button_DragEnter);
this->button2->MouseDown += gcnew
System::Windows::Forms::MouseEventHandler(this, &MyForm::button_MouseDown);
this->button2->MouseMove += gcnew
System::Windows::Forms::MouseEventHandler(this, &MyForm::button_MouseMove);
this->button2->MouseUp += gcnew
System::Windows::Forms::MouseEventHandler(this, &MyForm::button_MouseUp);
//
// MyForm
//
this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
this->AutoScroll = true;
this->AutoSize = true;
this->AutoSizeMode = System::Windows::Forms::AutoSizeMode::GrowAndShrink;
this->BackColor = System::Drawing::Color::White;
this->ClientSize = System::Drawing::Size(656, 463);
this->Controls->Add(this->splitContainer1);
this->ForeColor = System::Drawing::Color::Black;
this->Icon = (cli::safe_cast<System::Drawing::
Icon^>(resources->GetObject(L"$this.Icon")));
this->Margin = System::Windows::Forms::Padding(2);
this->MaximizeBox = false;
this->MinimizeBox = false;
this->Name = L"MyForm";
this->StartPosition =
System::Windows::Forms::FormStartPosition::CenterScreen;
this->Text = L"Run-time Control Manipulation";
this->Load += gcnew System::EventHandler(this, &MyForm::MyForm_Load);
this->splitContainer1->Panel1->ResumeLayout(false);
(cli::safe_cast<System::ComponentModel::
ISupportInitialize^>(this->splitContainer1))->EndInit();
this->splitContainer1->ResumeLayout(false);
this->ResumeLayout(false);
}
#pragma endregion
private: System::Void button_MouseDown(System::Object^ /*sender*/,
System::Windows::Forms::MouseEventArgs^ e)
{
isDragging = true;
oldX = e->X;
oldY = e->Y;
if ((e->Button == System::Windows::Forms::MouseButtons::Left)
||
(e->Button == System::Windows::Forms::MouseButtons::Right))
{
System::Drawing::Size dragSize = SystemInformation::DragSize;
dragBoxFromMouseDown = System::Drawing::Rectangle(Point(e->X -
(dragSize.Width / 2), e->Y - (dragSize.Height / 2)), dragSize);
}
else
{
this->button1->BackColor = System::Drawing::Color::Red;
}
}
private: System::Void button_MouseMove(Object^ sender,
System::Windows::Forms::MouseEventArgs^ e)
{
if (isDragging)
{
//top = (e->Y - oldY); //((Button^)sender)->Top + (e->Y - oldY);
//left = (e->X - oldX); //((Button^)sender)->Left + (e->X - oldX);
if ((e->Button & System::Windows::Forms::MouseButtons::Left) ==
System::Windows::Forms::MouseButtons::Left)
{
// If the mouse moves outside the rectangle, start the drag.
if (dragBoxFromMouseDown != Rectangle::Empty &&
dragBoxFromMouseDown.Contains(e->X, e->Y))
{
// The screenOffset is used to account for any desktop bands
// that may be at the top or left side of the screen when
// determining when to cancel the drag drop operation.
screenOffset = SystemInformation::WorkingArea.Location;
// Proceed with the drag-and-drop operation.
DragDropEffects dropEffect =
((Button^)sender)->DoDragDrop(((Button^)sender)->Text, DragDropEffects::Copy);
// If the drag operation was a move then capture the location of the
mouse pointer.
m_x_cord = e->X;
m_y_cord = e->Y;
}
}
}
}
private: System::Void button_MouseUp(Object^ /*sender*/,
System::Windows::Forms::MouseEventArgs^ /*e*/)
{
// Reset the drag rectangle when the mouse button is raised.
dragBoxFromMouseDown = Rectangle::Empty;
isDragging = false;
this->label1->Text = "Ready for Drag-Drop";
this->button1->BackColor = System::Drawing::Color::WhiteSmoke;
this->button1->AllowDrop = false;
this->button2->BackColor = System::Drawing::Color::WhiteSmoke;
this->button2->AllowDrop = false;
}
private: System::Void button_GiveFeedback(Object^ /*sender*/,
System::Windows::Forms::GiveFeedbackEventArgs^ e)
{
// Use custom cursors if the check box is checked.
if (isDragging)
{
// Sets the custom cursor based upon the effect.
e->UseDefaultCursors = false;
if ((e->Effect == DragDropEffects::Move)
|| (e->Effect == DragDropEffects::Copy))
System::Windows::Forms::Cursor::Current = MyNormalCursor;
else
System::Windows::Forms::Cursor::Current = MyNoDropCursor;
}
}
private: System::Void button_QueryContinueDrag(Object^ sender,
System::Windows::Forms::QueryContinueDragEventArgs^ e)
{
// Cancel the drag if the mouse moves off the form.
Button^ lb = dynamic_cast<Button^>(sender);
if (lb != nullptr)
{
Form^ f = lb->FindForm();
// Cancel the drag if the mouse moves off the form. The screenOffset takes
into
// account any desktop bands that may be at the top or left side of the
screen.
if (((Control::MousePosition.X - screenOffset.X) < f->DesktopBounds.Left)
|| ((Control::MousePosition.X - screenOffset.X) > f->DesktopBounds.Right)
|| ((Control::MousePosition.Y - screenOffset.Y) < f->DesktopBounds.Top)
|| ((Control::MousePosition.Y - screenOffset.Y) > f->DesktopBounds.Bottom))
{
e->Action = DragAction::Cancel;
}
}
}
private: System::Void button_DragEnter(System::Object^ /*sender*/,
System::Windows::Forms::DragEventArgs^ e)
{
e->Effect = DragDropEffects::Copy;
}
private: System::Void tableLayoutPanel1_Paint(System::Object^ sender,
System::Windows::Forms::PaintEventArgs^ e)
{
}
private: System::Void Panel2_DragLeave(System::Object^ /*sender*/,
System::EventArgs^ /*e*/)
{
// Reset the label text.
this->label1->Text = "";
}
private: System::Void Panel2_DragDrop(System::Object^ /*sender*/,
System::Windows::Forms::DragEventArgs^ e)
{
// Reset the label text.
this->label1->Text = "Ready for Drag-Drop";
// Ensure that the dragged item is contained in the data.
if (e->Data->GetDataPresent(System::String::typeid))
{
Object^ item =
dynamic_cast<Object^>(e->Data->GetData(System::String::typeid));
// Determine whether data exists in the drop data. If not, then
// the drop effect reflects that the drop cannot occur.
if ((e->AllowedEffect == DragDropEffects::Copy) || (e->AllowedEffect ==
DragDropEffects::Move))
{
if (item->ToString()->Contains("Add Button"))
{
this->label1->Text = "New Button dropped";
Button^ newBtn = gcnew Button();
newBtn->Left = left;
newBtn->Top = top;
newBtn->Name = L"newButton" + m_newButtoncounter;
newBtn->TabIndex = m_TabIndexer;
newBtn->Text = L"New Button";
m_newButtoncounter++;
m_TabIndexer++;
this->splitContainer1->Panel2->Controls->Add(newBtn);
this->button1->BackColor = System::Drawing::Color::GhostWhite;
}
else
if (item->ToString()->Contains("Add TextBox"))
{
this->label1->Text = "New textBox dropped";
TextBox^ newtxtbox = gcnew TextBox();
newtxtbox->Left = left;
newtxtbox->Top = top;
newtxtbox->Name = L"newButton" + m_textBoxCounter;
newtxtbox->TabIndex = m_TabIndexer;
newtxtbox->Text = L"New textBox";
m_textBoxCounter++;
m_TabIndexer++;
this->splitContainer1->Panel2->Controls->Add(newtxtbox);
this->button1->BackColor =
System::Drawing::Color::GhostWhite;
}
delete item;
return;
}
}
}
private: System::Void Panel2_DragEnter(System::Object^ sender,
System::Windows::Forms::DragEventArgs^ /*e*/)
{
Button^ lb = dynamic_cast<Button^>(sender);
// Reset the label text.
this->label1->Text = "Ready for Drop";
if (lb != nullptr)
{
// Determine whether data exists in the drop data. If not, then
// the drop effect reflects that the drop cannot occur.
if (((Button^)sender)->Text == "Add TextBox")
{
this->label1->Text = "TextBox can be dropped";
this->button1->BackColor = System::Drawing::Color::AntiqueWhite;
}
else
if (((Button^)sender)->Text == "Add Button")
{
this->label1->Text = "Button can be dropped";
this->button2->BackColor = System::Drawing::Color::AntiqueWhite;
}
delete lb;
return;
}
}
private: System::Void Panel2_DragOver(System::Object^ /*sender*/,
System::Windows::Forms::DragEventArgs^ e)
{
//Point^ location = this->button1->PointToScreen;
Object^ item =
dynamic_cast<Object^>(e->Data->GetData(System::String::typeid));
// Determine whether string data exists in the drop data. If not, then
// the drop effect reflects that the drop cannot occur.
if (!e->Data->GetDataPresent(System::String::typeid))
{
e->Effect = DragDropEffects::None;
this->label1->Text = "No Dropped Control.";
return;
}
// Set the effect based upon the KeyState.
if ((e->KeyState & (8 + 32)) == (8 + 32) && ((e->AllowedEffect &
DragDropEffects::Link) == DragDropEffects::Link))
{
// KeyState 8 + 32 = CTL + ALT
// Link drag-and-drop effect.
e->Effect = DragDropEffects::Link;
}
else
if ((e->KeyState & 32) == 32 &&
((e->AllowedEffect & DragDropEffects::Link) == DragDropEffects::Link))
{
// ALT KeyState for link.
e->Effect = DragDropEffects::Link;
}
else
if ((e->KeyState & 4) == 4 &&
((e->AllowedEffect & DragDropEffects::Move) == DragDropEffects::Move))
{
// SHIFT KeyState for move.
e->Effect = DragDropEffects::Move;
}
else
if ((e->KeyState & 8) == 8 &&
((e->AllowedEffect & DragDropEffects::Copy) == DragDropEffects::Copy))
{
// CTL KeyState for copy.
e->Effect = DragDropEffects::Copy;
}
else
if ((e->AllowedEffect & DragDropEffects::Move) ==
DragDropEffects::Move)
{
// By default, the drop action should be move, if allowed.
e->Effect = DragDropEffects::Move;
}
else
e->Effect = DragDropEffects::None;
if ((item->ToString()->Contains("Add TextBox"))
|| (item->ToString()->Contains("Add Button")))
{
e->Effect = DragDropEffects::Copy;
this->label1->Text = item->ToString()->Replace("Add ","") +" can be
Dropped";
}
}
private: System::Void splitContainer1_Panel2_MouseUP(System::Object^ /*sender*/,
System::Windows::Forms::MouseEventArgs^ /*e*/)
{
this->button1->BackColor = System::Drawing::Color::Aqua;
this->button2->BackColor = System::Drawing::Color::Aqua;
}
private: System::Void MyForm_Load(System::Object^ sender, System::EventArgs^ e)
{
this->Size = System::Drawing::Size(15, 265);
this->FormBorderStyle = System::Windows::Forms::FormBorderStyle::Fixed3D;
}
};
}
【讨论】：