imageviewer.cpp

Visual_C++[1].NET_Bible1 Visual_C++宝典书中的全部源码

#include "stdafx.h"

#using <mscorlib.dll>
#using <System.dll>
#using <System.Drawing.dll>
#using <System.Windows.Forms.dll>

using namespace System;
using namespace System::ComponentModel;
using namespace System::Drawing;
using namespace System::Windows::Forms;

__gc class ImageViewerForm : public Form
{
public:
 ImageViewerForm();
protected:
 void OnPaint(PaintEventArgs *e);
private:
 //Event handlers for menu pFileMenu clicks
 void OnExit (Object* sender, EventArgs *e);
 void OnAbout (Object* sender, EventArgs *e);
 void OnOpen (Object* sender, EventArgs *e);

 //Your member variable for the image
 Bitmap *m_pImage;
};

int __stdcall WinMain()
{   
 Application::Run(new ImageViewerForm());
 return 0;
}

ImageViewerForm::ImageViewerForm()
{
 // Set the title bar text.
 Text = "Image Viewer";

 // Create a top-level menu for your frame window.
 MainMenu* pMenu = new MainMenu();

 // Add a menu option to the File menu.
 MenuItem* pFileMenu = pMenu->MenuItems->Add("File");

 // Add the File menu items now that you have the File 
 // item added. Notice that the event handlers for these 
 // items are also specified as the items are added to 
 // the menu.
 pFileMenu->MenuItems->Add("Open...", 
                           new EventHandler(this,
                            &ImageViewerForm::OnOpen));
 pFileMenu->MenuItems->Add("Exit", 
                           new EventHandler(this,
                            &ImageViewerForm::OnExit));

 // Add another top-level menu option and its submenu.
 pFileMenu = pMenu->MenuItems->Add("Help");
 pFileMenu->MenuItems->Add("About...", 
                           new EventHandler(this, 
                            &ImageViewerForm::OnAbout));

 // Set the current Form object's menu 
 // to the newly created menu.
 Menu = pMenu;
}

void ImageViewerForm::OnExit(Object *sender, EventArgs *e)
{
 // Simply call the Form object's Close method.
 Close();
}

void ImageViewerForm::OnAbout(Object *sender, EventArgs *e)
{
 MessageBox::Show("This is version 1.0 of the Managed C++ "
                  "ImageViewer.  For the most up-to-date "
                  "version, please be sure and check "
                  "www.TheCodeChannel.com",  
                  "About ImageViewer");
}

void ImageViewerForm::OnOpen(Object *sender, EventArgs *e)
{
 // The OpenFileDialog is an encapsulation of the common
 // File Open dialog box.
 OpenFileDialog* pOpenFileDlg = new OpenFileDialog();

 // You can filter here just as you can with the standard
 // Win32 API or the MFC CFileDialog class.
 pOpenFileDlg->Filter 
  = "JPEG files (*.jpg;*.jpeg)|*.jpg;*.jpeg";

// Display the File Open dialog box so that the user
// can select an image file to be opened.
// If user has clicked OK...
if (DialogResult::OK == pOpenFileDlg->ShowDialog())
 {
  // Retrieve the dialog box's pstrFileName FileName property, which
  // is the name of the file the user selected to open.
  String *pstrFileName = pOpenFileDlg->FileName;

  // Now that you have a valid filename, set the 
  // ImageViewerForm image member to an instantiation
  // of the Bitmap class using the filename.
  m_pImage = new Bitmap(pstrFileName);

  // Here I'm setting the form to scroll if the image
  // is too large to be accommodated. Note the setting of the
  // minimum size to the image size.
  AutoScroll=true;
  AutoScrollMinSize = m_pImage->Size;

  // Invalidate the form to cause a repaint.
  Invalidate();
 }
}

void ImageViewerForm::OnPaint(PaintEventArgs *e)
{
 // If you've loaded an image...
 if (m_pImage)
 {
  // Get the Graphics object associated with your 
  // form's DC (device context).
  Graphics *pGraphics = e->Graphics;

  // Use the Graphics::DrawImage function to 
  // draw the image.
  pGraphics->DrawImage(m_pImage,
                       AutoScrollPosition.X,
                       AutoScrollPosition.Y,
                       m_pImage->Width,
                       m_pImage->Height);
 }
}