PreviewCtrl

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Introduction

Drawing a CBitmap into a CStatic is a piece of cake. At least if you stop to mess around with CStatic::SetBitmap(). To get some running code, I derived CPreviewRect from CStatic and implemented the display routines manually. This small application demonstrates its usage.

Features

• The shown images are resizable and always shown in correct aspect ratio.
• The shown images can be resized to thumbnail size to save up memory and to speed up drawing.
• The shown images can be specified by:
  • a path name
  • a resource ID
  • another CBitmap
  • raw RGB data (in conjunction with width and height information)
• Compared to CStatic::SetBitmap() it works.

Background

CStatic::SetBitmap() drove me mad.

Using the code

Guess you have a dialog with a CStatic control on it, and you want to show loaded bitmaps in this control. First of all please make sure that the control's name differs from IDC_STATIC and create a related member variable. Now modify your code as follows:

In your dialog's header file:

// change the control's class from CStatic to CPreviewRect
CPreviewRect m_bitmap;

In your FileOpen handler:

// create your file dialog
CFileDialog dlg(TRUE, 0, 0, OFN_HIDEREADONLY | OFN_FILEMUSTEXIST, 
                    "Bitmaps (.bmp)|*.bmp|All files(*.*)|*.*||");

// ask user
if (dlg.DoModal() == IDCANCEL) return;

// load the selected bitmap file
m_bitmap.LoadBitmap(dlg.GetPathName());

// check recent file operation (IsInitialized() should return TRUE)
if (!m_bitmap.IsInitialized())
{
    // load error bitmap from a resource (if you have any)
    m_bitmap.LoadBitmap(IDB_BLUESCREEN);
}

// resize bitmap to save up memory and speed up drawing
m_bitmap.CreateThumbnail(320, 240);

That's it!

History

Version 1.1

Added:

• BorrowBitmap(CBitmap* pBitmap)

Changed:

• CreateBitmap(CBitmap* pBitmap) has been renamed to CopyBitmap(CBitmap* pBitmap)

Version 1.0

Added:

• LoadBitmap(const CString& Path)
• LoadBitmap(UINT nIDResource)
• CreateBitmap(CBitmap* pBitmap)
• CreateBitmap(int Width, int Height, unsigned char* BGRA)
• CreateThumbnail(int MaxWidth, int MaxHeight)
• Reset(BOOL GraphicalUpdate = TRUE)