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Introduction

Displaying large Bitmap files on a Dialog, in its original size is quite difficult in the VC++ Environment. However, it is possible to display a large bitmap to a predefined area of the dialog using the StretchBlt( ) function. The major disadvantage of this is that some of the image's clarity will be lost. This article explains how to display large bitmaps in the desired area of your dialog in its original size with a scrolling technique used to show the entire bitmap.

Demo application

Although the primary aim of this article is to display a bitmap with scrolling, it also covers the following three main objectives.

Loading a Bitmap in to the Dialog During Run-time.
Displaying Bitmap in its Original size by using Scrolling technique.
Implementing Flicker free drawing Using Double Buffering technique.

Loading Bitmap in to the Dialog During Run-time:

Sometimes the user may require different bitmaps to be loaded in to the dialog depending on the requirements of his GUI. This can be achieved by calling the LoadImage( ) function. The implementation of this is explained below

Place a Picture control in your dialog. Adjust its size as you wish. Remember, you are going to display the bitmap in this control. Big bitmaps will confine to the entire area of this control with a vertical scroll bar on Right side ( the scroll bar will be displayed if the height of the image is greater than the height of this control) and a horizontal scroll bar at the bottom of this control (the scrollbar will be displayed if the width of the image is greater than the width of this control). Small bitmaps will be displayed at the centre of this control without scrollbars, with equal clearance to the left & right, and top & bottom with respect to the control. So place your control with an artistic touch to give your dialog a nice appearance.

Take the properties of the picture control. Change its ID to IDC_STATIC1 and Type as Frame and Colour as Gray. Also uncheck the Visible check button so that the tick mark is removed from it.

Using Class Wizard, create a control variable of type CStatic for IDC_STATIC1. Let it be m_st1.

In your dialog's header file (say MyDlg.h), add the following code:

public:
    CRect rectStaticClient;
    int sourcex, sourcey,offsetx,offsety;
protected:
    CDC m_dcMem;            // Compatible Memory DC for dialog

    HBITMAP m_hBmpOld;    // Handle of old bitmap to save

    HBITMAP m_hBmpNew;    // Handle of new bitmap from file

       BITMAP m_bmInfo;        // Bitmap Information structure

In your dialog's implementation file (say MyDlg.cpp), add the following code:

BOOL CMyDlg::OnInitDialog()
{
    
// TODO: Add extra initialization here

    CClientDC dc(this);
     m_dcMem.CreateCompatibleDC( &dc );
return TRUE;  // return TRUE  unless you set the focus to a control

}

Override the else part of your dialog's ::OnPaint() function:

void MyDlg::OnPaint()
{
    if (IsIconic())
    {
        CPaintDC dc(this); // device context for painting


        SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);

        // Center icon in client rectangle

        int cxIcon = GetSystemMetrics(SM_CXICON);
        int cyIcon = GetSystemMetrics(SM_CYICON);
        CRect rect;
        GetClientRect(&rect);
        int x = (rect.Width() - cxIcon + 1) / 2;
        int y = (rect.Height() - cyIcon + 1) / 2;

        // Draw the icon

        dc.DrawIcon(x, y, m_hIcon);
    }
    else
    {
        //Add the following Code 

        CPaintDC dc(this);
        dc.BitBlt(offsetx,offsety,m_size.cx,m_size.cy, 
                   &m_dcMem, sourcex, sourcey,SRCCOPY);
        CDialog::OnPaint();
    }
}

Write the following code whenever you want to load a bitmap in to your dialog.

m_hBmpNew = (HBITMAP) LoadImage(
    AfxGetInstanceHandle(),   // handle to instance

    filename,  // name or identifier of the image .say"C:\\NewFolder\\1.bmp"

    IMAGE_BITMAP,        // image types

    0,     // desired width

    0,     // desired height

    LR_LOADFROMFILE); 

    if( m_hBmpNew == NULL )
    {
        AfxMessageBox("Load Image Failed");
    }
    
    // put the HBITMAP info into the CBitmap (but not the bitmap itself)

    else {
        m_st1.GetClientRect( &rectStaticClient );
        rectStaticClient.NormalizeRect();
        m_size.cx=rectStaticClient.Size().cx;
        m_size.cy=rectStaticClient.Size().cy;
        m_size.cx = rectStaticClient.Width();    // zero based

        m_size.cy = rectStaticClient.Height();    // zero based


        // Convert to screen coordinates using static as base,

        // then to DIALOG (instead of static) client coords 

        // using dialog as base

        m_st1.ClientToScreen( &rectStaticClient );
        ScreenToClient( &rectStaticClient);
        
        m_pt.x = rectStaticClient.left;
        m_pt.y = rectStaticClient.top;
        GetObject( m_hBmpNew , sizeof(BITMAP), &m_bmInfo );
        VERIFY(m_hBmpOld = (HBITMAP)SelectObject(m_dcMem, m_hBmpNew )  );
        offsetx= m_pt.x;
        offsety=m_pt.y;    
        InvalidateRect(&rectStaticClient);

This much code will display a bitmap directly on to the picture control during run time. Remember the scrolling capability and alignment adjustments haven't been done yet and so the image will be displayed at the top corner of the Picture control, and if its size is bigger than that of the picture control, it will be clipped to the picture control's size. If the image is smaller than the size of the picture control it will be displayed without clipping, but without centre alignment. The following section describes how scrolling capability and alignment can be achieved.

Displaying the Bitmap at its original size using scrolling

Add a vertical scroll bar control to your dialog and place it touching the right edge of your picture control. Make its length to that of the height of your picture control. Add a Horizontal scroll bar control to your Dialog and place it touching the bottom edge of your picture control. Make its length to that of the width of your picture control.

Using Class Wizard, create member variables of type CScrollBar for your horizontal & vertical scrollbars. Let them be

    CScrollBar m_vbar; //For vertical Scroll Bar

    CScrollBar    m_hbar; //For Horizontal Scroll Bar.

You need to create two SCROLLINFO structures for storing scroll bar parameters for both the vertical and horizontal Scroll Bars, so declare two SCROLLINFO Structures in your dialog's header file.

public:
    CRect rectStaticClient;
    int sourcex, sourcey,offsetx,offsety;
    SCROLLINFO horz,vert;

You only need to show the scrollbars if the size of the bitmap is greater than that of the size of your picture control. So hide the scrollbars initially by writing the following code in your dialog's OnInitDialog() function.

BOOL CMyDlg::OnInitDialog()
{
    // TODO: Add extra initialization here

    CClientDC dc(this);
    m_dcMem.CreateCompatibleDC( &dc );
    m_vbar.ShowWindow(false);  //Hide Vertical Scroll Bar

    m_hbar.ShowWindow(false);  //Hide Horizontal Scroll Bar

    return TRUE;  // return TRUE  unless you set the focus to a control

}

Four situations arise when you are loading a bitmap in to your pre-defined picture control. They are:

Case 1: Both the width and height of the loaded bitmap is greater than that of the picture control. In such situations both the horizontal and vertical scrollbars are necessary to show the entire bitmap. The bitmap is displayed using the scrolling technique. The vertical scrolling range is equal to the height of bitmap-height of the picture control. The height and width of the bitmap is obtained by the following code, which is incorporated in the code which is needed for displaying bitmaps, which is reproduced here again as:

    m_size.cx = rectStaticClient.Width();    // zero based

    m_size.cy = rectStaticClient.Height();    // zero based

    GetObject( m_hBmpNew , sizeof(BITMAP), &m_bmInfo );

The maximum vertical scrolling range is m_bmInfo.bmHeight - m_size.cy, and the maximum horizontal scrolling range is m_bmInfo.bmWidth - m_size.cx. Make the horizontal and vertical scrollbars visible by calling

m_hbar.ShowWindow(true);
m_vbar.ShowWindow(true);

Case 2:THe width of the loaded bitmap is greater than that of the picture control and height is equal to or less than that of picture control. In such situations the horizontal scroll bar is necessary to show the entire bitmap. The bitmap is displayed using the scrolling technique. The horizontal scrolling range is given by m_bmInfo.bmWidth-m_size.cx.

In this case vertical scroll bar is not needed, but for displaying the bitmap centralised with respect to the picture control, the Bitmap should be drawn at an offset from the top corner of the picture control given by

offsety = m_pt.y + ((m_size.cy - m_bmInfo.bmHeight)/2);

Where offsety is the offsetted 'y1' co-ordinate in the (x1,y1) (x2,y2) co-ordinate system and m_pt.y is the original 'y1' co-ordinate.

A clearance of (m_size.cy - m_bmInfo.bmHeight)/2) is also produced from the bottom of the picture control. So the horizontal scrollbar should be shifted up by an amount (m_size.cy - m_bmInfo.bmHeight)/2 using the MoveWindow( ) function as explained below.

m_hbar.MoveWindow(offsetx,offsety+m_bmInfo.bmHeight,m_size.cx,18);

Make the horizontal scrollbar visible and the vertical scrollbar invisible by calling

m_hbar.ShowWindow(true);
m_vbar.ShowWindow(false);

Case 3: The height of the loaded bitmap is greater than that of the picture control and the width is equal to or less than that of picture control. In Such situations the vertical scrollbar is necessary to show the entire bitmap. The bitmap is displayed using scrolling technique. The vertical scrolling range is given by m_bmInfo.bmHeight-m_size.cy.

In this case horizontal scrollbar is not needed, But for displaying the bitmap centralised with respect to the picture control, the Bitmap should be displayed at an offset from the top corner of the picture control given by:

offsetx= m_pt.x + ((m_size.cx - m_bmInfo.bmWidth)/2);

Where offsetx is the offseted 'x1' co-ordinate in (x1,y1) (x2,y2) co-ordinate system and m_pt.x is the original 'x1' co-ordinate.

A clearance of ( (m_size.cx - m_bmInfo.bmWidth)/2) is also produced from the extreme right side of the picture control. So the vertical scroll bar should be shifted left of the right edge of picture control by an amount (m_size.cx - m_bmInfo.bmHeight)/2 using the MoveWindow( ) function as explained below.

m_vbar.MoveWindow(offsetx+m_bmInfo.bmWidth,offsety,18,m_size.cy);

Make the vertical scrollbar visible and horizontal scrollbar invisible by calling

m_hbar.ShowWindow(false);
m_vbar.ShowWindow(true);

Case 4: The height and width of the loaded bitmap is equal to or smaller than that of the picture control. In Such situations the vertical and horizontal scrollbars are not needed to show the entire Bitmap. The Bitmap is displayed centrally, as such, in the picture control. For displaying the bitmap centrally with respect to the picture control, the bitmap should be displayed at an offset from the top corner of the Picture control given by:

offsetx= m_pt.x + ((m_size.cx-  m_bmInfo.bmWidth)/2);
offsety= m_pt.y + ((m_size.cy - m_bmInfo.bmHeight)/2);

Where 'offsetx' is the offseted z co-ordinate, the 'x1' co-ordinate is in the (x1,y1) (x2,y2) co-ordinate system where m_pt.x is the original 'x1' co-ordinate and offsety is the offsetted y co-ordinate, and 'y1' co-ordinate is in the (x1,y1) (x2,y2) co-ordinate system and m_pt.y is the original 'y1' co-ordinate.

Make the vertical and horizontal scrollbars invisible by calling

m_hbar.ShowWindow(false);
m_vbar.ShowWindow(false);

Fill up the SCROLLINFO structure for horizontal scrollbar and vertical scrollbar as given below.

//Horizontal Scroll Info Structure

horz.cbSize = sizeof(SCROLLINFO);
horz.fMask = SIF_ALL;
horz.nMin = 0;
horz.nMax = m_bmInfo.bmWidth-m_size.cx;
horz.nPage =0;
horz.nPos = 0;
horz.nTrackPos=0;
m_hbar.SetScrollInfo(&horz);

//Vertical Scroll Info Structure

vert.cbSize = sizeof(SCROLLINFO);
vert.fMask = SIF_ALL;
vert.nMin = 0;
vert.nMax = m_bmInfo.bmHeight-m_size.cy;
vert.nPage = 0;
vert.nTrackPos=0;
m_vbar.SetScrollInfo(&vert);

Now display the picture by invalidating the picture control.

InvalidateRect(&rectStaticClient);

Remember, depending on the requirements of your loaded image, the positions of the scrollbars may be changed. So before displaying another bitmap in to your dialog, release the memory holding the current bitmap and reset the positions of scrollbars to their original location, i.e. to the positions where you placed them during the design of your dialog, by calling

    if(m_hBmpNew != NULL )
        DeleteObject(m_hBmpNew);         //Release Memory holding Bitmap


    // Reset position of Vertical Scroll Bar

    m_vbar.MoveWindow(offsetx+m_size.cx,offsety,18,m_size.cy);     

    // Reset position of Horizontal Scroll Bar

    m_hbar.MoveWindow(offsetx,offsety+m_size.cy,m_size.cx,18);

The code given below summarizes the things explained above:

    if(m_hBmpNew != NULL )
        DeleteObject(m_hBmpNew);    //Release Memory holding Bitmap


    sourcex=sourcey=0;        // Set starting Position of Source Bitmap to 

                              //be copied to (0,0)

    m_hBmpNew =    (HBITMAP) LoadImage(AfxGetInstanceHandle(), // handle to instance

        "Path of Bitmap",  // name or identifier of the image (say "C:\\bitmap.bmp")

        IMAGE_BITMAP,        // image types

        0,     // desired width

        0,     // desired height

        LR_LOADFROMFILE); 

    if( m_hBmpNew == NULL ) {
        AfxMessageBox("Load Image Failed");
    }    
    // put the HBITMAP info into the CBitmap (but not the bitmap itself)

    else {
        m_st1.GetClientRect( &rectStaticClient );
        rectStaticClient.NormalizeRect();
        m_size.cx=rectStaticClient.Size().cx;
        m_size.cy=rectStaticClient.Size().cy;
        m_size.cx = rectStaticClient.Width();    // zero based

        m_size.cy = rectStaticClient.Height();    // zero based


        // Convert to screen coordinates using static as base,

        // then to DIALOG (instead of static) client coords 

        // using dialog as base

        m_st1.ClientToScreen( &rectStaticClient );
        ScreenToClient( &rectStaticClient);
        
        m_pt.x = rectStaticClient.left;
        m_pt.y = rectStaticClient.top;
        GetObject( m_hBmpNew , sizeof(BITMAP), &m_bmInfo );
        VERIFY(m_hBmpOld = (HBITMAP)SelectObject(m_dcMem, m_hBmpNew )
    );

    offsetx= m_pt.x;
    offsety=m_pt.y;
    
    // Reset position of Vertical Scroll Bar

    m_vbar.MoveWindow(offsetx+m_size.cx,offsety,18,m_size.cy);    

    // Reset position of Horizontal Scroll Bar

    m_hbar.MoveWindow(offsetx,offsety+m_size.cy,m_size.cx,18);    
    horz.cbSize = sizeof(SCROLLINFO);
    horz.fMask = SIF_ALL;
    horz.nMin = 0;
    horz.nMax = m_bmInfo.bmWidth-m_size.cx;
    horz.nPage =0;
    horz.nPos = 0;
    horz.nTrackPos=0;
    if(m_bmInfo.bmWidth<=m_size.cx)
    {
        if((m_size.cx-m_bmInfo.bmWidth)==0)
            offsetx= m_pt.x;
        else
            offsetx= m_pt.x+((m_size.cx-m_bmInfo.bmWidth)/2);
        m_vbar.MoveWindow(offsetx+m_bmInfo.bmWidth,offsety,18,m_size.cy);
        m_hbar.ShowWindow(false);
    }
    else
        m_hbar.ShowWindow(true);
    
    m_hbar.SetScrollInfo(&horz);
    vert.cbSize = sizeof(SCROLLINFO);
    vert.fMask = SIF_ALL;
    vert.nMin = 0;
    vert.nMax = m_bmInfo.bmHeight-(m_size.cy);
    vert.nPage = 0;
    vert.nTrackPos=0;
    if(m_bmInfo.bmHeight<=m_size.cy)
    {
        if((m_size.cy-m_bmInfo.bmHeight)==0)
            offsety= m_pt.y;
        else
            offsety= m_pt.y+((m_size.cy-m_bmInfo.bmHeight)/2);
        m_hbar.MoveWindow(offsetx,offsety+m_bmInfo.bmHeight,m_size.cx,18);
        m_vbar.ShowWindow(false);
    }
    else
        m_vbar.ShowWindow(true);

    m_vbar.SetScrollInfo(&vert);

    InvalidateRect(&rectStaticClient);
}

Now your bitmap is ready to be displayed on the dialog with scrollbars (if needed). But still it's not able to scroll to show the remaining portions. We need to handle the WM_VSCROLL and WM_HSCROLL messages to re-draw the bitmap depending on the scroll bar positions for this.

Using Class Wizard, handle WM_VSCROLL and WM_HSCROLL messages and write the following code in their handler.

void CMyDlg::OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar) 
{
    // TODO: Add your message handler code here and/or call default

    switch (nSBCode)
    {
    case SB_TOP:
        sourcey = 0;
        break;
    case SB_BOTTOM:
        sourcey = INT_MAX;
        break;
    case SB_THUMBTRACK:
        sourcey = nPos;
        break;
    }

    m_vbar.SetScrollPos(sourcey);
    InvalidateRect(&rectStaticClient);
    CDialog::OnVScroll(nSBCode, nPos, pScrollBar);
}

void CMyDlg::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar) 
{
    // TODO: Add your message handler code here and/or call default

    switch (nSBCode)
    {
    case SB_TOP:
        sourcex = 0;
        break;
    case SB_BOTTOM:
        sourcex = INT_MAX;
        break;
    case SB_THUMBTRACK:
        sourcex= nPos;
        break;
    }    
    m_hbar.SetScrollPos(sourcex);
    InvalidateRect(&rectStaticClient);
    CDialog::OnHScroll(nSBCode, nPos, pScrollBar);
}

Now you can scroll your bitmap and the remaining portions of it can be viewed by horizontal and vertical scrolling. Still there exists a problem. The screen will flicker continuously when you scroll the bitmap. Here comes another technique to tackle this problem. The finishing touch to this Project. Nothing but "Double buffer technique for flicker free drawing", which we will adopt.

Implementing Flicker free drawing Using Double Buffering technique

To eliminate flicker in drawing you need to draw everything on a memory DC, and then copy it to the real DC using BitBlt or StretchBlt functions. This technique is called double buffering. The drawing technique used in this article is double buffering. It is explained in the earlier sections. Secondly, you need to override the OnEraseBackground( ) event. The default implementation of this event clears the background of the control with the current value of the BackColor property. However, it is not always necessary to repaint the entire area of the control, and doing so unnecessarily can cause flickering. Bypass the OnEraseBackground( ) event while you re-paint your dialog with InvalidateRect(&rectStatcClient). This can be achieved by signalling a global variable. Declare a global variable of type BOOL, say BOOL erase, and initialise it to false. Map the WM_ERASEBKGND message and override it as

BOOL MyDlg::OnEraseBkgnd(CDC* pDC) 
{
    // TODO: Add your message handler code here and/or call default

    if(erase)
        return false;
    else
    return CDialog::OnEraseBkgnd(pDC);
}

Before you call the InvalidateRect & rectStatcClient functions, set the variable 'erase' to true. Now OnEraseBkgnd( ) is bypassed.

Reset 'erase' flag to false at the end of your OnPaint function. This will remove the bypassing of OnEraseBkgnd(pDC) event and the background will be erased when WM_ERASEBKGND is sent by other events other than InvalidateRect( &rectStaticClient ).

    else
    {    
        CPaintDC dc(this);
         dc.BitBlt(offsetx,offsety,m_size.cx,m_size.cy, 
                    &m_dcMem, sourcex, sourcey,SRCCOPY);
        erase=false;
        CDialog::OnPaint();
    }

I hope that you are now able to draw a bitmap with scrolling capability in your dialog. Go through the demo project and learn more from it.

NOTE: This code has been tested on the Windows 2000 platform and it is found to work properly. Your valuable suggestions and corrections are always welcomed. Refer to the MSDN Documentation for more details on 'Double Buffering', 'MoveWindow( )' and 'BitBlt()'.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

Shibu K V

Currently working with the Embedded Systems & DSP Lab of Infosys Technologies, Thiruvananthapuram Development unit (www.infosys.com)

Occupation:	Architect
Company:	Infosys Technologies
Location:	India

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Msgs 1 to 25 of 68 (Total in Forum: 68) (Refresh)

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good work

luyi97989798

23:01 1 Sep '08

it's a good work
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Display Large Images In the same object using the same scroll bitmap object

paramesh

6:59 26 Aug '08

Hi, I want to know how we can use stretchblt function in the same scroll bitmap code. to resize the image.. Kindly reply as soon as possible. Regards Param
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another question

rorirami

20:18 19 Aug '08

hi
I did that and it worked but now I have another problem.I have a global variable of that bitmap class in my main dialog class and I have a button in my main dialog whitch has dialog2.domodal();but when I run the program and press the button and close dialog2 and press the button for second time it cause an error which I think is for initializing the class for just one time.how can I init it every time I use the button on main dialog,it doesent let me to call its oninitdialog().
thank you so much for your previous answer.

Re: another question

Shibu K V

7:23 20 Aug '08

Please let me know the details of the error mentioned and also about which is the global variable and how you are passing the global variable between the two dialogs. Rgds Shibu K V Embedded systems & DSP Lab Infosys Technologies Thiruvananthapuram
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please help me!!!!

rorirami

20:29 18 Aug '08

Hi I used this code to have a bitmap in my project.I'm new in VC6 and I need to use this bitmap in another class(an other Dialog) not in my main dialog and I don't know how to write the codes which are in the functions like onPaint() or onInitDialog().please help me and tell me where I should write them in my project.
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Re: please help me!!!!

Shibu K V

20:49 18 Aug '08

Hi,
I hope you know how to add a new dialog box to an existing project. Once the dialog box is added, take the class wizard and select the name of the dialog class from the 'Class name' selection combo box. Ensure that you are in the 'Message Maps' tab of the 'Class Wizard' dialog box. From the 'Member functions:'list box select 'OnInitDialog' & 'OnPaint'functions and press the 'Add Function' button. This will create the required function body in the .cpp file for your dialog class. Hope this will solve your problem.

Cheers

Rgds

Shibu K V
Embedded systems & DSP Lab
Infosys Technologies
Thiruvananthapuram

the Demo project is broken

crazystone2020

23:15 2 Jul '08

I downloaded the demo project, but can not unzip it ,it is broken
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to work for How to use this scrolling in my prog

lama madany

10:09 12 Sep '07

plase do instruct me to use this scrolling in my prog. I would like this scrolling to work for a pic box in a form with in my project where and what should I add? thank you Lama Madany
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How to gather the details of an Image from Clipboard???

gloriousgopi

23:30 2 Feb '07

Hello Sir,

After seeing your articles, i thought, why cant i ask you about my requirement.
Acctually i have to gather an image from the clipboard and i have to get all its details, like its length,breath,no.of pixes,and other details.
and i have to convert all the details into an array.

i could able to gather the image from clipboard. and then i got struck while gathering its details. and my code goes like this:

if( OpenClipboard(hwnd) )
{
HBITMAP handle = (HBITMAP) GetClipboardData(CF_BITMAP);
CBitmap *bm = CBitmap::FromHandle(handle);

// i have to access the details from the pointer bm

CloseClipboard();
}

Very much in need of help,
Thanking you in advance

Gopinath MV

Unable To load Large BMP Images

20:01 21 Jan '07

I tried to load a bmp image of size 11264 x 11264 pixels using your exe. It fails . Can you tell me any easy method to load and scroll very large images. savitha
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Re: Unable To load Large BMP Images

Shibu K V

20:21 21 Jan '07

Pls let me know the error you are getting while loading the image. I guess it happens due to the in sufficient memory. From the resolution of the image itself it is obvious that the image size will be too high. Also let me know the size of the image you are trying to load. Rgds Shibu Shibu K V Embedded systems & DSP Lab Infosys Technologies Thiruvananthapuram
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Unable To load Large BMP Images

20:00 21 Jan '07

I tried to load a bmp image of size 11264 x 11264 pixels using your exe. It fails . Can you tell me any easy method to load and scroll very large images. With Thanks, savitha
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Unable To load Large BMP Images

19:59 21 Jan '07

I tried to load a bmp image of size 11264 x 11264 pixels using your exe. It fails . Can you tell me any easy method to load and scroll very large images. With Thanks, savitha
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how to reset pixel of picture control ?

hansen.Xue

18:38 8 Oct '06

hi Sir! how to reset pixel of picture control ? for example , I want to set the pixel of picture control do like this: width =3600, and high=3000. how to rest ? can you tell me? Hansen
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Undeclared identifier

Igen1

5:32 17 Aug '06

error C2065: 'm_size' : undeclared identifier
error C2228: left of '.cx' must have class/struct/union
error C2228: left of '.cy' must have class/struct/union
error C2065: 'm_pt' : undeclared identifier
error C2228: left of '.x' must have class/struct/union
error C2228: left of '.y' must have class/struct/union

I'm getting these errors in OnPaint; I think U have to explain better on the displaying technic!!!

Re: Undeclared identifier

Shibu K V

21:53 17 Aug '06

Pls download the source code and sample code. It contains the entire variable declaration.
m_size is declared as a CSize variable and m_pt as CPoint in your dialogs header file.

In your dialog's header file (say MyDlg.h), add the following code:

public:
CRect rectStaticClient;
int sourcex, sourcey,offsetx,offsety;
protected:
CDC m_dcMem; // Compatible Memory DC for dialog
HBITMAP m_hBmpOld; // Handle of old bitmap to save
HBITMAP m_hBmpNew; // Handle of new bitmap from file
BITMAP m_bmInfo; // Bitmap Information structure
CPoint m_pt; // Position for upper left corner of bitmap
CSize m_size;

Shibu K V
Embedded systems & DSP Lab
Infosys Technologies
Thiruvananthapuram

5.00/5 (2 votes)

No SB_LINEDOWN handling?????

sheebz

19:03 1 Dec '05

Why are you only handling 3 events? The windows CSCrollBar class has 11. I'm especially suprised you didn't handle SB_LINEDOWN. Do you not expect the user to hit a down arrow? This article is very overrated IMO. From a Sun Microsystems bug report (#4102680): "Workaround: don't pound on the mouse like a wild monkey."
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Re: No SB_LINEDOWN handling?????

andrew_joseph

23:25 15 Dec '05

Displaying all is out of the scope of this work. Why don't you try handling the rest. You can never blame the author. The Author has presented a good idea in a neat manner. If it is not meeting your need it's your responsibility to tailor it for your needs. The author is not written the article for you alone. It's for the entire developers. Author's can never satisfy all kinds of readers. Under rating an article just because of the reason that it does not satisfy your needs is not fair.
Whatever missing you add it as a value addition to the code so that whole developers can make use of it. Your question is already answered by Okeno Palmar in the FAQ with title "Well Done + Code" http://codeproject.com/bitmap/bmpscroll.asp#xx732666xx

Can one use the CStatic frame's own scrollbars?

Jamaica

13:39 21 Nov '05

Every CWnd has scrolling functionality built-in. But I can't figure out if it is possible to use it. While calling m_myStaticFrame.SetScrollInfo( SB_VERT, ... ) and m_myStaticFrame.EnableScrollBarCtrl( SB_VERT ) is enough to show the vertical scrollbar, it simply doesn't behave as if it is enabled. Creating the static frame with SS_NOTIFY style has no obvious effect. The article at http://www.codeproject.com/staticctrl/staticctrl_tut.asp suggests only limited messages are supported in a CStatic.

I've seen this question asked in other places over the past 2-3 years... but with no answers. Can anyone confirm it one way or other?

1.50/5 (2 votes)

Good one

G Haranadh

21:10 6 Nov '05

This is very nice one. It helped me in a good way. Thanks for giving this as article. Thank you so much Nice talking to you.
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help , please ?

dynamica123

23:52 30 Sep '05

can i put AfxGetInstanceHandle()equal to NULL in LoadImage function and the program works ? how can i transform the bitap to grayscale and make transformations on it ?
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mouse click coordinates?

ori kovacsi

3:53 11 Sep '05

how can I get the coordinates of a mouse cursor click reletive to the upper left corner of the image? I wish to store a text file of coordinates and radiuses of bounding boxes and bounding circles of objects in the image. One more fan of Simplicity.
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Remark on "Flicking free drawing"

octopus_777

20:49 21 Aug '05

Thank you for the great article! Let me make tiny remark. Actually, to prevent background erasing after InvalidateRect(..) we just need to pass FALSE as second parameter: `InvalidateRect(&rectStaticClient,FALSE);` Thus additional variable `erase` is not necessary and code becomes neater.
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