animator.cpp

window下的多线程编程参考书。值得一读

//
// FILE: Animator.cpp
//
// Copyright (c) 1997 by Aaron Michael Cohen and Mike Woodring
//
/////////////////////////////////////////////////////////////////////////

#include "Animator.h"

// CAnimator class message map...
BEGIN_MESSAGE_MAP( CAnimator, CStatic)
    ON_WM_PAINT()
    ON_WM_DESTROY()
END_MESSAGE_MAP()

// CAnimator class constructor/destructor...
CAnimator::CAnimator() : 
    m_czFrame(0,0), 
    m_czBitmap(0,0), 
    m_nFrames(0), 
    m_bBackAndForth(FALSE),
    m_bTransparent(FALSE),
    m_nCurrentFrameIndex(0),
    m_dwFrameInterval(0),
    m_nFrameIncrement(1) {
    return;
}

afx_msg void CAnimator::OnPaint() {
    // just paint the current frame...
    CPaintDC dc(this);
    DrawCurrentFrame(&dc);
}

afx_msg void CAnimator::OnDestroy() {
    // make sure that the worker thread has exited
    // before our window is destroyed...
    Stop();

    // make sure that there is no bitmap
    // attached to the CBitmap object...
    // the animator just uses a passed in HBITMAP, 
    // it does not manage the resource's lifetime...
    m_cBitmap.Detach();

    // call the parent function...
    CStatic::OnDestroy();
}

void CAnimator::SetupAnimation( HBITMAP hBitmap, CSize czFrame, int nFrames, int nFramesPerSecond, BOOL bBackAndForth, BOOL bTransparent) {
    // make sure we have exclusive access to the object
    // while we modify its properties...
    CMclAutoLock autoLock(m_CritSec);

    // make sure that there is no bitmap
    // attached to the CBitmap object...
    m_cBitmap.Detach();

    // attach the passed in bitmap handle...
    m_cBitmap.Attach(hBitmap);

    // save the initial animation properties...
    m_czFrame = czFrame;
    m_nFrames = nFrames;
    m_dwFrameInterval = 1000 / nFramesPerSecond;
    m_bBackAndForth = bBackAndForth;

    // compute the overall size of the animation bitmap...
    BITMAP bm;
    m_cBitmap.GetObject(sizeof(BITMAP), &bm);
    m_czBitmap = CSize( bm.bmWidth, bm.bmHeight);

    // initialize mask for transparent animation if necessary,,,
    m_bTransparent = bTransparent;
    if (m_bTransparent)
        SetupBitmapsForTransparency();
    else
        CleanupBitmapsForTransparency();
}

void CAnimator::SetFrameRate( int nFramesPerSecond) {
    // make sure we have exclusive access to the object
    // while we modify its properties...
    CMclAutoLock autoLock(m_CritSec);

    // compute the frame interval in milliseconds...
    m_dwFrameInterval = 1000 / nFramesPerSecond;
}

void CAnimator::SetTransparency( BOOL bTransparent) {
    // make sure we have exclusive access to the object
    // while we modify its properties...
    CMclAutoLock autoLock(m_CritSec);

    if (bTransparent != m_bTransparent) {
        // change the transparency...
        if (bTransparent) {
            SetupBitmapsForTransparency();
        }
        else {
            CleanupBitmapsForTransparency();
        }

        // change the current mode...
        m_bTransparent = bTransparent;

        // redraw the control with the new transparency...
        RedrawWindow();
    }
}

void CAnimator::SetLoopStyle( BOOL bBackAndForth) {
    // make sure we have exclusive access to the object
    // while we modify its properties...
    CMclAutoLock autoLock(m_CritSec);

    // change the repeat pattern type...
    m_bBackAndForth = bBackAndForth;
}

void CAnimator::Start(void) {
    // create an animation thread if there is none...
    if (m_apAnimationThread.IsNull()) {
        m_apAnimationThread = new CMcl4MfcWorkerThread(this);
    }
}

void CAnimator::Stop(void) {
    // if there is an animation thread,
    // use the event to signal it to stop
    // and wait for the thread to exit before
    // resetting our auto-pointer to NULL...
    if (!m_apAnimationThread.IsNull()) {
        m_ceControl.Set();
        m_apAnimationThread->Wait(INFINITE);
        m_apAnimationThread = NULL;
    }
}

void CAnimator::SetFrame( int nFrameNumber) {
    // make sure we have exclusive access to the object
    // while we modify its properties...
    CMclAutoLock autoLock(m_CritSec);

    // set the new current frame...
    if ((nFrameNumber >= 0) && (nFrameNumber < m_nFrames))
        m_nCurrentFrameIndex = nFrameNumber;

    // redraw the control at the new frame...
    RedrawWindow();
}

void CAnimator::AdvanceFrame(void) {
    // make sure we have exclusive access to the object
    // while we modify its properties...
    CMclAutoLock autoLock(m_CritSec);

    if (m_bBackAndForth) {
        // oscillate back and forth, increment from frame zero to 
        // m_nFrames - 1, and then decrement back to frame zero
        // and store the current direction in m_nFrameIncrement...
        m_nCurrentFrameIndex = (m_nCurrentFrameIndex + m_nFrameIncrement);
        if (m_nCurrentFrameIndex >= m_nFrames) {
            m_nCurrentFrameIndex = m_nFrames - 1;
            m_nFrameIncrement = -1;
        }
        else if (m_nCurrentFrameIndex < 0) {
            m_nCurrentFrameIndex = 1;
            m_nFrameIncrement = 1;
        }     
    }
    else {
        // just cycle around the frames, when we go past the last
        // frame, start over at frame zero...
        m_nCurrentFrameIndex = (m_nCurrentFrameIndex + 1) % m_nFrames;
    }
}

void CAnimator::DrawCurrentFrame(CDC *pDC) {
    // all of the CDC calls such as SelectObject, BitBlt, and StretchBlt,
    // used in this function are simple wrappers around Win32 API
    // function and are safe to call from threads other than
    // the one which created the objects...

    // make sure we have exclusive access to the object
    // while we use its properties, we don't want some
    // other thread calling SetupAnimation() while we are
    // in the middle of drawing the current frame...
    CMclAutoLock autoLock(m_CritSec);

    // use the HBITMAP operator to determine if there is
    // an attached bitmap,
    // if there is no bitmap, we don't draw anything...
    if ((HBITMAP)(m_cBitmap) == NULL)
        return;

    // compute the offset into the bitmap, by counting m_nCurrentFrameIndex images
    // into the bitmap by rows and then columns...
    int bmx = m_czFrame.cx * (m_nCurrentFrameIndex % (m_czBitmap.cx / m_czFrame.cx));
    int bmy = m_czFrame.cy * ((m_nCurrentFrameIndex * m_czFrame.cx) / m_czBitmap.cx);

    // create a memory DC and select the animation bitmap...
    CDC bdc;
    bdc.CreateCompatibleDC(pDC);
    CBitmap *pcOldBitmap = bdc.SelectObject(&m_cBitmap);

    // get current client dimensions for our window...
    CRect cr;
    GetClientRect(cr);

    // use stretchblt to fill the control client area no matter
    // what the size of the animation frames...
    if (m_bTransparent) {
        // create an offscreen DC and select the offscreen bitmap into it...
        CDC odc;
        odc.CreateCompatibleDC(pDC);
        CBitmap *pcOldOffscreenBitmap = odc.SelectObject(&m_cOffscreenBitmap);

        // fill the offscreen bitmap with the background color...
        CBrush cbrush(::GetSysColor(COLOR_3DFACE));
        odc.FillRect( CRect( 0, 0,m_czFrame.cx, m_czFrame.cy), &cbrush);  

        // create a memory DC and select in the mask bitmap...
        CDC mdc;
        mdc.CreateCompatibleDC(pDC);
        CBitmap *pcOldMaskBitmap = mdc.SelectObject(&m_cMaskBitmap);

        COLORREF crOldBkColor = odc.SetBkColor(RGB(255,255,255));
        COLORREF crOldTextColor = odc.SetTextColor(RGB(0,0,0));
        odc.BitBlt( 0, 0, m_czFrame.cx, m_czFrame.cy, &mdc, bmx, bmy, SRCAND);
        odc.BitBlt( 0, 0, m_czFrame.cx, m_czFrame.cy, &bdc, bmx, bmy, SRCPAINT);
        odc.SetBkColor(crOldBkColor);
        odc.SetTextColor(crOldTextColor);

        // finally, blt the offscreen image into our client area...
        pDC->StretchBlt( 0, 0, cr.Width(), cr.Height(), &odc, 0, 0, m_czFrame.cx, m_czFrame.cy, SRCCOPY);

        // clean up...
        mdc.SelectObject(pcOldMaskBitmap);
        odc.SelectObject(pcOldOffscreenBitmap);
    }
    else {
        pDC->StretchBlt( 0, 0, cr.Width(), cr.Height(), &bdc, bmx, bmy, m_czFrame.cx, m_czFrame.cy, SRCCOPY);
    }

    // restore the orginal bitmap to the bitmap memory DC...
    bdc.SelectObject(pcOldBitmap);
}

void CAnimator::SetupBitmapsForTransparency(void) {
    // clean up any bitmaps used previously...
    CleanupBitmapsForTransparency();

    // create a bitmap object for the mask...
    // this type of mask only works if the non-image part of the 
    // bitmap (the "off" pixels) are black and the
    // image does not use black (very dark grey is okay)..
    m_cMaskBitmap.CreateBitmap( m_czBitmap.cx, m_czBitmap.cy, 1, 1, NULL);

    // select the bitmap into a DC...
    CDC bdc;
    bdc.CreateCompatibleDC(NULL);
    CBitmap *pOldBitmap = bdc.SelectObject(&m_cBitmap);

    // set up a DC for the mask...
    CDC mdc;
    mdc.CreateCompatibleDC(NULL);
    CBitmap *pOldMaskBitmap = mdc.SelectObject(&m_cMaskBitmap);

    // create the mask, "on" pixels are black, "off" pixels are white...
    bdc.SetBkColor(RGB(0,0,0));
    mdc.BitBlt( 0, 0, m_czBitmap.cx, m_czBitmap.cy, &bdc, 0, 0, SRCCOPY);

    // create an offscreen bitmap for use later on...
    m_cOffscreenBitmap.CreateCompatibleBitmap( &bdc, m_czBitmap.cx, m_czBitmap.cy);

    // clean up...
    bdc.SelectObject(pOldBitmap);
    mdc.SelectObject(pOldMaskBitmap);
}

void CAnimator::CleanupBitmapsForTransparency(void) {
    m_cMaskBitmap.DeleteObject();
    m_cOffscreenBitmap.DeleteObject();
}

unsigned CAnimator::ThreadHandlerProc(void) {
    // create a DC for our window...
    //
    // while the CClientDC is not an inline function
    // it is a simple wrapper around the Win32 
    // ::GetDC() API which simply accesses the m_hWnd
    // of the CAnimator object...
    //
    // notice that this is NOT the thread which created
    // the m_hWnd, but we can get a valid DC for it
    // anyway...
    //
    // we could have done it like this:
    //
    // CWnd *pWnd = CWnd::FromHandle(m_hWnd);
    // CClientDC dc(pWnd);
    //
    // which creates a temporary CWnd object but
    // otherwise winds up being the same thing as
    // what we have done here.
    CClientDC dc(this);

    // as long as the wait returns timeout, advance to the
    // next frame in the animation and draw it...
    while (TRUE) {
        DWORD dwStatus = m_ceControl.Wait(m_dwFrameInterval);
        if (CMclWaitTimeout(dwStatus)) {
            // advance m_nCurrentFrameIndex to the next frame...
            AdvanceFrame();

            // draw the next frame using this worker thread...
            DrawCurrentFrame(&dc);
        }
        else {
            return 0;
        }
    }
}