Painting bad issues (GDI)

[Rafael Fernandez Lopez]

Hi, If you can download the project, and help me in some way... is only a class and its goal es mainly: * To have an image at the back (alphablended with AlphaBlend function), and if the window receive ScrollWindow() messages, to don't move. It work all right, but if I've some controls on it, they will be drawn on the alphablended image, so if you move the window, later it will be visible. Just open the zip, compile it (I've Visual Studio .NET 2003), and press "ACCEPT" to load the alphablended image, and you must press "CANCEL" several times to make the window scroll. I'm new to GDI, and maybe there are lots of things very bad. I will appreciate a lot your comments, to learn more. Here you can download the file !! THANK YOU VERY MUCH !!!

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Written by: Rafael Fernández López.

Visit: http://www.maestroprogramador.com

[Rafael Fernandez Lopez]

Well if you're curious, here you are: ImagenTransparente.cpp // ImagenTransparente.cpp: archivo de implementación // #include "stdafx.h" #include "Transparencia.h" #include "ImagenTransparente.h" #include ".\imagentransparente.h" // ImagenTransparente IMPLEMENT_DYNAMIC(ImagenTransparente, CStatic) ImagenTransparente::ImagenTransparente(int nID, BYTE transparencia /* = 0x7f (50%) */) { bm.LoadBitmap(nID); bm.GetBitmap(&BitMap); m_nWidth = BitMap.bmWidth; m_nHeight = BitMap.bmHeight; bf.AlphaFormat = 0; bf.BlendFlags = 0; bf.BlendOp = AC_SRC_OVER; bf.SourceConstantAlpha = transparencia; this->nID = nID; } ImagenTransparente::~ImagenTransparente() { } BEGIN_MESSAGE_MAP(ImagenTransparente, CStatic) ON_WM_CREATE() ON_WM_PAINT() ON_WM_ERASEBKGND() ON_WM_MOVE() END_MESSAGE_MAP() // Controladores de mensajes de ImagenTransparente int ImagenTransparente::OnCreate(LPCREATESTRUCT lpCreateStruct) { if (CStatic::OnCreate(lpCreateStruct) == -1) return -1; CRect rect; GetWindowRect(&rect); GetParent()->ScreenToClient(&rect); miPosicion.left = rect.left; miPosicion.right = rect.right; miPosicion.top = rect.top; miPosicion.bottom = rect.bottom; this->izquierda = rect.left; this->arriba = rect.top; CClientDC dc(this); CDC MemDC; MemDC.CreateCompatibleDC(&dc); CBitmap MemBmp; MemBmp.CreateCompatibleBitmap(&dc, m_nWidth, m_nHeight); CBitmap *pOldMemBmp = MemDC.SelectObject(&MemBmp); CDC MemDC2; MemDC2.CreateCompatibleDC(&dc); CBitmap *pOldbmp = MemDC2.SelectObject(&bm); MemDC.BitBlt(0, 0, m_nWidth, m_nHeight, &MemDC2, 0, 0, SRCCOPY); MemDC2.SelectObject(pOldbmp); dc.AlphaBlend(0, 0, m_nWidth, m_nHeight, &MemDC, 0, 0, m_nWidth, m_nHeight, bf); MemDC.SelectObject(pOldMemBmp); return 0; } void ImagenTransparente::OnPaint() { CPaintDC dc(this); // device context for painting CDC MemDC; MemDC.CreateCompatibleDC(&dc); CBitmap MemBmp; MemBmp.CreateCompatibleBitmap(&dc, m_nWidth, m_nHeight); CBitmap *pOldMemBmp = MemDC.SelectObject(&MemBmp); CDC MemDC2; MemDC2.CreateCompatibleDC(&dc); CBitmap *pOldbmp = MemDC2.SelectObject(&bm); MemDC.BitBlt(0, 0, m_nWidth, m_nHeight, &MemDC2, 0, 0, SRCCOPY); MemDC2.SelectObject(pOldbmp); //dc.BitBlt(0, 0, m_nWidth, m_nHeight, &MemDC, 0, 0, SRCCOPY); dc.AlphaBlend(0, 0, m_nWidth, m_nHeight, &MemDC, 0, 0, m_nWidth, m_nHeight, bf); MemDC.SelectObject(pOldMemBmp); } BOOL ImagenTransparente::OnEraseBkgnd(CDC* p