/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
**
** Use, modification and distribution is allowed without limitation,
** warranty, liability or support of any kind.
**
****************************************************************************/

#include "qtwin.h"
#include <QLibrary>
#include <QApplication>
#include <QWidget>
#include <QList>
#include <QPointer>

#ifdef Q_WS_WIN

#include <qt_windows.h>

// Blur behind data structures
#define DWM_BB_ENABLE                 0x00000001  // fEnable has been specified
#define DWM_BB_BLURREGION             0x00000002  // hRgnBlur has been specified
#define DWM_BB_TRANSITIONONMAXIMIZED  0x00000004  // fTransitionOnMaximized has been specified
#define WM_DWMCOMPOSITIONCHANGED        0x031E    // Composition changed window message

typedef struct _DWM_BLURBEHIND
{
    DWORD dwFlags;
    BOOL fEnable;
    HRGN hRgnBlur;
    BOOL fTransitionOnMaximized;
} DWM_BLURBEHIND, *PDWM_BLURBEHIND;

typedef struct _MARGINS
{
    int cxLeftWidth;
    int cxRightWidth;
    int cyTopHeight;
    int cyBottomHeight;
} MARGINS, *PMARGINS;

typedef HRESULT (WINAPI *PtrDwmIsCompositionEnabled)(BOOL* pfEnabled);
typedef HRESULT (WINAPI *PtrDwmExtendFrameIntoClientArea)(HWND hWnd, const MARGINS* pMarInset);
typedef HRESULT (WINAPI *PtrDwmEnableBlurBehindWindow)(HWND hWnd, const DWM_BLURBEHIND* pBlurBehind);
typedef HRESULT (WINAPI *PtrDwmGetColorizationColor)(DWORD *pcrColorization, BOOL *pfOpaqueBlend);

static PtrDwmIsCompositionEnabled pDwmIsCompositionEnabled= 0;
static PtrDwmEnableBlurBehindWindow pDwmEnableBlurBehindWindow = 0;
static PtrDwmExtendFrameIntoClientArea pDwmExtendFrameIntoClientArea = 0;
static PtrDwmGetColorizationColor pDwmGetColorizationColor = 0;


/*
 * Internal helper class that notifies windows if the
 * DWM compositing state changes and updates the widget
 * flags correspondingly.
 */
class WindowNotifier : public QWidget
{
public:
    WindowNotifier() { winId(); }
    void addWidget(QWidget *widget) { widgets.append(widget); }
    void removeWidget(QWidget *widget) { widgets.removeAll(widget); }
    bool winEvent(MSG *message, long *result);

private:
    QWidgetList widgets;
};

static bool resolveLibs()
{
    if (!pDwmIsCompositionEnabled) {
        QLibrary dwmLib(QString::toLatin1("dwmapi"));
        pDwmIsCompositionEnabled =(PtrDwmIsCompositionEnabled)dwmLib.resolve("DwmIsCompositionEnabled");
        pDwmExtendFrameIntoClientArea = (PtrDwmExtendFrameIntoClientArea)dwmLib.resolve("DwmExtendFrameIntoClientArea");
        pDwmEnableBlurBehindWindow = (PtrDwmEnableBlurBehindWindow)dwmLib.resolve("DwmEnableBlurBehindWindow");
        pDwmGetColorizationColor = (PtrDwmGetColorizationColor)dwmLib.resolve("DwmGetColorizationColor");
    }
    return pDwmIsCompositionEnabled != 0;
}

#endif

/*!
  * Chekcs and returns true if Windows DWM composition
  * is currently enabled on the system.
  *
  * To get live notification on the availability of
  * this feature, you will currently have to
  * reimplement winEvent() on your widget and listen
  * for the WM_DWMCOMPOSITIONCHANGED event to occur.
  *
  */
bool QtWin::isCompositionEnabled()
{
#ifdef Q_WS_WIN
    if (resolveLibs()) {
        HRESULT hr = S_OK;
        BOOL isEnabled = false;
        hr = pDwmIsCompositionEnabled(&isEnabled);
        if (SUCCEEDED(hr))
            return isEnabled;
    }
#endif
    return false;
}

/*!
  * Enables Blur behind on a Widget.
  *
  * \a enable tells if the blur should be enabled or not
  */
bool QtWin::enableBlurBehindWindow(QWidget *widget, bool enable,
                                   const QRegion &region)
{
    Q_ASSERT(widget);
    bool result = false;
#ifdef Q_WS_WIN
    if (resolveLibs()) {
        DWM_BLURBEHIND bb = {0};
        HRESULT hr = S_OK;
        bb.fEnable = enable;
        bb.dwFlags = DWM_BB_ENABLE;
        bb.hRgnBlur = NULL;

        if (!region.isEmpty()) {
            bb.dwFlags |= DWM_BB_BLURREGION;
            bb.hRgnBlur = region.handle();
        }

        widget->setAttribute(Qt::WA_TranslucentBackground, enable);
        widget->setAttribute(Qt::WA_NoSystemBackground, enable);
        hr = pDwmEnableBlurBehindWindow(widget->winId(), &bb);
        if (SUCCEEDED(hr)) {
            result = true;
            windowNotifier()->addWidget(widget);
        }
    }
#endif
    return result;
}

/*!
  * ExtendFrameIntoClientArea.
  *
  * This controls the rendering of the frame inside the window.
  * Note that passing margins of -1 (the default value) will completely
  * remove the frame from the window.
  *
  * \note you should not call enableBlurBehindWindow before calling
  *       this functions
  *
  * \a enable tells if the blur should be enabled or not
  */
bool QtWin::extendFrameIntoClientArea(QWidget *widget, int left, int top, int right, int bottom)
{

    Q_ASSERT(widget);
    Q_UNUSED(left);
    Q_UNUSED(top);
    Q_UNUSED(right);
    Q_UNUSED(bottom);

    bool result = false;
#ifdef Q_WS_WIN
    if (resolveLibs()) {
        QLibrary dwmLib(QString::toLatin1("dwmapi"));
        HRESULT hr = S_OK;
        MARGINS m = {left, top, right, bottom};
        hr = pDwmExtendFrameIntoClientArea(widget->winId(), &m);
        if (SUCCEEDED(hr)) {
            result = true;
            windowNotifier()->addWidget(widget);
        }
        widget->setAttribute(Qt::WA_TranslucentBackground, result);
    }
#endif
    return result;
}

/*!
  * Returns the current colorizationColor for the window.
  *
  * \a enable tells if the blur should be enabled or not
  */
QColor QtWin::colorizatinColor()
{
    QColor resultColor = QApplication::palette().window().color();

#ifdef Q_WS_WIN
    if (resolveLibs()) {
        DWORD color = 0;
        BOOL opaque = FALSE;
        QLibrary dwmLib(QString::toLatin1("dwmapi"));
        HRESULT hr = S_OK;
        hr = pDwmGetColorizationColor(&color, &opaque);
        if (SUCCEEDED(hr))
            resultColor = QColor(color);
    }
#endif
    return resultColor;
}

#ifdef Q_WS_WIN
WindowNotifier *QtWin::windowNotifier()
{
    static WindowNotifier *windowNotifierInstance = 0;
    if (!windowNotifierInstance)
        windowNotifierInstance = new WindowNotifier;
    return windowNotifierInstance;
}


/* Notify all enabled windows that the DWM state changed */
bool WindowNotifier::winEvent(MSG *message, long *result)
{
    if (message && message->message == WM_DWMCOMPOSITIONCHANGED) {
        bool compositionEnabled = QtWin::isCompositionEnabled();
        foreach(QWidget * widget, widgets) {
            if (widget) {
                widget->setAttribute(Qt::WA_NoSystemBackground, compositionEnabled);
            }
            widget->update();
        }
    }
    return QWidget::winEvent(message, result);
}
#endif