add preview widget

Change-Id: Ifd6b9b63cae9c3773a1ea7b1146d27bd60154bd9

frame/item/appitem.cpp

@@ -518,7 +518,5 @@ void AppItem::showPreview()
     m_appPreviewTips->setWindowInfos(m_titles);
     m_appPreviewTips->updateLayoutDirection(DockPosition);
 
-    qApp->processEvents();
-
     showPopupWindow(m_appPreviewTips, true);
 }

frame/item/components/_previewcontainer.cpp

@@ -2,6 +2,7 @@
 
 #define FIXED_WIDTH       200
 #define FIXED_HEIGHT      130
+#define SPACING           5
 
 _PreviewContainer::_PreviewContainer(QWidget *parent)
     : QWidget(parent),
@@ -9,7 +10,7 @@ _PreviewContainer::_PreviewContainer(QWidget *parent)
       m_wmHelper(DWindowManagerHelper::instance())
 {
     m_windowListLayout = new QVBoxLayout;
-    m_windowListLayout->setSpacing(0);
+    m_windowListLayout->setSpacing(SPACING);
     m_windowListLayout->setMargin(0);
 
     setLayout(m_windowListLayout);
@@ -53,19 +54,22 @@ void _PreviewContainer::adjustSize()
     const bool horizontal = m_windowListLayout->direction() == QBoxLayout::LeftToRight;
     const int count = m_snapshots.size();
 
+    if (!count)
+        return;
+
     if (horizontal)
     {
         setFixedHeight(FIXED_HEIGHT);
-        setFixedWidth(FIXED_WIDTH * count);
+        setFixedWidth(FIXED_WIDTH * count + SPACING * (count - 1));
     } else {
         setFixedWidth(FIXED_WIDTH);
-        setFixedHeight(FIXED_HEIGHT * count);
+        setFixedHeight(FIXED_HEIGHT * count + SPACING * (count - 1));
     }
 }
 
 void _PreviewContainer::appendSnapWidget(const WId wid)
 {
-    AppSnapshot *snap = new AppSnapshot;
+    AppSnapshot *snap = new AppSnapshot(wid);
 
     m_windowListLayout->addWidget(snap);
 

frame/item/components/appsnapshot.cpp

@@ -1,7 +1,96 @@
 #include "appsnapshot.h"
 
-AppSnapshot::AppSnapshot(QWidget *parent)
-    : QWidget(parent)
-{
+#include <X11/Xlib.h>
+#include <X11/X.h>
+#include <X11/Xutil.h>
+#include <X11/Xatom.h>
 
+#include <QX11Info>
+#include <QPainter>
+
+AppSnapshot::AppSnapshot(const WId wid, QWidget *parent)
+    : QWidget(parent),
+
+      m_wid(wid),
+
+      m_fetchSnapshotTimer(new QTimer(this))
+{
+    m_fetchSnapshotTimer->setSingleShot(true);
+    m_fetchSnapshotTimer->setInterval(10);
+
+    connect(m_fetchSnapshotTimer, &QTimer::timeout, this, &AppSnapshot::fetchSnapshot, Qt::QueuedConnection);
+}
+
+void AppSnapshot::fetchSnapshot()
+{
+    if (!isVisible())
+        return;
+
+    const auto display = QX11Info::display();
+
+    XWindowAttributes attrs;
+    XGetWindowAttributes(display, m_wid, &attrs);
+    XImage *ximage = XGetImage(display, m_wid, 0, 0, attrs.width, attrs.height, AllPlanes, ZPixmap);
+    const QImage qimage((const uchar*)(ximage->data), ximage->width, ximage->height, ximage->bytes_per_line, QImage::Format_RGB32);
+    Q_ASSERT(!qimage.isNull());
+
+    const Atom gtk_frame_extents = XInternAtom(display, "_GTK_FRAME_EXTENTS", true);
+    Atom actual_type_return;
+    int actual_format_return;
+    unsigned long n_items_return;
+    unsigned long bytes_after_return;
+    unsigned char *prop_to_return;
+
+    const auto r = XGetWindowProperty(display, m_wid, gtk_frame_extents, 0, 4, false, XA_CARDINAL,
+                                      &actual_type_return, &actual_format_return, &n_items_return, &bytes_after_return, &prop_to_return);
+    if (!r && prop_to_return && n_items_return == 4 && actual_format_return == 32)
+    {
+        const unsigned long *extents = reinterpret_cast<const unsigned long *>(prop_to_return);
+        const int left = extents[0];
+        const int right = extents[1];
+        const int top = extents[2];
+        const int bottom = extents[3];
+        const int width = qimage.width();
+        const int height = qimage.height();
+
+        m_snapshot = qimage.copy(left, top, width - left - right, height - top - bottom);
+    } else {
+        m_snapshot = qimage;
+    }
+
+    const QSize s = size();
+    m_snapshot = m_snapshot.scaled(s.width(), s.height(), Qt::KeepAspectRatioByExpanding, Qt::SmoothTransformation);
+    m_snapshot = m_snapshot.copy((m_snapshot.width() - s.width()) / 2, (m_snapshot.height() - s.height()) / 2, s.width(), s.height());
+    XDestroyImage(ximage);
+    XFree(prop_to_return);
+
+    update();
+}
+
+void AppSnapshot::paintEvent(QPaintEvent *e)
+{
+    QWidget::paintEvent(e);
+
+    QPainter painter(this);
+
+    if (m_snapshot.isNull())
+        return;
+
+    const QRect r = rect();
+
+    // draw image
+//    const QRect ir = m_snapshot.rect();
+//    const QPoint offset = r.center() - ir.center();
+
+//    painter.fillRect(offset.x(), offset.y(), ir.width(), ir.height(), Qt::white);
+//    painter.drawImage(offset.x(), offset.y(), m_snapshot);
+    painter.fillRect(r, Qt::white);
+    painter.drawImage(r, m_snapshot);
+}
+
+void AppSnapshot::resizeEvent(QResizeEvent *e)
+{
+    QWidget::resizeEvent(e);
+
+    m_fetchSnapshotTimer->start();
 }

frame/item/components/appsnapshot.h

@@ -2,13 +2,29 @@
 #define APPSNAPSHOT_H
 
 #include <QWidget>
+#include <QDebug>
+#include <QTimer>
 
 class AppSnapshot : public QWidget
 {
     Q_OBJECT
 
 public:
-    explicit AppSnapshot(QWidget *parent = 0);
+    explicit AppSnapshot(const WId wid, QWidget *parent = 0);
+
+private slots:
+    void fetchSnapshot();
+
+private:
+    void paintEvent(QPaintEvent *e);
+    void resizeEvent(QResizeEvent *e);
+
+private:
+    const WId m_wid;
+
+    QImage m_snapshot;
+
+    QTimer *m_fetchSnapshotTimer;
 };
 
 #endif // APPSNAPSHOT_H