Add basic support for username auto-completion

fixes #40

src/SuggestionsPopup.cpp

@@ -0,0 +1,105 @@
+#include "Avatar.h"
+#include "AvatarProvider.h"
+#include "Config.h"
+#include "DropShadow.h"
+#include "SuggestionsPopup.hpp"
+#include "Utils.h"
+#include "timeline/TimelineViewManager.h"
+
+#include <QDebug>
+#include <QPaintEvent>
+#include <QPainter>
+#include <QStyleOption>
+
+constexpr int PopupHMargin    = 5;
+constexpr int PopupItemMargin = 4;
+
+PopupItem::PopupItem(QWidget *parent, const QString &user_id)
+  : QWidget(parent)
+  , avatar_{new Avatar(this)}
+  , user_id_{user_id}
+{
+        setMouseTracking(true);
+        setAttribute(Qt::WA_Hover);
+
+        topLayout_ = new QHBoxLayout(this);
+        topLayout_->setContentsMargins(
+          PopupHMargin, PopupItemMargin, PopupHMargin, PopupItemMargin);
+
+        QFont font;
+        font.setPixelSize(conf::popup::font);
+
+        auto displayName = TimelineViewManager::displayName(user_id);
+
+        avatar_->setSize(conf::popup::avatar);
+        avatar_->setLetter(utils::firstChar(displayName));
+
+        // If it's a matrix id we use the second letter.
+        if (displayName.size() > 1 && displayName.at(0) == '@')
+                avatar_->setLetter(QChar(displayName.at(1)));
+
+        userName_ = new QLabel(displayName, this);
+        userName_->setFont(font);
+
+        topLayout_->addWidget(avatar_);
+        topLayout_->addWidget(userName_, 1);
+
+        /* AvatarProvider::resolve(user_id, [this](const QImage &img) { avatar_->setImage(img); });
+         */
+}
+
+void
+PopupItem::paintEvent(QPaintEvent *)
+{
+        QStyleOption opt;
+        opt.init(this);
+        QPainter p(this);
+        style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);
+
+        if (underMouse())
+                p.fillRect(rect(), hoverColor_);
+}
+
+void
+PopupItem::mousePressEvent(QMouseEvent *event)
+{
+        if (event->buttons() != Qt::RightButton)
+                emit clicked(TimelineViewManager::displayName(user_id_));
+
+        QWidget::mousePressEvent(event);
+}
+
+SuggestionsPopup::SuggestionsPopup(QWidget *parent)
+  : QWidget(parent)
+{
+        setAttribute(Qt::WA_ShowWithoutActivating, true);
+        setWindowFlags(Qt::ToolTip | Qt::NoDropShadowWindowHint);
+
+        layout_ = new QVBoxLayout(this);
+        layout_->setMargin(0);
+        layout_->setSpacing(0);
+}
+
+void
+SuggestionsPopup::addUsers(const QVector<SearchResult> &users)
+{
+        // Remove all items from the layout.
+        QLayoutItem *item;
+        while ((item = layout_->takeAt(0)) != 0) {
+                delete item->widget();
+                delete item;
+        }
+
+        if (users.isEmpty()) {
+                hide();
+                return;
+        }
+
+        for (const auto &u : users) {
+                auto user = new PopupItem(this, u.user_id);
+                layout_->addWidget(user);
+                connect(user, &PopupItem::clicked, this, &SuggestionsPopup::itemSelected);
+        }
+
+        resize(geometry().width(), 40 * users.size());
+}