message preview refactor, several bugs about label size, animations are now playing in previews

shared/global.cpp

@@ -127,12 +127,19 @@ Shared::Global::FileInfo Shared::Global::getFileInfo(const QString& path)
         FileInfo::Preview p = FileInfo::Preview::none;
         QSize size;
         if (big == "image") {
-            if (parts.back() == "gif") {
+            QMovie mov(path);
-                //TODO need to consider GIF as a movie
+            if (mov.isValid()) {
+                p = FileInfo::Preview::animation;
+            } else {
+                p = FileInfo::Preview::picture;
             }
-            p = FileInfo::Preview::picture;
             QImage img(path);
             size = img.size();
+//         } else if (big == "video") {
+//             p = FileInfo::Preview::movie;
+//             QMovie mov(path);
+//             size = mov.scaledSize();
+//             qDebug() << mov.isValid();
         } else {
             size = defaultIconFileInfoHeight;
         }

shared/global.h

@@ -33,6 +33,7 @@
 #include <QMimeDatabase>
 #include <QFileInfo>
 #include <QImage>
+#include <QMovie>
 #include <QSize>
 #include <QUrl>
 #include <QLibrary>
@@ -51,7 +52,7 @@ namespace Shared {
             enum class Preview {
                 none,
                 picture,
-                movie
+                animation
             };
             
             QString name;

ui/models/CMakeLists.txt

@@ -13,8 +13,6 @@ target_sources(squawk PRIVATE
   group.h
   item.cpp
   item.h
-  messagefeed.cpp
-  messagefeed.h
   participant.cpp
   participant.h
   presence.cpp
@@ -25,4 +23,4 @@ target_sources(squawk PRIVATE
   room.h
   roster.cpp
   roster.h
-  )
+  )

ui/models/element.h

@@ -20,7 +20,8 @@
 #define ELEMENT_H
 
 #include "item.h"
-#include "messagefeed.h"
+
+#include "ui/widgets/messageline/messagefeed.h"
 
 namespace Models {
     

ui/utils/CMakeLists.txt

@@ -5,18 +5,10 @@ target_sources(squawk PRIVATE
   comboboxdelegate.h
   exponentialblur.cpp
   exponentialblur.h
-  feedview.cpp
-  feedview.h
   flowlayout.cpp
   flowlayout.h
   image.cpp
   image.h
-  message.cpp
-  message.h
-  messagedelegate.cpp
-  messagedelegate.h
-  messageline.cpp
-  messageline.h
   progress.cpp
   progress.h
   resizer.cpp

ui/widgets/CMakeLists.txt

@@ -21,3 +21,4 @@ target_sources(squawk PRIVATE
   )
 
 add_subdirectory(vcard)
+add_subdirectory(messageline)

ui/widgets/conversation.h

@@ -31,16 +31,19 @@
 
 #include "shared/message.h"
 #include "shared/order.h"
-#include "ui/models/account.h"
-#include "ui/models/roster.h"
-#include "ui/utils/flowlayout.h"
-#include "ui/utils/badge.h"
-#include "ui/utils/feedview.h"
-#include "ui/utils/messagedelegate.h"
-#include "ui/utils/shadowoverlay.h"
 #include "shared/icons.h"
 #include "shared/utils.h"
 
+#include "ui/models/account.h"
+#include "ui/models/roster.h"
+
+#include "ui/utils/flowlayout.h"
+#include "ui/utils/badge.h"
+#include "ui/utils/shadowoverlay.h"
+
+#include "ui/widgets/messageline/feedview.h"
+#include "ui/widgets/messageline/messagedelegate.h"
+
 namespace Ui
 {
 class Conversation;

ui/widgets/messageline/CMakeLists.txt

@@ -0,0 +1,14 @@
+target_sources(squawk PRIVATE
+  messagedelegate.cpp
+  messagedelegate.h
+  #messageline.cpp
+  #messageline.h
+  preview.cpp
+  preview.h
+  messagefeed.cpp
+  messagefeed.h
+  feedview.cpp
+  feedview.h
+  #message.cpp
+  #message.h
+  )

ui/widgets/messageline/feedview.cpp

@@ -24,7 +24,7 @@
 #include <QDebug>
 
 #include "messagedelegate.h"
-#include "ui/models/messagefeed.h"
+#include "messagefeed.h"
 
 constexpr int maxMessageHeight = 10000;
 constexpr int approximateSingleMessageHeight = 20;

ui/widgets/messageline/feedview.h

@@ -24,8 +24,8 @@
 #include <deque>
 #include <set>
 
-#include <ui/models/messagefeed.h>
+#include <ui/widgets/messageline/messagefeed.h>
-#include "progress.h"
+#include <ui/utils/progress.h>
 
 /**
  * @todo write docs

ui/widgets/messageline/messagedelegate.cpp

@@ -22,13 +22,12 @@
 #include <QMouseEvent>
 
 #include "messagedelegate.h"
-#include "ui/models/messagefeed.h"
+#include "messagefeed.h"
 
 constexpr int avatarHeight = 50;
 constexpr int margin = 6;
 constexpr int textMargin = 2;
 constexpr int statusIconSize = 16;
-constexpr int maxAttachmentHeight = 500;
 
 MessageDelegate::MessageDelegate(QObject* parent):
     QStyledItemDelegate(parent),
@@ -44,6 +43,7 @@ MessageDelegate::MessageDelegate(QObject* parent):
     bars(new std::map<QString, QProgressBar*>()),
     statusIcons(new std::map<QString, QLabel*>()),
     bodies(new std::map<QString, QLabel*>()),
+    previews(new std::map<QString, Preview*>()),
     idsToKeep(new std::set<QString>()),
     clearingWidgets(false)
 {
@@ -72,10 +72,15 @@ MessageDelegate::~MessageDelegate()
         delete pair.second;
     }
     
+    for (const std::pair<const QString, Preview*>& pair: *previews){
+        delete pair.second;
+    }
+    
     delete idsToKeep;
     delete buttons;
     delete bars;
     delete bodies;
+    delete previews;
 }
 
 void MessageDelegate::paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const
@@ -151,24 +156,14 @@ void MessageDelegate::paint(QPainter* painter, const QStyleOptionViewItem& optio
             break;
         case Models::errorDownload: {
             paintButton(getButton(data), painter, data.sentByMe, opt);
-            painter->setFont(dateFont);
+            paintComment(data, painter, opt);
-            QColor q = painter->pen().color();
-            q.setAlpha(180);
-            painter->setPen(q);
-            painter->drawText(opt.rect, opt.displayAlignment, data.attach.error, &rect);
-            opt.rect.adjust(0, rect.height() + textMargin, 0, 0);
         }
             
             break;
         case Models::errorUpload:{
             clearHelperWidget(data);
             paintPreview(data, painter, opt);
-            painter->setFont(dateFont);
+            paintComment(data, painter, opt);
-            QColor q = painter->pen().color();
-            q.setAlpha(180);
-            painter->setPen(q);
-            painter->drawText(opt.rect, opt.displayAlignment, data.attach.error, &rect);
-            opt.rect.adjust(0, rect.height() + textMargin, 0, 0);
         }
             break;
     }
@@ -181,6 +176,8 @@ void MessageDelegate::paint(QPainter* painter, const QStyleOptionViewItem& optio
         body->setParent(vp);
         body->setMaximumWidth(bodySize.width());
         body->setMinimumWidth(bodySize.width());
+        body->setMinimumHeight(bodySize.height());
+        body->setMaximumHeight(bodySize.height());
         body->setAlignment(opt.displayAlignment);
         messageLeft = opt.rect.x();
         if (data.sentByMe) {
@@ -232,7 +229,7 @@ QSize MessageDelegate::sizeHint(const QStyleOptionViewItem& option, const QModel
         case Models::none:
             break;
         case Models::uploading:
-            messageSize.rheight() += calculateAttachSize(attach.localPath, messageRect).height() + textMargin;
+            messageSize.rheight() += Preview::calculateAttachSize(attach.localPath, messageRect).height() + textMargin;
         case Models::downloading:
             messageSize.rheight() += barHeight + textMargin;
             break;
@@ -241,14 +238,14 @@ QSize MessageDelegate::sizeHint(const QStyleOptionViewItem& option, const QModel
             break;
         case Models::ready:
         case Models::local:
-            messageSize.rheight() += calculateAttachSize(attach.localPath, messageRect).height() + textMargin;
+            messageSize.rheight() += Preview::calculateAttachSize(attach.localPath, messageRect).height() + textMargin;
             break;
         case Models::errorDownload:
             messageSize.rheight() += buttonHeight + textMargin;
             messageSize.rheight() += dateMetrics.boundingRect(messageRect, Qt::TextWordWrap, attach.error).size().height() + textMargin;
             break;
         case Models::errorUpload:
-            messageSize.rheight() += calculateAttachSize(attach.localPath, messageRect).height() + textMargin;
+            messageSize.rheight() += Preview::calculateAttachSize(attach.localPath, messageRect).height() + textMargin;
             messageSize.rheight() += dateMetrics.boundingRect(messageRect, Qt::TextWordWrap, attach.error).size().height() + textMargin;
             break;
     }
@@ -319,6 +316,17 @@ void MessageDelegate::paintButton(QPushButton* btn, QPainter* painter, bool sent
     option.rect.adjust(0, buttonHeight + textMargin, 0, 0);
 }
 
+void MessageDelegate::paintComment(const Models::FeedItem& data, QPainter* painter, QStyleOptionViewItem& option) const
+{
+    painter->setFont(dateFont);
+    QColor q = painter->pen().color();
+    q.setAlpha(180);
+    painter->setPen(q);
+    QRect rect;
+    painter->drawText(option.rect, option.displayAlignment, data.attach.error, &rect);
+    option.rect.adjust(0, rect.height() + textMargin, 0, 0);
+}
+
 void MessageDelegate::paintBar(QProgressBar* bar, QPainter* painter, bool sentByMe, QStyleOptionViewItem& option) const
 {
     QPoint start = option.rect.topLeft();
@@ -332,49 +340,20 @@ void MessageDelegate::paintBar(QProgressBar* bar, QPainter* painter, bool sentBy
 
 void MessageDelegate::paintPreview(const Models::FeedItem& data, QPainter* painter, QStyleOptionViewItem& option) const
 {
-    Shared::Global::FileInfo info = Shared::Global::getFileInfo(data.attach.localPath);
+    Preview* preview = 0;
-    QSize size = constrainAttachSize(info.size, option.rect.size());
+    std::map<QString, Preview*>::iterator itr = previews->find(data.id);
-    
+
-    QPoint start;
+    QSize size = option.rect.size();
-    if (data.sentByMe) {
+    if (itr != previews->end()) {
-        start = {option.rect.width() - size.width(), option.rect.top()};
+        preview = itr->second;
-        start.rx() += margin;
+        preview->actualize(data.attach.localPath, size, option.rect.topLeft());
     } else {
-        start = option.rect.topLeft();
+        QWidget* vp = static_cast<QWidget*>(painter->device());
-    }
+        preview = new Preview(data.attach.localPath, size, option.rect.topLeft(), data.sentByMe, vp);
-    QRect rect(start, size);
+        previews->insert(std::make_pair(data.id, preview));
-    switch (info.preview) {
-        case Shared::Global::FileInfo::Preview::picture: {
-            QImage img(data.attach.localPath);
-            if (img.isNull()) {
-                emit invalidPath(data.id);
-            } else {
-                painter->drawImage(rect, img);
-            }
-        }
-        break;
-        default: {
-            QIcon icon = QIcon::fromTheme(info.mime.iconName());
-            
-            painter->save();
-            
-            painter->setFont(bodyFont);
-            int labelWidth = option.rect.width() - size.width() - margin;
-            QString elidedName = bodyMetrics.elidedText(info.name, Qt::ElideMiddle, labelWidth);
-            QSize nameSize = bodyMetrics.boundingRect(QRect(start, QSize(labelWidth, 0)), 0, elidedName).size();
-            if (data.sentByMe) {
-                start.rx() -= nameSize.width() + margin;
-            }
-            painter->drawPixmap({start, size}, icon.pixmap(info.size));
-            start.rx() += size.width() + margin;
-            start.ry() += nameSize.height() + (size.height() - nameSize.height()) / 2;
-            painter->drawText(start, elidedName);
-    
-            painter->restore();
-        }
     }
     
-    option.rect.adjust(0, size.height() + textMargin, 0, 0);
+    option.rect.adjust(0, preview->size().height() + textMargin, 0, 0);
 }
 
 QPushButton * MessageDelegate::getButton(const Models::FeedItem& data) const
@@ -432,6 +411,13 @@ QLabel * MessageDelegate::getStatusIcon(const Models::FeedItem& data) const
     std::map<QString, QLabel*>::const_iterator itr = statusIcons->find(data.id);
     QLabel* result = 0;
     
+    if (itr != statusIcons->end()) {
+        result = itr->second;
+    } else {
+        result = new QLabel();
+        statusIcons->insert(std::make_pair(data.id, result));
+    }
+    
     QIcon q(Shared::icon(Shared::messageStateThemeIcons[static_cast<uint8_t>(data.state)]));
     QString tt = Shared::Global::getName(data.state);
     if (data.state == Shared::Message::State::error) {
@@ -439,25 +425,11 @@ QLabel * MessageDelegate::getStatusIcon(const Models::FeedItem& data) const
             tt += ": " + data.error;
         }
     }
-    
+    if (result->toolTip() != tt) {                      //If i just assign pixmap every time unconditionally
-    if (itr != statusIcons->end()) {
+        result->setPixmap(q.pixmap(statusIconSize));    //it invokes an infinite cycle of repaint
-        result = itr->second;
+        result->setToolTip(tt);                         //may be it's better to subclass and store last condition in int?
-        if (result->toolTip() != tt) {                      //If i just assign pixmap every time unconditionally
-            result->setPixmap(q.pixmap(statusIconSize));    //it involves into an infinite cycle of repaint
-            result->setToolTip(tt);                         //may be it's better to subclass and store last condition in int?
-        }
-    } else {
-        result = new QLabel();
-        statusIcons->insert(std::make_pair(data.id, result));
-        result->setPixmap(q.pixmap(statusIconSize));
-        result->setToolTip(tt);
     }
     
-    
-    
-    result->setToolTip(tt);
-    //result->setText(std::to_string((int)data.state).c_str());
-    
     return result;
 }
 
@@ -488,50 +460,28 @@ void MessageDelegate::beginClearWidgets()
     clearingWidgets = true;
 }
 
+template <typename T>
+void removeElements(std::map<QString, T*>* elements, std::set<QString>* idsToKeep) {
+    std::set<QString> toRemove;
+    for (const std::pair<const QString, T*>& pair: *elements) {
+        if (idsToKeep->find(pair.first) == idsToKeep->end()) {
+            delete pair.second;
+            toRemove.insert(pair.first);
+        }
+    }
+    for (const QString& key : toRemove) {
+        elements->erase(key);
+    }
+}
+
 void MessageDelegate::endClearWidgets()
 {
     if (clearingWidgets) {
-        std::set<QString> toRemoveButtons;
+        removeElements(buttons, idsToKeep);
-        std::set<QString> toRemoveBars;
+        removeElements(bars, idsToKeep);
-        std::set<QString> toRemoveIcons;
+        removeElements(statusIcons, idsToKeep);
-        std::set<QString> toRemoveBodies;
+        removeElements(bodies, idsToKeep);
-        for (const std::pair<const QString, FeedButton*>& pair: *buttons) {
+        removeElements(previews, idsToKeep);
-            if (idsToKeep->find(pair.first) == idsToKeep->end()) {
-                delete pair.second;
-                toRemoveButtons.insert(pair.first);
-            }
-        }
-        for (const std::pair<const QString, QProgressBar*>& pair: *bars) {
-            if (idsToKeep->find(pair.first) == idsToKeep->end()) {
-                delete pair.second;
-                toRemoveBars.insert(pair.first);
-            }
-        }
-        for (const std::pair<const QString, QLabel*>& pair: *statusIcons) {
-            if (idsToKeep->find(pair.first) == idsToKeep->end()) {
-                delete pair.second;
-                toRemoveIcons.insert(pair.first);
-            }
-        }
-        for (const std::pair<const QString, QLabel*>& pair: *bodies) {
-            if (idsToKeep->find(pair.first) == idsToKeep->end()) {
-                delete pair.second;
-                toRemoveBodies.insert(pair.first);
-            }
-        }
-        
-        for (const QString& key : toRemoveButtons) {
-            buttons->erase(key);
-        }
-        for (const QString& key : toRemoveBars) {
-            bars->erase(key);
-        }
-        for (const QString& key : toRemoveIcons) {
-            statusIcons->erase(key);
-        }
-        for (const QString& key : toRemoveBodies) {
-            bodies->erase(key);
-        }
         
         idsToKeep->clear();
         clearingWidgets = false;
@@ -559,25 +509,6 @@ void MessageDelegate::clearHelperWidget(const Models::FeedItem& data) const
     }
 }
 
-QSize MessageDelegate::calculateAttachSize(const QString& path, const QRect& bounds) const
-{
-    Shared::Global::FileInfo info = Shared::Global::getFileInfo(path);
-    
-    return constrainAttachSize(info.size, bounds.size());
-}
-
-QSize MessageDelegate::constrainAttachSize(QSize src, QSize bounds) const
-{
-    bounds.setHeight(maxAttachmentHeight);
-    
-    if (src.width() > bounds.width() || src.height() > bounds.height()) {
-        src.scale(bounds, Qt::KeepAspectRatio);
-    }
-    
-    return src;
-}
-
-
 // void MessageDelegate::setModelData(QWidget* editor, QAbstractItemModel* model, const QModelIndex& index) const
 // {
 //     

ui/widgets/messageline/messagedelegate.h

@@ -34,6 +34,8 @@
 #include "shared/global.h"
 #include "shared/utils.h"
 
+#include "preview.h"
+
 namespace Models {
     struct FeedItem;
 };
@@ -62,13 +64,12 @@ protected:
     void paintButton(QPushButton* btn, QPainter* painter, bool sentByMe, QStyleOptionViewItem& option) const;
     void paintBar(QProgressBar* bar, QPainter* painter, bool sentByMe, QStyleOptionViewItem& option) const;
     void paintPreview(const Models::FeedItem& data, QPainter* painter, QStyleOptionViewItem& option) const;
+    void paintComment(const Models::FeedItem& data, QPainter* painter, QStyleOptionViewItem& option) const;
     QPushButton* getButton(const Models::FeedItem& data) const;
     QProgressBar* getBar(const Models::FeedItem& data) const;
     QLabel* getStatusIcon(const Models::FeedItem& data) const;
     QLabel* getBody(const Models::FeedItem& data) const;
     void clearHelperWidget(const Models::FeedItem& data) const;
-    QSize calculateAttachSize(const QString& path, const QRect& bounds) const;
-    QSize constrainAttachSize(QSize src, QSize bounds) const;
     
 protected slots:
     void onButtonPushed() const;
@@ -93,6 +94,7 @@ private:
     std::map<QString, QProgressBar*>* bars;
     std::map<QString, QLabel*>* statusIcons;
     std::map<QString, QLabel*>* bodies;
+    std::map<QString, Preview*>* previews;
     std::set<QString>* idsToKeep;
     bool clearingWidgets;
     

ui/widgets/messageline/messagefeed.cpp

@@ -17,8 +17,9 @@
  */
 
 #include "messagefeed.h"
-#include "element.h"
+
-#include "room.h"
+#include <ui/models/element.h>
+#include <ui/models/room.h>
 
 #include <QDebug>
 

ui/widgets/messageline/preview.cpp

@@ -0,0 +1,304 @@
+/*
+ * Squawk messenger. 
+ * Copyright (C) 2019  Yury Gubich <blue@macaw.me>
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "preview.h"
+
+
+constexpr int margin = 6;
+constexpr int maxAttachmentHeight = 500;
+
+bool Preview::fontInitialized = false;
+QFont Preview::font;
+QFontMetrics Preview::metrics(Preview::font);
+
+Preview::Preview(const QString& pPath, const QSize& pMaxSize, const QPoint& pos, bool pRight, QWidget* pParent):
+    info(Shared::Global::getFileInfo(pPath)),
+    path(pPath),
+    maxSize(pMaxSize),
+    actualSize(constrainAttachSize(info.size, maxSize)),
+    cachedLabelSize(0, 0),
+    position(pos),
+    widget(0),
+    label(0),
+    parent(pParent),
+    movie(0),
+    fileReachable(true),
+    actualPreview(false),
+    right(pRight)
+{
+    if (!fontInitialized) {
+        font.setBold(true);
+        font.setPixelSize(14);
+        metrics = QFontMetrics(font);
+        fontInitialized = true;
+    }
+    
+    initializeElements();
+    if (fileReachable) {
+        positionElements();
+    }
+}
+
+Preview::~Preview()
+{
+    clean();
+}
+
+void Preview::clean()
+{
+    if (fileReachable) {
+        if (info.preview == Shared::Global::FileInfo::Preview::animation) {
+            delete movie;
+        }
+        delete widget;
+        if (!actualPreview) {
+            delete label;
+        } else {
+            actualPreview = false;
+        }
+    } else {
+        fileReachable = true;
+    }
+}
+
+void Preview::actualize(const QString& newPath, const QSize& newSize, const QPoint& newPoint)
+{
+    bool positionChanged = false;
+    bool sizeChanged = false;
+    bool maxSizeChanged = false;
+    
+    if (maxSize != newSize) {
+        maxSize = newSize;
+        maxSizeChanged = true;
+        QSize ns = constrainAttachSize(info.size, maxSize);
+        if (actualSize != ns) {
+            sizeChanged = true;
+            actualSize = ns;
+        }
+    }
+    if (position != newPoint) {
+        position = newPoint;
+        positionChanged = true;
+    }
+    
+    if (!setPath(newPath) && fileReachable) {
+        if (sizeChanged) {
+            applyNewSize();
+            if (maxSizeChanged && !actualPreview) {
+                applyNewMaxSize();
+            }
+        } else if (maxSizeChanged) {
+            applyNewMaxSize();
+        }
+        if (positionChanged || !actualPreview) {
+            positionElements();
+        }
+    }
+}
+
+void Preview::setSize(const QSize& newSize)
+{
+    bool sizeChanged = false;
+    bool maxSizeChanged = false;
+    
+    if (maxSize != newSize) {
+        maxSize = newSize;
+        maxSizeChanged = true;
+        QSize ns = constrainAttachSize(info.size, maxSize);
+        if (actualSize != ns) {
+            sizeChanged = true;
+            actualSize = ns;
+        }
+    }
+    
+    if (fileReachable) {
+        if (sizeChanged) {
+            applyNewSize();
+        }
+        if (maxSizeChanged || !actualPreview) {
+            applyNewMaxSize();
+        }
+    }
+}
+
+void Preview::applyNewSize()
+{
+    switch (info.preview) {
+        case Shared::Global::FileInfo::Preview::picture: {
+            QPixmap img(path);
+            if (img.isNull()) {
+                fileReachable = false;
+            } else {
+                img = img.scaled(actualSize, Qt::KeepAspectRatio);
+                widget->resize(actualSize);
+                widget->setPixmap(img);
+            }
+        }
+            break;
+        case Shared::Global::FileInfo::Preview::animation:{
+            movie->setScaledSize(actualSize);
+            widget->resize(actualSize);
+        }
+            break;
+        default: {
+            QIcon icon = QIcon::fromTheme(info.mime.iconName());
+            widget->setPixmap(icon.pixmap(actualSize));
+            widget->resize(actualSize);
+        }
+    }
+}
+
+void Preview::applyNewMaxSize()
+{
+    switch (info.preview) {
+        case Shared::Global::FileInfo::Preview::picture: 
+        case Shared::Global::FileInfo::Preview::animation: 
+            break;
+        default: {
+            int labelWidth = maxSize.width() - actualSize.width() - margin;
+            QString elidedName = metrics.elidedText(info.name, Qt::ElideMiddle, labelWidth);
+            cachedLabelSize = metrics.size(0, elidedName);
+            label->setText(elidedName);
+            label->resize(cachedLabelSize);
+        }
+    }
+}
+
+
+QSize Preview::size() const
+{
+    if (actualPreview) {
+        return actualSize;
+    } else {
+        return QSize(actualSize.width() + margin + cachedLabelSize.width(), actualSize.height());
+    }
+}
+
+bool Preview::isFileReachable() const
+{
+    return fileReachable;
+}
+
+void Preview::setPosition(const QPoint& newPoint)
+{
+    if (position != newPoint) {
+        position = newPoint;
+        if (fileReachable) {
+            positionElements();
+        }
+    }
+}
+
+bool Preview::setPath(const QString& newPath)
+{
+    if (path != newPath) {
+        path = newPath;
+        info = Shared::Global::getFileInfo(path);
+        actualSize = constrainAttachSize(info.size, maxSize);
+        clean();
+        initializeElements();
+        if (fileReachable) {
+            positionElements();
+        }
+        return true;
+    } else {
+        return false;
+    }
+}
+
+void Preview::initializeElements()
+{
+    switch (info.preview) {
+        case Shared::Global::FileInfo::Preview::picture: {
+            QPixmap img(path);
+            if (img.isNull()) {
+                fileReachable = false;
+            } else {
+                actualPreview = true;
+                img = img.scaled(actualSize, Qt::KeepAspectRatio);
+                widget = new QLabel(parent);
+                widget->setPixmap(img);
+                widget->show();
+            }
+        }
+            break;
+        case Shared::Global::FileInfo::Preview::animation:{
+            movie = new QMovie(path);
+            if (!movie->isValid()) {
+                fileReachable = false;
+                delete movie;
+            } else {
+                actualPreview = true;
+                movie->setScaledSize(actualSize);
+                widget = new QLabel(parent);
+                widget->setMovie(movie);
+                movie->start();
+                widget->show();
+            }
+        }
+            break;
+        default: {
+            QIcon icon = QIcon::fromTheme(info.mime.iconName());
+            widget = new QLabel(parent);
+            widget->setPixmap(icon.pixmap(actualSize));
+            widget->show();
+            
+            label = new QLabel(parent);
+            label->setFont(font);
+            int labelWidth = maxSize.width() - actualSize.width() - margin;
+            QString elidedName = metrics.elidedText(info.name, Qt::ElideMiddle, labelWidth);
+            cachedLabelSize = metrics.size(0, elidedName);
+            label->setText(elidedName);
+            label->show();
+        }
+    }
+}
+
+void Preview::positionElements()
+{
+    int start = position.x();
+    if (right) {
+        start += maxSize.width() - size().width();
+    }
+    widget->move(start, position.y());
+    if (!actualPreview) {
+        int x = start + actualSize.width() + margin;
+        int y = position.y() + (actualSize.height() - cachedLabelSize.height()) / 2;
+        label->move(x, y);
+    }
+}
+
+QSize Preview::calculateAttachSize(const QString& path, const QRect& bounds)
+{
+    Shared::Global::FileInfo info = Shared::Global::getFileInfo(path);
+    
+    return constrainAttachSize(info.size, bounds.size());
+}
+
+QSize Preview::constrainAttachSize(QSize src, QSize bounds)
+{
+    if (bounds.height() > maxAttachmentHeight) {
+        bounds.setHeight(maxAttachmentHeight);
+    }
+    
+    if (src.width() > bounds.width() || src.height() > bounds.height()) {
+        src.scale(bounds, Qt::KeepAspectRatio);
+    }
+    
+    return src;
+}

ui/widgets/messageline/preview.h

@@ -0,0 +1,79 @@
+/*
+ * Squawk messenger. 
+ * Copyright (C) 2019  Yury Gubich <blue@macaw.me>
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef PREVIEW_H
+#define PREVIEW_H
+
+#include <QWidget>
+#include <QString>
+#include <QPoint>
+#include <QSize>
+#include <QLabel>
+#include <QIcon>
+#include <QPixmap>
+#include <QMovie>
+#include <QFont>
+#include <QFontMetrics>
+
+#include <shared/global.h>
+
+/**
+ * @todo write docs
+ */
+class Preview {
+public:
+    Preview(const QString& pPath, const QSize& pMaxSize, const QPoint& pos, bool pRight, QWidget* parent);
+    ~Preview();
+    
+    void actualize(const QString& newPath, const QSize& newSize, const QPoint& newPoint);
+    void setPosition(const QPoint& newPoint);
+    void setSize(const QSize& newSize);
+    bool setPath(const QString& newPath);
+    bool isFileReachable() const;
+    QSize size() const;
+    
+    static QSize constrainAttachSize(QSize src, QSize bounds);
+    static QSize calculateAttachSize(const QString& path, const QRect& bounds);
+    static bool fontInitialized;
+    static QFont font;
+    static QFontMetrics metrics;
+    
+private:
+    void initializeElements();
+    void positionElements();
+    void clean();
+    void applyNewSize();
+    void applyNewMaxSize();
+    
+private:
+    Shared::Global::FileInfo info;
+    QString path;
+    QSize maxSize;
+    QSize actualSize;
+    QSize cachedLabelSize;
+    QPoint position;
+    QLabel* widget;
+    QLabel* label;
+    QWidget* parent;
+    QMovie* movie;
+    bool fileReachable;
+    bool actualPreview;
+    bool right;
+};
+
+#endif // PREVIEW_H