experimental features: zoom and drag view (adressing #34)

man/beamerpresenter-ui.5

@@ -329,8 +329,11 @@ clear all drawings on the left/right part of current page, assuming that the pag
 .BR "scroll up" / normal / down
 scroll the slide view up / to normal position / down. This allows the presenter to add extra space for drawings.
 .TP
+.BR "zoom in" / reset / out
+experimental: zoom the slide view. Use the tool \[dq]drag view\[dq] (experimental) to drag the zoomed view.
+.TP
 .B save
-save drawings to file. Doesn't ask for file name if a file name is known.
+save drawings to file. Does not ask for file name if a file name is known.
 .TP
 .B save as
 save drawings to file. Always asks for the file name.
@@ -408,7 +411,7 @@ drop-down menu of draw tool widths. This must be provided as a JSON object in th
 Options in the dictionary for tools. All lengths (e.g. stroke width) are given in points (1/72 inch) in the PDF:
 .TP
 .B tool
-mandatory: pen, fixed width pen, highlighter, eraser, pointer, magnifier, torch, text, click select, rectangle select, freehand select, or none
+mandatory: pen, fixed width pen, highlighter, eraser, pointer, magnifier, torch, text, click select, rectangle select, freehand select, drag view, or none
 .TP
 .B color
 color name known to Qt or #RRGGBB or #AARRGGBB

src/CMakeLists.txt

@@ -16,6 +16,7 @@ add_executable(beamerpresenter
         drawing/tool.h drawing/tool.cpp
         drawing/drawtool.h
         drawing/texttool.h
+        drawing/dragtool.h
         drawing/selectiontool.h drawing/selectiontool.cpp
         drawing/pointingtool.h drawing/pointingtool.cpp
         drawing/selectionrectitem.h drawing/selectionrectitem.cpp

src/drawing/dragtool.h

@@ -0,0 +1,39 @@
+// SPDX-FileCopyrightText: 2024 Valentin Bruch <[email protected]>
+// SPDX-License-Identifier: GPL-3.0-or-later OR AGPL-3.0-or-later
+
+#ifndef DRAGTOOL_H
+#define DRAGTOOL_H
+
+#include <QPointF>
+#include <cmath>
+
+#include "src/drawing/tool.h"
+
+/** Experimental: DragTool for dragging view */
+class DragTool : public Tool
+{
+  QPointF reference_point;
+  static constexpr int skip_events = 3;
+  int event_counter = skip_events - 1;
+
+ public:
+  DragTool(const int device = AnyDevice) noexcept : Tool(DragViewTool, device)
+  {
+  }
+  DragTool(const DragTool &other) noexcept : Tool(DragViewTool, other.device())
+  {
+  }
+  ~DragTool() {}
+  const QPointF &reference() const noexcept { return reference_point; }
+  void setReference(const QPointF &pos) noexcept { reference_point = pos; }
+  QPointF dragTo(const QPointF target, const bool force) noexcept
+  {
+    if (force || ++event_counter >= skip_events)
+      event_counter = 0;
+    else
+      return QPointF();
+    return reference_point - target;
+  }
+};
+
+#endif  // DRAGTOOL_H

src/drawing/tool.cpp

@@ -6,6 +6,7 @@
 #if (QT_VERSION_MAJOR >= 6)
 #include <QPointingDevice>
 #endif
+#include "src/drawing/dragtool.h"
 #include "src/drawing/drawtool.h"
 #include "src/drawing/pointingtool.h"
 #include "src/drawing/selectiontool.h"
@@ -24,6 +25,8 @@ std::shared_ptr<Tool> Tool::copy() const
     newtool = new SelectionTool(*static_cast<const SelectionTool*>(this));
   else if (_tool == Tool::TextInputTool)
     newtool = new TextTool(*static_cast<const TextTool*>(this));
+  else if (_tool == Tool::DragViewTool)
+    newtool = new DragTool(*static_cast<const DragTool*>(this));
   else
     newtool = new Tool(*this);
   newtool->setDevice(_device);

src/drawing/tool.h

@@ -33,8 +33,10 @@ class Tool
     // General tools, class Tool
     /// Invalid tool
     InvalidTool = 0,
+    /// Draw view
+    DragViewTool = 1,
     /// Text input tool
-    TextInputTool = 1,
+    TextInputTool = 2,
     /// No tool
     NoTool = 0x1f,
 
@@ -165,6 +167,7 @@ static const QMap<QString, Tool::BasicTool> string_to_tool{
     {QT_TRANSLATE_NOOP("Tool", "torch"), Tool::Torch},
     {QT_TRANSLATE_NOOP("Tool", "magnifier"), Tool::Magnifier},
     {QT_TRANSLATE_NOOP("Tool", "text"), Tool::TextInputTool},
+    {QT_TRANSLATE_NOOP("Tool", "drag view"), Tool::DragViewTool},
     {QT_TRANSLATE_NOOP("Tool", "click select"), Tool::BasicSelectionTool},
     {QT_TRANSLATE_NOOP("Tool", "rectangle select"), Tool::RectSelectionTool},
     {QT_TRANSLATE_NOOP("Tool", "freehand select"), Tool::FreehandSelectionTool},

src/enumerates.h

@@ -151,6 +151,9 @@ enum Action {
   ScrollDown,    ///< scroll slide down
   ScrollUp,      ///< scroll slide up
   ScrollNormal,  ///< scroll slide back to normal
+  ZoomIn,        ///< zoom in on a slide
+  ZoomOut,       ///< zoom out of a slide
+  ZoomReset,     ///< reset slide zoom
   SaveDrawings,  ///< save drawings to known file name, ask for file name if no
                  ///< file name is known
   SaveDrawingsAs,       ///< save drawings to file, always ask for file name

src/gui/actionbutton.cpp

@@ -33,6 +33,12 @@ const char *action_to_theme_icon(const Action action) noexcept
       return "go-first";
     case LastPage:
       return "go-last";
+    case ZoomIn:
+      return "zoom-in";
+    case ZoomOut:
+      return "zoom-out";
+    case ZoomReset:
+      return "zoom-original";
       /* Drawing */
     case UndoDrawing:
       return "edit-undo";

src/names.h

@@ -40,6 +40,9 @@ static const QMap<QString, Action> string_to_action_map{
     {QT_TRANSLATE_NOOP("SettingsWidget", "scroll home"), ScrollNormal},
     {QT_TRANSLATE_NOOP("SettingsWidget", "scroll normal"), ScrollNormal},
     {QT_TRANSLATE_NOOP("SettingsWidget", "scroll reset"), ScrollNormal},
+    {QT_TRANSLATE_NOOP("SettingsWidget", "zoom in"), ZoomIn},
+    {QT_TRANSLATE_NOOP("SettingsWidget", "zoom out"), ZoomOut},
+    {QT_TRANSLATE_NOOP("SettingsWidget", "zoom reset"), ZoomReset},
     {QT_TRANSLATE_NOOP("SettingsWidget", "save"), SaveDrawings},
     {QT_TRANSLATE_NOOP("SettingsWidget", "save as"), SaveDrawingsAs},
     {QT_TRANSLATE_NOOP("SettingsWidget", "open"), LoadDrawings},

src/preferences.cpp

@@ -13,6 +13,7 @@
 #include <utility>
 
 #include "src/config.h"
+#include "src/drawing/dragtool.h"
 #include "src/drawing/drawtool.h"
 #include "src/drawing/pointingtool.h"
 #include "src/drawing/selectiontool.h"
@@ -132,6 +133,9 @@ std::shared_ptr<Tool> createTool(const QJsonObject &obj,
       tool = new TextTool(font, color, device);
       break;
     }
+    case Tool::DragViewTool:
+      tool = new DragTool(device);
+      break;
     case Tool::BasicSelectionTool:
     case Tool::RectSelectionTool:
     case Tool::FreehandSelectionTool:

src/slidescene.cpp

@@ -28,6 +28,7 @@
 #include "src/config.h"
 #include "src/drawing/arrowgraphicsitem.h"
 #include "src/drawing/basicgraphicspath.h"
+#include "src/drawing/dragtool.h"
 #include "src/drawing/ellipsegraphicsitem.h"
 #include "src/drawing/flexgraphicslineitem.h"
 #include "src/drawing/fullgraphicspath.h"
@@ -321,24 +322,27 @@ bool SlideScene::handleEvents(const int device, const QList<QPointF> &pos,
                 "Handling event" << tool->tool() << tool->device() << device);
   // Handle draw tool events.
   if (tool->tool() & Tool::AnyDrawTool)
-    handleDrawEvents(std::static_pointer_cast<const DrawTool>(tool), device,
+    handleDrawEvents(std::dynamic_pointer_cast<const DrawTool>(tool), device,
                      pos, pressure);
   // Handle pointing tool events.
   else if (tool->tool() & Tool::AnyPointingTool)
-    handlePointingEvents(std::static_pointer_cast<PointingTool>(tool), device,
+    handlePointingEvents(std::dynamic_pointer_cast<PointingTool>(tool), device,
                          pos);
   // Handle selection tool events.
   else if (tool->tool() & Tool::AnySelectionTool)
-    handleSelectionEvents(std::static_pointer_cast<SelectionTool>(tool), device,
-                          pos, start_pos);
+    handleSelectionEvents(std::dynamic_pointer_cast<SelectionTool>(tool),
+                          device, pos, start_pos);
   // Handle text tool events.
   // Here we detect start events and not stop events, because otherwise touch
   // events will be discarded: If a touch start event is not handled, the whole
   // touch event is treated as a mouse event.
   else if (tool->tool() == Tool::TextInputTool &&
            (device & Tool::AnyEvent) == Tool::StartEvent && pos.size() == 1)
-    return handleTextEvents(std::static_pointer_cast<const TextTool>(tool),
+    return handleTextEvents(std::dynamic_pointer_cast<const TextTool>(tool),
                             device, pos);
+  else if (tool->tool() == Tool::DragViewTool)
+    return handleDragView(std::dynamic_pointer_cast<DragTool>(tool), device,
+                          pos, start_pos);
   // Fall back to no tool.
   else if ((device & Tool::AnyEvent) == Tool::StopEvent && pos.size() == 1)
     noToolClicked(pos.constFirst(), start_pos);
@@ -347,6 +351,24 @@ bool SlideScene::handleEvents(const int device, const QList<QPointF> &pos,
   return true;
 }
 
+bool SlideScene::handleDragView(std::shared_ptr<DragTool> tool,
+                                const int device, const QList<QPointF> &pos,
+                                const QPointF &start_pos)
+{
+  if (!tool || pos.size() != 1) return false;
+  if ((device & Tool::AnyEvent) == Tool::StartEvent)
+    tool->setReference(pos.constFirst());
+  else {
+    const QPointF delta = tool->dragTo(
+        pos.constFirst(), (device & Tool::AnyEvent) == Tool::StopEvent);
+    if (delta.isNull()) return false;
+    QRectF rect = sceneRect();
+    rect.translate(delta);
+    setSceneRect(rect);
+  }
+  return true;
+}
+
 bool SlideScene::maybeStartSelectionEvent(const QPointF &pos,
                                           const int device) noexcept
 {
@@ -675,15 +697,58 @@ void SlideScene::receiveAction(const Action action)
   debug_verbose(DebugFunctionCalls, action << this);
   debug_msg(DebugKeyInput, "SlideScene received action" << action);
   switch (action) {
-    case ScrollDown:
-      setSceneRect(sceneRect().translated(0, sceneRect().height() / 5));
+    case ScrollDown: {
+      QRectF rect = sceneRect();
+      rect.translate(0, 0.2 * rect.height());
+      setSceneRect(rect);
       break;
-    case ScrollUp:
-      setSceneRect(sceneRect().translated(0, -sceneRect().height() / 5));
+    }
+    case ScrollUp: {
+      QRectF rect = sceneRect();
+      rect.translate(0, -0.2 * rect.height());
+      setSceneRect(rect);
       break;
+    }
     case ScrollNormal:
       setSceneRect({{0, 0}, sceneRect().size()});
       break;
+    case ZoomIn: {
+      const QRectF rect = sceneRect();
+      setSceneRect(rect.x() + 0.1 / 1.2 * rect.width(),
+                   rect.y() + 0.1 / 1.2 * rect.height(), rect.width() / 1.2,
+                   rect.height() / 1.2);
+      for (auto view : views()) {
+        auto *sview = dynamic_cast<SlideView *>(view);
+        if (sview) sview->setZoomRelative(1.2);
+      }
+      break;
+    }
+    case ZoomOut: {
+      const QRectF rect = sceneRect();
+      setSceneRect(rect.x() - 0.1 / 0.8 * rect.width(),
+                   rect.y() - 0.1 / 0.8 * rect.height(), rect.width() / 0.8,
+                   rect.height() / 0.8);
+      for (auto view : views()) {
+        auto *sview = dynamic_cast<SlideView *>(view);
+        if (sview) sview->setZoomRelative(0.8);
+      }
+      break;
+    }
+    case ZoomReset: {
+      qreal zoom = 1.0;
+      for (auto view : views()) {
+        auto *sview = dynamic_cast<SlideView *>(view);
+        if (sview) {
+          zoom = sview->getZoom();
+          sview->setZoom(1.0);
+        }
+      }
+      const QRectF rect = sceneRect();
+      setSceneRect(rect.x() - (zoom - 1) / 2 * rect.width(),
+                   rect.y() - (zoom - 1) / 2 * rect.height(),
+                   rect.width() * zoom, rect.height() * zoom);
+      break;
+    }
     case PauseMedia:
       pauseMedia();
       break;

src/slidescene.h

@@ -38,6 +38,7 @@ class QGraphicsRectItem;
 class PdfMaster;
 class DrawTool;
 class TextTool;
+class DragTool;
 class QFont;
 class PointingTool;
 class SelectionTool;
@@ -328,6 +329,8 @@ class SlideScene : public QGraphicsScene
   /// Helper function for handleEvents: text tool events
   bool handleTextEvents(std::shared_ptr<const TextTool> tool, const int device,
                         const QList<QPointF> &pos);
+  bool handleDragView(std::shared_ptr<DragTool> tool, const int device,
+                      const QList<QPointF> &pos, const QPointF &start_pos);
   /// Handle selection start events (only called from handleEvents().
   void handleSelectionStartEvents(std::shared_ptr<SelectionTool> tool,
                                   const QPointF &pos);

src/slideview.cpp

@@ -23,6 +23,7 @@ SlideView::SlideView(SlideScene *scene, const PixCache *cache, QWidget *parent)
 {
   setMouseTracking(true);
   setAttribute(Qt::WA_AcceptTouchEvents);
+  setTransformationAnchor(AnchorViewCenter);
   grabGesture(Qt::SwipeGesture);
   setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing |
                  QPainter::RenderHint::SmoothPixmapTransform);
@@ -55,7 +56,6 @@ void SlideView::pageChanged(const int page, SlideScene *scene)
   sliders.clear();
   setScene(scene);
   const QSizeF &pageSize = scene->sceneRect().size();
-  qreal resolution;
   if (pageSize.width() * height() > pageSize.height() * width())
     // page is too wide, determine resolution by x direction
     resolution = width() / pageSize.width();
@@ -78,7 +78,6 @@ void SlideView::pageChangedBlocking(const int page, SlideScene *scene)
   sliders.clear();
   setScene(scene);
   const QSizeF &pageSize = scene->sceneRect().size();
-  qreal resolution;
   if (pageSize.width() * height() > pageSize.height() * width())
     // page is too wide, determine resolution by x direction
     resolution = width() / pageSize.width();
@@ -206,10 +205,6 @@ bool SlideView::event(QEvent *event)
         return QGraphicsView::event(event);
     }
     */
-    // case QEvent::TabletTrackingChange:
-    // case QEvent::TabletEnterProximity:
-    // case QEvent::TabletLeaveProximity:
-    //     break;
     case QEvent::TabletPress: {
       auto tabletevent = static_cast<const QTabletEvent *>(event);
 #if (QT_VERSION_MAJOR >= 6)
@@ -253,6 +248,22 @@ bool SlideView::event(QEvent *event)
   }
 }
 
+void SlideView::requestScaledPage(const qreal zoom)
+{
+  const SlideScene *sscene = dynamic_cast<SlideScene *>(scene());
+  if (!sscene || zoom < 1e-6 || zoom > 1e6) return;
+  const PixmapGraphicsItem *pageItem = sscene->pageBackground();
+  if (!pageItem) return;
+  // Check whether an enlarged page is needed and not "in preparation" yet.
+  if (waitingForPage == INT_MAX &&
+      !pageItem->hasWidth(zoom * resolution * sceneRect().width())) {
+    debug_msg(DebugRendering, "Enlarged page: searched for"
+                                  << zoom * resolution * sceneRect().width());
+    waitingForPage = static_cast<SlideScene *>(scene())->getPage();
+    emit requestPage(waitingForPage, zoom * resolution);
+  }
+}
+
 void SlideView::showMagnifier(QPainter *painter,
                               std::shared_ptr<const PointingTool> tool) noexcept
 {
@@ -261,17 +272,7 @@ void SlideView::showMagnifier(QPainter *painter,
   painter->setCompositionMode(QPainter::CompositionMode_SourceOver);
   painter->setPen(tool->color());
   painter->setBrush(Qt::NoBrush);
-  const qreal resolution = tool->scale() * painter->transform().m11();
-  PixmapGraphicsItem *pageItem =
-      static_cast<SlideScene *>(scene())->pageBackground();
-  // Check whether an enlarged page is needed and not "in preparation" yet.
-  if (waitingForPage == INT_MAX &&
-      !pageItem->hasWidth(resolution * sceneRect().width())) {
-    debug_msg(DebugRendering, "Enlarged page: searched for"
-                                  << resolution * sceneRect().width());
-    waitingForPage = static_cast<SlideScene *>(scene())->getPage();
-    emit requestPage(waitingForPage, resolution);
-  }
+  requestScaledPage(tool->scale());
   // Draw magnifier(s) at all positions of tool.
   for (const auto &pos : tool->pos()) {
     // calculate target rect: size of the magnifier