From ed76d8fa7dd7aa9785e3f08172a908dafdf7adcc Mon Sep 17 00:00:00 2001
From: "Thiago Marcos P. Santos" <tmpsantos@gmail.com>
Date: Tue, 17 Sep 2019 23:44:31 +0300
Subject: [qt] Add touch support to the Qt app

---
 platform/qt/app/mapwindow.cpp | 70 +++++++++++++++++++++++++++++++++++++++++++
 platform/qt/app/mapwindow.hpp |  7 +++++
 2 files changed, 77 insertions(+)

diff --git a/platform/qt/app/mapwindow.cpp b/platform/qt/app/mapwindow.cpp
index 6171c8bf35..eb759d2504 100644
--- a/platform/qt/app/mapwindow.cpp
+++ b/platform/qt/app/mapwindow.cpp
@@ -9,12 +9,15 @@
 #include <QMouseEvent>
 #include <QString>
 
+#include <cmath>
+
 int kAnimationDuration = 10000;
 
 MapWindow::MapWindow(const QMapboxGLSettings &settings)
     : m_settings(settings)
 {
     setWindowIcon(QIcon(":icon.png"));
+    setAttribute(Qt::WA_AcceptTouchEvents);
 }
 
 MapWindow::~MapWindow()
@@ -494,3 +497,70 @@ void MapWindow::paintGL()
     m_map->setFramebufferObject(defaultFramebufferObject(), size() * pixelRatio());
     m_map->render();
 }
+
+void MapWindow::touchEvent(QTouchEvent* ev) {
+    switch (ev->type()) {
+        case QTouchEvent::TouchBegin:
+            m_accumulatedTouchAngle = 0.0;
+            m_touchRotation = false;
+            // fall through
+        case QTouchEvent::TouchUpdate:
+        case QTouchEvent::TouchEnd: {
+            QList<QTouchEvent::TouchPoint> tps = ev->touchPoints();
+            if (tps.count() == 1) {
+                QPointF delta = tps.first().pos() - tps.first().lastPos();
+                m_map->moveBy(delta);
+            } else if (tps.count() == 2) {
+                QLineF last(tps.first().lastPos(), tps.last().lastPos());
+                QLineF end(tps.first().pos(), tps.last().pos());
+
+                QPointF lastCenter(0.5 * last.p1() + 0.5 * last.p2());
+                QPointF endCenter(0.5 * end.p1() + 0.5 * end.p2());
+
+                QPointF delta = endCenter - lastCenter;
+                m_map->moveBy(delta);
+
+                float s = end.length() / last.length();
+                m_map->scaleBy(s, endCenter);
+
+                if (end.length() > 75.0) {
+                    m_accumulatedTouchAngle = std::fmod(m_accumulatedTouchAngle + last.angleTo(end), 360.0);
+                    if (m_accumulatedTouchAngle >= 180.0) {
+                        m_accumulatedTouchAngle -= 360.0;
+                    }
+                }
+                if (m_touchRotation || m_accumulatedTouchAngle > 10.0 || m_accumulatedTouchAngle < -10.0) {
+                    m_touchRotation = true;
+
+                    QMapboxGLCameraOptions camera;
+                    camera.anchor = endCenter;
+                    camera.bearing = m_map->bearing() + last.angleTo(end);
+
+                    m_map->jumpTo(camera);
+
+                }
+            } else if (tps.count() == 3) {
+                float s = 100.0 * (tps.first().pos().y() - tps.first().lastPos().y()) / width();
+                m_map->pitchBy(s);
+            }
+        }; break;
+        default:
+            ev->ignore();
+            break;
+    }
+}
+
+bool MapWindow::event(QEvent* ev) {
+    switch (ev->type()) {
+        case QEvent::TouchBegin:
+        case QEvent::TouchUpdate:
+        case QEvent::TouchEnd: {
+            touchEvent(static_cast<QTouchEvent *>(ev));
+            return true;
+        }; break;
+        default:
+           break;
+    }
+
+    return QOpenGLWidget::event(ev);
+}
diff --git a/platform/qt/app/mapwindow.hpp b/platform/qt/app/mapwindow.hpp
index 0671c42518..37b7f1d5d5 100644
--- a/platform/qt/app/mapwindow.hpp
+++ b/platform/qt/app/mapwindow.hpp
@@ -6,6 +6,7 @@
 #include <QOpenGLWidget>
 #include <QPropertyAnimation>
 #include <QScopedPointer>
+#include <QTouchEvent>
 #include <QtGlobal>
 
 class QKeyEvent;
@@ -31,6 +32,7 @@ private:
     qreal pixelRatio();
 
     // QWidget implementation.
+    bool event(QEvent *e) final;
     void keyPressEvent(QKeyEvent *ev) final;
     void mousePressEvent(QMouseEvent *ev) final;
     void mouseMoveEvent(QMouseEvent *ev) final;
@@ -40,6 +42,8 @@ private:
     void initializeGL() final;
     void paintGL() final;
 
+    void touchEvent(QTouchEvent *ev);
+
     QPointF m_lastPos;
 
     QMapboxGLSettings m_settings;
@@ -55,6 +59,9 @@ private:
     QVariant m_lineAnnotationId;
     QVariant m_fillAnnotationId;
 
+    bool m_touchRotation = false;
+    double m_accumulatedTouchAngle = 0.0;
+
     bool m_sourceAdded = false;
 };
 
-- 
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