From 02f2b9c75c4031c084c177a582f18d3e888596fa Mon Sep 17 00:00:00 2001
From: Bruno de Oliveira Abinader <bruno@mapbox.com>
Date: Wed, 27 Feb 2019 17:49:01 +0200
Subject: [core] Added Map::scaleBy()

---
 include/mbgl/map/map.hpp      | 1 +
 platform/glfw/glfw_view.cpp   | 6 +++---
 platform/qt/src/qmapboxgl.cpp | 2 +-
 src/mbgl/map/map.cpp          | 5 +++++
 4 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/include/mbgl/map/map.hpp b/include/mbgl/map/map.hpp
index fec67eb281..35821457fa 100644
--- a/include/mbgl/map/map.hpp
+++ b/include/mbgl/map/map.hpp
@@ -81,6 +81,7 @@ public:
     void resetPosition(const EdgeInsets& = {});
 
     // Zoom
+    void scaleBy(double scale, optional<ScreenCoordinate> anchor, const AnimationOptions& animation);
     void setZoom(double zoom, const AnimationOptions& = {});
     void setZoom(double zoom, optional<ScreenCoordinate>, const AnimationOptions& = {});
     void setZoom(double zoom, const EdgeInsets&, const AnimationOptions& = {});
diff --git a/platform/glfw/glfw_view.cpp b/platform/glfw/glfw_view.cpp
index 97c4cde657..2a1afdfe1e 100644
--- a/platform/glfw/glfw_view.cpp
+++ b/platform/glfw/glfw_view.cpp
@@ -487,7 +487,7 @@ void GLFWView::onScroll(GLFWwindow *window, double /*xOffset*/, double yOffset)
         scale = 1.0 / scale;
     }
 
-    view->map->setZoom(view->map->getZoom() + ::log2(scale), mbgl::ScreenCoordinate { view->lastX, view->lastY });
+    view->map->scaleBy(scale, mbgl::ScreenCoordinate { view->lastX, view->lastY });
 }
 
 void GLFWView::onWindowResize(GLFWwindow *window, int width, int height) {
@@ -530,9 +530,9 @@ void GLFWView::onMouseClick(GLFWwindow *window, int button, int action, int modi
             double now = glfwGetTime();
             if (now - view->lastClick < 0.4 /* ms */) {
                 if (modifiers & GLFW_MOD_SHIFT) {
-                    view->map->setZoom(view->map->getZoom() - 1, mbgl::ScreenCoordinate { view->lastX, view->lastY }, mbgl::AnimationOptions{{mbgl::Milliseconds(500)}});
+                    view->map->scaleBy(0.5, mbgl::ScreenCoordinate { view->lastX, view->lastY }, mbgl::AnimationOptions{{mbgl::Milliseconds(500)}});
                 } else {
-                    view->map->setZoom(view->map->getZoom() + 1, mbgl::ScreenCoordinate { view->lastX, view->lastY }, mbgl::AnimationOptions{{mbgl::Milliseconds(500)}});
+                    view->map->scaleBy(2.0, mbgl::ScreenCoordinate { view->lastX, view->lastY }, mbgl::AnimationOptions{{mbgl::Milliseconds(500)}});
                 }
             }
             view->lastClick = now;
diff --git a/platform/qt/src/qmapboxgl.cpp b/platform/qt/src/qmapboxgl.cpp
index 35ff7f7c29..e512b23901 100644
--- a/platform/qt/src/qmapboxgl.cpp
+++ b/platform/qt/src/qmapboxgl.cpp
@@ -1126,7 +1126,7 @@ void QMapboxGL::moveBy(const QPointF &offset)
     can be used for implementing a pinch gesture.
 */
 void QMapboxGL::scaleBy(double scale_, const QPointF &center) {
-    d_ptr->mapObj->setZoom(d_ptr->mapObj->getZoom() + ::log2(scale_), mbgl::ScreenCoordinate { center.x(), center.y() });
+    d_ptr->mapObj->scaleBy(scale_, mbgl::ScreenCoordinate { center.x(), center.y() });
 }
 
 /*!
diff --git a/src/mbgl/map/map.cpp b/src/mbgl/map/map.cpp
index 7c19375542..25c4b5398d 100644
--- a/src/mbgl/map/map.cpp
+++ b/src/mbgl/map/map.cpp
@@ -187,6 +187,11 @@ void Map::resetPosition(const EdgeInsets& padding) {
 
 #pragma mark - Zoom
 
+void Map::scaleBy(double scale, optional<ScreenCoordinate> anchor, const AnimationOptions& animation) {
+    double zoom = getZoom() + impl->transform.getState().scaleZoom(scale);
+    easeTo(CameraOptions().withZoom(zoom).withAnchor(anchor), animation);
+}
+
 void Map::setZoom(double zoom, const AnimationOptions& animation) {
     easeTo(CameraOptions().withZoom(zoom), animation);
 }
-- 
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