From c602346cadb02bff69ff0f96f6c610a64f1b4671 Mon Sep 17 00:00:00 2001
From: "Anthony J. Thibault" <ajt@highfidelity.io>
Date: Fri, 24 Jul 2015 11:14:09 -0700
Subject: [PATCH] Update ApplicationCompositor to use QPropertyAnimation for
 alpha fades

---
 interface/src/ui/ApplicationCompositor.cpp | 32 +++++++++++++++++-----
 interface/src/ui/ApplicationCompositor.h   | 15 +++++++---
 interface/src/ui/OverlayConductor.cpp      |  4 ---
 3 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/interface/src/ui/ApplicationCompositor.cpp b/interface/src/ui/ApplicationCompositor.cpp
index 82a9090d18..fe0e8a2568 100644
--- a/interface/src/ui/ApplicationCompositor.cpp
+++ b/interface/src/ui/ApplicationCompositor.cpp
@@ -165,6 +165,8 @@ ApplicationCompositor::ApplicationCompositor() {
             }
         }
     });
+
+    _alphaPropertyAnimation = std::make_unique<QPropertyAnimation>(this, "alpha");
 }
 
 ApplicationCompositor::~ApplicationCompositor() {
@@ -730,12 +732,28 @@ void ApplicationCompositor::updateTooltips() {
     }
 }
 
-void ApplicationCompositor::update(float dt) {
-    const int ALPHA_FADE_RATE = 2.0f;
-    _prevAlpha = _alpha;
-    if (_fadeInAlpha && _alpha < 1.0f) {
-        _alpha = std::min(_alpha + ALPHA_FADE_RATE * dt, 1.0f);
-    } else if (!_fadeInAlpha && _alpha > 0.0f) {
-        _alpha = std::max(_alpha - ALPHA_FADE_RATE * dt, 0.0f);
+static const float FADE_DURATION = 500.0f;
+void ApplicationCompositor::fadeIn() {
+    _fadeInAlpha = true;
+
+    _alphaPropertyAnimation->setDuration(FADE_DURATION);
+    _alphaPropertyAnimation->setStartValue(_alpha);
+    _alphaPropertyAnimation->setEndValue(1.0f);
+    _alphaPropertyAnimation->start();
+}
+void ApplicationCompositor::fadeOut() {
+    _fadeInAlpha = false;
+
+    _alphaPropertyAnimation->setDuration(FADE_DURATION);
+    _alphaPropertyAnimation->setStartValue(_alpha);
+    _alphaPropertyAnimation->setEndValue(0.0f);
+    _alphaPropertyAnimation->start();
+}
+
+void ApplicationCompositor::toggle() {
+    if (_fadeInAlpha) {
+        fadeOut();
+    } else {
+        fadeIn();
     }
 }
diff --git a/interface/src/ui/ApplicationCompositor.h b/interface/src/ui/ApplicationCompositor.h
index aa3a0a1e4d..3074708e70 100644
--- a/interface/src/ui/ApplicationCompositor.h
+++ b/interface/src/ui/ApplicationCompositor.h
@@ -10,6 +10,7 @@
 #define hifi_ApplicationCompositor_h
 
 #include <QObject>
+#include <QPropertyAnimation>
 #include <cstdint>
 
 #include <EntityItemID.h>
@@ -33,6 +34,8 @@ const float DEFAULT_HMD_UI_ANGULAR_SIZE = 72.0f;
 // facilities of this class
 class ApplicationCompositor : public QObject {
     Q_OBJECT
+
+    Q_PROPERTY(float alpha READ getAlpha WRITE setAlpha)
 public:
     ApplicationCompositor();
     ~ApplicationCompositor();
@@ -70,10 +73,12 @@ public:
     void setModelTransform(const Transform& transform) { _modelTransform = transform; }
     const Transform& getModelTransform() const { return _modelTransform; }
 
-    void fadeIn() { _fadeInAlpha = true; }
-    void fadeOut() { _fadeInAlpha = false; }
-    void toggle() { _fadeInAlpha = !_fadeInAlpha; }
-    void update(float dt);
+    void fadeIn();
+    void fadeOut();
+    void toggle();
+
+    float getAlpha() const { return _alpha; }
+    void setAlpha(float alpha) { _alpha = alpha; }
 
     static glm::vec2 directionToSpherical(const glm::vec3 & direction);
     static glm::vec3 sphericalToDirection(const glm::vec2 & sphericalPos);
@@ -131,6 +136,8 @@ private:
 
     Transform _modelTransform;
     Transform _cameraBaseTransform;
+
+    std::unique_ptr<QPropertyAnimation> _alphaPropertyAnimation;
 };
 
 #endif // hifi_ApplicationCompositor_h
diff --git a/interface/src/ui/OverlayConductor.cpp b/interface/src/ui/OverlayConductor.cpp
index 01f666d50b..21165b8c20 100644
--- a/interface/src/ui/OverlayConductor.cpp
+++ b/interface/src/ui/OverlayConductor.cpp
@@ -62,10 +62,6 @@ void OverlayConductor::update(float dt) {
         // do nothing
         break;
     }
-
-
-    // process alpha fade animations
-    qApp->getApplicationCompositor().update(dt);
 }
 
 void OverlayConductor::updateMode() {