From 621e14d092775fc4f785036a844b516c624a2e04 Mon Sep 17 00:00:00 2001
From: attila <attila@juce.com>
Date: Thu, 13 Oct 2022 18:11:43 +0200
Subject: [PATCH] Add AnimatedAppComponent::setSynchroniseToVBlank

---
 examples/GUI/AnimationAppDemo.h               |  2 +-
 .../misc/juce_AnimatedAppComponent.cpp        | 34 ++++++++++++++++---
 .../misc/juce_AnimatedAppComponent.h          | 14 ++++++--
 3 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/examples/GUI/AnimationAppDemo.h b/examples/GUI/AnimationAppDemo.h
index ef0d1f3903..8d92e06f10 100644
--- a/examples/GUI/AnimationAppDemo.h
+++ b/examples/GUI/AnimationAppDemo.h
@@ -59,7 +59,7 @@ public:
     AnimationAppDemo()
     {
         setSize (800, 600);
-        setFramesPerSecond (60);
+        setSynchroniseToVBlank (true);
     }
 
     void update() override
diff --git a/modules/juce_gui_extra/misc/juce_AnimatedAppComponent.cpp b/modules/juce_gui_extra/misc/juce_AnimatedAppComponent.cpp
index f2798e483a..ab2b8fcb3c 100644
--- a/modules/juce_gui_extra/misc/juce_AnimatedAppComponent.cpp
+++ b/modules/juce_gui_extra/misc/juce_AnimatedAppComponent.cpp
@@ -27,15 +27,41 @@ namespace juce
 {
 
 AnimatedAppComponent::AnimatedAppComponent()
-    : lastUpdateTime (Time::getCurrentTime()), totalUpdates (0)
 {
     setOpaque (true);
 }
 
-void AnimatedAppComponent::setFramesPerSecond (int framesPerSecond)
+void AnimatedAppComponent::setFramesPerSecond (int framesPerSecondIn)
 {
-    jassert (framesPerSecond > 0 && framesPerSecond < 1000);
-    startTimerHz (framesPerSecond);
+    jassert (0 < framesPerSecond && framesPerSecond < 1000);
+    framesPerSecond = framesPerSecondIn;
+    updateSync();
+}
+
+void AnimatedAppComponent::updateSync()
+{
+    if (useVBlank)
+    {
+        stopTimer();
+
+        if (vBlankAttachment.isEmpty())
+            vBlankAttachment = { this, [this] { timerCallback(); } };
+    }
+    else
+    {
+        vBlankAttachment = {};
+
+        const auto interval = 1000 / framesPerSecond;
+
+        if (getTimerInterval() != interval)
+            startTimer (interval);
+    }
+}
+
+void AnimatedAppComponent::setSynchroniseToVBlank (bool syncToVBlank)
+{
+    useVBlank = syncToVBlank;
+    updateSync();
 }
 
 int AnimatedAppComponent::getMillisecondsSinceLastUpdate() const noexcept
diff --git a/modules/juce_gui_extra/misc/juce_AnimatedAppComponent.h b/modules/juce_gui_extra/misc/juce_AnimatedAppComponent.h
index b4e55a8100..ef1e87fb52 100644
--- a/modules/juce_gui_extra/misc/juce_AnimatedAppComponent.h
+++ b/modules/juce_gui_extra/misc/juce_AnimatedAppComponent.h
@@ -47,6 +47,11 @@ public:
     */
     void setFramesPerSecond (int framesPerSecond);
 
+    /** You can use this function to synchronise animation updates with the current display's vblank
+        events. When this mode is enabled the value passed to setFramesPerSecond() is ignored.
+    */
+    void setSynchroniseToVBlank (bool syncToVBlank);
+
     /** Called periodically, at the frequency specified by setFramesPerSecond().
         This is a the best place to do things like advancing animation parameters,
         checking the mouse position, etc.
@@ -66,8 +71,13 @@ public:
 
 private:
     //==============================================================================
-    Time lastUpdateTime;
-    int totalUpdates;
+    void updateSync();
+
+    Time lastUpdateTime = Time::getCurrentTime();
+    int totalUpdates = 0;
+    int framesPerSecond = 60;
+    bool useVBlank = false;
+    VBlankAttachment vBlankAttachment;
 
     void timerCallback() override;