From 07873332e79d257a3ee6a26a3139b3420c8f34d2 Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Sat, 12 Jan 2019 06:57:17 +0100
Subject: [PATCH] Coalesce mouse events to make the GUI go fast.

A simple but effective optimization that avoids tons of redraw. :^)
---
 Widgets/EventLoop.cpp | 17 ++++++++++++++++-
 Widgets/Rect.cpp      |  2 --
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/Widgets/EventLoop.cpp b/Widgets/EventLoop.cpp
index f470201f58..d4c026cebc 100644
--- a/Widgets/EventLoop.cpp
+++ b/Widgets/EventLoop.cpp
@@ -66,11 +66,26 @@ void EventLoop::postEvent(Object* receiver, OwnPtr<Event>&& event)
 void EventLoop::waitForEvent()
 {
     auto& mouse = PS2MouseDevice::the();
+    auto& screen = AbstractScreen::the();
+    bool prev_left_button = screen.left_mouse_button_pressed();
+    bool prev_right_button = screen.right_mouse_button_pressed();
+    int dx = 0;
+    int dy = 0;
     while (mouse.has_data_available_for_reading()) {
         signed_byte data[3];
         ssize_t nread = mouse.read((byte*)data, 3);
         ASSERT(nread == 3);
-        AbstractScreen::the().on_receive_mouse_data(data[1], -data[2], data[0] & 1, data[0] & 2);
+        bool left_button = data[0] & 1;
+        bool right_button = data[0] & 2;
+        dx += data[1];
+        dy += -data[2];
+        if (left_button != prev_left_button || right_button != prev_right_button || !mouse.has_data_available_for_reading()) {
+            prev_left_button = left_button;
+            prev_right_button = right_button;
+            screen.on_receive_mouse_data(dx, dy, left_button, right_button);
+            dx = 0;
+            dy = 0;
+        }
     }
 }
 #endif
diff --git a/Widgets/Rect.cpp b/Widgets/Rect.cpp
index fa4aa7aef9..4656a82f0f 100644
--- a/Widgets/Rect.cpp
+++ b/Widgets/Rect.cpp
@@ -19,6 +19,4 @@ void Rect::intersect(const Rect& other)
     m_location.setY(t);
     m_size.setWidth((r - l) + 1);
     m_size.setHeight((b - t) + 1);
-
-    dbgprintf("intersection result: %d,%d %dx%d\n", x(), y(), width(), height());
 }