From 4c98de9bcd9754965877e0c45714979f45aad4b7 Mon Sep 17 00:00:00 2001
From: "Joakim L. Gilje" <jgilje@jgilje.net>
Date: Fri, 3 Dec 2021 12:57:56 +0100
Subject: [PATCH] don't need the reqUpdate_() slot, update is already a slot.
 lock the image data with a mutex

---
 src/qt/qt_gleswidget.cpp | 50 ++++++++++++++++++----------------------
 src/qt/qt_gleswidget.hpp |  6 ++---
 2 files changed, 26 insertions(+), 30 deletions(-)

diff --git a/src/qt/qt_gleswidget.cpp b/src/qt/qt_gleswidget.cpp
index 40daa2e0c..5bab0910d 100644
--- a/src/qt/qt_gleswidget.cpp
+++ b/src/qt/qt_gleswidget.cpp
@@ -60,20 +60,14 @@ void GLESWidget::resizeGL(int w, int h)
 void GLESWidget::initializeGL()
 {
     initializeOpenGLFunctions();
-    connect(this, &GLESWidget::reqUpdate, this, &GLESWidget::reqUpdate_);
+    connect(this, &GLESWidget::reqUpdate, this, static_cast<void (GLESWidget::*)()>(&GLESWidget::update));
 }
 
 void GLESWidget::paintGL()
 {
+    std::scoped_lock lock(image_mx);
     QPainter painter(this);
     painter.drawImage(QRect(0, 0, width(), height()), m_image.convertToFormat(QImage::Format_RGBX8888), QRect(sx, sy, sw, sh));
-    painter.end();
-    firstupdate = true;
-}
-
-void GLESWidget::reqUpdate_()
-{
-    update();
 }
 
 void GLESWidget::mouseReleaseEvent(QMouseEvent *event)
@@ -136,26 +130,28 @@ void GLESWidget::mouseMoveEvent(QMouseEvent *event)
 
 void GLESWidget::qt_real_blit(int x, int y, int w, int h)
 {
-    if ((w <= 0) || (h <= 0) || (w > 2048) || (h > 2048) || (buffer32 == NULL) || !firstupdate)
     {
+        std::scoped_lock lock(image_mx);
+        if ((w <= 0) || (h <= 0) || (w > 2048) || (h > 2048) || (buffer32 == NULL))
+        {
+            video_blit_complete();
+            return;
+        }
+        sx = x;
+        sy = y;
+        sw = this->w = w;
+        sh = this->h = h;
+        static auto imagebits = m_image.bits();
+        for (int y1 = y; y1 < (y + h - 1); y1++)
+        {
+            auto scanline = imagebits + (y1 * (2048 + 64) * 4);
+            video_copy(scanline + (x * 4), &(buffer32->line[y1][x]), w * 4);
+        }
+        if (screenshots)
+        {
+            video_screenshot((uint32_t *)imagebits, 0, 0, 2048 + 64);
+        }
         video_blit_complete();
-        return;
     }
-    sx = x;
-    sy = y;
-    sw = this->w = w;
-    sh = this->h = h;
-    static auto imagebits = m_image.bits();
-    for (int y1 = y; y1 < (y + h - 1); y1++)
-    {
-        auto scanline = imagebits + (y1 * (2048 + 64) * 4);
-        video_copy(scanline + (x * 4), &(buffer32->line[y1][x]), w * 4);
-    }
-    if (screenshots)
-    {
-        video_screenshot((uint32_t *)imagebits, 0, 0, 2048 + 64);
-    }
-    video_blit_complete();
-    firstupdate = false;
-    this->reqUpdate();
+    reqUpdate();
 }
diff --git a/src/qt/qt_gleswidget.hpp b/src/qt/qt_gleswidget.hpp
index 9c7e9a6cd..c5f4087b0 100644
--- a/src/qt/qt_gleswidget.hpp
+++ b/src/qt/qt_gleswidget.hpp
@@ -7,7 +7,8 @@
 #include <QKeyEvent>
 
 #include <atomic>
-#include <qapplication.h>
+#include <mutex>
+#include <QApplication>
 
 #ifdef WAYLAND
 #include "wl_mouse.hpp"
@@ -19,6 +20,7 @@ class GLESWidget : public QOpenGLWidget, protected QOpenGLFunctions
 
 private:
     QImage m_image{QSize(2048 + 64, 2048 + 64), QImage::Format_RGB32};
+    std::mutex image_mx;
     int x, y, w, h, sx, sy, sw, sh;
     bool wayland = false;
 public:
@@ -58,7 +60,6 @@ signals:
 public slots:
 	void qt_real_blit(int x, int y, int w, int h);
     void qt_mouse_poll();
-    void reqUpdate_();
 
 private:
     struct mouseinputdata {
@@ -66,5 +67,4 @@ private:
         int mousebuttons;
     };
     mouseinputdata mousedata;
-    std::atomic<bool> firstupdate{false};
 };