fix initialization of QGLWidget waveform widgets & renderers

QGLWidget documentation says:
The initialization of OpenGL rendering state, etc. should be done by overriding
the initializeGL() function, rather than in the constructor of your QGLWidget
subclass.

Calling QOpenGLFunctions_2_1::initializeOpenGLFunctions in the QGLWidget
constructors crashed on macOS:
https://bugs.launchpad.net/mixxx/+bug/1877487
I am surprised it did not crash on Linux and Windows.

The calls to makeCurrent in the QGLWidget constructors were futile; that
does nothing before Qt calls QGLWidget::initializeGL. This can be verified
by adding:
qDebug() << "Context current" << (QGLContext::currentContext() == context());
after the call to makeCurrent.

21 files changed, 76 insertions, 60 deletions

diff --git a/src/waveform/renderers/glslwaveformrenderersignal.cpp b/src/waveform/renderers/glslwaveformrenderersignal.cpp
index 8777ff0e5a..c62172a5e1 100644
--- a/src/waveform/renderers/glslwaveformrenderersignal.cpp
+++ b/src/waveform/renderers/glslwaveformrenderersignal.cpp
@@ -17,7 +17,6 @@ GLSLWaveformRendererSignal::GLSLWaveformRendererSignal(WaveformWidgetRenderer* w
           m_bDumpPng(false),
           m_shadersValid(false),
           m_rgbShader(rgbShader) {
-    initializeOpenGLFunctions();
 }
 
 GLSLWaveformRendererSignal::~GLSLWaveformRendererSignal() {
@@ -189,7 +188,8 @@ void GLSLWaveformRendererSignal::createFrameBuffers() {
     }
 }
 
-bool GLSLWaveformRendererSignal::onInit() {
+void GLSLWaveformRendererSignal::onInitializeGL() {
+    initializeOpenGLFunctions();
     m_textureRenderedWaveformCompletion = 0;
 
     if (!m_frameShaderProgram) {
@@ -197,14 +197,12 @@ bool GLSLWaveformRendererSignal::onInit() {
     }
 
     if (!loadShaders()) {
-        return false;
+        return;
     }
     createGeometry();
     if (!loadTexture()) {
-        return false;
+        return;
     }
-
-    return true;
 }
 
 void GLSLWaveformRendererSignal::onSetup(const QDomNode& node) {
diff --git a/src/waveform/renderers/glslwaveformrenderersignal.h b/src/waveform/renderers/glslwaveformrenderersignal.h
index 8e5f3ca803..9ebfc7920d 100644
--- a/src/waveform/renderers/glslwaveformrenderersignal.h
+++ b/src/waveform/renderers/glslwaveformrenderersignal.h
@@ -1,6 +1,5 @@
 #pragma once
 
-#include <QOpenGLFunctions_2_1>
 #if !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
 
 #include <QGLFramebufferObject>
@@ -11,17 +10,17 @@
 #include "util/memory.h"
 #include "waveform/renderers/waveformrenderersignalbase.h"
 
-class GLSLWaveformRendererSignal: public QObject,
-        public WaveformRendererSignalBase,
-        protected QOpenGLFunctions_2_1 {
+class GLSLWaveformRendererSignal : public QObject,
+                                   public WaveformRendererSignalBase,
+                                   public GLWaveformRenderer {
     Q_OBJECT
   public:
     GLSLWaveformRendererSignal(WaveformWidgetRenderer* waveformWidgetRenderer,
                                bool rgbShader);
     ~GLSLWaveformRendererSignal() override;
 
-    bool onInit() override;
     void onSetup(const QDomNode& node) override;
+    void onInitializeGL() override;
     void draw(QPainter* painter, QPaintEvent* event) override;
 
     void onSetTrack() override;
diff --git a/src/waveform/renderers/glvsynctestrenderer.cpp b/src/waveform/renderers/glvsynctestrenderer.cpp
index dc5e42e966..cad6a2205d 100644
--- a/src/waveform/renderers/glvsynctestrenderer.cpp
+++ b/src/waveform/renderers/glvsynctestrenderer.cpp
@@ -11,7 +11,6 @@ GLVSyncTestRenderer::GLVSyncTestRenderer(
         WaveformWidgetRenderer* waveformWidgetRenderer)
     : WaveformRendererSignalBase(waveformWidgetRenderer),
       m_drawcount(0) {
-    initializeOpenGLFunctions();
 }
 
 GLVSyncTestRenderer::~GLVSyncTestRenderer() {
diff --git a/src/waveform/renderers/glvsynctestrenderer.h b/src/waveform/renderers/glvsynctestrenderer.h
index b9a31049eb..a74ef88e64 100644
--- a/src/waveform/renderers/glvsynctestrenderer.h
+++ b/src/waveform/renderers/glvsynctestrenderer.h
@@ -1,15 +1,14 @@
 #pragma once
 
-#include <QOpenGLFunctions_2_1>
 #if !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
 
 #include "waveformrenderersignalbase.h"
 
 class ControlObject;
 
-class GLVSyncTestRenderer: public WaveformRendererSignalBase,
-        protected QOpenGLFunctions_2_1 {
-public:
+class GLVSyncTestRenderer : public WaveformRendererSignalBase,
+                            public GLWaveformRenderer {
+  public:
     explicit GLVSyncTestRenderer(
             WaveformWidgetRenderer* waveformWidgetRenderer);
     virtual ~GLVSyncTestRenderer();
diff --git a/src/waveform/renderers/glwaveformrendererfilteredsignal.cpp b/src/waveform/renderers/glwaveformrendererfilteredsignal.cpp
index 8cb59e1e40..9043ee5262 100644
--- a/src/waveform/renderers/glwaveformrendererfilteredsignal.cpp
+++ b/src/waveform/renderers/glwaveformrendererfilteredsignal.cpp
@@ -12,7 +12,6 @@
 GLWaveformRendererFilteredSignal::GLWaveformRendererFilteredSignal(
         WaveformWidgetRenderer* waveformWidgetRenderer)
         : WaveformRendererSignalBase(waveformWidgetRenderer) {
-    initializeOpenGLFunctions();
 }
 
 GLWaveformRendererFilteredSignal::~GLWaveformRendererFilteredSignal() {
diff --git a/src/waveform/renderers/glwaveformrendererfilteredsignal.h b/src/waveform/renderers/glwaveformrendererfilteredsignal.h
index 807ee928ea..be4b30780b 100644
--- a/src/waveform/renderers/glwaveformrendererfilteredsignal.h
+++ b/src/waveform/renderers/glwaveformrendererfilteredsignal.h
@@ -1,6 +1,5 @@
 #pragma once
 
-#include <QOpenGLFunctions_2_1>
 #if !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
 
 #include <QDomNode>
@@ -9,9 +8,9 @@
 
 class ControlObject;
 
-class GLWaveformRendererFilteredSignal: public WaveformRendererSignalBase,
-        protected QOpenGLFunctions_2_1 {
-public:
+class GLWaveformRendererFilteredSignal : public WaveformRendererSignalBase,
+                                         public GLWaveformRenderer {
+  public:
     explicit GLWaveformRendererFilteredSignal(
             WaveformWidgetRenderer* waveformWidgetRenderer);
     virtual ~GLWaveformRendererFilteredSignal();
diff --git a/src/waveform/renderers/glwaveformrendererrgb.cpp b/src/waveform/renderers/glwaveformrendererrgb.cpp
index 8bfac3f5f4..50ac786781 100644
--- a/src/waveform/renderers/glwaveformrendererrgb.cpp
+++ b/src/waveform/renderers/glwaveformrendererrgb.cpp
@@ -16,7 +16,6 @@ const float kHeightScaleFactor = 255.0f / sqrtf(255 * 255 * 3);
 GLWaveformRendererRGB::GLWaveformRendererRGB(
         WaveformWidgetRenderer* waveformWidgetRenderer)
         : WaveformRendererSignalBase(waveformWidgetRenderer) {
-    initializeOpenGLFunctions();
 }
 
 GLWaveformRendererRGB::~GLWaveformRendererRGB() {
diff --git a/src/waveform/renderers/glwaveformrendererrgb.h b/src/waveform/renderers/glwaveformrendererrgb.h
index 4b435d6746..8bbfd7fd93 100644
--- a/src/waveform/renderers/glwaveformrendererrgb.h
+++ b/src/waveform/renderers/glwaveformrendererrgb.h
@@ -1,14 +1,13 @@
 #pragma once
 
-#include <QOpenGLFunctions_2_1>
 #if !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
 
 #include "waveformrenderersignalbase.h"
 
 class ControlObject;
 
-class GLWaveformRendererRGB: public WaveformRendererSignalBase,
-        protected QOpenGLFunctions_2_1 {
+class GLWaveformRendererRGB : public WaveformRendererSignalBase,
+                              public GLWaveformRenderer {
   public:
     explicit GLWaveformRendererRGB(
             WaveformWidgetRenderer* waveformWidgetRenderer);
diff --git a/src/waveform/renderers/glwaveformrenderersimplesignal.cpp b/src/waveform/renderers/glwaveformrenderersimplesignal.cpp
index d9651356bf..56d9f5448e 100644
--- a/src/waveform/renderers/glwaveformrenderersimplesignal.cpp
+++ b/src/waveform/renderers/glwaveformrenderersimplesignal.cpp
@@ -10,7 +10,6 @@
 GLWaveformRendererSimpleSignal::GLWaveformRendererSimpleSignal(
         WaveformWidgetRenderer* waveformWidgetRenderer)
         : WaveformRendererSignalBase(waveformWidgetRenderer) {
-    initializeOpenGLFunctions();
 }
 
 GLWaveformRendererSimpleSignal::~GLWaveformRendererSimpleSignal() {
diff --git a/src/waveform/renderers/glwaveformrenderersimplesignal.h b/src/waveform/renderers/glwaveformrenderersimplesignal.h
index 48e698803d..ae3aae6111 100644
--- a/src/waveform/renderers/glwaveformrenderersimplesignal.h
+++ b/src/waveform/renderers/glwaveformrenderersimplesignal.h
@@ -1,14 +1,14 @@
 #pragma once
 
-#include <QOpenGLFunctions_2_1>
 #if !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
 
 #include "waveformrenderersignalbase.h"
 
 class ControlObject;
 
-class GLWaveformRendererSimpleSignal : public WaveformRendererSignalBase, protected QOpenGLFunctions_2_1 {
-public:
+class GLWaveformRendererSimpleSignal : public WaveformRendererSignalBase,
+                                       public GLWaveformRenderer {
+  public:
     explicit GLWaveformRendererSimpleSignal(WaveformWidgetRenderer* waveformWidgetRenderer);
     virtual ~GLWaveformRendererSimpleSignal();
 
diff --git a/src/waveform/renderers/waveformrendererabstract.h b/src/waveform/renderers/waveformrendererabstract.h
index efb0a7a507..6a1bba6f6d 100644
--- a/src/waveform/renderers/waveformrendererabstract.h
+++ b/src/waveform/renderers/waveformrendererabstract.h
@@ -2,6 +2,7 @@
 #define WAVEFORMRENDERERABSTRACT_H
 
 #include <QDomNode>
+#include <QOpenGLFunctions_2_1>
 #include <QPaintEvent>
 #include <QPainter>
 
@@ -47,4 +48,16 @@ class WaveformRendererAbstract {
     friend class WaveformWidgetRenderer;
 };
 
+/// GLWaveformRenderer is a WaveformRendererAbstract which directly calls OpenGL functions.
+///
+/// Note that the Qt OpenGL WaveformRendererAbstracts are not GLWaveformRenderers because
+/// they do not call OpenGL functions directly. Instead, they inherit QGLWidget and use the
+/// QPainter API which Qt translates to OpenGL under the hood.
+class GLWaveformRenderer : protected QOpenGLFunctions_2_1 {
+  public:
+    virtual void onInitializeGL() {
+        initializeOpenGLFunctions();
+    }
+};
+
 #endif // WAVEFORMRENDERERABSTRACT_H
diff --git a/src/waveform/widgets/glrgbwaveformwidget.cpp b/src/waveform/widgets/glrgbwaveformwidget.cpp
index 271b5cb6f1..f3d6e82ce2 100644
--- a/src/waveform/widgets/glrgbwaveformwidget.cpp
+++ b/src/waveform/widgets/glrgbwaveformwidget.cpp
@@ -13,21 +13,17 @@
 #include "util/performancetimer.h"
 
 GLRGBWaveformWidget::GLRGBWaveformWidget(const QString& group, QWidget* parent)
-        : QGLWidget(parent, SharedGLContext::getWidget()),
-          WaveformWidgetAbstract(group) {
+        : GLWaveformWidgetAbstract(group, parent) {
     qDebug() << "Created QGLWidget. Context"
              << "Valid:" << context()->isValid()
              << "Sharing:" << context()->isSharing();
-    if (QGLContext::currentContext() != context()) {
-        makeCurrent();
-    }
 
     addRenderer<WaveformRenderBackground>();
     addRenderer<WaveformRendererEndOfTrack>();
     addRenderer<WaveformRendererPreroll>();
     addRenderer<WaveformRenderMarkRange>();
 #if !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
-    addRenderer<GLWaveformRendererRGB>();
+    m_pGlRenderer = addRenderer<GLWaveformRendererRGB>();
 #endif // !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
     addRenderer<WaveformRenderBeat>();
     addRenderer<WaveformRenderMark>();
diff --git a/src/waveform/widgets/glrgbwaveformwidget.h b/src/waveform/widgets/glrgbwaveformwidget.h
index d479c22d95..96bd8c166d 100644
--- a/src/waveform/widgets/glrgbwaveformwidget.h
+++ b/src/waveform/widgets/glrgbwaveformwidget.h
@@ -5,7 +5,7 @@
 
 #include "waveformwidgetabstract.h"
 
-class GLRGBWaveformWidget : public QGLWidget, public WaveformWidgetAbstract {
+class GLRGBWaveformWidget : public GLWaveformWidgetAbstract {
     Q_OBJECT
   public:
     GLRGBWaveformWidget(const QString& group, QWidget* parent);
diff --git a/src/waveform/widgets/glsimplewaveformwidget.cpp b/src/waveform/widgets/glsimplewaveformwidget.cpp
index b36dc23ed2..1d6a10dcd2 100644
--- a/src/waveform/widgets/glsimplewaveformwidget.cpp
+++ b/src/waveform/widgets/glsimplewaveformwidget.cpp
@@ -16,21 +16,17 @@
 #include "util/performancetimer.h"
 
 GLSimpleWaveformWidget::GLSimpleWaveformWidget(const QString& group, QWidget* parent)
-        : QGLWidget(parent, SharedGLContext::getWidget()),
-          WaveformWidgetAbstract(group) {
+        : GLWaveformWidgetAbstract(group, parent) {
     qDebug() << "Created QGLWidget. Context"
              << "Valid:" << context()->isValid()
              << "Sharing:" << context()->isSharing();
-    if (QGLContext::currentContext() != context()) {
-        makeCurrent();
-    }
 
     addRenderer<WaveformRenderBackground>();
     addRenderer<WaveformRendererEndOfTrack>();
     addRenderer<WaveformRendererPreroll>();
     addRenderer<WaveformRenderMarkRange>();
 #if !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
-    addRenderer<GLWaveformRendererSimpleSignal>();
+    m_pGlRenderer = addRenderer<GLWaveformRendererSimpleSignal>();
 #endif // !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
     addRenderer<WaveformRenderBeat>();
     addRenderer<WaveformRenderMark>();
diff --git a/src/waveform/widgets/glsimplewaveformwidget.h b/src/waveform/widgets/glsimplewaveformwidget.h
index 7cc3ddfc7c..00c20bfdf3 100644
--- a/src/waveform/widgets/glsimplewaveformwidget.h
+++ b/src/waveform/widgets/glsimplewaveformwidget.h
@@ -5,7 +5,7 @@
 
 #include "waveformwidgetabstract.h"
 
-class GLSimpleWaveformWidget : public QGLWidget, public WaveformWidgetAbstract {
+class GLSimpleWaveformWidget : public GLWaveformWidgetAbstract {
     Q_OBJECT
   public:
     GLSimpleWaveformWidget(const QString& group, QWidget* parent);
diff --git a/src/waveform/widgets/glslwaveformwidget.cpp b/src/waveform/widgets/glslwaveformwidget.cpp
index 6c8c22fc7b..152b710ea9 100644
--- a/src/waveform/widgets/glslwaveformwidget.cpp
+++ b/src/waveform/widgets/glslwaveformwidget.cpp
@@ -31,8 +31,7 @@ GLSLWaveformWidget::GLSLWaveformWidget(
         const QString& group,
         QWidget* parent,
         bool rgbRenderer)
-        : QGLWidget(parent, SharedGLContext::getWidget()),
-          WaveformWidgetAbstract(group) {
+        : GLWaveformWidgetAbstract(group, parent) {
     qDebug() << "Created QGLWidget. Context"
              << "Valid:" << context()->isValid()
              << "Sharing:" << context()->isSharing();
@@ -46,9 +45,9 @@ GLSLWaveformWidget::GLSLWaveformWidget(
     addRenderer<WaveformRenderMarkRange>();
 #if !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
     if (rgbRenderer) {
-        m_signalRenderer = addRenderer<GLSLWaveformRendererRGBSignal>();
+        m_pGlRenderer = addRenderer<GLSLWaveformRendererRGBSignal>();
     } else {
-        m_signalRenderer = addRenderer<GLSLWaveformRendererFilteredSignal>();
+        m_pGlRenderer = addRenderer<GLSLWaveformRendererFilteredSignal>();
     }
 #else
     Q_UNUSED(rgbRenderer);
diff --git a/src/waveform/widgets/glslwaveformwidget.h b/src/waveform/widgets/glslwaveformwidget.h
index 85baf50dcd..229bbc2fca 100644
--- a/src/waveform/widgets/glslwaveformwidget.h
+++ b/src/waveform/widgets/glslwaveformwidget.h
@@ -6,7 +6,7 @@
 
 class GLSLWaveformRendererSignal;
 
-class GLSLWaveformWidget : public QGLWidget, public WaveformWidgetAbstract {
+class GLSLWaveformWidget : public GLWaveformWidgetAbstract {
     Q_OBJECT
   public:
     GLSLWaveformWidget(
diff --git a/src/waveform/widgets/glwaveformwidget.cpp b/src/waveform/widgets/glwaveformwidget.cpp
index 071f476dcd..14cc8b97c5 100644
--- a/src/waveform/widgets/glwaveformwidget.cpp
+++ b/src/waveform/widgets/glwaveformwidget.cpp
@@ -16,21 +16,17 @@
 #include "util/performancetimer.h"
 
 GLWaveformWidget::GLWaveformWidget(const QString& group, QWidget* parent)
-        : QGLWidget(parent, SharedGLContext::getWidget()),
-          WaveformWidgetAbstract(group) {
+        : GLWaveformWidgetAbstract(group, parent) {
     qDebug() << "Created QGLWidget. Context"
              << "Valid:" << context()->isValid()
              << "Sharing:" << context()->isSharing();
-    if (QGLContext::currentContext() != context()) {
-        makeCurrent();
-    }
 
     addRenderer<WaveformRenderBackground>();
     addRenderer<WaveformRendererEndOfTrack>();
     addRenderer<WaveformRendererPreroll>();
     addRenderer<WaveformRenderMarkRange>();
 #if !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
-    addRenderer<GLWaveformRendererFilteredSignal>();
+    m_pGlRenderer = addRenderer<GLWaveformRendererFilteredSignal>();
 #endif // !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
     addRenderer<WaveformRenderBeat>();
     addRenderer<WaveformRenderMark>();
diff --git a/src/waveform/widgets/glwaveformwidget.h b/src/waveform/widgets/glwaveformwidget.h
index ea81612bca..63e186d4f4 100644
--- a/src/waveform/widgets/glwaveformwidget.h
+++ b/src/waveform/widgets/glwaveformwidget.h
@@ -5,7 +5,7 @@
 
 #include "waveformwidgetabstract.h"
 
-class GLWaveformWidget : public QGLWidget, public WaveformWidgetAbstract {
+class GLWaveformWidget : public GLWaveformWidgetAbstract {
     Q_OBJECT
   public:
     GLWaveformWidget(const QString& group, QWidget* parent);
diff --git a/src/waveform/widgets/waveformwidgetabstract.cpp b/src/waveform/widgets/waveformwidgetabstract.cpp
index 7dc1d995e0..bec1e190a3 100644
--- a/src/waveform/widgets/waveformwidgetabstract.cpp
+++ b/src/waveform/widgets/waveformwidgetabstract.cpp
@@ -1,9 +1,11 @@
 #include "waveformwidgetabstract.h"
-#include "waveform/renderers/waveformwidgetrenderer.h"
-#include "util/compatibility.h"
 
-#include <QtDebug>
 #include <QWidget>
+#include <QtDebug>
+
+#include "util/compatibility.h"
+#include "waveform/renderers/waveformwidgetrenderer.h"
+#include "waveform/sharedglcontext.h"
 
 WaveformWidgetAbstract::WaveformWidgetAbstract(const QString& group)
         : WaveformWidgetRenderer(group),
@@ -46,3 +48,8 @@ void WaveformWidgetAbstract::resize(int width, int height) {
     }
     WaveformWidgetRenderer::resize(width, height, static_cast<float>(devicePixelRatio));
 }
+
+GLWaveformWidgetAbstract::GLWaveformWidgetAbstract(const QString& group, QWidget* parent)
+        : WaveformWidgetAbstract(group),
+          QGLWidget(parent, SharedGLContext::getWidget()) {
+}
diff --git a/src/waveform/widgets/waveformwidgetabstract.h b/src/waveform/widgets/waveformwidgetabstract.h
index 5f79f2f69c..cc6df485cd 100644
--- a/src/waveform/widgets/waveformwidgetabstract.h
+++ b/src/waveform/widgets/waveformwidgetabstract.h
@@ -1,12 +1,13 @@
 #ifndef WAVEFORMWIDGETABSTRACT_H
 #define WAVEFORMWIDGETABSTRACT_H
 
-#include <QWidget>
+#include <QGLWidget>
 #include <QString>
+#include <QWidget>
 
+#include "util/duration.h"
 #include "waveform/renderers/waveformwidgetrenderer.h"
 #include "waveformwidgettype.h"
-#include "util/duration.h"
 
 class VSyncThread;
 
@@ -43,4 +44,22 @@ class WaveformWidgetAbstract : public WaveformWidgetRenderer {
     friend class WaveformWidgetFactory;
 };
 
+/// GLWaveformWidgetAbstract is a WaveformWidgetAbstract & QGLWidget that has
+/// a GLWaveformRenderer member which requires initialization that must be
+/// deferred until Qt calls QGLWidget::initializeGL and cannot be done in the
+/// constructor.
+class GLWaveformWidgetAbstract : public WaveformWidgetAbstract, public QGLWidget {
+  public:
+    GLWaveformWidgetAbstract(const QString& group, QWidget* parent);
+
+  protected:
+    void initializeGL() override {
+        if (m_pGlRenderer) {
+            m_pGlRenderer->onInitializeGL();
+        }
+    }
+
+    GLWaveformRenderer* m_pGlRenderer;
+};
+
 #endif // WAVEFORMWIDGETABSTRACT_H