LazOpenGLContextEx: TOpenGLControl с Qt-бэкендом на QOpenGLWidget

Форк штатного пакета LazOpenGLContext (Lazarus components/opengl).
Qt5/Qt6-бэкенд (glqtnativecontext.pas) использует собственный контекст
настоящего QOpenGLWidget вместо ручного GLX на winId(): EGL на Wayland,
GLX на X11, WGL/CGL на Windows/macOS под ws=qt6.

QOpenGLWidget-наследник с paintGL-хуком живёт в маленькой C++-либе
csrc/qlclglwidget.cpp (QLCLOpenGLWidget из libQt6Pas — не QOpenGLWidget,
а голый QWidget под внешний GLX). Сборка: csrc/Makefile
(linux/macos/windows-кросс mingw-w64/windows-native MSYS2, install,
install-app) + build-msvc.bat для MSVC-Qt. Либа грузится в рантайме
рядом с бинарником приложения.

Бэкенды gtk2/gtk3/win32/cocoa скопированы из стока без изменений
(юниты переименованы с суффиксом Ex). Детали и нюансы — в README.md.

Проверено: EWSDR, спектр/водопад через GL в нативном Wayland (KDE, qt6),
живой эфир QO-100.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

csrc/qlclglwidget.cpp

@@ -0,0 +1,124 @@
+//******************************************************************************
+// qlclglwidget - a real QOpenGLWidget subclass with a Pascal paintGL hook.
+//
+// libQt6Pas's QLCLOpenGLWidget is NOT a QOpenGLWidget: it is a plain QWidget
+// with WA_NativeWindow/paintEngine()=nullptr, designed as a target for an
+// external GLX context (X11 only). This tiny library provides the missing
+// piece: a genuine QOpenGLWidget whose context is created and managed by Qt
+// itself (EGL on Wayland, GLX on X11, WGL on Windows, CGL on macOS), plus
+// flat C exports for the methods the Lazarus side needs.
+//
+// Build: make            (Linux .so / macOS .dylib)
+//        make windows    (cross-build .dll with mingw-w64, see Makefile)
+//        make install    (into /usr/local/lib)
+//******************************************************************************
+
+#include <QOpenGLWidget>
+#include <QOpenGLContext>
+#include <QOpenGLFunctions>
+#include <QSurfaceFormat>
+
+// mirrors QHook/QOverrideHook from libQt6Pas pascalbind.h:
+// an FPC "procedure of object; cdecl" method pointer passed by value
+typedef struct {
+  void *func;
+  void *data;
+} QGLOverrideHook;
+
+class QLCLGLWidget : public QOpenGLWidget {
+public:
+  QGLOverrideHook paintGLHook;
+  // The widget renders into an RGBA FBO that Qt composites with alpha into
+  // the window. Legacy GL code written for GLX/WGL windows leaves arbitrary
+  // alpha in the framebuffer (there it was simply ignored), which makes the
+  // widget translucent here. Unless the user explicitly asked for an alpha
+  // channel, force alpha to 1 after each paint.
+  bool forceOpaque;
+
+  explicit QLCLGLWidget(QWidget *parent = nullptr,
+                        Qt::WindowFlags flags = Qt::WindowFlags())
+      : QOpenGLWidget(parent, flags) {
+    paintGLHook.func = nullptr;
+    paintGLHook.data = nullptr;
+    forceOpaque = true;
+  }
+
+protected:
+  // Qt makes the context current and binds the widget's FBO before this call
+  void paintGL() override {
+    if (paintGLHook.func) {
+      typedef void (*func_type)(void *data);
+      (*(func_type)paintGLHook.func)(paintGLHook.data);
+      if (forceOpaque)
+        fillAlpha();
+    } else {
+      QOpenGLWidget::paintGL();
+    }
+  }
+
+private:
+  void fillAlpha() {
+    QOpenGLFunctions *f = QOpenGLContext::currentContext()->functions();
+    GLboolean mask[4];
+    GLfloat clearColor[4];
+    f->glGetBooleanv(GL_COLOR_WRITEMASK, mask);
+    f->glGetFloatv(GL_COLOR_CLEAR_VALUE, clearColor);
+    GLboolean scissor = f->glIsEnabled(GL_SCISSOR_TEST);
+    if (scissor)
+      f->glDisable(GL_SCISSOR_TEST);
+    f->glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_TRUE);
+    f->glClearColor(0.f, 0.f, 0.f, 1.f);
+    f->glClear(GL_COLOR_BUFFER_BIT);
+    f->glColorMask(mask[0], mask[1], mask[2], mask[3]);
+    f->glClearColor(clearColor[0], clearColor[1], clearColor[2], clearColor[3]);
+    if (scissor)
+      f->glEnable(GL_SCISSOR_TEST);
+  }
+};
+
+extern "C" {
+
+Q_DECL_EXPORT void *QLCLGLWidget_Create(void *parent, unsigned int flags) {
+  return (void *)new QLCLGLWidget((QWidget *)parent, (Qt::WindowFlags)flags);
+}
+
+Q_DECL_EXPORT void QLCLGLWidget_Destroy(void *handle) {
+  delete (QLCLGLWidget *)handle;
+}
+
+Q_DECL_EXPORT void QLCLGLWidget_override_paintGL(void *handle,
+                                                 QGLOverrideHook hook) {
+  ((QLCLGLWidget *)handle)->paintGLHook = hook;
+}
+
+Q_DECL_EXPORT void QLCLGLWidget_makeCurrent(void *handle) {
+  ((QLCLGLWidget *)handle)->makeCurrent();
+}
+
+Q_DECL_EXPORT void QLCLGLWidget_doneCurrent(void *handle) {
+  ((QLCLGLWidget *)handle)->doneCurrent();
+}
+
+Q_DECL_EXPORT bool QLCLGLWidget_isValid(void *handle) {
+  return ((QLCLGLWidget *)handle)->isValid();
+}
+
+// fmt is a QSurfaceFormatH created via libQt6Pas QSurfaceFormat_Create
+Q_DECL_EXPORT void QLCLGLWidget_setFormat(void *handle, void *fmt) {
+  ((QLCLGLWidget *)handle)->setFormat(*(const QSurfaceFormat *)fmt);
+}
+
+// enabled by default; pass false when the control requests AlphaBits > 0
+Q_DECL_EXPORT void QLCLGLWidget_setForceOpaque(void *handle, bool enable) {
+  ((QLCLGLWidget *)handle)->forceOpaque = enable;
+}
+
+Q_DECL_EXPORT unsigned int QLCLGLWidget_defaultFramebufferObject(void *handle) {
+  return ((QLCLGLWidget *)handle)->defaultFramebufferObject();
+}
+
+Q_DECL_EXPORT double QLCLGLWidget_devicePixelRatioF(void *handle) {
+  return ((QLCLGLWidget *)handle)->devicePixelRatioF();
+}
+
+} // extern "C"