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50
51#include "glextensions.h"
52#include "scene.h"
53
54#include <QGLWidget>
55#include <QtWidgets>
56
57class GraphicsView : public QGraphicsView
58{
59public:
60 GraphicsView()
61 {
62 setWindowTitle(tr(s: "Boxes"));
63 setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
64 //setRenderHints(QPainter::SmoothPixmapTransform);
65 }
66
67protected:
68 void resizeEvent(QResizeEvent *event) override {
69 if (scene())
70 scene()->setSceneRect(QRect(QPoint(0, 0), event->size()));
71 QGraphicsView::resizeEvent(event);
72 }
73};
74
75inline bool matchString(const char *extensionString, const char *subString)
76{
77 int subStringLength = strlen(s: subString);
78 return (strncmp(s1: extensionString, s2: subString, n: subStringLength) == 0)
79 && ((extensionString[subStringLength] == ' ') || (extensionString[subStringLength] == '\0'));
80}
81
82bool necessaryExtensionsSupported()
83{
84 const char *extensionString = reinterpret_cast<const char *>(glGetString(GL_EXTENSIONS));
85 const char *p = extensionString;
86
87 const int GL_EXT_FBO = 1;
88 const int GL_ARB_VS = 2;
89 const int GL_ARB_FS = 4;
90 const int GL_ARB_SO = 8;
91 int extensions = 0;
92
93 while (*p) {
94 if (matchString(extensionString: p, subString: "GL_EXT_framebuffer_object"))
95 extensions |= GL_EXT_FBO;
96 else if (matchString(extensionString: p, subString: "GL_ARB_vertex_shader"))
97 extensions |= GL_ARB_VS;
98 else if (matchString(extensionString: p, subString: "GL_ARB_fragment_shader"))
99 extensions |= GL_ARB_FS;
100 else if (matchString(extensionString: p, subString: "GL_ARB_shader_objects"))
101 extensions |= GL_ARB_SO;
102 while ((*p != ' ') && (*p != '\0'))
103 ++p;
104 if (*p == ' ')
105 ++p;
106 }
107 return (extensions == 15);
108}
109
110int main(int argc, char **argv)
111{
112 QApplication app(argc, argv);
113
114 if ((QGLFormat::openGLVersionFlags() & QGLFormat::OpenGL_Version_1_5) == 0) {
115 QMessageBox::critical(parent: nullptr, title: "OpenGL features missing",
116 text: "OpenGL version 1.5 or higher is required to run this demo.\n"
117 "The program will now exit.");
118 return -1;
119 }
120
121 int maxTextureSize = 1024;
122 QGLWidget *widget = new QGLWidget(QGLFormat(QGL::SampleBuffers));
123 widget->makeCurrent();
124
125 if (!necessaryExtensionsSupported()) {
126 QMessageBox::critical(parent: nullptr, title: "OpenGL features missing",
127 text: "The OpenGL extensions required to run this demo are missing.\n"
128 "The program will now exit.");
129 delete widget;
130 return -2;
131 }
132
133 // Check if all the necessary functions are resolved.
134 if (!getGLExtensionFunctions().resolve(context: widget->context())) {
135 QMessageBox::critical(parent: nullptr, title: "OpenGL features missing",
136 text: "Failed to resolve OpenGL functions required to run this demo.\n"
137 "The program will now exit.");
138 delete widget;
139 return -3;
140 }
141
142 // TODO: Make conditional for final release
143 QMessageBox::information(parent: nullptr, title: "For your information",
144 text: "This demo can be GPU and CPU intensive and may\n"
145 "work poorly or not at all on your system.");
146
147 widget->makeCurrent(); // The current context must be set before calling Scene's constructor
148 Scene scene(1024, 768, maxTextureSize);
149 GraphicsView view;
150 view.setViewport(widget);
151 view.setViewportUpdateMode(QGraphicsView::FullViewportUpdate);
152 view.setScene(&scene);
153 view.show();
154
155 return app.exec();
156}
157
158

source code of qtbase/examples/widgets/graphicsview/boxes/main.cpp