Support RGB30 formats in OpenGL framebuffers and paint engine

This patch adds support for binding RGB30 images as textures, and as
internal format of framebuffer objects. Together with the
QOpenGLPaintDevice
this provides support for rendering to and from RGB30 in full precision.

[ChangeLog][QtGui][QOpenGLFramebufferObject] Support 10-bit per color
channels formats as the internal framebuffer format, making it possible
to render in that precision.

Change-Id: I06de2d12dfe1c1adc466d574fdffbc77f88f4f16
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

1 files changed, 109 insertions, 1 deletions

diff --git a/tests/auto/gui/qopengl/tst_qopengl.cpp b/tests/auto/gui/qopengl/tst_qopengl.cpp
index 972c2a7ea4..6d83defdeb 100644
--- a/tests/auto/gui/qopengl/tst_qopengl.cpp
+++ b/tests/auto/gui/qopengl/tst_qopengl.cpp
@@ -43,6 +43,7 @@
 #include <QtGui/private/qopenglcontext_p.h>
 #include <QtGui/QOpenGLFramebufferObject>
 #include <QtGui/QOpenGLFunctions>
+#include <QtGui/QOpenGLFunctions_4_2_Core>
 #include <QtGui/QOpenGLVertexArrayObject>
 #include <QtGui/QOpenGLPaintDevice>
 #include <QtGui/QPainter>
@@ -88,6 +89,8 @@ private slots:
     void fboTextureOwnership();
     void fboRendering_data();
     void fboRendering();
+    void fboRenderingRGB30_data();
+    void fboRenderingRGB30();
     void fboHandleNulledAfterContextDestroyed();
     void openGLPaintDevice_data();
     void openGLPaintDevice();
@@ -563,7 +566,7 @@ void tst_QOpenGL::fboRendering()
     QOpenGLFramebufferObjectFormat fboFormat;
     fboFormat.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
 
-    // Uncomplicate things by using NPOT:
+    // Uncomplicate things by using POT:
     const QSize size(256, 128);
     QOpenGLFramebufferObject fbo(size, fboFormat);
 
@@ -587,6 +590,111 @@ void tst_QOpenGL::fboRendering()
     qt_opengl_check_test_pattern(fb);
 }
 
+void tst_QOpenGL::fboRenderingRGB30_data()
+{
+    common_data();
+}
+
+#ifndef GL_RGB10_A2
+#define GL_RGB10_A2                       0x8059
+#endif
+
+#ifndef GL_FRAMEBUFFER_RENDERABLE
+#define GL_FRAMEBUFFER_RENDERABLE         0x8289
+#endif
+
+#ifndef GL_FULL_SUPPORT
+#define GL_FULL_SUPPORT                   0x82B7
+#endif
+
+void tst_QOpenGL::fboRenderingRGB30()
+{
+#if defined(Q_OS_LINUX) && defined(Q_CC_GNU) && !defined(__x86_64__)
+    QSKIP("QTBUG-22617");
+#endif
+
+    QFETCH(int, surfaceClass);
+    QScopedPointer<QSurface> surface(createSurface(surfaceClass));
+
+    QOpenGLContext ctx;
+    QVERIFY(ctx.create());
+
+    QVERIFY(ctx.makeCurrent(surface.data()));
+
+    if (!QOpenGLFramebufferObject::hasOpenGLFramebufferObjects())
+        QSKIP("QOpenGLFramebufferObject not supported on this platform");
+
+    if (ctx.format().majorVersion() < 3)
+        QSKIP("An internal RGB30_A2 format is not guaranteed on this platform");
+
+#if !defined(QT_NO_OPENGL) && !defined(QT_OPENGL_ES_2)
+    // NVidia currently only supports RGB30 and RGB30_A2 in their Quadro drivers,
+    // but they do provide an extension for querying the support. We use the query
+    // in case they implement the required formats later.
+    if (!ctx.isOpenGLES() && ctx.format().majorVersion() >= 4) {
+        GLint value = -1;
+        QOpenGLFunctions_4_2_Core* vFuncs = ctx.versionFunctions<QOpenGLFunctions_4_2_Core>();
+        if (vFuncs && vFuncs->initializeOpenGLFunctions()) {
+            vFuncs->glGetInternalformativ(GL_TEXTURE_2D, GL_RGB10_A2, GL_FRAMEBUFFER_RENDERABLE, 1, &value);
+            if (value != GL_FULL_SUPPORT)
+                QSKIP("The required RGB30_A2 format is not supported by this driver");
+        }
+    }
+#endif
+
+    // No multisample with combined depth/stencil attachment:
+    QOpenGLFramebufferObjectFormat fboFormat;
+    fboFormat.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
+    fboFormat.setInternalTextureFormat(GL_RGB10_A2);
+
+    // Uncomplicate things by using POT:
+    const QSize size(256, 128);
+    QOpenGLFramebufferObject fbo(size, fboFormat);
+
+    if (fbo.attachment() != QOpenGLFramebufferObject::CombinedDepthStencil)
+        QSKIP("FBOs missing combined depth~stencil support");
+
+    QVERIFY(fbo.bind());
+
+    QPainter fboPainter;
+    QOpenGLPaintDevice device(fbo.width(), fbo.height());
+    bool painterBegun = fboPainter.begin(&device);
+    QVERIFY(painterBegun);
+
+    qt_opengl_draw_test_pattern(&fboPainter, fbo.width(), fbo.height());
+
+    fboPainter.end();
+
+    QImage fb = fbo.toImage();
+    QCOMPARE(fb.format(), QImage::Format_A2BGR30_Premultiplied);
+    QCOMPARE(fb.size(), size);
+
+    qt_opengl_check_test_pattern(fb);
+
+    // Check rendering can handle color values below 1/256.
+    fboPainter.begin(&device);
+    fboPainter.fillRect(QRect(0, 0, 256, 128), QColor::fromRgbF(1.0/512, 1.0/512, 1.0/512));
+    fboPainter.end();
+    fb = fbo.toImage();
+    uint pixel = ((uint*)fb.bits())[0];
+    QVERIFY((pixel & 0x3f) > 0);
+    QVERIFY(((pixel >> 10) & 0x3f) > 0);
+    QVERIFY(((pixel >> 20) & 0x3f) > 0);
+
+    pixel = (3U << 30) | (2U << 20) | (2U << 10) | 2U;
+    fb.fill(pixel);
+
+    fboPainter.begin(&device);
+    fboPainter.setCompositionMode(QPainter::CompositionMode_Source);
+    fboPainter.drawImage(0, 0, fb);
+    fboPainter.end();
+    fb = fbo.toImage();
+    pixel = ((uint*)fb.bits())[0];
+    QVERIFY((pixel & 0x3f) > 0);
+    QVERIFY(((pixel >> 10) & 0x3f) > 0);
+    QVERIFY(((pixel >> 20) & 0x3f) > 0);
+}
+
 void tst_QOpenGL::fboHandleNulledAfterContextDestroyed()
 {
     QWindow window;