rhi: gl: Add support for importing an existing renderbuffer object

Normally we only allow creating wrappers for texture objects. These
can then be used with a QRhiTextureRenderTarget to allow rendering into
an externally created texture.

With OpenGL (ES), there are additional, special cases, especially on
embedded. Consider EGLImages for example. An EGLImageKHR can be bound to
a renderbuffer object (glEGLImageTargetRenderbufferStorageOES), which
can then be associated with a framebuffer object to allow rendering into
the external buffer represented by the EGLImage. To implement the same
via QRhi one needs a way to create a wrapping QRhiRenderBuffer for the
native OpenGL renderbuffer object.

Here we add a createFrom() to QRhiRenderBuffer, while providing a dummy,
default implementation. The only real implementation is in the OpenGL
backend, which simply takes a renderbuffer id, without taking ownership.

Task-number: QTBUG-92116
Change-Id: I4e68e665fb35a7d7803b7780db901c8bed5740e2
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/gui/rhi/qrhimetal.mm b/src/gui/rhi/qrhimetal.mm
index 850b3a91aa..384e23598c 100644
--- a/src/gui/rhi/qrhimetal.mm
+++ b/src/gui/rhi/qrhimetal.mm
@@ -595,6 +595,8 @@ bool QRhiMetal::isFeatureSupported(QRhi::Feature feature) const
         return false;
     case QRhi::ImageDataStride:
         return true;
+    case QRhi::RenderBufferImport:
+        return false;
     default:
         Q_UNREACHABLE();
         return false;