software: Add support for QSGRenderNode

Have to change getResource() a bit since it turns out it is not suitable
currently for backends that do not have a per-window rendercontext and do
not implement the interface on the rendercontext. Pass in the window to
make sure it can always figure out which window we want the resources for.
(we do not want rendererInterface() to return window-specific instances
created on the fly, with ownership issues, so stick with the simple model
where backends implement the interface on one of their existing classes)

To support clipping, QSGRenderNode::RenderState is extended accordingly.
Also updated the docs since some claims in the rendernode docs are not true
since Qt 5.3.

Change-Id: I34779c83926f5231b888fcab7131e873ae97964f
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

7 files changed, 169 insertions, 6 deletions

diff --git a/examples/quick/scenegraph/rendernode/customrenderitem.cpp b/examples/quick/scenegraph/rendernode/customrenderitem.cpp
index 433f3c5a1e..2465f4cbc7 100644
--- a/examples/quick/scenegraph/rendernode/customrenderitem.cpp
+++ b/examples/quick/scenegraph/rendernode/customrenderitem.cpp
@@ -44,6 +44,7 @@
 
 #include "openglrenderer.h"
 #include "d3d12renderer.h"
+#include "softwarerenderer.h"
 
 CustomRenderItem::CustomRenderItem(QQuickItem *parent)
     : QQuickItem(parent)
@@ -70,6 +71,10 @@ QSGNode *CustomRenderItem::updatePaintNode(QSGNode *node, UpdatePaintNodeData *)
                 n = new D3D12RenderNode(this);
                 break;
 #endif
+            case QSGRendererInterface::Software:
+                n = new SoftwareRenderNode(this);
+                break;
+
             default:
                 return nullptr;
         }
diff --git a/examples/quick/scenegraph/rendernode/d3d12renderer.cpp b/examples/quick/scenegraph/rendernode/d3d12renderer.cpp
index b7dc62fe86..f475ec838b 100644
--- a/examples/quick/scenegraph/rendernode/d3d12renderer.cpp
+++ b/examples/quick/scenegraph/rendernode/d3d12renderer.cpp
@@ -78,7 +78,7 @@ void D3D12RenderNode::releaseResources()
 void D3D12RenderNode::init()
 {
     QSGRendererInterface *rif = m_item->window()->rendererInterface();
-    m_device = static_cast<ID3D12Device *>(rif->getResource(QSGRendererInterface::Device));
+    m_device = static_cast<ID3D12Device *>(rif->getResource(m_item->window(), QSGRendererInterface::Device));
     Q_ASSERT(m_device);
 
     D3D12_ROOT_PARAMETER rootParameter;
@@ -235,7 +235,7 @@ void D3D12RenderNode::render(const RenderState *state)
         init();
 
     QSGRendererInterface *rif = m_item->window()->rendererInterface();
-    ID3D12GraphicsCommandList *commandList = static_cast<ID3D12GraphicsCommandList *>(rif->getResource(QSGRendererInterface::CommandList));
+    ID3D12GraphicsCommandList *commandList = static_cast<ID3D12GraphicsCommandList *>(rif->getResource(m_item->window(), QSGRendererInterface::CommandList));
     Q_ASSERT(commandList);
 
     const int msize = 16 * sizeof(float);
diff --git a/examples/quick/scenegraph/rendernode/main.qml b/examples/quick/scenegraph/rendernode/main.qml
index a91656dfaa..7c8d82181f 100644
--- a/examples/quick/scenegraph/rendernode/main.qml
+++ b/examples/quick/scenegraph/rendernode/main.qml
@@ -90,7 +90,10 @@ Item {
             anchors.margins: 20
             wrapMode: Text.WordWrap
             property int api: GraphicsInfo.api
-            text: "Custom rendering via the graphics API " + (api === GraphicsInfo.OpenGL ? "OpenGL" : (api === GraphicsInfo.Direct3D12 ? "Direct3D 12" : ""))
+            text: "Custom rendering via the graphics API "
+                  + (api === GraphicsInfo.OpenGL ? "OpenGL"
+                     : api === GraphicsInfo.Direct3D12 ? "Direct3D 12"
+                     : api === GraphicsInfo.Software ? "Software" : "")
             color: "yellow"
         }
     }
diff --git a/examples/quick/scenegraph/rendernode/openglrenderer.cpp b/examples/quick/scenegraph/rendernode/openglrenderer.cpp
index 3eff70cb42..33c59198b8 100644
--- a/examples/quick/scenegraph/rendernode/openglrenderer.cpp
+++ b/examples/quick/scenegraph/rendernode/openglrenderer.cpp
@@ -97,8 +97,6 @@ void OpenGLRenderNode::init()
 
     const int VERTEX_SIZE = 6 * sizeof(GLfloat);
 
-    // A fully featured renderer should also take inheritedOpacity() into account
-    // and blend, but ignore that for now.
     static GLfloat colors[] = {
         1.0f, 0.0f, 0.0f,
         0.0f, 1.0f, 0.0f,
@@ -140,6 +138,8 @@ void OpenGLRenderNode::render(const RenderState *state)
     m_program->enableAttributeArray(0);
     m_program->enableAttributeArray(1);
 
+    // Note that clipping (scissor or stencil) is ignored in this example.
+
     f->glEnable(GL_BLEND);
     f->glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
 
diff --git a/examples/quick/scenegraph/rendernode/rendernode.pro b/examples/quick/scenegraph/rendernode/rendernode.pro
index d7ae715a7d..851d5927bd 100644
--- a/examples/quick/scenegraph/rendernode/rendernode.pro
+++ b/examples/quick/scenegraph/rendernode/rendernode.pro
@@ -1,10 +1,12 @@
 QT += qml quick
 
 HEADERS += customrenderitem.h \
-           openglrenderer.h
+           openglrenderer.h \
+           softwarerenderer.h
 
 SOURCES += customrenderitem.cpp \
            openglrenderer.cpp \
+           softwarerenderer.cpp \
            main.cpp
 
 RESOURCES += rendernode.qrc
diff --git a/examples/quick/scenegraph/rendernode/softwarerenderer.cpp b/examples/quick/scenegraph/rendernode/softwarerenderer.cpp
new file mode 100644
index 0000000000..2f11c56f29
--- /dev/null
+++ b/examples/quick/scenegraph/rendernode/softwarerenderer.cpp
@@ -0,0 +1,91 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "softwarerenderer.h"
+#include <QQuickItem>
+#include <QQuickWindow>
+#include <QSGRendererInterface>
+#include <QPainter>
+
+SoftwareRenderNode::SoftwareRenderNode(QQuickItem *item)
+    : m_item(item)
+{
+}
+
+SoftwareRenderNode::~SoftwareRenderNode()
+{
+    releaseResources();
+}
+
+void SoftwareRenderNode::releaseResources()
+{
+}
+
+void SoftwareRenderNode::render(const RenderState *renderState)
+{
+    QSGRendererInterface *rif = m_item->window()->rendererInterface();
+    QPainter *p = static_cast<QPainter *>(rif->getResource(m_item->window(), QSGRendererInterface::Painter));
+    Q_ASSERT(p);
+
+    p->setTransform(matrix()->toTransform());
+    p->setOpacity(inheritedOpacity());
+    const QRegion *clipRegion = renderState->clipRegion();
+    if (clipRegion && !clipRegion->isEmpty())
+        p->setClipRegion(*clipRegion);
+
+    const QPointF p0(m_item->width() - 1, m_item->height() - 1);
+    const QPointF p1(0, 0);
+    const QPointF p2(0, m_item->height() - 1);
+    QPainterPath path(p0);
+    path.lineTo(p1);
+    path.lineTo(p2);
+    path.closeSubpath();
+
+    QLinearGradient gradient(QPointF(0, 0), QPointF(m_item->width(), m_item->height()));
+    gradient.setColorAt(0, Qt::green);
+    gradient.setColorAt(1, Qt::red);
+
+    p->fillPath(path, gradient);
+}
+
+QSGRenderNode::StateFlags SoftwareRenderNode::changedStates() const
+{
+    return 0;
+}
diff --git a/examples/quick/scenegraph/rendernode/softwarerenderer.h b/examples/quick/scenegraph/rendernode/softwarerenderer.h
new file mode 100644
index 0000000000..60036f96a1
--- /dev/null
+++ b/examples/quick/scenegraph/rendernode/softwarerenderer.h
@@ -0,0 +1,62 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef SOFTWARERENDERER_H
+#define SOFTWARERENDERER_H
+
+#include <qsgrendernode.h>
+
+class QQuickItem;
+
+class SoftwareRenderNode : public QSGRenderNode
+{
+public:
+    SoftwareRenderNode(QQuickItem *item);
+    ~SoftwareRenderNode();
+
+    void render(const RenderState *state) override;
+    void releaseResources() override;
+    StateFlags changedStates() const override;
+
+private:
+    QQuickItem *m_item;
+};
+
+#endif