From 8459fc47feb4647acd1a306b4cfb2ef7094d7588 Mon Sep 17 00:00:00 2001
From: Atul R <atulanand94@gmail.com>
Date: Sun, 26 May 2019 20:25:45 +0200
Subject: [PATCH] Adds custom flex layout manager based on yoga

---
 config/application.gypi                |   1 +
 src/cpp/core/FlexLayout/flexlayout.cpp | 105 +++++++++++++++++++++++++
 src/cpp/core/FlexLayout/flexlayout.h   |  32 ++++++++
 3 files changed, 138 insertions(+)
 create mode 100644 src/cpp/core/FlexLayout/flexlayout.cpp
 create mode 100644 src/cpp/core/FlexLayout/flexlayout.h

diff --git a/config/application.gypi b/config/application.gypi
index 3f846ad5d..4d8b95ca1 100644
--- a/config/application.gypi
+++ b/config/application.gypi
@@ -9,6 +9,7 @@
                 "../src/cpp/main.cpp",
                 # non-wrapped cpps
                 "../src/cpp/Extras/Utils/utils.cpp",
+                "../src/cpp/core/FlexLayout/flexlayout.cpp",
                 # wrapped cpps
                 "../src/cpp/QtGui/QApplication/qapplication_wrap.cpp",
                 "../src/cpp/QtGui/QWidget/qwidget_wrap.cpp",
diff --git a/src/cpp/core/FlexLayout/flexlayout.cpp b/src/cpp/core/FlexLayout/flexlayout.cpp
new file mode 100644
index 000000000..9077466a1
--- /dev/null
+++ b/src/cpp/core/FlexLayout/flexlayout.cpp
@@ -0,0 +1,105 @@
+#include "flexlayout.h"
+#include <QDebug>
+#include <QPushButton>
+
+FlexLayout::NodeContext *FlexLayout::getNodeContext(YGNodeRef node) const
+{
+    void* childContext = YGNodeGetContext(node);
+    NodeContext *ctx = reinterpret_cast<NodeContext*>(childContext);
+    return ctx;
+}
+
+FlexLayout::FlexLayout(QWidget *parentWidget, YGNodeRef parentNode): QLayout(parentWidget)
+{
+    this->node = parentNode;
+}
+
+FlexLayout::~FlexLayout()
+{
+    const uint32_t childCount = YGNodeGetChildCount(this->node);
+    for (uint32_t i = 0; i < childCount; i++) {
+        const YGNodeRef oldChild = YGNodeGetChild(this->node, i);
+        NodeContext* ctx = getNodeContext(oldChild);
+        delete ctx->item;
+    }
+    YGNodeRemoveAllChildren(this->node);
+}
+
+QSize FlexLayout::sizeHint() const{
+    QSize size;
+    int width = static_cast<int>(YGNodeLayoutGetWidth(this->node));
+    int height = static_cast<int>(YGNodeLayoutGetHeight(this->node));
+    size.setWidth(width);
+    size.setHeight(height);
+    return size;
+}
+
+void FlexLayout::addItem(QLayoutItem * item){
+    qDebug() <<"Unsupported method addItem. item:"<<item<<". Use FlexLayout::addWidget instead";
+}
+
+QLayoutItem *FlexLayout::itemAt(int index) const
+{
+    YGNodeRef childNode = YGNodeGetChild(this->node, static_cast<uint>(index));
+    NodeContext *ctx = getNodeContext(childNode);
+    return ctx->item;
+}
+
+QLayoutItem *FlexLayout::takeAt(int index)
+{
+
+    YGNodeRef childNode = YGNodeGetChild(this->node, static_cast<uint>(index));
+    NodeContext *ctx = getNodeContext(childNode);
+    QLayoutItem* childLayoutItem = ctx->item;
+    YGNodeRemoveChild(this->node, childNode);
+    delete ctx;
+    return childLayoutItem;
+}
+
+int FlexLayout::count() const
+{
+    return static_cast<int>(YGNodeGetChildCount(this->node));
+
+}
+
+void FlexLayout::addWidget(QWidget* childWidget, YGNodeRef childNode)
+{
+    uint count =  YGNodeGetChildCount(this->node);
+    YGNodeInsertChild(this->node,childNode, count);
+    QLayoutItem* layoutItem = new QWidgetItem(childWidget);
+    NodeContext* childContext = new NodeContext(layoutItem);
+    YGNodeSetContext(childNode, static_cast<void *>(childContext));
+}
+
+void FlexLayout::setGeometry(const QRect &rect)
+{
+
+    int availableWidth = rect.width();
+    int availableHeight = rect.height();
+    YGDirection direction = YGDirection::YGDirectionLTR; //TODO
+
+    YGNodeCalculateLayout(this->node,availableWidth,availableHeight,direction);
+
+    uint count = YGNodeGetChildCount(this->node);
+
+    for (uint i = 0; i < count; ++i) {
+        YGNode *childNode = YGNodeGetChild(this->node, i);
+        int width = static_cast<int>(YGNodeLayoutGetWidth(childNode));
+        int height = static_cast<int>(YGNodeLayoutGetHeight(childNode));
+        int left = static_cast<int>(YGNodeLayoutGetLeft(childNode));
+        int top = static_cast<int>(YGNodeLayoutGetTop(childNode));
+
+        QRect childRect(left, top,width, height);
+        NodeContext *ctx =  getNodeContext(childNode);
+        QLayoutItem* childLayoutItem = ctx->item;
+        QWidget* childWidget = childLayoutItem->widget();
+
+        if(childWidget){
+            childWidget->setGeometry(childRect);
+        }else {
+           childLayoutItem->setGeometry(childRect);
+        }
+    }
+      QLayout::setGeometry(rect);
+}
+
diff --git a/src/cpp/core/FlexLayout/flexlayout.h b/src/cpp/core/FlexLayout/flexlayout.h
new file mode 100644
index 000000000..d080c2686
--- /dev/null
+++ b/src/cpp/core/FlexLayout/flexlayout.h
@@ -0,0 +1,32 @@
+#ifndef FLEXLAYOUT_H
+#define FLEXLAYOUT_H
+
+#include "deps/yoga/YGNode.h"
+#include <QLayout>
+
+class FlexLayout: public QLayout
+{
+private:
+    YGNodeRef node;
+    struct NodeContext
+    {
+        NodeContext(QLayoutItem *i) {
+            item = i;
+        }
+        QLayoutItem *item;
+    };
+    NodeContext* getNodeContext(YGNodeRef node) const;
+
+public:
+    FlexLayout(QWidget* parentWidget, YGNodeRef parentNode);
+    ~FlexLayout() override;
+    QSize sizeHint() const override;
+    void addItem(QLayoutItem *) override;
+    QLayoutItem *itemAt(int index) const override;
+    QLayoutItem *takeAt(int index) override;
+    int count() const override;
+    void addWidget(QWidget* childWidget, YGNodeRef childNode);
+    void setGeometry(const QRect &rect) override;
+};
+
+#endif // FLEXLAYOUT_H