[escher] Add a BankViewController

escher/Makefile

@@ -3,6 +3,7 @@ SFLAGS += -Iescher/include
 objs += $(addprefix escher/src/,\
   alternate_empty_view_controller.o\
   app.o\
+  bank_view_controller.o\
   buffer_text_view.o\
   button.o\
   button_row_controller.o\

escher/include/escher.h

@@ -4,6 +4,7 @@
 #include <escher/alternate_empty_view_controller.h>
 #include <escher/alternate_empty_view_delegate.h>
 #include <escher/app.h>
+#include <escher/bank_view_controller.h>
 #include <escher/buffer_text_view.h>
 #include <escher/button.h>
 #include <escher/button_row_controller.h>

escher/include/escher/bank_view_controller.h

@@ -0,0 +1,46 @@
+#ifndef ESCHER_BANK_VIEW_CONTROLLER_H
+#define ESCHER_BANK_VIEW_CONTROLLER_H
+
+#include <escher/view_controller.h>
+
+class BankViewController : public ViewController {
+public:
+  BankViewController(Responder * parentViewController);
+
+  virtual ViewController * childAtIndex(int i) = 0;
+  virtual int numberOfChildren() = 0;
+
+  void setActiveIndex(int i);
+  int activeIndex() const { return m_activeIndex; }
+
+  View * view() override { return &m_view; }
+  void didEnterResponderChain(Responder * previousResponder) override;
+  void viewWillAppear() override;
+  void viewDidDisappear() override;
+private:
+  class ContentView : public View {
+  public:
+    ContentView(): View(), m_subview(nullptr) {}
+    void setSubview(View * view);
+  private:
+    int numberOfSubviews() const override {
+      return m_subview == nullptr ? 0 : 1;
+    }
+    View * subviewAtIndex(int index) override {
+      assert(index == 0);
+      return m_subview;
+    }
+    void layoutSubviews() override {
+      m_subview->setFrame(bounds());
+    }
+    View * m_subview;
+  };
+  ViewController * activeViewController() {
+    assert(m_activeIndex >= 0 && m_activeIndex < numberOfChildren());
+    return childAtIndex(m_activeIndex);
+  }
+  ContentView m_view;
+  int m_activeIndex;
+};
+
+#endif

escher/src/bank_view_controller.cpp

@@ -0,0 +1,40 @@
+#include <escher/bank_view_controller.h>
+#include <escher/app.h>
+
+BankViewController::BankViewController(Responder * parentViewController) :
+  ViewController(parentViewController),
+  m_activeIndex(0)
+{
+}
+
+void BankViewController::setActiveIndex(int i) {
+  assert(i >= 0 && i < numberOfChildren());
+  if (i == m_activeIndex) {
+    return;
+  }
+  ViewController * upcomingVC = childAtIndex(i);
+  upcomingVC->viewWillAppear();
+  app()->setFirstResponder(upcomingVC);
+  childAtIndex(m_activeIndex)->viewDidDisappear();
+  m_activeIndex = i;
+  m_view.setSubview(upcomingVC->view());
+}
+
+void BankViewController::didEnterResponderChain(Responder * previousResponder) {
+  app()->setFirstResponder(activeViewController());
+}
+
+void BankViewController::viewWillAppear() {
+  m_view.setSubview(activeViewController()->view());
+  activeViewController()->viewWillAppear();
+}
+
+void BankViewController::viewDidDisappear() {
+  activeViewController()->viewDidDisappear();
+}
+
+void BankViewController::ContentView::setSubview(View * view) {
+  m_subview = view;
+  layoutSubviews();
+  markRectAsDirty(bounds());
+}