[escher/scroll_view] Add arrow indicators

escher/include/escher/scroll_view.h

@@ -43,6 +43,22 @@ public:
     KDCoordinate m_barsFrameBreadth;
   };
 
+  class DecoratorV2 {
+  public:
+    DecoratorV2();
+    int numberOfIndicators() { return 4; }
+    View * indicatorAtIndex(int index) {
+      assert(0 < index && index <= numberOfIndicators());
+      return &m_topArrow + (index-1);
+    }
+    void layoutIndicators(KDSize content, KDPoint offset, KDSize frame);
+  private:
+    ScrollViewArrow m_topArrow;
+    ScrollViewArrow m_rightArrow;
+    ScrollViewArrow m_bottomArrow;
+    ScrollViewArrow m_leftArrow;
+  };
+
   Decorator * decorator() { return &m_decorator; }
   void setShowsIndicators(bool s) { m_showsIndicators = s; }
   bool showsIndicators() const { return m_showsIndicators; }

escher/include/escher/scroll_view_indicator.h

@@ -43,4 +43,21 @@ private:
   KDCoordinate totalLength() const { return m_frame.height() - 2*m_margin; }
 };
 
+class ScrollViewArrow : public ScrollViewIndicator {
+public:
+  enum Side : char { //FIXME
+    Top = 't',
+    Right = '>',
+    Bottom = 'b',
+    Left = '<'
+  };
+  ScrollViewArrow(Side side);
+  bool update(bool visible);
+  void drawRect(KDContext * ctx, KDRect rect) const override;
+private:
+  bool m_visible;
+  const char m_arrow;
+  KDColor m_backgroundColor;
+};
+
 #endif

escher/src/scroll_view.cpp

@@ -175,6 +175,38 @@ void ScrollView::Decorator::layoutIndicators(KDSize content, KDPoint offset, KDS
   ));
 }
 
+ScrollView::DecoratorV2::DecoratorV2() :
+  m_topArrow(ScrollViewArrow::Side::Top),
+  m_rightArrow(ScrollViewArrow::Side::Right),
+  m_bottomArrow(ScrollViewArrow::Side::Bottom),
+  m_leftArrow(ScrollViewArrow::Side::Left)
+{
+}
+
+void ScrollView::DecoratorV2::layoutIndicators(KDSize content, KDPoint offset, KDSize frame) {
+  KDSize arrowSize = KDFont::LargeFont->glyphSize();
+  KDCoordinate topArrowFrameBreadth = arrowSize.height() * m_topArrow.update(0 < offset.y());
+  KDCoordinate rightArrowFrameBreadth = arrowSize.width() * m_rightArrow.update(offset.x() + frame.width() < content.width());
+  KDCoordinate bottomArrowFrameBreadth = arrowSize.height() * m_bottomArrow.update(offset.y() + frame.height() < content.height());
+  KDCoordinate leftArrowFrameBreadth = arrowSize.width() * m_leftArrow.update(0 < offset.x());
+  m_topArrow.setFrame(KDRect(
+    0, 0,
+    frame.width(), topArrowFrameBreadth
+  ));
+  m_rightArrow.setFrame(KDRect(
+    frame.width() - rightArrowFrameBreadth, 0,
+    rightArrowFrameBreadth, frame.height()
+  ));
+  m_bottomArrow.setFrame(KDRect(
+    0, frame.height() - bottomArrowFrameBreadth,
+    frame.width(), bottomArrowFrameBreadth
+  ));
+  m_leftArrow.setFrame(KDRect(
+    0, 0,
+    leftArrowFrameBreadth, frame.height()
+  ));
+}
+
 #if ESCHER_VIEW_LOGGING
 const char * ScrollView::className() const {
   return "ScrollView";

escher/src/scroll_view_indicator.cpp

@@ -72,6 +72,30 @@ void ScrollViewVerticalBar::drawRect(KDContext * ctx, KDRect rect) const {
   );
 }
 
+ScrollViewArrow::ScrollViewArrow(Side side) :
+  m_visible(false),
+  m_arrow(side)
+{
+}
+
+bool ScrollViewArrow::update(bool visible) {
+  if (m_visible != visible) {
+    markRectAsDirty(bounds());
+  }
+  m_visible = visible;
+  return visible;
+}
+
+void ScrollViewArrow::drawRect(KDContext * ctx, KDRect rect) const {
+  ctx->fillRect(bounds(), m_backgroundColor);
+  KDSize arrowSize = KDFont::LargeFont->glyphSize();
+  const KDPoint arrowAlign = KDPoint(
+    (m_arrow == Top || m_arrow == Bottom) * (m_frame.width() - arrowSize.width()) / 2,
+    (m_arrow == Left || m_arrow == Right) * (m_frame.height() - arrowSize.height()) / 2
+  );
+  ctx->drawString(&m_arrow, arrowAlign, KDFont::LargeFont, m_color, m_backgroundColor, m_visible);
+}
+
 #if ESCHER_VIEW_LOGGING
 const char * ScrollViewIndicator::className() const {
   return "ScrollViewIndicator";