GUI: Added support for fixed-size scrollarea markers

Due to getVerticalMarkerDimension and getHorizontalMarkerDimension not
being virtual, this unfortunately required copying a lot of code from
Guichan to make sure it calls our versions of these functions.

Also addressed a small issue where gcn::ScrollArea::checkPolicies was
not taking the frame size of the content into account.

3 files changed, 354 insertions, 23 deletions

diff --git a/data/graphics/gui/jewelry/theme.xml b/data/graphics/gui/jewelry/theme.xml
index ba85278d..ea173658 100644
--- a/data/graphics/gui/jewelry/theme.xml
+++ b/data/graphics/gui/jewelry/theme.xml
@@ -254,33 +254,33 @@
     </state>
   </skin>
 
-  <skin type="ScrollAreaVBar">
+  <skin type="ScrollAreaVBar" width="20">
     <state>
-      <img src="window.png" x="51" y="186" width="18" height="34" left="18" top="6" bottom="6" fill="repeat" />
+      <img src="window.png" x="51" y="186" width="18" height="34" left="18" top="6" bottom="6" fill="repeat" offsetX="1" />
     </state>
   </skin>
 
-  <skin type="ScrollAreaHBar">
+  <skin type="ScrollAreaHBar" height="20">
     <state>
-      <img src="window.png" x="69" y="181" width="34" height="18" left="6" top="18" right="6" fill="repeat" />
+      <img src="window.png" x="69" y="181" width="34" height="18" left="6" top="18" right="6" fill="repeat" offsetY="1" />
     </state>
   </skin>
 
-  <skin type="ScrollAreaHMarker">
+  <skin type="ScrollAreaHMarker" width="20" height="20">
     <state hovered="true">
-      <img src="window.png" x="26" y="165" width="18" height="18" left="8" right="9" top="18" />
+      <img src="window.png" x="26" y="165" width="18" height="18" offsetX="1" offsetY="1" />
     </state>
     <state>
-      <img src="window.png" x="3" y="165" width="18" height="18" left="8" right="9" top="18" />
+      <img src="window.png" x="3" y="165" width="18" height="18" offsetX="1" offsetY="1" />
     </state>
   </skin>
 
-  <skin type="ScrollAreaVMarker">
+  <skin type="ScrollAreaVMarker" width="20" height="20">
     <state hovered="true">
-      <img src="window.png" x="26" y="165" width="18" height="18" left="18" top="8" bottom="9" />
+      <img src="window.png" x="26" y="165" width="18" height="18" offsetX="1" offsetY="1" />
     </state>
     <state>
-      <img src="window.png" x="3" y="165" width="18" height="18" left="18" top="8" bottom="9" />
+      <img src="window.png" x="3" y="165" width="18" height="18" offsetX="1" offsetY="1" />
     </state>
   </skin>
 
@@ -311,28 +311,28 @@
 
   <skin type="ButtonUp">
     <state selected="true">
-      <img src="window.png" x="17" y="148" width="12" height="12" offsetX="3" offsetY="3" />
+      <img src="window.png" x="17" y="148" width="12" height="12" offsetX="4" offsetY="4" />
     </state>
     <state>
-      <img src="window.png" x="1" y="148" width="12" height="12" offsetX="3" offsetY="3" />
+      <img src="window.png" x="1" y="148" width="12" height="12" offsetX="4" offsetY="4" />
     </state>
   </skin>
 
   <skin type="ButtonDown">
     <state selected="true">
-      <img src="window.png" x="17" y="132" width="12" height="12" offsetX="3" offsetY="3" />
+      <img src="window.png" x="17" y="132" width="12" height="12" offsetX="4" offsetY="4" />
     </state>
     <state>
-      <img src="window.png" x="1" y="132" width="12" height="12" offsetX="3" offsetY="3" />
+      <img src="window.png" x="1" y="132" width="12" height="12" offsetX="4" offsetY="4" />
     </state>
   </skin>
 
   <skin type="ButtonLeft">
     <state selected="true">
-      <img src="window.png" x="17" y="100" width="12" height="12" offsetX="3" offsetY="3" />
+      <img src="window.png" x="17" y="100" width="12" height="12" offsetX="4" offsetY="4" />
     </state>
     <state>
-      <img src="window.png" x="1" y="100" width="12" height="12" offsetX="3" offsetY="3" />
+      <img src="window.png" x="1" y="100" width="12" height="12" offsetX="4" offsetY="4" />
     </state>
   </skin>
 
diff --git a/src/gui/widgets/scrollarea.cpp b/src/gui/widgets/scrollarea.cpp
index c4d55072..a7e94971 100644
--- a/src/gui/widgets/scrollarea.cpp
+++ b/src/gui/widgets/scrollarea.cpp
@@ -25,6 +25,8 @@
 
 #include "gui/gui.h"
 
+#include <guichan/exception.hpp>
+
 ScrollArea::ScrollArea()
 {
     init();
@@ -48,9 +50,9 @@ void ScrollArea::init()
 
     auto theme = gui->getTheme();
 
-    int minWidth = theme->getSkin(SkinType::ScrollAreaVBar).getMinWidth();
-    if (minWidth > 0)
-        setScrollbarWidth(minWidth);
+    int scrollBarWidth = theme->getSkin(SkinType::ScrollAreaVBar).width;
+    if (scrollBarWidth > 0)
+        setScrollbarWidth(scrollBarWidth);
 
     if (auto content = getContent())
         content->setFrameSize(theme->getSkin(SkinType::ScrollArea).padding);
@@ -198,6 +200,9 @@ void ScrollArea::drawHBar(gcn::Graphics *graphics)
 void ScrollArea::drawVMarker(gcn::Graphics *graphics)
 {
     WidgetState state(getVerticalMarkerDimension());
+    if (state.height == 0)
+        return;
+
     if (mHasMouse && (mX > (getWidth() - getScrollbarWidth())))
         state.flags |= STATE_HOVERED;
 
@@ -207,6 +212,9 @@ void ScrollArea::drawVMarker(gcn::Graphics *graphics)
 void ScrollArea::drawHMarker(gcn::Graphics *graphics)
 {
     WidgetState state(getHorizontalMarkerDimension());
+    if (state.width == 0)
+        return;
+
     if (mHasMouse && (mY > (getHeight() - getScrollbarWidth())))
         state.flags |= STATE_HOVERED;
 
@@ -225,6 +233,108 @@ void ScrollArea::drawButton(gcn::Graphics *graphics,
     gui->getTheme()->drawSkin(static_cast<Graphics *>(graphics), skinType, state);
 }
 
+/**
+ * Code copied from gcn::ScrollArea::checkPolicies to make sure it takes the
+ * frame size of the content into account.
+ */
+void ScrollArea::checkPolicies()
+{
+    int w = getWidth();
+    int h = getHeight();
+
+    mHBarVisible = false;
+    mVBarVisible = false;
+
+    if (!getContent())
+    {
+        mHBarVisible = (mHPolicy == SHOW_ALWAYS);
+        mVBarVisible = (mVPolicy == SHOW_ALWAYS);
+        return;
+    }
+
+    const int contentFrameSize = getContent()->getFrameSize();
+    w -= 2 * contentFrameSize;
+    h -= 2 * contentFrameSize;
+
+    if (mHPolicy == SHOW_AUTO &&
+        mVPolicy == SHOW_AUTO)
+    {
+        if (getContent()->getWidth() <= w
+            && getContent()->getHeight() <= h)
+        {
+            mHBarVisible = false;
+            mVBarVisible = false;
+        }
+
+        if (getContent()->getWidth() > w)
+        {
+            mHBarVisible = true;
+        }
+
+        if ((getContent()->getHeight() > h)
+            || (mHBarVisible && getContent()->getHeight() > h - mScrollbarWidth))
+        {
+            mVBarVisible = true;
+        }
+
+        if (mVBarVisible && getContent()->getWidth() > w - mScrollbarWidth)
+        {
+            mHBarVisible = true;
+        }
+
+        return;
+    }
+
+    switch (mHPolicy)
+    {
+    case SHOW_NEVER:
+        mHBarVisible = false;
+        break;
+
+    case SHOW_ALWAYS:
+        mHBarVisible = true;
+        break;
+
+    case SHOW_AUTO:
+        if (mVPolicy == SHOW_NEVER)
+        {
+            mHBarVisible = getContent()->getWidth() > w;
+        }
+        else // (mVPolicy == SHOW_ALWAYS)
+        {
+            mHBarVisible = getContent()->getWidth() > w - mScrollbarWidth;
+        }
+        break;
+
+    default:
+        throw GCN_EXCEPTION("Horizontal scroll policy invalid.");
+    }
+
+    switch (mVPolicy)
+    {
+    case SHOW_NEVER:
+        mVBarVisible = false;
+        break;
+
+    case SHOW_ALWAYS:
+        mVBarVisible = true;
+        break;
+
+    case SHOW_AUTO:
+        if (mHPolicy == SHOW_NEVER)
+        {
+            mVBarVisible = getContent()->getHeight() > h;
+        }
+        else // (mHPolicy == SHOW_ALWAYS)
+        {
+            mVBarVisible = getContent()->getHeight() > h - mScrollbarWidth;
+        }
+        break;
+    default:
+        throw GCN_EXCEPTION("Vertical scroll policy invalid.");
+    }
+}
+
 void ScrollArea::mouseMoved(gcn::MouseEvent& event)
 {
     mX = event.getX();
@@ -240,3 +350,209 @@ void ScrollArea::mouseExited(gcn::MouseEvent& event)
 {
     mHasMouse = false;
 }
+
+/**
+ * Code copied from gcn::ScrollArea::mousePressed to make it call our custom
+ * getVerticalMarkerDimension and getHorizontalMarkerDimension functions.
+ */
+void ScrollArea::mousePressed(gcn::MouseEvent &mouseEvent)
+{
+    int x = mouseEvent.getX();
+    int y = mouseEvent.getY();
+
+    if (getUpButtonDimension().isPointInRect(x, y))
+    {
+        setVerticalScrollAmount(getVerticalScrollAmount()
+                                - mUpButtonScrollAmount);
+        mUpButtonPressed = true;
+    }
+    else if (getDownButtonDimension().isPointInRect(x, y))
+    {
+        setVerticalScrollAmount(getVerticalScrollAmount()
+                                + mDownButtonScrollAmount);
+        mDownButtonPressed = true;
+    }
+    else if (getLeftButtonDimension().isPointInRect(x, y))
+    {
+        setHorizontalScrollAmount(getHorizontalScrollAmount()
+                                  - mLeftButtonScrollAmount);
+        mLeftButtonPressed = true;
+    }
+    else if (getRightButtonDimension().isPointInRect(x, y))
+    {
+        setHorizontalScrollAmount(getHorizontalScrollAmount()
+                                  + mRightButtonScrollAmount);
+        mRightButtonPressed = true;
+    }
+    else if (getVerticalMarkerDimension().isPointInRect(x, y))
+    {
+        mIsHorizontalMarkerDragged = false;
+        mIsVerticalMarkerDragged = true;
+
+        mVerticalMarkerDragOffset = y - getVerticalMarkerDimension().y;
+    }
+    else if (getVerticalBarDimension().isPointInRect(x,y))
+    {
+        if (y < getVerticalMarkerDimension().y)
+        {
+            setVerticalScrollAmount(getVerticalScrollAmount()
+                                    - (int)(getChildrenArea().height * 0.95));
+        }
+        else
+        {
+            setVerticalScrollAmount(getVerticalScrollAmount()
+                                    + (int)(getChildrenArea().height * 0.95));
+        }
+    }
+    else if (getHorizontalMarkerDimension().isPointInRect(x, y))
+    {
+        mIsHorizontalMarkerDragged = true;
+        mIsVerticalMarkerDragged = false;
+
+        mHorizontalMarkerDragOffset = x - getHorizontalMarkerDimension().x;
+    }
+    else if (getHorizontalBarDimension().isPointInRect(x,y))
+    {
+        if (x < getHorizontalMarkerDimension().x)
+        {
+            setHorizontalScrollAmount(getHorizontalScrollAmount()
+                                      - (int)(getChildrenArea().width * 0.95));
+        }
+        else
+        {
+            setHorizontalScrollAmount(getHorizontalScrollAmount()
+                                      + (int)(getChildrenArea().width * 0.95));
+        }
+    }
+}
+
+/**
+ * Code copied from gcn::ScrollArea::mouseDragged to make it call our custom
+ * getVerticalMarkerDimension and getHorizontalMarkerDimension functions.
+ */
+void ScrollArea::mouseDragged(gcn::MouseEvent &mouseEvent)
+{
+    if (mIsVerticalMarkerDragged)
+    {
+        int pos = mouseEvent.getY() - getVerticalBarDimension().y  - mVerticalMarkerDragOffset;
+        int length = getVerticalMarkerDimension().height;
+
+        gcn::Rectangle barDim = getVerticalBarDimension();
+
+        if ((barDim.height - length) > 0)
+        {
+            setVerticalScrollAmount((getVerticalMaxScroll() * pos)
+                                    / (barDim.height - length));
+        }
+        else
+        {
+            setVerticalScrollAmount(0);
+        }
+    }
+
+    if (mIsHorizontalMarkerDragged)
+    {
+        int pos = mouseEvent.getX() - getHorizontalBarDimension().x  - mHorizontalMarkerDragOffset;
+        int length = getHorizontalMarkerDimension().width;
+
+        gcn::Rectangle barDim = getHorizontalBarDimension();
+
+        if ((barDim.width - length) > 0)
+        {
+            setHorizontalScrollAmount((getHorizontalMaxScroll() * pos)
+                                      / (barDim.width - length));
+        }
+        else
+        {
+            setHorizontalScrollAmount(0);
+        }
+    }
+
+    mouseEvent.consume();
+}
+
+static void getMarkerValues(int barSize,
+                            int maxScroll, int scrollAmount,
+                            int contentHeight, int viewHeight,
+                            int fixedMarkerSize, int minMarkerSize,
+                            int &markerSize, int &markerPos)
+{
+    markerSize = barSize;
+    markerPos = 0;
+
+    if (fixedMarkerSize == 0)
+    {
+        if (contentHeight != 0 && contentHeight > viewHeight)
+            markerSize = std::max((barSize * viewHeight) / contentHeight, minMarkerSize);
+    }
+    else
+    {
+        if (viewHeight > contentHeight)
+            markerSize = 0;
+        else
+            markerSize = fixedMarkerSize;
+    }
+
+    // Hide the marker when it doesn't fit
+    if (markerSize > barSize)
+        markerSize = 0;
+
+    if (maxScroll != 0)
+        markerPos = ((barSize - markerSize) * scrollAmount + maxScroll / 2) / maxScroll;
+}
+
+gcn::Rectangle ScrollArea::getVerticalMarkerDimension()
+{
+    if (!mVBarVisible)
+        return gcn::Rectangle(0, 0, 0, 0);
+
+    auto &markerSkin = gui->getTheme()->getSkin(SkinType::ScrollAreaVMarker);
+    const gcn::Rectangle barDim = getVerticalBarDimension();
+
+    int contentHeight = 0;
+    if (auto content = getContent())
+        contentHeight = content->getHeight() + content->getFrameSize() * 2;
+
+    int length;
+    int pos;
+
+    getMarkerValues(barDim.height,
+                    getVerticalMaxScroll(),
+                    getVerticalScrollAmount(),
+                    contentHeight,
+                    getChildrenArea().height,
+                    markerSkin.height,
+                    mScrollbarWidth,
+                    length,
+                    pos);
+
+    return gcn::Rectangle(barDim.x, barDim.y + pos, mScrollbarWidth, length);
+}
+
+gcn::Rectangle ScrollArea::getHorizontalMarkerDimension()
+{
+    if (!mHBarVisible)
+        return gcn::Rectangle(0, 0, 0, 0);
+
+    auto &markerSkin = gui->getTheme()->getSkin(SkinType::ScrollAreaHMarker);
+    const gcn::Rectangle barDim = getHorizontalBarDimension();
+
+    int contentWidth = 0;
+    if (auto content = getContent())
+        contentWidth = content->getWidth() + content->getFrameSize() * 2;
+
+    int length;
+    int pos;
+
+    getMarkerValues(barDim.width,
+                    getHorizontalMaxScroll(),
+                    getHorizontalScrollAmount(),
+                    contentWidth,
+                    getChildrenArea().width,
+                    markerSkin.width,
+                    mScrollbarWidth,
+                    length,
+                    pos);
+
+    return gcn::Rectangle(barDim.x + pos, barDim.y, length, mScrollbarWidth);
+}
diff --git a/src/gui/widgets/scrollarea.h b/src/gui/widgets/scrollarea.h
index 40f1adc1..7cdcfa19 100644
--- a/src/gui/widgets/scrollarea.h
+++ b/src/gui/widgets/scrollarea.h
@@ -32,6 +32,8 @@
  * content. However, it won't delete a previously set content widget when
  * setContent is called!
  *
+ * Also overrides several functions to support fixed-size scroll bar markers.
+ *
  * \ingroup GUI
  */
 class ScrollArea : public gcn::ScrollArea
@@ -74,7 +76,7 @@ class ScrollArea : public gcn::ScrollArea
         /**
          * Applies clipping to the contents.
          */
-        void drawChildren(gcn::Graphics* graphics) override;
+        void drawChildren(gcn::Graphics *graphics) override;
 
         /**
          * Sets whether the widget should draw its background or not.
@@ -89,17 +91,20 @@ class ScrollArea : public gcn::ScrollArea
         /**
          * Called when the mouse moves in the widget area.
          */
-        void mouseMoved(gcn::MouseEvent& event) override;
+        void mouseMoved(gcn::MouseEvent &event) override;
 
         /**
          * Called when the mouse enteres the widget area.
          */
-        void mouseEntered(gcn::MouseEvent& event) override;
+        void mouseEntered(gcn::MouseEvent &event) override;
 
         /**
          * Called when the mouse leaves the widget area.
          */
-        void mouseExited(gcn::MouseEvent& event) override;
+        void mouseExited(gcn::MouseEvent &event) override;
+
+        void mousePressed(gcn::MouseEvent &mouseEvent) override;
+        void mouseDragged(gcn::MouseEvent &mouseEvent) override;
 
     protected:
         /**
@@ -122,6 +127,16 @@ class ScrollArea : public gcn::ScrollArea
                                bool pressed,
                                const gcn::Rectangle &dim);
 
+        void checkPolicies() override;
+
+        /**
+         * Shadowing these functions from gcn::ScrollArea with versions that
+         * supports fixed-size scroll bar markers. We need to make sure we
+         * always use these versions.
+         */
+        gcn::Rectangle getVerticalMarkerDimension();
+        gcn::Rectangle getHorizontalMarkerDimension();
+
         int mX = 0;
         int mY = 0;
         bool mHasMouse = false;