Fixed SUPER old bug in ListWindow and ScrollAdapter where an adapter

refresh may scroll the view to a weird location. Also cleaned up
ScrollPosition handling.

src/musikbox/cursespp/IScrollAdapter.h

@@ -73,7 +73,7 @@ namespace cursespp {
             virtual void SetDisplaySize(size_t width, size_t height) = 0;
             virtual size_t GetEntryCount() = 0;
             virtual EntryPtr GetEntry(ScrollableWindow* window, size_t index) = 0;
-            virtual void DrawPage(ScrollableWindow* window, size_t index, ScrollPosition *result = NULL) = 0;
+            virtual void DrawPage(ScrollableWindow* window, size_t index, ScrollPosition& result) = 0;
     };
 
     typedef std::shared_ptr<IScrollAdapter> IScrollAdapterPtr;

src/musikbox/cursespp/ListWindow.cpp

@@ -191,7 +191,7 @@ void ListWindow::PageDown() {
 
 void ListWindow::ScrollTo(size_t index) {
     this->GetScrollAdapter().DrawPage(
-        this, index, &this->GetMutableScrollPosition());
+        this, index, this->GetMutableScrollPosition());
 
     this->Invalidate();
 }
@@ -215,7 +215,7 @@ void ListWindow::SetSelectedIndex(size_t index) {
         this->GetScrollAdapter().DrawPage(
             this,
             this->scrollPosition.firstVisibleEntryIndex,
-            &this->GetMutableScrollPosition());
+            this->GetMutableScrollPosition());
 
         this->Invalidate();
 
@@ -257,7 +257,7 @@ void ListWindow::OnAdapterChanged() {
 
 void ListWindow::OnDimensionsChanged() {
     ScrollableWindow::OnDimensionsChanged();
-    this->ScrollTo(this->selectedIndex);
+    this->ScrollTo(this->GetScrollPosition().firstVisibleEntryIndex);
 }
 
 IScrollAdapter::ScrollPosition& ListWindow::GetMutableScrollPosition() {

src/musikbox/cursespp/ScrollAdapterBase.cpp

@@ -72,20 +72,22 @@ void ScrollAdapterBase::GetVisibleItems(
     to the end. if we don't try to back up a bit until we can fill
     the buffer */
     int totalHeight = (int) this->height;
+    int entryCount = (int) this->GetEntryCount();
 
-    /* forward search first... */
-    int end = (int) GetEntryCount();
-    for (int i = (int) desired; i < end && totalHeight > 0; i++) {
+    /* we assume the general case -- we're some where in the middle of the
+    list. we'll start from the specified first item and work our way down */
+    for (int i = (int) desired; i < entryCount && totalHeight > 0; i++) {
         EntryPtr entry = this->GetEntry(window, i);
         entry->SetWidth(this->width);
         totalHeight -= entry->GetLineCount();
         target.push_back(entry);
     }
 
+    /* however, if the list is short, we can actually draw more items above
+    the specified one. let's work our way backwards! */
     if (totalHeight > 0) {
         target.clear();
 
-        /* oops, let's move backwards from the end */
         totalHeight = this->height;
         int i = GetEntryCount() - 1;
         while (i >= 0 && totalHeight >= 0) {
@@ -108,15 +110,7 @@ void ScrollAdapterBase::GetVisibleItems(
     start = actual;
 }
 
-void ScrollAdapterBase::DrawPage(ScrollableWindow* scrollable, size_t index, ScrollPosition *result) {
-    if (result != NULL) {
-        result->visibleEntryCount = 0;
-        result->firstVisibleEntryIndex = 0;
-        result->lineCount = 0;
-        result->totalEntries = 0;
-        result->logicalIndex = 0;
-    }
-
+void ScrollAdapterBase::DrawPage(ScrollableWindow* scrollable, size_t index, ScrollPosition& result) {
     WINDOW* window = scrollable->GetContent();
 
     werase(window);
@@ -131,7 +125,7 @@ void ScrollAdapterBase::DrawPage(ScrollableWindow* scrollable, size_t index, Scr
 
     /* unfortunately this needs to go here so the GetEntry() method knows
     what the the implied focus is */
-    result->logicalIndex = index;
+    //result.logicalIndex = index;
 
     std::deque<EntryPtr> visible;
     size_t topIndex; /* calculated by GetVisibleItems */
@@ -181,11 +175,9 @@ void ScrollAdapterBase::DrawPage(ScrollableWindow* scrollable, size_t index, Scr
         }
     }
 
-    if (result != NULL) {
-        result->visibleEntryCount = visible.size();
-        result->firstVisibleEntryIndex = topIndex;
-        result->lineCount = drawnLines;
-        result->totalEntries = GetEntryCount();
-        result->logicalIndex = index;
-    }
+    result.visibleEntryCount = visible.size();
+    result.firstVisibleEntryIndex = topIndex;
+    result.lineCount = drawnLines;
+    result.totalEntries = GetEntryCount();
+    //result.logicalIndex = index;
 }

src/musikbox/cursespp/ScrollAdapterBase.h

@@ -56,7 +56,7 @@ namespace cursespp {
             virtual void DrawPage(
                 ScrollableWindow* window,
                 size_t index,
-                ScrollPosition *result = nullptr);
+                ScrollPosition& result);
 
             virtual size_t GetEntryCount() = 0;
             virtual EntryPtr GetEntry(cursespp::ScrollableWindow* window, size_t index) = 0;

src/musikbox/cursespp/ScrollableWindow.cpp

@@ -52,7 +52,7 @@ public:
     virtual void SetDisplaySize(size_t width, size_t height) { }
     virtual size_t GetEntryCount() { return 0; }
     virtual EntryPtr GetEntry(cursespp::ScrollableWindow* window, size_t index) { return IScrollAdapter::EntryPtr(); }
-    virtual void DrawPage(ScrollableWindow* window, size_t index, ScrollPosition *result = NULL) { }
+    virtual void DrawPage(ScrollableWindow* window, size_t index, ScrollPosition& result) { }
 };
 
 static EmptyAdapter emptyAdapter;
@@ -63,7 +63,7 @@ static EmptyAdapter emptyAdapter;
         GetScrollAdapter().DrawPage( \
             this, \
             pos.firstVisibleEntryIndex, \
-            &pos); \
+            pos); \
     } \
 
 ScrollableWindow::ScrollableWindow(std::shared_ptr<IScrollAdapter> adapter, IWindow *parent)
@@ -144,7 +144,7 @@ bool ScrollableWindow::KeyPress(const std::string& key) {
 void ScrollableWindow::Redraw() {
     IScrollAdapter *adapter = &GetScrollAdapter();
     ScrollPos &pos = this->GetMutableScrollPosition();
-    adapter->DrawPage(this, pos.firstVisibleEntryIndex, &pos);
+    adapter->DrawPage(this, pos.firstVisibleEntryIndex, pos);
     this->Invalidate();
 }
 
@@ -158,7 +158,7 @@ void ScrollableWindow::OnAdapterChanged() {
     }
     else {
         ScrollPos &pos = this->GetMutableScrollPosition();
-        adapter->DrawPage(this, pos.firstVisibleEntryIndex, &pos);
+        adapter->DrawPage(this, pos.firstVisibleEntryIndex, pos);
         this->Invalidate();
     }
 }
@@ -169,7 +169,7 @@ void ScrollableWindow::Show() {
 }
 
 void ScrollableWindow::ScrollToTop() {
-    GetScrollAdapter().DrawPage(this, 0, &this->GetMutableScrollPosition());
+    GetScrollAdapter().DrawPage(this, 0, this->GetMutableScrollPosition());
     this->Invalidate();
 }
 
@@ -177,7 +177,7 @@ void ScrollableWindow::ScrollToBottom() {
     GetScrollAdapter().DrawPage(
         this,
         GetScrollAdapter().GetEntryCount(),
-        &this->GetMutableScrollPosition());
+        this->GetMutableScrollPosition());
 
     this->Invalidate();
 }
@@ -187,7 +187,7 @@ void ScrollableWindow::ScrollUp(int delta) {
 
     if (pos.firstVisibleEntryIndex > 0) {
         GetScrollAdapter().DrawPage(
-            this, pos.firstVisibleEntryIndex - delta, &pos);
+            this, pos.firstVisibleEntryIndex - delta, pos);
 
         this->Invalidate();
     }
@@ -197,7 +197,7 @@ void ScrollableWindow::ScrollDown(int delta) {
     ScrollPos &pos = this->GetMutableScrollPosition();
 
     GetScrollAdapter().DrawPage(
-        this, pos.firstVisibleEntryIndex + delta, &pos);
+        this, pos.firstVisibleEntryIndex + delta, pos);
 
     this->Invalidate();
 }