Add menu item to center view at a point; and move non-ID list data

structure from polygon.h into dsc.h, since it is used outside the
polygon/mesh code.

[git-p4: depot-paths = "//depot/solvespace/": change = 1892]

dsc.h

@@ -89,6 +89,56 @@ public:
     Point2d WithMagnitude(double v);
 };
 
+// A simple list
+template <class T>
+class List {
+public:
+    T   *elem;
+    int  n;
+    int  elemsAllocated;
+
+    void Add(T *t) {
+        if(n >= elemsAllocated) {
+            elemsAllocated = (elemsAllocated + 32)*2;
+            elem = (T *)MemRealloc(elem, elemsAllocated*sizeof(elem[0]));
+        }
+        elem[n++] = *t;
+    }
+
+    void ClearTags(void) {
+        int i;
+        for(i = 0; i < n; i++) {
+            elem[i].tag = 0;
+        }
+    }
+
+    void Clear(void) {
+        if(elem) MemFree(elem);
+        elem = NULL;
+        n = elemsAllocated = 0;
+    }
+
+    void RemoveTagged(void) {
+        int src, dest;
+        dest = 0;
+        for(src = 0; src < n; src++) {
+            if(elem[src].tag) {
+                // this item should be deleted
+            } else {
+                if(src != dest) {
+                    elem[dest] = elem[src];
+                }
+                dest++;
+            }
+        }
+        n = dest;
+        // and elemsAllocated is untouched, because we didn't resize
+    }
+};
+
+// A list, where each element has an integer identifier. The list is kept
+// sorted by that identifier, and items can be looked up in log n time by
+// id.
 template <class T, class H>
 class IdList {
 public:

graphicswin.cpp

@@ -39,8 +39,9 @@ const GraphicsWindow::MenuEntry GraphicsWindow::menu[] = {
 { 1, "Zoom &Out\t-",                        MNU_ZOOM_OUT,       '-',    mView },
 { 1, "Zoom To &Fit\tF",                     MNU_ZOOM_TO_FIT,    'F',    mView },
 { 1,  NULL,                                 0,                          NULL  },
-{ 1, "Nearest &Ortho View\tF1",             MNU_NEAREST_ORTHO,  F(1),   mView },
-{ 1, "Nearest &Isometric View\tF2",         MNU_NEAREST_ISO,    F(2),   mView },
+{ 1, "Nearest &Ortho View\tF2",             MNU_NEAREST_ORTHO,  F(2),   mView },
+{ 1, "Nearest &Isometric View\tF3",         MNU_NEAREST_ISO,    F(3),   mView },
+{ 1, "&Center View At Point\tF4",           MNU_CENTER_VIEW,    F(4),   mView },
 { 1,  NULL,                                 0,                          NULL  },
 { 1, "Show Text &Window\tTab",              MNU_SHOW_TEXT_WND,  '\t',   mView },
 { 1, "Show &Toolbar",                       MNU_SHOW_TOOLBAR,   0,      mView },
@@ -394,6 +395,21 @@ void GraphicsWindow::MenuView(int id) {
             break;
         }
 
+        case MNU_CENTER_VIEW:
+            SS.GW.GroupSelection();
+            if(SS.GW.gs.n == 1 && SS.GW.gs.points == 1) {
+                Quaternion quat0;
+                // Offset is the selected point, quaternion is same as before
+                Vector pt = SS.GetEntity(SS.GW.gs.point[0])->PointGetNum();
+                quat0 = Quaternion::From(SS.GW.projRight, SS.GW.projUp);
+                SS.GW.AnimateOnto(quat0, pt.ScaledBy(-1));
+                SS.GW.ClearSelection();
+            } else {
+                Error("Select a point; this point will become the center "
+                      "of the view on screen.");
+            }
+            break;
+
         case MNU_SHOW_TEXT_WND:
             SS.GW.showTextWindow = !SS.GW.showTextWindow;
             SS.GW.EnsureValidActives();

polygon.h

@@ -7,52 +7,6 @@ class SContour;
 class SMesh;
 class SBsp3;
 
-template <class T>
-class SList {
-public:
-    T   *elem;
-    int  n;
-    int  elemsAllocated;
-
-    void Add(T *t) {
-        if(n >= elemsAllocated) {
-            elemsAllocated = (elemsAllocated + 32)*2;
-            elem = (T *)MemRealloc(elem, elemsAllocated*sizeof(elem[0]));
-        }
-        elem[n++] = *t;
-    }
-
-    void ClearTags(void) {
-        int i;
-        for(i = 0; i < n; i++) {
-            elem[i].tag = 0;
-        }
-    }
-
-    void Clear(void) {
-        if(elem) MemFree(elem);
-        elem = NULL;
-        n = elemsAllocated = 0;
-    }
-
-    void RemoveTagged(void) {
-        int src, dest;
-        dest = 0;
-        for(src = 0; src < n; src++) {
-            if(elem[src].tag) {
-                // this item should be deleted
-            } else {
-                if(src != dest) {
-                    elem[dest] = elem[src];
-                }
-                dest++;
-            }
-        }
-        n = dest;
-        // and elemsAllocated is untouched, because we didn't resize
-    }
-};
-
 class SEdge {
 public:
     int    tag;
@@ -63,7 +17,7 @@ public:
 
 class SEdgeList {
 public:
-    SList<SEdge>    l;
+    List<SEdge>     l;
 
     void Clear(void);
     void AddEdge(Vector a, Vector b);
@@ -80,7 +34,7 @@ public:
 
 class SContour {
 public:
-    SList<SPoint>   l;
+    List<SPoint>    l;
 
     void AddPoint(Vector p);
     void MakeEdgesInto(SEdgeList *el);
@@ -99,7 +53,7 @@ typedef struct {
 
 class SPolygon {
 public:
-    SList<SContour> l;
+    List<SContour>  l;
     Vector          normal;
 
     Vector ComputeNormal(void);
@@ -188,7 +142,7 @@ public:
 
 class SMesh {
 public:
-    SList<STriangle>    l;
+    List<STriangle>     l;
 
     bool    flipNormal;
     bool    keepCoplanar;

sketch.h

@@ -110,7 +110,7 @@ public:
     struct {
         int                 how;
         int                 dof;
-        SList<hConstraint>  remove;
+        List<hConstraint>   remove;
     } solved;
 
     // For drawings in 2d

solvespace.h

@@ -319,7 +319,7 @@ public:
 class TtfFontList {
 public:
     bool                loaded;
-    SList<TtfFont>      l;
+    List<TtfFont>       l;
 
     void LoadAll(void);
 

ui.h

@@ -186,6 +186,7 @@ public:
         MNU_ZOOM_TO_FIT,
         MNU_NEAREST_ORTHO,
         MNU_NEAREST_ISO,
+        MNU_CENTER_VIEW,
         MNU_SHOW_TEXT_WND,
         MNU_SHOW_TOOLBAR,
         MNU_UNITS_INCHES,