Refactor|libgui: Added the VertexBuilder template

The VertexBuilder will contain various utilities for constructing
simple geometric shapes out of triangle strips. Strips can easily be
concatenated into a longer strip using the + and += operators.

doomsday/client/include/ui/widgets/gltextcomposer.h

@@ -35,7 +35,7 @@ class GLTextComposer
 public:
     typedef de::Vertex2TexRgba    Vertex;
     typedef de::GLBufferT<Vertex> VertexBuf;
-    typedef VertexBuf::Vertices   Vertices;
+    typedef VertexBuf::Builder    Vertices;
 
     /**
      * Flags for specifying alignment.

doomsday/client/src/ui/widgets/gltextcomposer.cpp

@@ -212,7 +212,7 @@ void GLTextComposer::makeVertices(Vertices &triStrip,
             Rectanglef const uv  = d->atlas->imageRectf(d->lines[i].id);
 
             Vertex v;
-            Vertices quad;
+            VertexBuf::Builder quad;
 
             v.rgba = Vector4f(1, 1, 1, 1); // should be a param
 
@@ -233,7 +233,7 @@ void GLTextComposer::makeVertices(Vertices &triStrip,
             v.pos = linePos + Vector2f(0, size.y);      v.texCoord = uv.bottomLeft(); quad << v;
             v.pos = linePos + Vector2f(size.x, size.y); v.texCoord = uv.bottomRight;  quad << v;
 
-            VertexBuf::concatenate(quad, triStrip);
+            triStrip += quad;
         }
         p.y += d->font->lineSpacing().value();
     }

doomsday/client/src/ui/widgets/lineeditwidget.cpp

@@ -159,7 +159,7 @@ DENG2_OBSERVES(Atlas, Reposition)
 
         Vector4f bgColor = self.style().colors().colorf("background");
 
-        VertexBuf::Vertices verts;
+        VertexBuf::Builder verts;
         VertexBuf::Type v;
 
         v.rgba     = bgColor;
@@ -192,7 +192,7 @@ DENG2_OBSERVES(Atlas, Reposition)
                 Vector2i start = wraps.charTopLeftInPixels(i, i == startPos.y? startPos.x : span.start) + offset;
                 Vector2i end   = wraps.charTopLeftInPixels(i, i == endPos.y?   endPos.x   : span.end)   + offset;
 
-                VertexBuf::Vertices quad;
+                VertexBuf::Builder quad;
                 v.rgba = Vector4f(1, 1, 1, 1);
                 v.texCoord = atlas().imageRectf(bgTex).middle();
 
@@ -201,7 +201,7 @@ DENG2_OBSERVES(Atlas, Reposition)
                 v.pos = start + Vector2i(0, 1); quad << v;
                 v.pos = end + Vector2i(0, 1); quad << v;
 
-                VertexBuf::concatenate(quad, verts);
+                verts += quad;
             }
         }
 

doomsday/client/src/ui/widgets/logwidget.cpp

@@ -29,6 +29,7 @@
 #include <de/LogBuffer>
 #include <de/AtlasTexture>
 #include <de/Drawable>
+#include <de/VertexBuilder>
 
 #include <QImage>
 #include <QPainter>
@@ -418,7 +419,7 @@ DENG2_PIMPL(LogWidget), public Font::RichFormat::IStyle
         firstVisibleIndex = -1;
         lastVisibleIndex = -1;
 
-        VertexBuf::Vertices verts;
+        VertexBuf::Builder verts;
 
         // Copy all visible entries to the buffer.
         for(int idx = sink.entryCount() - 1; yBottom > 0 && idx >= 0; --idx)
@@ -448,7 +449,7 @@ DENG2_PIMPL(LogWidget), public Font::RichFormat::IStyle
             float const avail = contentSize.y - indHeight;
             for(int i = 0; i < indHeight; ++i)
             {
-                VertexBuf::Vertices quad;
+                VertexBuf::Builder quad;
                 VertexBuf::Type v;
                 v.rgba = Vector4f(1, 1, 1, scrollOpacity) * accentColor / 255.f;
                 v.texCoord = entryAtlas->imageRectf(scrollTex).middle();
@@ -461,7 +462,7 @@ DENG2_PIMPL(LogWidget), public Font::RichFormat::IStyle
                 v.pos = indRect.bottomLeft(); quad << v;
                 v.pos = indRect.bottomRight; quad << v;
 
-                VertexBuf::concatenate(quad, verts);
+                verts += quad;
             }
         }
 

doomsday/libgui/include/de/VertexBuilder

@@ -0,0 +1 @@
+#include "gui/vertexbuilder.h"

doomsday/libgui/include/de/gui/glbuffer.h

@@ -28,6 +28,7 @@
 
 #include "libgui.h"
 #include "opengl.h"
+#include "../VertexBuilder"
 
 namespace de {
 
@@ -181,6 +182,7 @@ class GLBufferT : public GLBuffer
 public:
     typedef VertexType Type;
     typedef QVector<VertexType> Vertices;
+    typedef typename VertexBuilder<VertexType>::Vertices Builder;
 
 public:
     GLBufferT() {
@@ -202,15 +204,6 @@ class GLBufferT : public GLBuffer
     void setVertices(gl::Primitive primitive, Vertices const &vertices, gl::Usage usage) {
         GLBuffer::setVertices(primitive, vertices.size(), vertices.constData(), sizeof(VertexType) * vertices.size(), usage);
     }
-
-    static void concatenate(Vertices const &triStripSequence, Vertices &longTriStrip) {
-        if(!triStripSequence.size()) return;
-        if(!longTriStrip.isEmpty()) {
-            longTriStrip << longTriStrip.back();
-            longTriStrip << triStripSequence.front();
-        }
-        longTriStrip << triStripSequence;
-    }
 };
 
 } // namespace de

doomsday/libgui/include/de/gui/vertexbuilder.h

@@ -0,0 +1,57 @@
+/** @file vertexbuilder.h  Utility for composing triangle strips.
+ *
+ * @authors Copyright (c) 2013 Jaakko Keränen <jaakko.keranen@iki.fi>
+ *
+ * @par License
+ * GPL: http://www.gnu.org/licenses/gpl.html
+ *
+ * <small>This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version. This program is distributed in the hope that it
+ * will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details. You should have received a copy of the GNU
+ * General Public License along with this program; if not, see:
+ * http://www.gnu.org/licenses</small> 
+ */
+
+#ifndef LIBGUI_VERTEXBUILDER_H
+#define LIBGUI_VERTEXBUILDER_H
+
+#include <QVector>
+
+namespace de {
+
+/**
+ * Utility for composing simple geometric constructs (using triangle strips).
+ */
+template <typename VertexType>
+struct VertexBuilder
+{
+    struct Vertices : public QVector<VertexType> {
+        Vertices &operator += (Vertices const &other) {
+            concatenate(other, *this);
+            return *this;
+        }
+        Vertices operator + (Vertices const &other) const {
+            Vertices v(*this);
+            return v += other;
+        }
+    };
+
+    static void concatenate(Vertices const &stripSequence, Vertices &destStrip)
+    {
+        if(!stripSequence.size()) return;
+        if(!destStrip.isEmpty())
+        {
+            destStrip << destStrip.back();
+            destStrip << stripSequence.front();
+        }
+        destStrip << stripSequence;
+    }
+};
+
+} // namespace de
+
+#endif // LIBGUI_VERTEXBUILDER_H

doomsday/libgui/libgui.pro

@@ -71,6 +71,7 @@ HEADERS += \
     include/de/MouseEventSource \
     include/de/PersistentCanvasWindow \
     include/de/RowAtlasAllocator \
+    include/de/VertexBuilder \
     \
     include/de/gui/atlas.h \
     include/de/gui/atlastexture.h \
@@ -101,7 +102,8 @@ HEADERS += \
     include/de/gui/mouseeventsource.h \
     include/de/gui/opengl.h \
     include/de/gui/persistentcanvaswindow.h \
-    include/de/gui/rowatlasallocator.h
+    include/de/gui/rowatlasallocator.h \
+    include/de/gui/vertexbuilder.h
 
 # Sources and private headers.
 SOURCES +=  \