Fix up widget bounds within the window

dgl/NanoVG.hpp

@@ -279,7 +279,6 @@ public:
         return fContext;
     }
 
-protected:
    /**
       Begin drawing a new frame.
       @param withAlha Controls if drawing the shapes to the render target should be done using straight or pre-multiplied alpha.
@@ -695,6 +694,13 @@ protected:
     */
     void textAlign(Align align);
 
+   /**
+      Sets the text align of current text style.
+      Overloaded function for convenience.
+      @see Align
+    */
+    void textAlign(int align);
+
    /**
       Sets the font face based on specified id of current text style.
     */

dgl/Widget.hpp

@@ -296,6 +296,12 @@ protected:
     */
     virtual void onResize(const ResizeEvent&);
 
+   /**
+      Wherever the Y position is inverted.
+      (starts at the bottom)
+    */
+    bool fInvertedY;
+
 private:
     Window& fParent;
     bool    fVisible;

dgl/src/NanoVG.cpp

@@ -529,6 +529,11 @@ void NanoVG::textAlign(NanoVG::Align align)
     nvgTextAlign(fContext, align);
 }
 
+void NanoVG::textAlign(int align)
+{
+    nvgTextAlign(fContext, align);
+}
+
 void NanoVG::fontFaceId(FontId font)
 {
     nvgFontFaceId(fContext, font);

dgl/src/Widget.cpp

@@ -23,7 +23,8 @@ START_NAMESPACE_DGL
 // Widget
 
 Widget::Widget(Window& parent)
-    : fParent(parent),
+    : fInvertedY(false),
+      fParent(parent),
       fVisible(true)
 {
     fParent._addWidget(this);

dgl/src/Window.cpp

@@ -575,8 +575,23 @@ struct Window::PrivateData {
 
             if (widget->isVisible())
             {
-                glViewport(widget->getAbsoluteX(), -widget->getAbsoluteY(), fView->width, fView->height);
+                const int ypos = widget->fInvertedY ? fView->height - widget->getHeight() - widget->getAbsoluteY() : widget->getAbsoluteY();
+
+                // reset color
+                glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
+
+                // limit viewport to widget bounds
+                glViewport(widget->getAbsoluteX(), ypos, widget->getWidth(), widget->getHeight());
+
+                // need scale contents to match viewport
+                glPushMatrix();
+                glScalef(float(fView->width)/float(widget->getWidth()), float(fView->height)/float(widget->getHeight()), 1.0f);
+
+                // display widget
                 widget->onDisplay();
+
+                // pop
+                glPopMatrix();
             }
         }