Add text overlay textWidth() method

Is accessible from JavaScript.

interface/src/ui/overlays/Overlays.cpp

@@ -9,6 +9,7 @@
 //
 
 #include <limits>
+#include <typeinfo>
 #include <Application.h>
 #include <Menu.h>
 
@@ -357,3 +358,18 @@ bool Overlays::isLoaded(unsigned int id) {
     return overlay->isLoaded();
 }
 
+float Overlays::textWidth(unsigned int id, const QString& text) {
+    if (_overlays2D.contains(id)) {
+        Overlay* thisOverlay = _overlays2D[id];
+        if (typeid(*thisOverlay) == typeid(TextOverlay)) {
+            return static_cast<TextOverlay*>(thisOverlay)->textWidth(text);
+        }
+    } 
+    if (_overlays3D.contains(id)) {
+        Overlay* thisOverlay = _overlays3D[id];
+        if (typeid(*thisOverlay) == typeid(Text3DOverlay)) {
+            return static_cast<Text3DOverlay*>(thisOverlay)->textWidth(text);
+        }
+    }
+    return 0.f;
+}

interface/src/ui/overlays/Overlays.h

@@ -65,6 +65,10 @@ public slots:
     /// returns whether the overlay's assets are loaded or not
     bool isLoaded(unsigned int id);
 
+    /// returns the width of the given text in the specified overlay if it is a text overlay: in pixels if it is a 2D text
+    /// overlay; in meters if it is a 3D text overlay
+    float textWidth(unsigned int id, const QString& text);
+
 private:
     QMap<unsigned int, Overlay*> _overlays2D;
     QMap<unsigned int, Overlay*> _overlays3D;

interface/src/ui/overlays/Text3DOverlay.cpp

@@ -17,6 +17,8 @@
 
 const xColor DEFAULT_BACKGROUND_COLOR = { 0, 0, 0 };
 const float DEFAULT_MARGIN = 0.1f;
+const int FIXED_FONT_POINT_SIZE = 40;
+const float LINE_SCALE_RATIO = 1.2f;
 
 Text3DOverlay::Text3DOverlay() :
     _backgroundColor(DEFAULT_BACKGROUND_COLOR),
@@ -87,11 +89,9 @@ void Text3DOverlay::render(RenderArgs* args) {
             glVertex3f(-halfDimensions.x, halfDimensions.y, SLIGHTLY_BEHIND);
         glEnd();
         
-        const int FIXED_FONT_POINT_SIZE = 40;
         const int FIXED_FONT_SCALING_RATIO = FIXED_FONT_POINT_SIZE * 40.0f; // this is a ratio determined through experimentation
         
         TextRenderer* textRenderer = TextRenderer::getInstance(SANS_FONT_FAMILY, FIXED_FONT_POINT_SIZE);
-        float LINE_SCALE_RATIO = 1.2f;
         float maxHeight = (float)textRenderer->calculateHeight("Xy") * LINE_SCALE_RATIO;
         
         float scaleFactor =  (maxHeight / FIXED_FONT_SCALING_RATIO) * _lineHeight; 
@@ -179,4 +179,11 @@ void Text3DOverlay::setProperties(const QScriptValue& properties) {
 
 }
 
+float Text3DOverlay::textWidth(const QString& text) {
+    const int TEXT3DOVERLAY_TEXTWIDTH_RENDERER = 2;  // Separate to that used for drawing text so that doesn't interfere.
+    TextRenderer* textRenderer = TextRenderer::getInstance(SANS_FONT_FAMILY, FIXED_FONT_POINT_SIZE, -1, false, 
+        TextRenderer::NO_EFFECT, 1, QColor(255, 255, 255), TEXT3DOVERLAY_TEXTWIDTH_RENDERER);
 
+    float scaleFactor = _lineHeight * LINE_SCALE_RATIO / (float)textRenderer->calculateHeight("X");
+    return scaleFactor * (float)textRenderer->computeWidth(qPrintable(text));
+}

interface/src/ui/overlays/Text3DOverlay.h

@@ -48,6 +48,8 @@ public:
 
     virtual void setProperties(const QScriptValue& properties);
 
+    float textWidth(const QString& text);  // Meters
+
 private:
     void enableClipPlane(GLenum plane, float x, float y, float z, float w);
 

interface/src/ui/overlays/TextOverlay.cpp

@@ -126,3 +126,10 @@ void TextOverlay::setProperties(const QScriptValue& properties) {
 }
 
 
+float TextOverlay::textWidth(const QString& text) {
+    const int TEXTOVERLAY_GETTEXTWIDTH_TEXTRENDERER = 1;  // Separate to that used for drawing text so that doesn't interfere.
+    TextRenderer* textRenderer = TextRenderer::getInstance(SANS_FONT_FAMILY, _fontSize, -1, FALSE, TextRenderer::NO_EFFECT, 1, 
+        QColor(255, 255, 255), TEXTOVERLAY_GETTEXTWIDTH_TEXTRENDERER);
+
+    return textRenderer->computeWidth(qPrintable(text));
+}

interface/src/ui/overlays/TextOverlay.h

@@ -53,6 +53,8 @@ public:
 
     virtual void setProperties(const QScriptValue& properties);
 
+    float textWidth(const QString& text);  // Pixels
+
 private:
 
     QString _text;