Font rendering functional: test string

src/util/GLFont.cpp

@@ -277,7 +277,7 @@ void GLFont::loadFont(std::string fontFile) {
         glGenTextures(1, &texId);
         glEnable(GL_TEXTURE_2D);
         glBindTexture(GL_TEXTURE_2D, texId);
-        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
         glTexImage2D(GL_TEXTURE_2D, 0, 4, imageWidth, imageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, &image[0]);
         glDisable(GL_TEXTURE_2D);
@@ -292,7 +292,7 @@ void GLFont::loadFont(std::string fontFile) {
             int charId = (*char_i).first;
             GLFontChar *fchar = (*char_i).second;
 
-            float faspect = fchar->getAspect()/8.0;
+            float faspect = fchar->getAspect();
 
             float uv_xpos = (float) fchar->getX() / (float) imageWidth;
             float uv_ypos = ((float) fchar->getY() / (float) imageHeight);
@@ -340,16 +340,50 @@ void GLFont::loadFont(std::string fontFile) {
     input.close();
 }
 
-void GLFont::drawString(std::string str, float xpos, float ypos, float size) {
+float GLFont::getStringWidth(std::string str, float size, float viewAspect) {
+
+    float scalex = size/viewAspect;
+
+    float width = 0;
+
+    for (int i = 0, iMax = str.length(); i < iMax; i++) {
+        int charId = str.at(i);
+
+        if (characters.find(charId) == characters.end()) {
+            continue;
+        }
+
+        GLFontChar *fchar = characters[charId];
+
+        float ofsx = (float)fchar->getXOffset()/(float)imageWidth;
+        float advx = (float)fchar->getXAdvance()/(float)imageWidth;
+
+        if (charId == 32) {
+            advx = characters['_']->getAspect();
+         }
+
+        width += fchar->getAspect()+advx-ofsx;
+    }
+
+    width *= scalex;
+
+    return width;
+}
+
+
+void GLFont::drawString(std::string str, float xpos, float ypos, float size, float viewAspect) {
 
     glPushMatrix();
     glTranslatef(xpos, ypos, 0.0f);
-    glScalef(size, size, 1.0f);
     glPushMatrix();
+    glScalef(size/viewAspect, size, 1.0f);
 
     glEnable(GL_TEXTURE_2D);
     glBindTexture(GL_TEXTURE_2D, texId);
 
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
+
     glEnableClientState(GL_VERTEX_ARRAY);
     glEnableClientState(GL_TEXTURE_COORD_ARRAY);
     glVertexPointer(2, GL_FLOAT, 0, &gl_vertices[0]);
@@ -364,13 +398,25 @@ void GLFont::drawString(std::string str, float xpos, float ypos, float size) {
 
         GLFontChar *fchar = characters[charId];
 
+
+        float ofsx = (float)fchar->getXOffset()/(float)imageWidth;
+        float advx = (float)fchar->getXAdvance()/(float)imageWidth;
+
+
+        if (charId == 32) {
+            advx = characters['_']->getAspect();
+         }
+
+        glTranslatef(-ofsx,0.0,0.0);
         glDrawArrays(GL_QUADS, fchar->getIndex()/2, 4);
-        glTranslatef(fchar->getAspect()/8.0,0.0,0.0);
+        glTranslatef(fchar->getAspect()+advx,0.0,0.0);
     }
 
     glDisableClientState(GL_VERTEX_ARRAY);
     glDisableClientState(GL_TEXTURE_COORD_ARRAY);
     glPopMatrix();
     glPopMatrix();
+
+    glDisable(GL_BLEND);
 }
 

src/util/GLFont.h

@@ -55,7 +55,9 @@ public:
     GLFont();
     ~GLFont();
     void loadFont(std::string fontFile);
-    void drawString(std::string str, float xpos, float ypos, float height);
+
+    float getStringWidth(std::string str, float size, float viewAspect);
+    void drawString(std::string str, float xpos, float ypos, float height, float viewAspect);
 
 private:
     std::string nextParam(std::istringstream &str);

src/visual/SpectrumContext.cpp

@@ -33,7 +33,16 @@ void SpectrumContext::Draw(std::vector<float> &points) {
         glPopMatrix();
     }
 
-    getFont()->drawString("Testing",0.0,0.0,0.7);
+    GLint vp[4];
+
+    glGetIntegerv( GL_VIEWPORT, vp);
+
+    std::string msgStr("Welcome to CubicSDR -- This is a test string. 01234567890!@#$%^&*()_[]");
+    float charHeight = 62.0;
+    float viewAspect = (float)vp[2]/(float)vp[3];
+    float msgWidth = getFont()->getStringWidth(msgStr,charHeight/(float)vp[3],viewAspect);
+
+    getFont()->drawString(msgStr,0.0-(msgWidth/2.0),0.0,charHeight/(float)vp[3],viewAspect);
 
     CheckGLError();
 }