fontrenderer: Rework rendering for better font presentation

- For the correct use of the changes should be built freetype
   with the following settings:
     #define FT_CONFIG_OPTION_SUBPIXEL_RENDERING
     #define TT_CONFIG_OPTION_SUBPIXEL_HINTING

BS-Patch for freetype 2.5-2.7
-----------------------------
** include/freetype/config/ftoption.h **

-/* #define FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
+#define FT_CONFIG_OPTION_SUBPIXEL_RENDERING

-/* #define TT_CONFIG_OPTION_SUBPIXEL_HINTING */
+#define TT_CONFIG_OPTION_SUBPIXEL_HINTING

BS-Patch for freetype 2.7.1
---------------------------
** include/freetype/config/ftoption.h **

-/* #define FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
+#define FT_CONFIG_OPTION_SUBPIXEL_RENDERING

src/driver/fontrenderer.cpp

@@ -3,6 +3,7 @@
 
 	Copyright (C) 2001 Steffen Hehn 'McClean'
         Copyright (C) 2003 thegoodguy
+        Copyright (C) 2013-2017 M. Liebmann (micha-bbg)
 
 	License: GPL
 
@@ -240,6 +241,9 @@ Font::Font(FBFontRenderClass *render, FTC_FaceID faceid, const int isize, const
 	scaler.y_res   = render->yres;
 
 	setSize(isize);
+	fg_red = 0, fg_green = 0, fg_blue = 0;
+	memset((void*)colors, '\0', sizeof(colors));
+	useFullBG = false;
 }
 
 FT_Error Font::getGlyphBitmap(FT_ULong glyph_index, FTC_SBit *sbit)
@@ -383,43 +387,56 @@ int UTF8ToUnicode(const char * &text, const bool utf8_encoded) // returns -1 on
 	return unicode_value;
 }
 
-#define F_MUL 0x7FFF
+void Font::paintFontPixel(fb_pixel_t *td, uint8_t src)
-
-void Font::paintFontPixel(fb_pixel_t *td, uint8_t fg_red, uint8_t fg_green, uint8_t fg_blue, int faktor, uint8_t index)
 {
-	fb_pixel_t bg_col = *td;
+#define DST_BLUE  0x80
-	if (bg_col == (fb_pixel_t)0)
+#define DST_GREEN 0x80
-		bg_col = 0xE0808080;
+#define DST_RED   0x80
-	uint8_t bg_trans =  (bg_col & 0xFF000000) >> 24;
+#define DST_TRANS 0x80
-	int korr_r = ((bg_col & 0x00FF0000) >> 16) - fg_red;
+	if (useFullBG) {
-	int korr_g = ((bg_col & 0x0000FF00) >>  8) - fg_green;
+		uint8_t *dst = (uint8_t *)td;
-	int korr_b =  (bg_col & 0x000000FF)        - fg_blue;
+		if (*td == (fb_pixel_t)0) {
-
+			*dst = DST_BLUE  + ((fg_blue  - DST_BLUE)  * src) / 256;
-	*td =   ((g_settings.contrast_fonts && (index > 128)) ? 0xFF000000 : (((bg_trans == 0) ? 0xFF : bg_trans) << 24) & 0xFF000000) |
+			dst++;
-		(((fg_red   + ((korr_r*faktor)/F_MUL)) << 16) & 0x00FF0000) |
+			*dst = DST_GREEN + ((fg_green - DST_GREEN) * src) / 256;
-		(((fg_green + ((korr_g*faktor)/F_MUL)) <<  8) & 0x0000FF00) |
+			dst++;
-		 ((fg_blue  + ((korr_b*faktor)/F_MUL))        & 0x000000FF);
+			*dst = DST_RED   + ((fg_red   - DST_RED)   * src) / 256;
+			dst++;
+			*dst = (uint8_t)int_min(255, DST_TRANS + src);
+		}
+		else {
+			*dst = *dst + ((fg_blue  - *dst) * src) / 256;
+			dst++;
+			*dst = *dst + ((fg_green - *dst) * src) / 256;
+			dst++;
+			*dst = *dst + ((fg_red   - *dst) * src) / 256;
+			dst++;
+			*dst = (uint8_t)int_min(0xFF, *dst + src);
+		}
+	}
+	else
+		*td = colors[src];
 }
 
 void Font::RenderString(int x, int y, const int width, const char *text, const fb_pixel_t color, const int boxheight, const unsigned int flags)
 {
-	const bool utf8_encoded = flags & IS_UTF8;
-	const bool useFullBg = flags & FULLBG;
-/*
-	useFullBg (default = false)
-
-	useFullBg = false
-	fetch bgcolor from framebuffer, using lower left edge of the font
-
-	useFullBg = true
-	fetch bgcolor from framebuffer, using the respective real font position
-	- font rendering slower
-	- e.g. required for font rendering on images
-*/
-
 	if (!frameBuffer->getActive())
 		return;
 
+	const bool utf8_encoded = flags & IS_UTF8;
+	useFullBG               = flags & FULLBG;
+/*
+	useFullBg = false
+	 fetch bgcolor from framebuffer, using lower left edge of the font
+	  - default render mode
+	  - font rendering faster
+
+	useFullBg = true
+	 fetch bgcolor from framebuffer, using the respective real fontpixel position
+	  - better quality at font rendering on images or background with color gradient
+	  - font rendering slower
+*/
+
 	frameBuffer->checkFbArea(x, y-height, width, height, true);
 
 	pthread_mutex_lock( &renderer->render_mutex );
@@ -478,55 +495,33 @@ void Font::RenderString(int x, int y, const int width, const char *text, const f
 	int lastindex=0; // 0 == missing glyph (never has kerning values)
 	FT_Vector kerning;
 	int pen1 = -1; // "pen" positions for kerning, pen2 is "x"
-	static fb_pixel_t old_bgcolor    = 0, old_fgcolor = 0;
-	static uint8_t bg_trans          = 0, fg_red = 0, fg_green = 0, fg_blue = 0;
-	static bool olduseFullBg         = false;
-	static fb_pixel_t colors[256]    = {0};
-	static int faktor[256]           = {0};
-	static bool fontRecsInit         = false;
-	fb_pixel_t bg_color              = 1;
-	fb_pixel_t fg_color              = color;
 
-	if (!useFullBg) {
+	fg_red     = (color & 0x00FF0000) >> 16;
+	fg_green   = (color & 0x0000FF00) >>  8;
+	fg_blue    = color  & 0x000000FF;
+	fb_pixel_t bg_color = 0;
+
 	/* the GXA seems to do it's job asynchonously, so we need to wait until
 	   it's ready, otherwise the font will sometimes "be overwritten" with
 	   background color or bgcolor will be wrong */
 	frameBuffer->waitForIdle("Font::RenderString 1");
+	if (!useFullBG) {
 		/* fetch bgcolor from framebuffer, using lower left edge of the font... */
 		bg_color = *(frameBuffer->getFrameBufferPointer() + x +
 				y * frameBuffer->getStride() / sizeof(fb_pixel_t));
-	}
-	else
-		bg_color = 0;
 
-	if ((old_fgcolor != fg_color) || (old_bgcolor != bg_color) || (olduseFullBg != useFullBg) || !fontRecsInit) {
+		if (bg_color == (fb_pixel_t)0)
-		old_bgcolor  = bg_color;
+			bg_color = 0x80808080;
-		old_fgcolor  = fg_color;
-		olduseFullBg = useFullBg;
-		fontRecsInit = true;
 
-		bg_trans   =  (bg_color & 0xFF000000) >> 24;
+		uint8_t bg_trans = (bg_color & 0xFF000000) >> 24;
-		fg_red     =  (fg_color & 0x00FF0000) >> 16;
+		uint8_t bg_red   = (bg_color & 0x00FF0000) >> 16;
-		fg_green   =  (fg_color & 0x0000FF00) >>  8;
+		uint8_t bg_green = (bg_color & 0x0000FF00) >>  8;
-		fg_blue    =   fg_color & 0x000000FF;
+		uint8_t bg_blue  =  bg_color & 0x000000FF;
-
+		for (int i = 0; i < 256; i++) {
-		int korr_r=0, korr_g=0, korr_b=0;
+			colors[i] = (((int_min(0xFF, bg_trans + i))           << 24) & 0xFF000000) |
-		if (!useFullBg) {
+				    (((bg_red  +((fg_red  -bg_red)  * i)/256) << 16) & 0x00FF0000) |
-			korr_r = ((bg_color & 0x00FF0000) >> 16) - fg_red;
+				    (((bg_green+((fg_green-bg_green)* i)/256) <<  8) & 0x0000FF00) |
-			korr_g = ((bg_color & 0x0000FF00) >>  8) - fg_green;
+				     ((bg_blue +((fg_blue -bg_blue) * i)/256)        & 0x000000FF);
-			korr_b =  (bg_color & 0x000000FF)        - fg_blue;
-		}
-
-		for (int i = 0; i <= 0xFF; i++) {
-			int _faktor = ((0xFF - i) * F_MUL) / 0xFF;
-
-			if (useFullBg)
-				faktor[i]   = _faktor;
-			else
-				colors[i] =  ((g_settings.contrast_fonts && (i > 128)) ? 0xFF000000 : (((bg_trans == 0) ? 0xFF : bg_trans) << 24) & 0xFF000000) |
-					     (((fg_red   + ((korr_r*_faktor)/F_MUL)) << 16) & 0x00FF0000) |
-					     (((fg_green + ((korr_g*_faktor)/F_MUL)) <<  8) & 0x0000FF00) |
-					      ((fg_blue  + ((korr_b*_faktor)/F_MUL))        & 0x000000FF);
 		}
 	}
 
@@ -596,12 +591,8 @@ void Font::RenderString(int x, int y, const int width, const char *text, const f
 				for (ax = 0; ax < w + spread_by; ax++) {
 					if (stylemodifier != Font::Embolden) {
 						/* do not paint the backgroundcolor (*s = 0) */
-						if(*s != 0) {
+						if (*s != 0)
-							if (useFullBg)
+							paintFontPixel(td, *s);
-								paintFontPixel(td, fg_red, fg_green, fg_blue, faktor[*s], *s);
-							else
-								*td = colors[*s];
-						}
 					}
 					else {
 						int lcolor = -1;
@@ -611,12 +602,8 @@ void Font::RenderString(int x, int y, const int width, const char *text, const f
 							if (lcolor < *(s - i))
 								lcolor = *(s - i);
 						/* do not paint the backgroundcolor (lcolor = 0) */
-						if(lcolor != 0) {
+						if (lcolor != 0)
-							if (useFullBg)
+							paintFontPixel(td, (uint8_t)lcolor);
-								paintFontPixel(td, fg_red, fg_green, fg_blue, faktor[lcolor], (uint8_t)lcolor);
-							else
-								*td = colors[lcolor];
-						}
 					}
 					td++; s++;
 				}

src/driver/fontrenderer.h

@@ -3,6 +3,7 @@
 
 	Copyright (C) 2001 Steffen Hehn 'McClean'
         Copyright (C) 2003 thegoodguy
+        Copyright (C) 2013-2017 M. Liebmann (micha-bbg)
 
 	License: GPL
 
@@ -54,8 +55,12 @@ class Font
 	int height,DigitHeight,DigitOffset,ascender,descender,upper,lower;
 	int fontwidth;
 	int maxdigitwidth;
+	uint8_t fg_red, fg_green, fg_blue;
+	fb_pixel_t colors[256];
+	bool useFullBG;
 
-	inline void paintFontPixel(fb_pixel_t *td, uint8_t fg_red, uint8_t fg_green, uint8_t fg_blue, int faktor, uint8_t index);
+	inline int int_min(int a, int b) { return (a < b) ? a : b; }
+	inline void paintFontPixel(fb_pixel_t *td, uint8_t src);
 
  public:
 	enum fontmodifier

src/gui/widget/textbox.cpp

@@ -716,7 +716,7 @@ void CTextBox::refreshText(void)
 		frameBuffer->paintBoxRel(tx, ty-th, tw, th, COL_RED, m_nBgRadius, m_nBgRadiusType);
 #endif
 		//TRACE("[CTextBox] %s Line %d m_cFrame.iX %d m_cFrameTextRel.iX %d\r\n", __FUNCTION__, __LINE__, m_cFrame.iX, m_cFrameTextRel.iX);
-		m_pcFontText->RenderString(tx, ty, tw, m_cLineArray[i].c_str(), m_textColor, 0, (m_renderMode | m_utf8_encoded) ? Font::IS_UTF8 : 0);
+		m_pcFontText->RenderString(tx, ty, tw, m_cLineArray[i].c_str(), m_textColor, 0, m_renderMode | ((m_utf8_encoded) ? Font::IS_UTF8 : 0));
 		m_old_cText = m_cText;
 		y += m_nFontTextHeight;
 	}