Improved and cleaned up transparent text drawing

4 files changed, 31 insertions, 33 deletions

diff --git a/PLUGINS/src/osddemo/osddemo.c b/PLUGINS/src/osddemo/osddemo.c
index 87d94638..2e6a33bf 100644
--- a/PLUGINS/src/osddemo/osddemo.c
+++ b/PLUGINS/src/osddemo/osddemo.c
@@ -3,7 +3,7 @@
  *
  * See the README file for copyright information and how to reach the author.
  *
- * $Id: osddemo.c 2.2 2011/02/20 15:06:18 kls Exp $
+ * $Id: osddemo.c 2.3 2011/02/26 12:08:13 kls Exp $
  */
 
 #include <vdr/osd.h>
@@ -338,7 +338,8 @@ void cTrueColorDemo::Action(void)
                        const int Size = Font->Width(Text) + 10;
                        const int NumDots = 12;
                        const int AnimFrames = NumDots;
-                       AnimPixmap = osd->CreatePixmap(3, cRect((osd->Width() - Size) / 2, StartLine, Size, Size), cRect(0, 0, Size, Size * AnimFrames));
+                       // Temporarily using pixmap layer 0 to have the text alpha blended:
+                       AnimPixmap = osd->CreatePixmap(0, cRect((osd->Width() - Size) / 2, StartLine, Size, Size), cRect(0, 0, Size, Size * AnimFrames));
                        if (AnimPixmap) {
                           AnimPixmap->SetAlpha(0);
                           AnimPixmap->Clear();
@@ -356,8 +357,9 @@ void cTrueColorDemo::Action(void)
                                   AnimPixmap->DrawEllipse(cRect(x, y, Diameter, Diameter), ArgbToColor(0xFF, Color, Color, Color));
                                   Color -= Delta;
                                   }
-                              AnimPixmap->DrawText(cPoint(0, Frame * Size), "Animation", clrBlack, clrTransparent, cFont::GetFont(fontSml), Size, Size, taCenter);
+                              AnimPixmap->DrawText(cPoint(0, Frame * Size), Text, clrBlack, clrTransparent, cFont::GetFont(fontSml), Size, Size, taCenter);
                               }
+                          AnimPixmap->SetLayer(3); // now setting the actual pixmap layer
                           FadeInPixmap = AnimPixmap;
                           LOCK_THREAD;
                           OldCursor = cursor = AnimPixmap->ViewPort().Point();
diff --git a/font.c b/font.c
index 227dd63f..db1bd893 100644
--- a/font.c
+++ b/font.c
@@ -6,7 +6,7 @@
  *
  * BiDi support by Osama Alrawab <alrawab@hotmail.com> @2008 Tripoli-Libya.
  *
- * $Id: font.c 2.6 2011/02/20 14:15:38 kls Exp $
+ * $Id: font.c 2.7 2011/02/26 12:09:18 kls Exp $
  */
 
 #include "font.h"
@@ -338,7 +338,6 @@ void cFreetypeFont::DrawText(cPixmap *Pixmap, int x, int y, const char *s, tColo
      s = bs;
 #endif
      bool AntiAliased = Setup.AntiAlias;
-     bool TransparentBackground = ColorBg == clrTransparent;
      uint prevSym = 0;
      while (*s) {
            int sl = Utf8CharLen(s);
@@ -358,16 +357,8 @@ void cFreetypeFont::DrawText(cPixmap *Pixmap, int x, int y, const char *s, tColo
                   for (int pitch = 0; pitch < g->Pitch(); pitch++) {
                       uchar bt = *(buffer + (row * g->Pitch() + pitch));
                       if (AntiAliased) {
-                         if (bt > 0x00) {
-                            tColor bg;
-                            if (bt == 0xFF || TransparentBackground)
-                               bg = ColorFg;
-                            else {
-                               bg = AlphaBlend(ColorFg, ColorBg, bt);
-                               bt = ALPHA_OPAQUE;
-                               }
-                            Pixmap->DrawPixel(cPoint(x + pitch + g->Left() + kerning, y + row + (height - Bottom() - g->Top())), bg, bt);
-                            }
+                         if (bt > 0x00)
+                            Pixmap->DrawPixel(cPoint(x + pitch + g->Left() + kerning, y + row + (height - Bottom() - g->Top())), AlphaBlend(ColorFg, ColorBg, bt));
                          }
                       else { //monochrome rendering
                          for (int col = 0; col < 8 && col + pitch * 8 <= symWidth; col++) {
diff --git a/osd.c b/osd.c
index 1516bf57..aeedb721 100644
--- a/osd.c
+++ b/osd.c
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: osd.c 2.13 2011/02/20 21:35:48 kls Exp $
+ * $Id: osd.c 2.14 2011/02/26 11:36:58 kls Exp $
  */
 
 #include "osd.h"
@@ -69,7 +69,7 @@ public:
 
 cInitAlphaLut initAlphaLut;
 
-tColor AlphaBlend(tColor ColorFg, tColor ColorBg, tColor AlphaLayer)
+tColor AlphaBlend(tColor ColorFg, tColor ColorBg, uint8_t AlphaLayer)
 {
   tColor Alpha = (ColorFg & 0xFF000000) >> 24;
   Alpha *= AlphaLayer;
@@ -84,7 +84,7 @@ tColor AlphaBlend(tColor ColorFg, tColor ColorBg, tColor AlphaLayer)
 // Alpha blending without lookup table.
 // Also works fast, but doesn't return the theoretically correct result.
 // It's "good enough", though.
-static tColor Multiply(tColor Color, tColor Alpha)
+static tColor Multiply(tColor Color, uint8_t Alpha)
 {
   tColor RB = (Color & 0x00FF00FF) * Alpha;
   RB = ((RB + ((RB >> 8) & 0x00FF00FF) + 0x00800080) >> 8) & 0x00FF00FF;
@@ -93,7 +93,7 @@ static tColor Multiply(tColor Color, tColor Alpha)
   return AG | RB;
 }
 
-tColor AlphaBlend(tColor ColorFg, tColor ColorBg, tColor AlphaLayer)
+tColor AlphaBlend(tColor ColorFg, tColor ColorBg, uint8_t AlphaLayer)
 {
   tColor Alpha = (ColorFg & 0xFF000000) >> 24;
   if (AlphaLayer < ALPHA_OPAQUE) {
@@ -1174,12 +1174,15 @@ void cPixmapMemory::DrawImage(const cPoint &Point, int ImageHandle)
   Unlock();
 }
 
-void cPixmapMemory::DrawPixel(const cPoint &Point, tColor Color, tColor Alpha)
+void cPixmapMemory::DrawPixel(const cPoint &Point, tColor Color)
 {
   Lock();
   if (DrawPort().Size().Contains(Point)) {
      int p = Point.Y() * DrawPort().Width() + Point.X();
-     data[p] = AlphaBlend(Color, data[p], Alpha);
+     if (Layer() == 0 && !IS_OPAQUE(Color))
+        data[p] = AlphaBlend(Color, data[p]);
+     else
+        data[p] = Color;
      MarkDrawPortDirty(Point);
      }
   Unlock();
diff --git a/osd.h b/osd.h
index 2bb6e0a0..86a660c5 100644
--- a/osd.h
+++ b/osd.h
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: osd.h 2.6 2011/02/20 14:52:17 kls Exp $
+ * $Id: osd.h 2.7 2011/02/26 12:13:59 kls Exp $
  */
 
 #ifndef __OSD_H
@@ -24,6 +24,7 @@
 #define MAXNUMCOLORS 256
 #define ALPHA_TRANSPARENT  0x00
 #define ALPHA_OPAQUE       0xFF
+#define IS_OPAQUE(c)       ((c >> 24) == ALPHA_OPAQUE)
 
 enum {
                    //AARRGGBB
@@ -73,7 +74,7 @@ tColor HsvToColor(double H, double S, double V);
    ///< to an RGB tColor value. The alpha value of the result is 0x00, so
    ///< the caller may need to set it accordingly.
 
-tColor AlphaBlend(tColor ColorFg, tColor ColorBg, tColor AlphaLayer = ALPHA_OPAQUE);
+tColor AlphaBlend(tColor ColorFg, tColor ColorBg, uint8_t AlphaLayer = ALPHA_OPAQUE);
 
 class cPalette {
 private:
@@ -479,11 +480,13 @@ public:
        ///< for defining the rendering sequence. If Layer is less than zero, this
        ///< pixmap will not be rendered into the final OSD (it can be activated by a
        ///< later call to SetLayer()). The value 0 is reserved for the background
-       ///< pixmap and shall not be used otherwise. If there are several pixmaps with
-       ///< the same value of Layer, their rendering sequence within that layer is
-       ///< undefined.
-       ///< I order to allow devices that can handle only a limited number of layers,
-       ///< the Layer parameters must be less than 8 (MAXPIXMAPLAYERS).
+       ///< pixmap and shall not be used otherwise (with the sole exception of
+       ///< temporarily using layer 0 to have a text with transparent background
+       ///< rendered with alpha blending into that pixmap; see also DrawPixel()).
+       ///< If there are several pixmaps with the same value of Layer, their rendering
+       ///< sequence within that layer is undefined.
+       ///< In order to allow devices that can handle only a limited number of layers,
+       ///< the Layer parameter must be less than 8 (MAXPIXMAPLAYERS).
        ///< ViewPort defines the rectangle in which this pixmap will be rendered on
        ///< the OSD. If no DrawPort ist given, it defaults to the same size as the
        ///< ViewPort, with its upper left corner set to (0, 0).
@@ -567,12 +570,11 @@ public:
        ///< the given Point. ImageHandle must be a value that has previously been
        ///< returned by a call to cOsdProvider::StoreImage(). If ImageHandle
        ///< has an invalid value, nothing happens.
-  virtual void DrawPixel(const cPoint &Point, tColor Color, tColor Alpha = ALPHA_OPAQUE) = 0;
+  virtual void DrawPixel(const cPoint &Point, tColor Color) = 0;
        ///< Sets the pixel at the given Point to the given Color, which is
        ///< a full 32 bit ARGB value. If the alpha value of Color is not 0xFF
-       ///< (fully opaque), the pixel is alpha blended with the existing color
-       ///< at the given position in this pixmap. If Alpha is less than
-       ///< ALPHA_OPAQUE, the alpha value of Color will be reduced accordingly.
+       ///< (fully opaque), and this is the background pixmap (layer 0), the pixel is
+       ///< alpha blended with the existing color at the given position in this pixmap.
   virtual void DrawBitmap(const cPoint &Point, const cBitmap &Bitmap, tColor ColorFg = 0, tColor ColorBg = 0, bool Overlay = false) = 0;
        ///< Sets the pixels in the OSD with the data from the given
        ///< Bitmap, putting the upper left corner of the Bitmap at Point.
@@ -662,7 +664,7 @@ public:
   virtual void Fill(tColor Color);
   virtual void DrawImage(const cPoint &Point, const cImage &Image);
   virtual void DrawImage(const cPoint &Point, int ImageHandle);
-  virtual void DrawPixel(const cPoint &Point, tColor Color, tColor Alpha = ALPHA_OPAQUE);
+  virtual void DrawPixel(const cPoint &Point, tColor Color);
   virtual void DrawBitmap(const cPoint &Point, const cBitmap &Bitmap, tColor ColorFg = 0, tColor ColorBg = 0, bool Overlay = false);
   virtual void DrawText(const cPoint &Point, const char *s, tColor ColorFg, tColor ColorBg, const cFont *Font, int Width = 0, int Height = 0, int Alignment = taDefault);
   virtual void DrawRectangle(const cRect &Rect, tColor Color);