Fix:graphics/sdl:Implement own text-blending routine. SDL_BlitSurface

doesn't handle transparency the way we need it. Heavily based on work
by tegzed.

git-svn-id: https://navit.svn.sourceforge.net/svnroot/navit/trunk@4077 ffa7fe5e-494d-0410-b361-a75ebd5db220

diff --git a/navit/navit/graphics/sdl/graphics_sdl.c b/navit/navit/graphics/sdl/graphics_sdl.c
index cb3ae76..75448c2 100644 (file)
--- a/navit/navit/graphics/sdl/graphics_sdl.c
+++ b/navit/navit/graphics/sdl/graphics_sdl.c
@@ -922,6 +922,48 @@ draw_lines(struct graphics_priv *gr, struct graphics_gc_priv *gc, struct point *
     }
 #endif
 }
+
+static void set_pixel(SDL_Surface *surface, int x, int y, Uint32 pixel)
+{
+    if(x<0 || y<0 || x>=surface->w || y>=surface->h) {
+       return;
+    }
+    switch(surface->format->BytesPerPixel) {
+       case 2:
+           {
+               Uint16 *target_pixel = (Uint16 *)((Uint8*)surface->pixels + y * surface->pitch + x * surface->format->BytesPerPixel);
+
+               Uint8 r1,g1,b1,a1;
+               Uint8 r2,g2,b2,a2;
+               SDL_GetRGBA(*target_pixel, surface->format, &r1, &g1, &b1, &a1);
+               SDL_GetRGBA(pixel, surface->format, &r2, &g2, &b2, &a2);
+
+               *target_pixel = (Uint16) SDL_MapRGBA(surface->format,
+                       (r1*(0xff-a2)/0xff) + (r2*a2/0xff),
+                       (g1*(0xff-a2)/0xff) + (g2*a2/0xff),
+                       (b1*(0xff-a2)/0xff) + (b2*a2/0xff),
+                       a2 + a1*(0xff-a2)/0xff );
+               break;
+           }
+       case 4:
+           {
+               Uint32 *target_pixel = (Uint32 *)((Uint8*)surface->pixels + y * surface->pitch + x * surface->format->BytesPerPixel);
+
+               Uint8 r1,g1,b1,a1;
+               Uint8 r2,g2,b2,a2;
+               SDL_GetRGBA(*target_pixel, surface->format, &r1, &g1, &b1, &a1);
+               SDL_GetRGBA(pixel, surface->format, &r2, &g2, &b2, &a2);
+
+               *target_pixel = (Uint32) SDL_MapRGBA(surface->format,
+                       (r1*(0xff-a2)/0xff) + (r2*a2/0xff),
+                       (g1*(0xff-a2)/0xff) + (g2*a2/0xff),
+                       (b1*(0xff-a2)/0xff) + (b2*a2/0xff),
+                       a2 + a1*(0xff-a2)/0xff );
+               break;
+           }
+    }
+}
+
 static void
 display_text_draw(struct font_freetype_text *text,
                  struct graphics_priv *gr, struct graphics_gc_priv *fg,
@@ -1040,41 +1082,25 @@ display_text_draw(struct font_freetype_text *text,
                gr->freetype_methods.get_glyph(g, glyph, 32, stride,
                                               &black, &white,
                                               &transparent);
-               //convert ABGR to RGBA
-               int j;
-               unsigned char *pGlyph = glyph;
-               for (j = 0; j < g->w * g->h; ++j) {
-                   unsigned char tmp;
-                   tmp = *(pGlyph + 0);
-                   *(pGlyph + 0) = *(pGlyph + 2);
-                   *(pGlyph + 2) = tmp;
-                   pGlyph += 4;
-               }
-               SDL_Surface *glyph_surface =
-                   SDL_CreateRGBSurfaceFrom(glyph, g->w, g->h, 32,
-                                               stride,
-                                               0x000000ff,0x0000ff00,0x00ff0000,0xff000000);
-               if (glyph_surface) {
-                   SDL_Rect r;
-                   r.x = (x + g->x) >> 6;
-                   r.y = (y + g->y) >> 6;
-                   r.w = g->w;
-                   r.h = g->h;
-
-                   SDL_BlitSurface(glyph_surface, NULL, gr->screen, &r);
-                   SDL_FreeSurface(glyph_surface);
-               }
-
                int ii, jj;
+               unsigned char* pGlyph = glyph;
                for (jj = 0; jj < g->h; ++jj) {
                    for (ii = 0; ii < g->w; ++ii) {
                        int sx = (x + g->x) >> 6;
                        int sy = (y + g->y) >> 6;
                        sx = sx < 0 ? 0 : sx;
                        sy = sy < 0 ? 0 : sy;
-                       int poff =
-                           gr->screen->w * ((jj) + sy) + ((ii) + sx);
-                       poff *= gr->screen->format->BytesPerPixel;
+
+                       if(*(pGlyph+0)>10 || *(pGlyph+1)>10 || *(pGlyph+2)>10 || *(pGlyph+3)>10) {
+                            set_pixel(gr->screen, ii+sx, jj+sy,
+                                 SDL_MapRGBA(gr->screen->format,
+                                      *(pGlyph+2),                     // Pixels are in BGRA format
+                                      *(pGlyph+1),
+                                      *(pGlyph+0),
+                                      *(pGlyph+3)
+                                      ));
+                        }
+                        pGlyph += 4;
                    }
                }
                g_free(glyph);