dvi: Fix drawing glyphs with transparency

[evince.git] / backend / dvi / cairo-device.c

diff --git a/backend/dvi/cairo-device.c b/backend/dvi/cairo-device.c
index 51aea3790c5fe2d6501db737e759740d87242012..8d6553d6cd6ea89b98cd0f71a2e2ecf8855d27f4 100644 (file)
--- a/backend/dvi/cairo-device.c
+++ b/backend/dvi/cairo-device.c
@@ -202,12 +202,9 @@ dvi_cairo_alloc_colors (void  *device_data,
                        int    density)
 {
        double  frac;
-       GdkColor color, color_fg, color_bg;
+       GdkColor color, color_fg;
        int     i, n;
-
-       color_bg.red = (bg >> 16) & 0xff;
-       color_bg.green = (bg >> 8) & 0xff;
-       color_bg.blue = (bg >> 0) & 0xff;
+       unsigned int alpha;
 
        color_fg.red = (fg >> 16) & 0xff;
        color_fg.green = (fg >> 8) & 0xff;
@@ -219,11 +216,12 @@ dvi_cairo_alloc_colors (void  *device_data,
                        pow ((double)i / n, 1 / gamma) :
                        1 - pow ((double)(n - i) / n, -gamma);
                
-               color.red = frac * ((double)color_fg.red - color_bg.red) + color_bg.red;
-               color.green = frac * ((double)color_fg.green - color_bg.green) + color_bg.green;
-               color.blue = frac * ((double)color_fg.blue - color_bg.blue) + color_bg.blue;
-               
-               pixels[i] = (color.red << 16) + (color.green << 8) + color.blue + 0xff000000;
+               color.red = frac * color_fg.red;
+               color.green = frac * color_fg.green;
+               color.blue = frac * color_fg.blue;
+               alpha = frac * 0xFF;
+
+               pixels[i] = (alpha << 24) + (color.red << 16) + (color.green << 8) + color.blue;
        }
 
        return npixels;
@@ -235,7 +233,7 @@ dvi_cairo_create_image (void *device_data,
                        Uint  height,
                        Uint  bpp)
 {
-       return cairo_image_surface_create (CAIRO_FORMAT_RGB24, width, height);
+       return cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width, height);
 }
 
 static void
@@ -256,6 +254,8 @@ dvi_cairo_put_pixel (void *image, int x, int y, Ulong color)
        rowstride = cairo_image_surface_get_stride (surface);
        p = (guint32*) (cairo_image_surface_get_data (surface) + y * rowstride + x * 4);
 
+        /* per cairo docs, must flush before modifying outside of cairo */
+        cairo_surface_flush(surface);
        *p = color;
 }
 
@@ -343,7 +343,7 @@ mdvi_cairo_device_render (DviContext* dvi)
        memset (pixels, 0xff, page_height * rowstride);
 
        surface = cairo_image_surface_create_for_data (pixels,
-                                                      CAIRO_FORMAT_RGB24,
+                                                      CAIRO_FORMAT_ARGB32,
                                                       page_width, page_height,
                                                       rowstride);
        cairo_surface_set_user_data (surface, &key,