blitter: Base horizontal adjust on scanline, not width

When we draw a BMP that has a width that is not a multiple of 8, some
black pixels show up on the right, and the left part is truncated.

The root cause is that the horizontal adjustment uses the width and
not the scanline, so we don't get the correct range of pixels.

Code inspection also showed that there was an error in the size of the
datalen being returned from `grob::pixels`, because it returnes the
size of the object, not the size of the data bitmap.

Fixes: #1043

Signed-off-by: Christophe de Dinechin <christophe@dinechin.org>

src/blitter.h

@@ -430,6 +430,7 @@ struct blitter
             drawable &= rect(w, h);
         }
 
+
         void clip(coord x1, coord y1, coord x2, coord y2)
         // --------------------------------------------------------------------
         //   Clip an area given in coordinates
@@ -1672,7 +1673,7 @@ inline void blitter::surface<blitter::MONOCHROME_REVERSE>::horizontal_adjust(
 //   On the DM42, we need horizontal adjustment for coordinates
 // ----------------------------------------------------------------------------
 {
-    size  w   = width() - 1;
+    size  w   = scanline - 1;
     coord ox1 = w - x2;
     x2        = w - x1;
     x1        = ox1;
@@ -1697,7 +1698,7 @@ inline void blitter::surface<blitter::RGB_16BPP>::horizontal_adjust(
 //   On the DM42, we need horizontal adjustment for coordinates
 // ----------------------------------------------------------------------------
 {
-    size  w   = width() - 1;
+    size  w   = scanline - 1;
     coord ox1 = w - x2;
     x2        = w - x1;
     x1        = ox1;

src/grob.cc

@@ -79,15 +79,16 @@ static void bitflip(byte *start, uint width, uint height, bool forward)
 {
 #ifdef REVERSE_GROBS
     uint scan = (width + 7) / 8;
+    uint scanline = scan * 8;
     for (uint y = 0; y < height; y++)
     {
         byte *row = start + scan * y;
         if (forward)
             for (uint r = 0; r < scan; r++)
                 row[r] = ~((row[r] >> 4) | (row[r] << 4));
-        for (uint x = 0; x < width / 2; x++)
+        for (uint x = 0; x < scanline / 2; x++)
         {
-            uint r = width - 1 - x;
+            uint r = scanline - 1 - x;
             uint lo = x / 8;
             uint ro = r / 8;
             uint lb = x % 8;

src/grob.h

@@ -173,7 +173,7 @@ struct grob : object
         if (height)
             *height = h;
         if (datalen)
-            *datalen = bytesize(type(), w, h);
+            *datalen = datasize(type(), w, h);
         return p;
     }