Commit 6b9a8044be0da700970e1cf5c0a7d6f3e92345f3
2020-08-20T21:09:23
[sdf] Add function to copy source bitmap to distance map. * src/sdf/ftbsdf.c (bsdf_init_distance_map): New function.
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diff --git a/ChangeLog b/ChangeLog
index 950d7d5..318f9d9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
2020-08-20 Anuj Verma <anujv@iitbhilai.ac.in>
+ [sdf] Add function to copy source bitmap to distance map.
+
+ * src/sdf/ftbsdf.c (bsdf_init_distance_map): New function.
+
+2020-08-20 Anuj Verma <anujv@iitbhilai.ac.in>
+
[sdf] Add functions to compute pixel edge distances.
* src/sdf/ftbsdf.c (compute_edge_distance, bsdf_approximate_edge):
diff --git a/src/sdf/ftbsdf.c b/src/sdf/ftbsdf.c
index 9dc6953..da4d9f9 100644
--- a/src/sdf/ftbsdf.c
+++ b/src/sdf/ftbsdf.c
@@ -494,4 +494,205 @@
return error;
}
+
+ /**************************************************************************
+ *
+ * @Function:
+ * bsdf_init_distance_map
+ *
+ * @Description:
+ * Initialize the distance map according to the '8-point sequential
+ * Euclidean distance mapping' (8SED) algorithm. Basically it copies
+ * the `source` bitmap alpha values to the `distance_map->alpha`
+ * parameter of `worker`.
+ *
+ * @Input:
+ * source ::
+ * Source bitmap to copy the data from.
+ *
+ * @Output:
+ * worker ::
+ * Target distance map to copy the data to.
+ *
+ * @Return:
+ * FreeType error, 0 means success.
+ *
+ */
+ static FT_Error
+ bsdf_init_distance_map( const FT_Bitmap* source,
+ BSDF_Worker* worker )
+ {
+ FT_Error error = FT_Err_Ok;
+
+ FT_Int x_diff, y_diff;
+ FT_Int t_i, t_j, s_i, s_j;
+ FT_Byte* s;
+ ED* t;
+
+
+ /* again check the parameters (probably unnecessary) */
+ if ( !source || !worker )
+ {
+ error = FT_THROW( Invalid_Argument );
+ goto Exit;
+ }
+
+ /* Because of the way we convert a bitmap to SDF, */
+ /* i.e., aligning the source to the center of the */
+ /* target, the target's width and rows must be */
+ /* checked before copying. */
+ if ( worker->width < (FT_Int)source->width ||
+ worker->rows < (FT_Int)source->rows )
+ {
+ error = FT_THROW( Invalid_Argument );
+ goto Exit;
+ }
+
+ /* check pixel mode */
+ if ( source->pixel_mode == FT_PIXEL_MODE_NONE )
+ {
+ FT_ERROR(( "bsdf_copy_source_to_target:"
+ " Invalid pixel mode of source bitmap" ));
+ error = FT_THROW( Invalid_Argument );
+ goto Exit;
+ }
+
+#ifdef FT_DEBUG_LEVEL_TRACE
+ if ( source->pixel_mode == FT_PIXEL_MODE_MONO )
+ {
+ FT_TRACE0(( "bsdf_copy_source_to_target:"
+ " The `bsdf' renderer can convert monochrome\n" ));
+ FT_TRACE0(( " "
+ " bitmaps to SDF but the results are not perfect\n" ));
+ FT_TRACE0(( " "
+ " because there is no way to approximate actual\n" ));
+ FT_TRACE0(( " "
+ " outlines from monochrome bitmaps. Consider\n" ));
+ FT_TRACE0(( " "
+ " using an anti-aliased bitmap instead.\n" ));
+ }
+#endif
+
+ /* Calculate the width and row differences */
+ /* between target and source. */
+ x_diff = worker->width - source->width;
+ y_diff = worker->rows - source->rows;
+
+ x_diff /= 2;
+ y_diff /= 2;
+
+ t = (ED*)worker->distance_map;
+ s = source->buffer;
+
+ /* For now we only support pixel mode `FT_PIXEL_MODE_MONO` */
+ /* and `FT_PIXEL_MODE_GRAY`. More will be added later. */
+ /* */
+ /* [NOTE]: We can also use @FT_Bitmap_Convert to convert */
+ /* bitmap to 8bpp. To avoid extra allocation and */
+ /* since the target bitmap can be 16bpp we manually */
+ /* convert the source bitmap to the desired bpp. */
+
+ switch ( source->pixel_mode )
+ {
+ case FT_PIXEL_MODE_MONO:
+ {
+ FT_Int t_width = worker->width;
+ FT_Int t_rows = worker->rows;
+ FT_Int s_width = source->width;
+ FT_Int s_rows = source->rows;
+
+
+ for ( t_j = 0; t_j < t_rows; t_j++ )
+ {
+ for ( t_i = 0; t_i < t_width; t_i++ )
+ {
+ FT_Int t_index = t_j * t_width + t_i;
+ FT_Int s_index;
+ FT_Int div, mod;
+ FT_Byte pixel, byte;
+
+
+ t[t_index] = zero_ed;
+
+ s_i = t_i - x_diff;
+ s_j = t_j - y_diff;
+
+ /* Assign 0 to padding similar to */
+ /* the source bitmap. */
+ if ( s_i < 0 || s_i >= s_width ||
+ s_j < 0 || s_j >= s_rows )
+ continue;
+
+ if ( worker->params.flip_y )
+ s_index = ( s_rows - s_j - 1 ) * source->pitch;
+ else
+ s_index = s_j * source->pitch;
+
+ div = s_index + s_i / 8;
+ mod = 7 - s_i % 8;
+
+ pixel = s[div];
+ byte = 1 << mod;
+
+ t[t_index].alpha = pixel & byte ? 255 : 0;
+
+ pixel = 0;
+ }
+ }
+ }
+ break;
+
+ case FT_PIXEL_MODE_GRAY:
+ {
+ FT_Int t_width = worker->width;
+ FT_Int t_rows = worker->rows;
+ FT_Int s_width = source->width;
+ FT_Int s_rows = source->rows;
+
+
+ /* loop over all pixels and assign pixel values from source */
+ for ( t_j = 0; t_j < t_rows; t_j++ )
+ {
+ for ( t_i = 0; t_i < t_width; t_i++ )
+ {
+ FT_Int t_index = t_j * t_width + t_i;
+ FT_Int s_index;
+
+
+ t[t_index] = zero_ed;
+
+ s_i = t_i - x_diff;
+ s_j = t_j - y_diff;
+
+ /* Assign 0 to padding similar to */
+ /* the source bitmap. */
+ if ( s_i < 0 || s_i >= s_width ||
+ s_j < 0 || s_j >= s_rows )
+ continue;
+
+ if ( worker->params.flip_y )
+ s_index = ( s_rows - s_j - 1 ) * s_width + s_i;
+ else
+ s_index = s_j * s_width + s_i;
+
+ /* simply copy the alpha values */
+ t[t_index].alpha = s[s_index];
+ }
+ }
+ }
+ break;
+
+ default:
+ FT_ERROR(( "bsdf_copy_source_to_target:"
+ " unsopported pixel mode of source bitmap\n" ));
+
+ error = FT_THROW( Unimplemented_Feature );
+ break;
+ }
+
+ Exit:
+ return error;
+ }
+
+
/* END */