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-rw-r--r--src/palette.c32
-rw-r--r--src/plot/8bpp.c2
-rw-r--r--src/plot/common.c69
-rw-r--r--src/surface/sdl.c2
4 files changed, 81 insertions, 24 deletions
diff --git a/src/palette.c b/src/palette.c
index eba95cd..d600001 100644
--- a/src/palette.c
+++ b/src/palette.c
@@ -13,12 +13,13 @@
#include <assert.h>
#include <stdbool.h>
#include <stdlib.h>
+#include <string.h>
#include "palette.h"
/** Create an empty palette object. */
-bool nsfb_palette_new(struct nsfb_palette_s **palette)
+bool nsfb_palette_new(struct nsfb_palette_s **palette, int width)
{
*palette = malloc(sizeof(struct nsfb_palette_s));
if (*palette == NULL) {
@@ -28,14 +29,41 @@ bool nsfb_palette_new(struct nsfb_palette_s **palette)
(*palette)->type = NSFB_PALETTE_EMPTY;
(*palette)->last = 0;
+ (*palette)->dither = false;
+ (*palette)->dither_ctx.data_len = width * 3;
+ (*palette)->dither_ctx.data = malloc(width * 3 * sizeof(int));
+ if ((*palette)->dither_ctx.data == NULL) {
+ nsfb_palette_free(*palette);
+ return false;
+ }
+
return true;
}
/** Free a palette object. */
void nsfb_palette_free(struct nsfb_palette_s *palette)
{
- if (palette != NULL)
+ if (palette != NULL) {
+ if (palette->dither_ctx.data != NULL) {
+ free(palette->dither_ctx.data);
+ }
free(palette);
+ }
+}
+
+/** Init error diffusion for a plot. */
+void nsfb_palette_dither_init(struct nsfb_palette_s *palette, int width)
+{
+ palette->dither = true;
+ memset(palette->dither_ctx.data, 0, palette->dither_ctx.data_len);
+ palette->dither_ctx.width = width * 3;
+ palette->dither_ctx.current = 0;
+}
+
+/** Finalise error diffusion after a plot. */
+void nsfb_palette_dither_fini(struct nsfb_palette_s *palette)
+{
+ palette->dither = false;
}
/** Generate libnsfb 8bpp default palette. */
diff --git a/src/plot/8bpp.c b/src/plot/8bpp.c
index 05574d8..0245542 100644
--- a/src/plot/8bpp.c
+++ b/src/plot/8bpp.c
@@ -39,7 +39,7 @@ static uint8_t colour_to_pixel(nsfb_t *nsfb, nsfb_colour_t c)
if (nsfb->palette == NULL)
return 0;
- return nsfb_palette_best_match(nsfb->palette, c);
+ return nsfb_palette_best_match_dither(nsfb->palette, c);
}
#define PLOT_TYPE uint8_t
diff --git a/src/plot/common.c b/src/plot/common.c
index 185e323..c9f9dc1 100644
--- a/src/plot/common.c
+++ b/src/plot/common.c
@@ -16,6 +16,8 @@
#error PLOT_LINELEN must be a macro to increment a line length
#endif
+#include "palette.h"
+
#define SIGN(x) ((x<0) ? -1 : ((x>0) ? 1 : 0))
static bool
@@ -249,8 +251,7 @@ static bool bitmap_scaled(nsfb_t *nsfb, const nsfb_bbox_t *loc,
nsfb_bbox_t clipped; /* clipped display */
/* The part of the scaled image actually displayed is cropped to the
- * current context.
- */
+ * current context. */
clipped.x0 = x;
clipped.y0 = y;
clipped.x1 = x + width;
@@ -271,6 +272,10 @@ static bool bitmap_scaled(nsfb_t *nsfb, const nsfb_bbox_t *loc,
else
rwidth = width;
+ if (nsfb->palette != NULL) {
+ nsfb_palette_dither_init(nsfb->palette, rwidth);
+ }
+
/* get veritcal (y) and horizontal (x) scale factors; both integer
* part and remainder */
dx = bmp_width / width;
@@ -299,7 +304,8 @@ static bool bitmap_scaled(nsfb_t *nsfb, const nsfb_bbox_t *loc,
pvideo = get_xy_loc(nsfb, clipped.x0, clipped.y0);
pvideo_limit = pvideo + PLOT_LINELEN(nsfb->linelen) * rheight;
if (alpha) {
- for (; pvideo < pvideo_limit; pvideo += PLOT_LINELEN(nsfb->linelen)) {
+ for (; pvideo < pvideo_limit;
+ pvideo += PLOT_LINELEN(nsfb->linelen)) {
/* looping through render area vertically */
xoff = xoffs;
rx = rxs;
@@ -322,7 +328,8 @@ static bool bitmap_scaled(nsfb_t *nsfb, const nsfb_bbox_t *loc,
xloop)));
}
/* plot pixel */
- *(pvideo + xloop) = colour_to_pixel(nsfb, abpixel);
+ *(pvideo + xloop) = colour_to_pixel(
+ nsfb, abpixel);
}
/* handle horizontal interpolation */
xoff += dx;
@@ -341,7 +348,8 @@ static bool bitmap_scaled(nsfb_t *nsfb, const nsfb_bbox_t *loc,
}
}
} else {
- for (; pvideo < pvideo_limit; pvideo += PLOT_LINELEN(nsfb->linelen)) {
+ for (; pvideo < pvideo_limit;
+ pvideo += PLOT_LINELEN(nsfb->linelen)) {
/* looping through render area vertically */
xoff = xoffs;
rx = rxs;
@@ -350,7 +358,8 @@ static bool bitmap_scaled(nsfb_t *nsfb, const nsfb_bbox_t *loc,
/* get value of source pixel in question */
abpixel = pixel[yoff + xoff];
/* plot pixel */
- *(pvideo + xloop) = colour_to_pixel(nsfb, abpixel);
+ *(pvideo + xloop) = colour_to_pixel(
+ nsfb, abpixel);
/* handle horizontal interpolation */
xoff += dx;
@@ -369,6 +378,11 @@ static bool bitmap_scaled(nsfb_t *nsfb, const nsfb_bbox_t *loc,
}
}
}
+
+ if (nsfb->palette != NULL) {
+ nsfb_palette_dither_fini(nsfb->palette);
+ }
+
return true;
}
@@ -391,17 +405,16 @@ bitmap(nsfb_t *nsfb,
int height = loc->y1 - loc->y0;
nsfb_bbox_t clipped; /* clipped display */
- if (width == 0 || height == 0)
- return true;
+ if (width == 0 || height == 0)
+ return true;
/* Scaled bitmaps are handled by a separate function */
if (width != bmp_width || height != bmp_height)
return bitmap_scaled(nsfb, loc, pixel, bmp_width, bmp_height,
bmp_stride, alpha);
- /* The part of the scaled image actually displayed is cropped to the
- * current context.
- */
+ /* The part of the image actually displayed is cropped to the
+ * current context. */
clipped.x0 = x;
clipped.y0 = y;
clipped.x1 = x + width;
@@ -416,6 +429,10 @@ bitmap(nsfb_t *nsfb,
if (width > (clipped.x1 - clipped.x0))
width = (clipped.x1 - clipped.x0);
+ if (nsfb->palette != NULL) {
+ nsfb_palette_dither_init(nsfb->palette, width);
+ }
+
xoff = clipped.x0 - x;
yoff = (clipped.y0 - y) * bmp_stride;
height = height * bmp_stride + yoff;
@@ -428,16 +445,22 @@ bitmap(nsfb_t *nsfb,
for (xloop = 0; xloop < width; xloop++) {
abpixel = pixel[yloop + xloop + xoff];
if ((abpixel & 0xFF000000) != 0) {
- /* pixel is not transparent; have to
- * plot something */
- if ((abpixel & 0xFF000000) != 0xFF000000) {
- /* pixel is not opaque; need to
- * blend */
- abpixel = nsfb_plot_ablend(abpixel,
- pixel_to_colour(nsfb, *(pvideo + xloop)));
+ /* pixel is not transparent; have to
+ * plot something */
+ if ((abpixel & 0xFF000000) !=
+ 0xFF000000) {
+ /* pixel is not opaque; need to
+ * blend */
+ abpixel = nsfb_plot_ablend(
+ abpixel,
+ pixel_to_colour(
+ nsfb,
+ *(pvideo +
+ xloop)));
}
- *(pvideo + xloop) = colour_to_pixel(nsfb, abpixel);
+ *(pvideo + xloop) = colour_to_pixel(
+ nsfb, abpixel);
}
}
pvideo += PLOT_LINELEN(nsfb->linelen);
@@ -446,11 +469,17 @@ bitmap(nsfb_t *nsfb,
for (yloop = yoff; yloop < height; yloop += bmp_stride) {
for (xloop = 0; xloop < width; xloop++) {
abpixel = pixel[yloop + xloop + xoff];
- *(pvideo + xloop) = colour_to_pixel(nsfb, abpixel);
+ *(pvideo + xloop) = colour_to_pixel(
+ nsfb, abpixel);
}
pvideo += PLOT_LINELEN(nsfb->linelen);
}
}
+
+ if (nsfb->palette != NULL) {
+ nsfb_palette_dither_fini(nsfb->palette);
+ }
+
return true;
}
diff --git a/src/surface/sdl.c b/src/surface/sdl.c
index 7a86dc1..0554e26 100644
--- a/src/surface/sdl.c
+++ b/src/surface/sdl.c
@@ -458,7 +458,7 @@ static int sdl_initialise(nsfb_t *nsfb)
nsfb->surface_priv = sdl_screen;
if (nsfb->bpp == 8) {
- nsfb_palette_new(&nsfb->palette);
+ nsfb_palette_new(&nsfb->palette, nsfb->width);
set_palette(nsfb);
}