new scaling, based on the Bresenham algorithm
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Dana Jansens
parent
cb3aaab102
commit
55ed757c5f
1 changed files with 158 additions and 62 deletions
196
render/image.c
196
render/image.c
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@ -4,70 +4,166 @@
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#include <glib.h>
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void RrImageDraw(RrPixel32 *target, RrTextureRGBA *rgba, RrRect *area)
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#define AVERAGE(a, b) ( ((((a) ^ (b)) & 0xfefefefeL) >> 1) + ((a) & (b)) )
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static void scale_line(RrPixel32 *dest, RrPixel32 *source, gint w, gint dw)
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{
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RrPixel32 *draw = rgba->data;
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gint c, i, e, t, sfw, sfh;
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sfw = area->width;
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sfh = area->height;
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gint num_pixels = dw;
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gint int_part = w / dw;
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gint fract_part = w % dw;
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gint err = 0;
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g_assert(rgba->data != NULL);
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if ((rgba->width != sfw || rgba->height != sfh) &&
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(rgba->width != rgba->cwidth || rgba->height != rgba->cheight)) {
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double dx = rgba->width / (double)sfw;
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double dy = rgba->height / (double)sfh;
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double px = 0.0;
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double py = 0.0;
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int iy = 0;
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/* scale it and cache it */
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if (rgba->cache != NULL)
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g_free(rgba->cache);
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rgba->cache = g_new(RrPixel32, sfw * sfh);
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rgba->cwidth = sfw;
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rgba->cheight = sfh;
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for (i = 0, c = 0, e = sfw*sfh; i < e; ++i) {
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rgba->cache[i] = rgba->data[(int)px + iy];
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if (++c >= sfw) {
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c = 0;
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px = 0;
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py += dy;
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iy = (int)py * rgba->width;
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} else
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px += dx;
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while (num_pixels-- > 0) {
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*dest++ = *source;
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source += int_part;
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err += fract_part;
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if (err >= dw) {
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err -= dw;
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source++;
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}
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}
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}
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/* do we use the cache we may have just created, or the original? */
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if (rgba->width != sfw || rgba->height != sfh)
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draw = rgba->cache;
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static RrPixel32* scale_half(RrPixel32 *source, gint w, gint h)
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{
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RrPixel32 *out, *dest, *sourceline, *sourceline2;
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gint dw, dh, x, y;
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/* apply the alpha channel */
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for (i = 0, c = 0, t = area->x, e = sfw*sfh; i < e; ++i, ++t) {
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sourceline = source;
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sourceline2 = source + w;
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dw = w >> 1;
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dh = h >> 1;
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out = dest = g_new(RrPixel32, dw * dh);
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for (y = 0; y < dh; ++y) {
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RrPixel32 *s, *s2;
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s = sourceline;
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s2 = sourceline2;
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for (x = 0; x < dw; ++x) {
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*dest++ = AVERAGE(AVERAGE(*s, *(s+1)),
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AVERAGE(*s2, *(s2+1)));
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s += 2;
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s2 += 2;
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}
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sourceline += w << 1;
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sourceline2 += w << 1;
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}
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return out;
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}
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static RrPixel32* scale_rect(RrPixel32 *fullsource,
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gint w, gint h, gint dw, gint dh)
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{
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RrPixel32 *out, *dest;
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RrPixel32 *source = fullsource;
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RrPixel32 *oldsource = NULL;
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RrPixel32 *prev_source = NULL;
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gint num_pixels;
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gint int_part;
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gint fract_part;
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gint err = 0;
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while (dw <= (w >> 1) && dh <= (h >> 1)) {
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source = scale_half(source, w, h);
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w >>= 1; h >>= 1;
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g_free(oldsource);
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oldsource = source;
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}
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num_pixels = dh;
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int_part = (h / dh) * w;
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fract_part = h % dh;
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out = dest = g_new(RrPixel32, dw * dh);
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while (num_pixels-- > 0) {
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if (source == prev_source) {
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memcpy(dest, dest - dw, dw * sizeof(RrPixel32));
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} else {
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scale_line(dest, source, w, dw);
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prev_source = source;
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}
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dest += dw;
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source += int_part;
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err += fract_part;
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if (err >= dh) {
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err -= dh;
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source += w;
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}
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}
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g_free(oldsource);
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return out;
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}
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void RrImageDraw(RrPixel32 *target, RrTextureRGBA *rgba,
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gint target_w, gint target_h,
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RrRect *area)
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{
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RrPixel32 *dest;
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RrPixel32 *source;
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gint sw, sh, dw, dh;
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gint col, num_pixels;
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sw = rgba->width;
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sh = rgba->height;
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/* keep the ratio */
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dw = area->width;
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dh = (int)(dw * ((double)sh / sw));
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if (dh > area->height) {
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dh = area->height;
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dw = (int)(dh * ((double)sw / sh));
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}
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if (sw != dw || sh != dh) {
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/*if (!(rgba->cache && dw == rgba->cwidth && dh == rgba->cheight))*/ {
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g_free(rgba->cache);
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rgba->cache = scale_rect(rgba->data, sw, sh, dw, dh);
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rgba->cwidth = dw;
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rgba->cheight = dh;
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}
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source = rgba->cache;
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} else {
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source = rgba->data;
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}
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/* copy source -> dest, and apply the alpha channel */
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col = 0;
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num_pixels = dw * dh;
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dest = target + area->x + target_w * area->y;
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while (num_pixels-- > 0) {
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guchar alpha, r, g, b, bgr, bgg, bgb;
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alpha = draw[i] >> RrDefaultAlphaOffset;
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r = draw[i] >> RrDefaultRedOffset;
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g = draw[i] >> RrDefaultGreenOffset;
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b = draw[i] >> RrDefaultBlueOffset;
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if (c >= sfw) {
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c = 0;
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t += area->width - sfw;
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}
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alpha = *source >> RrDefaultAlphaOffset;
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r = *source >> RrDefaultRedOffset;
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g = *source >> RrDefaultGreenOffset;
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b = *source >> RrDefaultBlueOffset;
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/* background color */
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bgr = target[t] >> RrDefaultRedOffset;
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bgg = target[t] >> RrDefaultGreenOffset;
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bgb = target[t] >> RrDefaultBlueOffset;
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bgr = *dest >> RrDefaultRedOffset;
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bgg = *dest >> RrDefaultGreenOffset;
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bgb = *dest >> RrDefaultBlueOffset;
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r = bgr + (((r - bgr) * alpha) >> 8);
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g = bgg + (((g - bgg) * alpha) >> 8);
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b = bgb + (((b - bgb) * alpha) >> 8);
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target[t] = (r << RrDefaultRedOffset)
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| (g << RrDefaultGreenOffset)
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| (b << RrDefaultBlueOffset);
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*dest = ((r << RrDefaultRedOffset) |
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(g << RrDefaultGreenOffset) |
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(b << RrDefaultBlueOffset));
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dest++;
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source++;
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if (col++ >= dw) {
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col = 0;
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dest += target_w - dw;
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}
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}
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}
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