memononen
/
nanosvg
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
nanosvg/src/nanosvgrast.h

611 lines
15 KiB
C
Raw Blame History

/*
* Copyright (c) 2013-14 Mikko Mononen memon@inside.org
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*
* The polygon rasterization is heavily based on stb_truetype rasterizer
* by Sean Barrett - http://nothings.org/
*
*/
#ifndef NANOSVGRAST_H
#define NANOSVGRAST_H
#ifdef __cplusplus
extern "C" {
#endif
/* Example Usage:
// Load SVG
struct SNVGImage* image = nsvgParseFromFile("test.svg.");
// Create rasterizer (can be used to render multiple images).
struct NSVGrasterizer* rast = nsvgCreateRasterizer();
// Allocate memory for image
unsigned char* img = malloc(w*h*4);
// Rasterize
nsvgRasterize(rast, image, 0,0,1, img, w, h, w*4);
*/
// Allocated rasterizer context.
struct NSVGrasterizer* nsvgCreateRasterizer();
// Rasterizes SVG image, returns RGBA image (non-premultiplied alpha)
// r - pointer to rasterizer context
// image - pointer to image to rasterize
// tx,ty - image offset (applied after scaling)
// scale - image scale
// dst - pointer to destination image data, 4 bytes per pixel (RGBA)
// w - width of the image to render
// h - height of the image to render
// stride - number of bytes per scaleline in the destination buffer
void nsvgRasterize(struct NSVGrasterizer* r,
struct NSVGimage* image, float tx, float ty, float scale,
unsigned char* dst, int w, int h, int stride);
// Deletes rasterizer context.
void nsvgDeleteRasterizer(struct NSVGrasterizer*);
#ifdef __cplusplus
};
#endif
#endif // NANOSVGRAST_H
#ifdef NANOSVGRAST_IMPLEMENTATION
#include <math.h>
#define NSVG__SUBSAMPLES 5
#define NSVG__FIXSHIFT 10
#define NSVG__FIX (1 << NSVG__FIXSHIFT)
#define NSVG__FIXMASK (NSVG__FIX-1)
#define NSVG__MEMPAGE_SIZE 1024
struct NSVGedge {
float x0,y0, x1,y1;
int dir;
struct NSVGedge* next;
};
struct NSVGactiveEdge {
int x,dx;
float ey;
int dir;
struct NSVGactiveEdge *next;
};
struct NSVGmemPage {
unsigned char mem[NSVG__MEMPAGE_SIZE];
int size;
struct NSVGmemPage* next;
};
struct NSVGrasterizer
{
float px, py;
struct NSVGedge* edges;
int nedges;
int cedges;
struct NSVGactiveEdge* freelist;
struct NSVGmemPage* pages;
struct NSVGmemPage* curpage;
unsigned char* scanline;
int cscanline;
unsigned char* bitmap;
int width, height, stride;
};
struct NSVGrasterizer* nsvgCreateRasterizer()
{
struct NSVGrasterizer* r = (struct NSVGrasterizer*)malloc(sizeof(struct NSVGrasterizer));
if (r == NULL) goto error;
memset(r, 0, sizeof(struct NSVGrasterizer));
return r;
error:
nsvgDeleteRasterizer(r);
return NULL;
}
void nsvgDeleteRasterizer(struct NSVGrasterizer* r)
{
struct NSVGmemPage* p;
if (r == NULL) return;
p = r->pages;
while (p != NULL) {
struct NSVGmemPage* next = p->next;
free(p);
p = next;
}
if (r->edges) free(r->edges);
if (r->scanline) free(r->scanline);
free(r);
}
static struct NSVGmemPage* nsvg__nextPage(struct NSVGrasterizer* r, struct NSVGmemPage* cur)
{
struct NSVGmemPage *newp;
// If using existing chain, return the next page in chain
if (cur != NULL && cur->next != NULL) {
return cur->next;
}
// Alloc new page
newp = (struct NSVGmemPage*)malloc(sizeof(struct NSVGmemPage));
if (newp == NULL) return NULL;
memset(newp, 0, sizeof(struct NSVGmemPage));
// Add to linked list
if (cur != NULL)
cur->next = newp;
else
r->pages = newp;
return newp;
}
static void nsvg__resetPool(struct NSVGrasterizer* r)
{
struct NSVGmemPage* p = r->pages;
while (p != NULL) {
p->size = 0;
p = p->next;
}
r->curpage = r->pages;
}
static unsigned char* nsvg__alloc(struct NSVGrasterizer* r, int size)
{
unsigned char* buf;
if (size > NSVG__MEMPAGE_SIZE) return NULL;
if (r->curpage == NULL || r->curpage->size+size > NSVG__MEMPAGE_SIZE) {
r->curpage = nsvg__nextPage(r, r->curpage);
}
buf = &r->curpage->mem[r->curpage->size];
r->curpage->size += size;
return buf;
}
static void nsvg__addEdge(struct NSVGrasterizer* r, float x0, float y0, float x1, float y1)
{
struct NSVGedge* e;
// Skip horizontal edges
if (y0 == y1)
return;
if (r->nedges+1 > r->cedges) {
r->cedges = r->cedges > 0 ? r->cedges * 2 : 64;
r->edges = (struct NSVGedge*)realloc(r->edges, sizeof(struct NSVGedge) * r->cedges);
if (r->edges == NULL) return;
}
e = &r->edges[r->nedges];
r->nedges++;
if (y0 < y1) {
e->x0 = x0;
e->y0 = y0;
e->x1 = x1;
e->y1 = y1;
e->dir = 1;
} else {
e->x0 = x1;
e->y0 = y1;
e->x1 = x0;
e->y1 = y0;
e->dir = -1;
}
}
static float nsvg__absf(float x) { return x < 0 ? -x : x; }
static void nsvg__flattenCubicBez(struct NSVGrasterizer* r,
float x1, float y1, float x2, float y2,
float x3, float y3, float x4, float y4,
float tol, int level)
{
float x12,y12,x23,y23,x34,y34,x123,y123,x234,y234,x1234,y1234;
if (level > 10) return;
if (nsvg__absf(x1+x3-x2-x2) + nsvg__absf(y1+y3-y2-y2) + nsvg__absf(x2+x4-x3-x3) + nsvg__absf(y2+y4-y3-y3) < tol) {
nsvg__addEdge(r, r->px, r->py, x4, y4);
r->px = x4;
r->py = y4;
return;
}
x12 = (x1+x2)*0.5f;
y12 = (y1+y2)*0.5f;
x23 = (x2+x3)*0.5f;
y23 = (y2+y3)*0.5f;
x34 = (x3+x4)*0.5f;
y34 = (y3+y4)*0.5f;
x123 = (x12+x23)*0.5f;
y123 = (y12+y23)*0.5f;
x234 = (x23+x34)*0.5f;
y234 = (y23+y34)*0.5f;
x1234 = (x123+x234)*0.5f;
y1234 = (y123+y234)*0.5f;
nsvg__flattenCubicBez(r, x1,y1, x12,y12, x123,y123, x1234,y1234, tol, level+1);
nsvg__flattenCubicBez(r, x1234,y1234, x234,y234, x34,y34, x4,y4, tol, level+1);
}
static void nsvg__flattenShape(struct NSVGrasterizer* r,
struct NSVGshape* shape, float tx, float ty, float scale)
{
struct NSVGpath* path;
float tol = 0.5f * 4.0f / scale;
int i;
for (path = shape->paths; path != NULL; path = path->next) {
// Flatten path
r->px = path->pts[0];
r->py = path->pts[1];
for (i = 0; i < path->npts-1; i += 3) {
float* p = &path->pts[i*2];
nsvg__flattenCubicBez(r, p[0],p[1], p[2],p[3], p[4],p[5], p[6],p[7], tol, 0);
}
// Close path
nsvg__addEdge(r, r->px,r->py, path->pts[0],path->pts[1]);
}
}
static int nsvg__cmpEdge(const void *p, const void *q)
{
struct NSVGedge* a = (struct NSVGedge*)p;
struct NSVGedge* b = (struct NSVGedge*)q;
if (a->y0 < b->y0) return -1;
if (a->y0 > b->y0) return 1;
return 0;
}
static struct NSVGactiveEdge* nsvg__addActive(struct NSVGrasterizer* r, struct NSVGedge* e, float startPoint)
{
struct NSVGactiveEdge* z;
if (r->freelist != NULL) {
// Restore from freelist.
z = r->freelist;
r->freelist = z->next;
} else {
// Alloc new edge.
z = (struct NSVGactiveEdge*)nsvg__alloc(r, sizeof(struct NSVGactiveEdge));
if (z == NULL) return NULL;
}
float dxdy = (e->x1 - e->x0) / (e->y1 - e->y0);
// STBTT_assert(e->y0 <= start_point);
// round dx down to avoid going too far
if (dxdy < 0)
z->dx = -floorf(NSVG__FIX * -dxdy);
else
z->dx = floorf(NSVG__FIX * dxdy);
z->x = floorf(NSVG__FIX * (e->x0 + dxdy * (startPoint - e->y0)));
// z->x -= off_x * FIX;
z->ey = e->y1;
z->next = 0;
z->dir = e->dir;
return z;
}
static void nsvg__freeActive(struct NSVGrasterizer* r, struct NSVGactiveEdge* z)
{
z->next = r->freelist;
r->freelist = z;
}
// note: this routine clips fills that extend off the edges... ideally this
// wouldn't happen, but it could happen if the truetype glyph bounding boxes
// are wrong, or if the user supplies a too-small bitmap
static void nsvg__fillActiveEdges(unsigned char* scanline, int len, struct NSVGactiveEdge* e, int maxWeight, int* xmin, int* xmax)
{
// non-zero winding fill
int x0 = 0, w = 0;
while (e != NULL) {
if (w == 0) {
// if we're currently at zero, we need to record the edge start point
x0 = e->x; w += e->dir;
} else {
int x1 = e->x; w += e->dir;
// if we went to zero, we need to draw
if (w == 0) {
int i = x0 >> NSVG__FIXSHIFT;
int j = x1 >> NSVG__FIXSHIFT;
if (i < *xmin) *xmin = i;
if (j > *xmax) *xmax = j;
if (i < len && j >= 0) {
if (i == j) {
// x0,x1 are the same pixel, so compute combined coverage
scanline[i] += (unsigned char)((x1 - x0) * maxWeight >> NSVG__FIXSHIFT);
} else {
if (i >= 0) // add antialiasing for x0
scanline[i] += (unsigned char)(((NSVG__FIX - (x0 & NSVG__FIXMASK)) * maxWeight) >> NSVG__FIXSHIFT);
else
i = -1; // clip
if (j < len) // add antialiasing for x1
scanline[j] += (unsigned char)(((x1 & NSVG__FIXMASK) * maxWeight) >> NSVG__FIXSHIFT);
else
j = len; // clip
for (++i; i < j; ++i) // fill pixels between x0 and x1
scanline[i] += (unsigned char)maxWeight;
}
}
}
}
e = e->next;
}
}
static void nsvg__scanlineSolid(unsigned char* dst, int count, unsigned char* cover, unsigned int color)
{
int x, cr, cg, cb, ca;
cr = color & 0xff;
cg = (color >> 8) & 0xff;
cb = (color >> 16) & 0xff;
ca = (color >> 24) & 0xff;
for (x = 0; x < count; x++) {
int r,g,b;
int a = ((int)cover[0] * ca) >> 8;
int ia = 255 - a;
// Premultiply
r = (cr * a) >> 8;
g = (cg * a) >> 8;
b = (cb * a) >> 8;
// Blend over
r += ((ia * (int)dst[0]) >> 8);
g += ((ia * (int)dst[1]) >> 8);
b += ((ia * (int)dst[2]) >> 8);
a += ((ia * (int)dst[3]) >> 8);
dst[0] = (unsigned char)r;
dst[1] = (unsigned char)g;
dst[2] = (unsigned char)b;
dst[3] = (unsigned char)a;
cover++;
dst += 4;
}
}
static void nsvg__rasterizeSortedEdges(struct NSVGrasterizer *r, unsigned int color)
{
struct NSVGactiveEdge *active = NULL;
int y, s;
int e = 0;
int maxWeight = (255 / NSVG__SUBSAMPLES); // weight per vertical scanline
int xmin, xmax;
for (y = 0; y < r->height; y++) {
memset(r->scanline, 0, r->width);
xmin = r->width;
xmax = 0;
for (s = 0; s < NSVG__SUBSAMPLES; ++s) {
// find center of pixel for this scanline
float scany = y*NSVG__SUBSAMPLES + s + 0.5f;
struct NSVGactiveEdge **step = &active;
// update all active edges;
// remove all active edges that terminate before the center of this scanline
while (*step) {
struct NSVGactiveEdge *z = *step;
if (z->ey <= scany) {
*step = z->next; // delete from list
// NSVG__assert(z->valid);
nsvg__freeActive(r, z);
} else {
z->x += z->dx; // advance to position for current scanline
step = &((*step)->next); // advance through list
}
}
// resort the list if needed
for (;;) {
int changed = 0;
step = &active;
while (*step && (*step)->next) {
if ((*step)->x > (*step)->next->x) {
struct NSVGactiveEdge* t = *step;
struct NSVGactiveEdge* q = t->next;
t->next = q->next;
q->next = t;
*step = q;
changed = 1;
}
step = &(*step)->next;
}
if (!changed) break;
}
// insert all edges that start before the center of this scanline -- omit ones that also end on this scanline
while (e < r->nedges && r->edges[e].y0 <= scany) {
if (r->edges[e].y1 > scany) {
struct NSVGactiveEdge* z = nsvg__addActive(r, &r->edges[e], scany);
if (z == NULL) break;
// find insertion point
if (active == NULL) {
active = z;
} else if (z->x < active->x) {
// insert at front
z->next = active;
active = z;
} else {
// find thing to insert AFTER
struct NSVGactiveEdge* p = active;
while (p->next && p->next->x < z->x)
p = p->next;
// at this point, p->next->x is NOT < z->x
z->next = p->next;
p->next = z;
}
}
e++;
}
// now process all active edges in non-zero fashion
if (active != NULL)
nsvg__fillActiveEdges(r->scanline, r->width, active, maxWeight, &xmin, &xmax);
}
// Blit
if (xmin <= xmax) {
nsvg__scanlineSolid(&r->bitmap[y * r->stride] + xmin*4, xmax-xmin+1, &r->scanline[xmin], color);
}
}
}
static void nsvg__unpremultiplyAlpha(unsigned char* image, int w, int h, int stride)
{
int x,y;
// Unpremultiply
for (y = 0; y < h; y++) {
unsigned char *row = &image[y*stride];
for (x = 0; x < w; x++) {
int r = row[0], g = row[1], b = row[2], a = row[3];
if (a != 0) {
r = (r*255/a);
g = (g*255/a);
b = (b*255/a);
}
row += 4;
}
}
// Defringe
for (y = 0; y < h; y++) {
unsigned char *row = &image[y*stride];
for (x = 0; x < w; x++) {
int r = 0, g = 0, b = 0, a = row[3], n = 0;
if (a == 0) {
if (x-1 > 0 && row[-1] != 0) {
r += row[-4];
g += row[-3];
b += row[-2];
n++;
}
if (x+1 < w && row[7] != 0) {
r += row[4];
g += row[5];
b += row[6];
n++;
}
if (y-1 > 0 && row[-stride+3] != 0) {
r += row[-stride];
g += row[-stride+1];
b += row[-stride+2];
n++;
}
if (y+1 < h && row[stride+3] != 0) {
r += row[stride];
g += row[stride+1];
b += row[stride+2];
n++;
}
if (n > 0) {
row[0] = r/n;
row[1] = g/n;
row[2] = b/n;
}
}
row += 4;
}
}
}
void nsvgRasterize(struct NSVGrasterizer* r,
struct NSVGimage* image, float tx, float ty, float scale,
unsigned char* dst, int w, int h, int stride)
{
struct NSVGshape *shape = NULL;
struct NSVGedge *e = NULL;
int i;
r->bitmap = dst;
r->width = w;
r->height = h;
r->stride = stride;
if (w > r->cscanline) {
r->cscanline = w;
r->scanline = (unsigned char*)realloc(r->scanline, w);
if (r->scanline == NULL) return;
}
for (i = 0; i < h; i++)
memset(&dst[i*stride], 0, w*4);
for (shape = image->shapes; shape != NULL; shape = shape->next) {
if (!shape->hasFill)
continue;
nsvg__resetPool(r);
r->freelist = NULL;
r->nedges = 0;
nsvg__flattenShape(r, shape, tx,ty,scale);
// Scale and translate edges
for (i = 0; i < r->nedges; i++) {
e = &r->edges[i];
e->x0 = tx + e->x0 * scale;
e->y0 = (ty + e->y0 * scale) * NSVG__SUBSAMPLES;
e->x1 = tx + e->x1 * scale;
e->y1 = (ty + e->y1 * scale) * NSVG__SUBSAMPLES;
}
// Rasterize edges
qsort(r->edges, r->nedges, sizeof(struct NSVGedge), nsvg__cmpEdge);
// now, traverse the scanlines and find the intersections on each scanline, use non-zero rule
nsvg__rasterizeSortedEdges(r, shape->fillColor);
}
nsvg__unpremultiplyAlpha(dst, w, h, stride);
r->bitmap = NULL;
r->width = 0;
r->height = 0;
r->stride = 0;
}
#endif
Reference in New Issue View Git Blame Copy Permalink