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author | Tor Andersson <tor.andersson@artifex.com> | 2011-04-04 18:08:53 +0200 |
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committer | Tor Andersson <tor.andersson@artifex.com> | 2011-04-04 18:08:53 +0200 |
commit | c8d226b5bfb5dab2db10ea5175966de7bac9640e (patch) | |
tree | 982435a97942aeaf6a527eb3a07ac2c5242aaa9b /draw/draw_scale.c | |
parent | 53faeef5a0f2e352cc89b1695ec1db1eda85e707 (diff) | |
download | mupdf-c8d226b5bfb5dab2db10ea5175966de7bac9640e.tar.xz |
draw: Rename files in draw directory.
Diffstat (limited to 'draw/draw_scale.c')
-rw-r--r-- | draw/draw_scale.c | 1175 |
1 files changed, 1175 insertions, 0 deletions
diff --git a/draw/draw_scale.c b/draw/draw_scale.c new file mode 100644 index 00000000..6254e3e4 --- /dev/null +++ b/draw/draw_scale.c @@ -0,0 +1,1175 @@ +/* +This code does smooth scaling of a pixmap. + +This function returns a new pixmap representing the area starting at (0,0) +given by taking the source pixmap src, scaling it to width w, and height h, +and then positioning it at (frac(x),frac(y)). +*/ + +#include "fitz.h" + +/* Do we special case handling of single pixel high/wide images? The + * 'purest' handling is given by not special casing them, but certain + * files that use such images 'stack' them to give full images. Not + * special casing them results in then being fainter and giving noticable + * rounding errors. + */ +#define SINGLE_PIXEL_SPECIALS + +#ifdef DEBUG_SCALING +#ifdef WIN32 +#include <windows.h> +static void debug_print(const char *fmt, ...) +{ + va_list args; + char text[256]; + va_start(args, fmt); + vsprintf(text, fmt, args); + va_end(args); + OutputDebugStringA(text); + printf(text); +} +#else +static void debug_print(const char *fmt, ...) +{ + va_list args; + va_start(args, fmt); + vfprintf(stderr, fmt, args); + va_end(args); +} +#endif +#endif +#ifdef DEBUG_SCALING +#define DBUG(A) debug_print A +#else +#define DBUG(A) do {} while(0==1) +#endif + +/* +Consider a row of source samples, src, of width src_w, positioned at x, +scaled to width dst_w. + +src[i] is centred at: x + (i + 0.5)*dst_w/src_w + +Therefore the distance between the centre of the jth output pixel and +the centre of the ith source sample is: + +dist[j,i] = j + 0.5 - (x + (i + 0.5)*dst_w/src_w) + +When scaling up, therefore: + +dst[j] = SUM(filter(dist[j,i]) * src[i]) + (for all ints i) + +This can be simplified by noticing that filters are only non zero within +a given filter width (henceforth called W). So: + +dst[j] = SUM(filter(dist[j,i]) * src[i]) + (for ints i, s.t. (j*src_w/dst_w)-W < i < (j*src_w/dst_w)+W) + +When scaling down, each filtered source sample is stretched to be wider +to avoid aliasing issues. This effectively reduces the distance between +centres. + +dst[j] = SUM(filter(dist[j,i] * F) * F * src[i]) + (where F = dst_w/src_w) + (for ints i, s.t. (j-W)/F < i < (j+W)/F) + +*/ + +typedef struct fz_scalefilter_s fz_scalefilter; + +struct fz_scalefilter_s +{ + int width; + float (*fn)(fz_scalefilter *, float); +}; + +/* Image scale filters */ + +static float +triangle(fz_scalefilter *filter, float f) +{ + if (f >= 1) + return 0; + return 1-f; +} + +static float +box(fz_scalefilter *filter, float f) +{ + if (f >= 0.5f) + return 0; + return 1; +} + +static float +simple(fz_scalefilter *filter, float x) +{ + if (x >= 1) + return 0; + return 1 + (2*x - 3)*x*x; +} + +static float +lanczos2(fz_scalefilter *filter, float x) +{ + if (x >= 2) + return 0; + return sinf(M_PI*x) * sinf(M_PI*x/2) / (M_PI*x) / (M_PI*x/2); +} + +static float +lanczos3(fz_scalefilter *filter, float f) +{ + if (f >= 3) + return 0; + return sinf(M_PI*f) * sinf(M_PI*f/3) / (M_PI*f) / (M_PI*f/3); +} + +/* +The Mitchell family of filters is defined: + + f(x) = 1 { (12-9B-6C)x^3 + (-18+12B+6C)x^2 + (6-2B) for x < 1 + - { + 6 { (-B-6C)x^3+(6B+30C)x^2+(-12B-48C)x+(8B+24C) for 1<=x<=2 + +The 'best' ones lie along the line B+2C = 1. +The literature suggests that B=1/3, C=1/3 is best. + + f(x) = 1 { (12-3-2)x^3 - (-18+4+2)x^2 + (16/3) for x < 1 + - { + 6 { (-7/3)x^3 + 12x^2 - 20x + (32/3) for 1<=x<=2 + + f(x) = 1 { 21x^3 - 36x^2 + 16 for x < 1 + - { + 18{ -7x^3 + 36x^2 - 60x + 32 for 1<=x<=2 +*/ + +static float +mitchell(fz_scalefilter *filter, float x) +{ + if (x >= 2) + return 0; + if (x >= 1) + return (32 + x*(-60 + x*(36 - 7*x)))/18; + return (16 + x*x*(-36 + 21*x))/18; +} + +fz_scalefilter fz_scalefilter_box = { 1, box }; +fz_scalefilter fz_scalefilter_triangle = { 1, triangle }; +fz_scalefilter fz_scalefilter_simple = { 1, simple }; +fz_scalefilter fz_scalefilter_lanczos2 = { 2, lanczos2 }; +fz_scalefilter fz_scalefilter_lanczos3 = { 3, lanczos3 }; +fz_scalefilter fz_scalefilter_mitchell = { 2, mitchell }; + +/* +We build ourselves a set of tables to contain the precalculated weights +for a given set of scale settings. + +The first dst_w entries in index are the index into index of the +sets of weight for each destination pixel. + +Each of the sets of weights is a set of values consisting of: + the minimum source pixel index used for this destination pixel + the number of weights used for this destination pixel + the weights themselves + +So to calculate dst[i] we do the following: + + weights = &index[index[i]]; + min = *weights++; + len = *weights++; + dst[i] = 0; + while (--len > 0) + dst[i] += src[min++] * *weights++ + +in addition, we guarantee that at the end of this process weights will now +point to the weights value for dst pixel i+1. + +In the simplest version of this algorithm, we would scale the whole image +horizontally first into a temporary buffer, then scale that temporary +buffer again vertically to give us our result. Using such a simple +algorithm would mean that could use the same style of weights for both +horizontal and vertical scaling. + +Unfortunately, this would also require a large temporary buffer, +particularly in the case where we are scaling up. + +We therefore modify the algorithm as follows; we scale scanlines from the +source image horizontally into a temporary buffer, until we have all the +contributors for a given output scanline. We then produce that output +scanline from the temporary buffer. In this way we restrict the height +of the temporary buffer to a small fraction of the final size. + +Unfortunately, this means that the pseudo code for recombining a +scanline of fully scaled pixels is as follows: + + weights = &index[index[y]]; + min = *weights++; + len = *weights++; + for (x=0 to dst_w) + min2 = min + len2 = len + weights2 = weights + dst[x] = 0; + while (--len2 > 0) + dst[x] += temp[x][(min2++) % tmp_buf_height] * *weights2++ + +i.e. it requires a % operation for every source pixel - this is typically +expensive. + +To avoid this, we alter the order in which vertical weights are stored, +so that they are ordered in the same order as the temporary buffer lines +would appear. This simplifies the algorithm to: + + weights = &index[index[y]]; + min = *weights++; + len = *weights++; + for (x=0 to dst_w) + min2 = 0 + len2 = len + weights2 = weights + dst[x] = 0; + while (--len2 > 0) + dst[x] += temp[i][min2++] * *weights2++ + +This means that len may be larger than it needs to be (due to the +possible inclusion of a zero weight row or two), but in practise this +is only an increase of 1 or 2 at worst. + +We implement this by generating the weights as normal (but ensuring we +leave enough space) and then reordering afterwards. + +*/ + +typedef struct fz_weights_s fz_weights; + +struct fz_weights_s +{ + int count; + int max_len; + int n; + int flip; + int new_line; + int index[1]; +}; + +static fz_weights * +newweights(fz_scalefilter *filter, int src_w, float dst_w, int dst_w_i, int n, int flip) +{ + int max_len; + fz_weights *weights; + + if (src_w > dst_w) + { + /* Scaling down, so there will be a maximum of + * 2*filterwidth*src_w/dst_w src pixels + * contributing to each dst pixel. */ + max_len = (int)ceilf((2 * filter->width * src_w)/dst_w); + if (max_len > src_w) + max_len = src_w; + } + else + { + /* Scaling up, so there will be a maximum of + * 2*filterwidth src pixels contributing to each dst pixel. + */ + max_len = 2 * filter->width; + } + /* We need the size of the struct, + * plus dst_w*sizeof(int) for the index + * plus (2+max_len)*sizeof(int) for the weights + * plus room for an extra set of weights for reordering. + */ + weights = fz_malloc(sizeof(*weights)+(max_len+3)*(dst_w_i+1)*sizeof(int)); + if (weights == NULL) + return NULL; + weights->count = -1; + weights->max_len = max_len; + weights->index[0] = dst_w_i; + weights->n = n; + weights->flip = flip; + return weights; +} + +static void +init_weights(fz_weights *weights, int j) +{ + int index; + + assert(weights->count == j-1); + weights->count++; + weights->new_line = 1; + if (j == 0) + index = weights->index[0]; + else + { + index = weights->index[j-1]; + index += 2 + weights->index[index+1]; + } + weights->index[j] = index; /* row pointer */ + weights->index[index] = 0; /* min */ + weights->index[index+1] = 0; /* len */ +} + +static void +add_weight(fz_weights *weights, int j, int i, fz_scalefilter *filter, + float x, float F, float G, int src_w, float dst_w) +{ + float dist = j - x + 0.5f - ((i + 0.5f)*dst_w/src_w); + float f; + int min, len, index, weight; + + dist *= G; + if (dist < 0) + dist = -dist; + f = filter->fn(filter, dist)*F; + weight = (int)(256*f+0.5f); + if (weight == 0) + return; + + /* wrap i back into range */ +#ifdef MIRROR_WRAP + do + { + if (i < 0) + i = -1-i; + else if (i >= src_w) + i = 2*src_w-1-i; + else + break; + } + while (1); +#elif defined(WRAP) + if (i < 0) + i = 0; + else if (i >= src_w) + i = src_w-1; +#else + if (i < 0) + { + i = 0; + weight = 0; + } + else if (i >= src_w) + { + i = src_w-1; + weight = 0; + } +#endif + + DBUG(("add_weight[%d][%d] = %d(%g) dist=%g\n",j,i,weight,f,dist)); + + if (weights->new_line) + { + /* New line */ + weights->new_line = 0; + index = weights->index[j]; /* row pointer */ + weights->index[index] = i; /* min */ + weights->index[index+1] = 0; /* len */ + } + index = weights->index[j]; + min = weights->index[index++]; + len = weights->index[index++]; + while (i < min) + { + /* This only happens in rare cases, but we need to insert + * one earlier. In exceedingly rare cases we may need to + * insert more than one earlier. */ + int k; + + for (k = len; k > 0; k--) + { + weights->index[index+k] = weights->index[index+k-1]; + } + weights->index[index] = 0; + min--; + len++; + weights->index[index-2] = min; + weights->index[index-1] = len; + } + if (i-min >= len) + { + /* The usual case */ + while (i-min >= ++len) + { + weights->index[index+len-1] = 0; + } + assert(len-1 == i-min); + weights->index[index+i-min] = weight; + weights->index[index-1] = len; + assert(len <= weights->max_len); + } + else + { + /* Infrequent case */ + weights->index[index+i-min] += weight; + } +} + +static void +reorder_weights(fz_weights *weights, int j, int src_w) +{ + int idx = weights->index[j]; + int min = weights->index[idx++]; + int len = weights->index[idx++]; + int max = weights->max_len; + int tmp = idx+max; + int i, off; + + /* Copy into the temporary area */ + memcpy(&weights->index[tmp], &weights->index[idx], sizeof(int)*len); + + /* Pad out if required */ + assert(len <= max); + assert(min+len <= src_w); + off = 0; + if (len < max) + { + memset(&weights->index[tmp+len], 0, sizeof(int)*(max-len)); + len = max; + if (min + len > src_w) + { + off = min + len - src_w; + min = src_w - len; + weights->index[idx-2] = min; + } + weights->index[idx-1] = len; + } + + /* Copy back into the proper places */ + for (i = 0; i < len; i++) + { + weights->index[idx+((min+i+off) % max)] = weights->index[tmp+i]; + } +} + +static void +check_weights(fz_weights *weights, int j, int w) +{ + int idx, len; + int sum = 0; + int max = -256; + int maxidx = 0; + int i; + + idx = weights->index[j]; + idx++; /* min */ + len = weights->index[idx++]; + + for(i=0; i < len; i++) + { + int v = weights->index[idx++]; + sum += v; + if (v > max) + { + max = v; + maxidx = idx; + } + } + if (((j != 0) && (j != w-1)) || (sum > 256)) + weights->index[maxidx-1] += 256-sum; + DBUG(("total weight %d = %d\n", j, sum)); +} + +static fz_weights * +make_weights(int src_w, float x, float dst_w, fz_scalefilter *filter, int vertical, int dst_w_int, int n, int flip) +{ + fz_weights *weights; + float F, G; + float window; + int j; + + if (dst_w < src_w) + { + /* Scaling down */ + F = dst_w / src_w; + G = 1; + } + else + { + /* Scaling up */ + F = 1; + G = src_w / dst_w; + } + window = filter->width / F; + DBUG(("make_weights src_w=%d x=%g dst_w=%g dst_w_int=%d F=%g window=%g\n", src_w, x, dst_w, dst_w_int, F, window)); + weights = newweights(filter, src_w, dst_w, dst_w_int, n, flip); + if (weights == NULL) + return NULL; + for (j = 0; j < dst_w_int; j++) + { + /* find the position of the centre of dst[j] in src space */ + float centre = (j - x + 0.5f)*src_w/dst_w - 0.5f; + int l, r; + l = ceilf(centre - window); + r = floorf(centre + window); + DBUG(("%d: centre=%g l=%d r=%d\n", j, centre, l, r)); + init_weights(weights, j); + for (; l <= r; l++) + { + add_weight(weights, j, l, filter, x, F, G, src_w, dst_w); + } + check_weights(weights, j, dst_w_int); + if (vertical) + { + reorder_weights(weights, j, src_w); + } + } + weights->count++; /* weights->count = dst_w_int now */ + return weights; +} + +static void +scale_row_to_temp(int *dst, unsigned char *src, fz_weights *weights) +{ + int *contrib = &weights->index[weights->index[0]]; + int len, i, j, n; + unsigned char *min; + + n = weights->n; + if (weights->flip) + { + dst += (weights->count-1)*n; + for (i=weights->count; i > 0; i--) + { + min = &src[n * *contrib++]; + len = *contrib++; + for (j = 0; j < n; j++) + dst[j] = 0; + while (len-- > 0) + { + for (j = n; j > 0; j--) + *dst++ += *min++ * *contrib; + dst -= n; + contrib++; + } + dst -= n; + } + } + else + { + for (i=weights->count; i > 0; i--) + { + min = &src[n * *contrib++]; + len = *contrib++; + for (j = 0; j < n; j++) + dst[j] = 0; + while (len-- > 0) + { + for (j = n; j > 0; j--) + *dst++ += *min++ * *contrib; + dst -= n; + contrib++; + } + dst += n; + } + } +} + +static void +scale_row_to_temp1(int *dst, unsigned char *src, fz_weights *weights) +{ + int *contrib = &weights->index[weights->index[0]]; + int len, i; + unsigned char *min; + + assert(weights->n == 1); + if (weights->flip) + { + dst += weights->count; + for (i=weights->count; i > 0; i--) + { + int val = 0; + min = &src[*contrib++]; + len = *contrib++; + while (len-- > 0) + { + val += *min++ * *contrib++; + } + *--dst = val; + } + } + else + { + for (i=weights->count; i > 0; i--) + { + int val = 0; + min = &src[*contrib++]; + len = *contrib++; + while (len-- > 0) + { + val += *min++ * *contrib++; + } + *dst++ = val; + } + } +} + +static void +scale_row_to_temp2(int *dst, unsigned char *src, fz_weights *weights) +{ + int *contrib = &weights->index[weights->index[0]]; + int len, i; + unsigned char *min; + + assert(weights->n == 2); + if (weights->flip) + { + dst += 2*weights->count; + for (i=weights->count; i > 0; i--) + { + int c1 = 0; + int c2 = 0; + min = &src[2 * *contrib++]; + len = *contrib++; + while (len-- > 0) + { + c1 += *min++ * *contrib; + c2 += *min++ * *contrib++; + } + *--dst = c2; + *--dst = c1; + } + } + else + { + for (i=weights->count; i > 0; i--) + { + int c1 = 0; + int c2 = 0; + min = &src[2 * *contrib++]; + len = *contrib++; + while (len-- > 0) + { + c1 += *min++ * *contrib; + c2 += *min++ * *contrib++; + } + *dst++ = c1; + *dst++ = c2; + } + } +} + +static void +scale_row_to_temp4(int *dst, unsigned char *src, fz_weights *weights) +{ + int *contrib = &weights->index[weights->index[0]]; +#ifndef ARCH_ARM + int len, i; + unsigned char *min; +#endif + + assert(weights->n == 4); + if (weights->flip) + { + dst += 4*weights->count; +#ifdef ARCH_ARM + asm volatile( + "1:" + "ldr r4, [%2], #4 @ r4 = *contrib++ \n" + "ldr r9, [%2], #4 @ r9 = len = *contrib++ \n" + "mov r5, #0 @ r5 = r = 0 \n" + "mov r6, #0 @ r6 = g = 0 \n" + "mov r7, #0 @ r7 = b = 0 \n" + "mov r8, #0 @ r8 = a = 0 \n" + "add r4, %1, r4, LSL #2 @ r4 = min = &src[4*r4] \n" + "cmp r9, #0 @ while (len-- > 0) \n" + "beq 3f @ { \n" + "2: \n" + "ldr r10,[%2], #4 @ r10 = *contrib++ \n" + "ldrb r11,[r4], #1 @ r11 = *min++ \n" + "ldrb r12,[r4], #1 @ r12 = *min++ \n" + "ldrb r14,[r4], #1 @ r14 = *min++ \n" + "mla r5, r10,r11,r5 @ r += r11 * r10 \n" + "ldrb r11,[r4], #1 @ r11 = *min++ \n" + "mla r6, r10,r12,r6 @ g += r12 * r10 \n" + "mla r7, r10,r14,r7 @ b += r14 * r10 \n" + "mla r8, r10,r11,r8 @ a += r11 * r10 \n" + "subs r9, r9, #1 @ r9 = len-- \n" + "bgt 2b @ } \n" + "stmdb %0!,{r5,r6,r7,r8} @ *--dst=a;*--dst=b; \n" + "3: @ *--dst=g;*--dst=r; \n" + "subs %3, %3, #1 @ i-- \n" + "bgt 1b @ \n" + : + : + "r" (dst), + "r" (src), + "r" (contrib), + "r" (weights->count) + : + "r4","r5","r6","r7","r8","r9","r10","r11","r12","r14", + "memory","cc" + ); +#else + for (i=weights->count; i > 0; i--) + { + int r = 0; + int g = 0; + int b = 0; + int a = 0; + min = &src[4 * *contrib++]; + len = *contrib++; + while (len-- > 0) + { + r += *min++ * *contrib; + g += *min++ * *contrib; + b += *min++ * *contrib; + a += *min++ * *contrib++; + } + *--dst = a; + *--dst = b; + *--dst = g; + *--dst = r; + } +#endif + } + else + { +#ifdef ARCH_ARM + asm volatile( + "1:" + "ldr r4, [%2], #4 @ r4 = *contrib++ \n" + "ldr r9, [%2], #4 @ r9 = len = *contrib++ \n" + "mov r5, #0 @ r5 = r = 0 \n" + "mov r6, #0 @ r6 = g = 0 \n" + "mov r7, #0 @ r7 = b = 0 \n" + "mov r8, #0 @ r8 = a = 0 \n" + "add r4, %1, r4, LSL #2 @ r4 = min = &src[4*r4] \n" + "cmp r9, #0 @ while (len-- > 0) \n" + "beq 3f @ { \n" + "2: \n" + "ldr r10,[%2], #4 @ r10 = *contrib++ \n" + "ldrb r11,[r4], #1 @ r11 = *min++ \n" + "ldrb r12,[r4], #1 @ r12 = *min++ \n" + "ldrb r14,[r4], #1 @ r14 = *min++ \n" + "mla r5, r10,r11,r5 @ r += r11 * r10 \n" + "ldrb r11,[r4], #1 @ r11 = *min++ \n" + "mla r6, r10,r12,r6 @ g += r12 * r10 \n" + "mla r7, r10,r14,r7 @ b += r14 * r10 \n" + "mla r8, r10,r11,r8 @ a += r11 * r10 \n" + "subs r9, r9, #1 @ r9 = len-- \n" + "bgt 2b @ } \n" + "stmia %0!,{r5,r6,r7,r8} @ *dst++=r;*dst++=g; \n" + "3: @ *dst++=b;*dst++=a; \n" + "subs %3, %3, #1 @ i-- \n" + "bgt 1b @ \n" + : + : + "r" (dst), + "r" (src), + "r" (contrib), + "r" (weights->count) + : + "r4","r5","r6","r7","r8","r9","r10","r11","r12","r14", + "memory","cc" + ); +#else + for (i=weights->count; i > 0; i--) + { + int r = 0; + int g = 0; + int b = 0; + int a = 0; + min = &src[4 * *contrib++]; + len = *contrib++; + while (len-- > 0) + { + r += *min++ * *contrib; + g += *min++ * *contrib; + b += *min++ * *contrib; + a += *min++ * *contrib++; + } + *dst++ = r; + *dst++ = g; + *dst++ = b; + *dst++ = a; + } +#endif + } +} + +static void +scale_row_from_temp(unsigned char *dst, int *src, fz_weights *weights, int width, int row) +{ + int *contrib = &weights->index[weights->index[row]]; + int len, x; + + contrib++; /* Skip min */ + len = *contrib++; + for (x=width; x > 0; x--) + { + int *min = src; + int val = 0; + int len2 = len; + int *contrib2 = contrib; + + while (len2-- > 0) + { + val += *min * *contrib2++; + min += width; + } + val = (val+(1<<15))>>16; + if (val < 0) + val = 0; + else if (val > 255) + val = 255; + *dst++ = val; + src++; + } +} + +#ifdef SINGLE_PIXEL_SPECIALS +static void +duplicate_single_pixel(unsigned char *dst, unsigned char *src, int n, int w, int h) +{ + int i; + + for (i = n; i > 0; i--) + *dst++ = *src++; + for (i = (w*h-1)*n; i > 0; i--) + { + *dst = dst[-n]; + dst++; + } +} + +static void +scale_single_row(unsigned char *dst, unsigned char *src, fz_weights *weights, int src_w, int h) +{ + int *contrib = &weights->index[weights->index[0]]; + int min, len, i, j, val, n; + int tmp[FZ_MAXCOLORS]; + + n = weights->n; + /* Scale a single row */ + if (weights->flip) + { + dst += (weights->count-1)*n; + for (i=weights->count; i > 0; i--) + { + min = *contrib++; + len = *contrib++; + min *= n; + for (j = 0; j < n; j++) + tmp[j] = 0; + while (len-- > 0) + { + for (j = 0; j < n; j++) + tmp[j] += src[min++] * *contrib; + contrib++; + } + for (j = 0; j < n; j++) + { + val = (tmp[j]+(1<<7))>>8; + if (val < 0) + val = 0; + else if (val > 255) + val = 255; + *dst++ = val; + } + dst -= 2*n; + } + dst += n; + } + else + { + for (i=weights->count; i > 0; i--) + { + min = *contrib++; + len = *contrib++; + min *= n; + for (j = 0; j < n; j++) + tmp[j] = 0; + while (len-- > 0) + { + for (j = 0; j < n; j++) + tmp[j] += src[min++] * *contrib; + contrib++; + } + for (j = 0; j < n; j++) + { + val = (tmp[j]+(1<<7))>>8; + if (val < 0) + val = 0; + else if (val > 255) + val = 255; + *dst++ = val; + } + } + } + /* And then duplicate it h times */ + n *= weights->count; + while (--h > 0) + { + memcpy(dst, dst-n, n); + dst += n; + } +} + +static void +scale_single_col(unsigned char *dst, unsigned char *src, fz_weights *weights, int src_w, int n, int w, int flip_y) +{ + int *contrib = &weights->index[weights->index[0]]; + int min, len, i, j, val; + int tmp[FZ_MAXCOLORS]; + + if (flip_y) + { + src_w = (src_w-1)*n; + w = (w-1)*n; + for (i=weights->count; i > 0; i--) + { + /* Scale the next pixel in the column */ + min = *contrib++; + len = *contrib++; + min = src_w-min*n; + for (j = 0; j < n; j++) + tmp[j] = 0; + while (len-- > 0) + { + for (j = 0; j < n; j++) + tmp[j] += src[src_w-min+j] * *contrib; + contrib++; + } + for (j = 0; j < n; j++) + { + val = (tmp[j]+(1<<7))>>8; + if (val < 0) + val = 0; + else if (val > 255) + val = 255; + *dst++ = val; + } + /* And then duplicate it across the row */ + for (j = w; j > 0; j--) + { + *dst = dst[-n]; + dst++; + } + } + } + else + { + w = (w-1)*n; + for (i=weights->count; i > 0; i--) + { + /* Scale the next pixel in the column */ + min = *contrib++; + len = *contrib++; + min *= n; + for (j = 0; j < n; j++) + tmp[j] = 0; + while (len-- > 0) + { + for (j = 0; j < n; j++) + tmp[j] += src[min++] * *contrib; + contrib++; + } + for (j = 0; j < n; j++) + { + val = (tmp[j]+(1<<7))>>8; + if (val < 0) + val = 0; + else if (val > 255) + val = 255; + *dst++ = val; + } + /* And then duplicate it across the row */ + for (j = w; j > 0; j--) + { + *dst = dst[-n]; + dst++; + } + } + } +} +#endif /* SINGLE_PIXEL_SPECIALS */ + +fz_pixmap * +fz_scalepixmap(fz_pixmap *src, float x, float y, float w, float h) +{ + fz_scalefilter *filter = &fz_scalefilter_simple; + fz_weights *contrib_rows = NULL; + fz_weights *contrib_cols = NULL; + fz_pixmap *output = NULL; + int *temp = NULL; + int max_row, temp_span, temp_rows, row; + int dst_w_int, dst_h_int, dst_x_int, dst_y_int; + int flip_x, flip_y; + + DBUG(("Scale: (%d,%d) to (%g,%g) at (%g,%g)\n",src->w,src->h,w,h,x,y)); + + /* Find the destination bbox, width/height, and sub pixel offset, + * allowing for whether we're flipping or not. */ + /* Note that the x and y sub pixel offsets here are different. + * The (x,y) position given describes where the bottom left corner + * of the source image should be mapped to (i.e. where (0,h) in image + * space ends up, not the more logical and sane (0,0)). Also there + * are differences in the way we scale horizontally and vertically. + * When scaling rows horizontally, we always read forwards through + * the source, and store either forwards or in reverse as required. + * When scaling vertically, we always store out forwards, but may + * feed source rows in in a different order. + * + * Consider the image rectange 'r' to which the image is mapped, + * and the (possibly) larger rectangle 'R', given by expanding 'r' to + * complete pixels. + * + * x can either be r.xmin-R.xmin or R.xmax-r.xmax depending on whether + * the image is x flipped or not. Whatever happens 0 <= x < 1. + * y is always R.ymax - r.ymax. + */ + /* dst_x_int is calculated to be the left of the scaled image, and + * x (the sub_pixel_offset) is the distance in from either the left + * or right pixel expanded edge. */ + flip_x = (w < 0); + if (flip_x) + { + float tmp; + w = -w; + dst_x_int = floor(x-w); + tmp = ceilf(x); + dst_w_int = (int)tmp; + x = tmp - x; + dst_w_int -= dst_x_int; + } + else + { + dst_x_int = floor(x); + x -= (float)dst_x_int; + dst_w_int = (int)ceilf(x + w); + } + flip_y = (h < 0); + /* dst_y_int is calculated to be the bottom of the scaled image, but + * y (the sub pixel offset) has to end up being the value at the top. + */ + if (flip_y) + { + h = -h; + dst_y_int = floor(y-h); + dst_h_int = (int)ceilf(y) - dst_y_int; + } else { + dst_y_int = floor(y); + y += h; + dst_h_int = (int)ceilf(y) - dst_y_int; + } + /* y is the top edge position in floats. We want it to be the + * distance down from the next pixel boundary. */ + y = ceilf(y) - y; + + DBUG(("Result image: (%d,%d) at (%d,%d) (subpix=%g,%g)\n", dst_w_int, dst_h_int, dst_x_int, dst_y_int, x, y)); + + /* Step 1: Calculate the weights for columns and rows */ +#ifdef SINGLE_PIXEL_SPECIALS + if (src->w == 1) + { + contrib_cols = NULL; + } + else +#endif /* SINGLE_PIXEL_SPECIALS */ + { + contrib_cols = make_weights(src->w, x, w, filter, 0, dst_w_int, src->n, flip_x); + if (contrib_cols == NULL) + goto cleanup; + } +#ifdef SINGLE_PIXEL_SPECIALS + if (src->h == 1) + { + contrib_rows = NULL; + } + else +#endif /* SINGLE_PIXEL_SPECIALS */ + { + contrib_rows = make_weights(src->h, y, h, filter, 1, dst_h_int, src->n, flip_y); + if (contrib_rows == NULL) + goto cleanup; + } + + assert(contrib_cols == NULL || contrib_cols->count == dst_w_int); + assert(contrib_rows == NULL || contrib_rows->count == dst_h_int); + output = fz_newpixmap(src->colorspace, dst_x_int, dst_y_int, dst_w_int, dst_h_int); + if (output == NULL) + goto cleanup; + + /* Step 2: Apply the weights */ +#ifdef SINGLE_PIXEL_SPECIALS + if (contrib_rows == NULL) + { + /* Only 1 source pixel high. */ + if (contrib_cols == NULL) + { + /* Only 1 pixel in the entire image! */ + duplicate_single_pixel(output->samples, src->samples, src->n, dst_w_int, dst_h_int); + } + else + { + /* Scale the row once, then copy it. */ + scale_single_row(output->samples, src->samples, contrib_cols, src->w, dst_h_int); + } + } + else if (contrib_cols == NULL) + { + /* Only 1 source pixel wide. Scale the col and duplicate. */ + scale_single_col(output->samples, src->samples, contrib_rows, src->h, src->n, dst_w_int, flip_y); + } + else +#endif /* SINGLE_PIXEL_SPECIALS */ + { + void (*row_scale)(int *dst, unsigned char *src, fz_weights *weights); + + temp_span = contrib_cols->count * src->n; + temp_rows = contrib_rows->max_len; + if (temp_span <= 0 || temp_rows > INT_MAX / temp_span) + goto cleanup; + temp = fz_calloc(temp_span*temp_rows, sizeof(int)); + if (temp == NULL) + goto cleanup; + switch (src->n) + { + default: + row_scale = scale_row_to_temp; + break; + case 1: /* Image mask case */ + row_scale = scale_row_to_temp1; + break; + case 2: /* Greyscale with alpha case */ + row_scale = scale_row_to_temp2; + break; + case 4: /* RGBA */ + row_scale = scale_row_to_temp4; + break; + } + max_row = 0; + for (row = 0; row < contrib_rows->count; row++) + { + /* + Which source rows do we need to have scaled into the + temporary buffer in order to be able to do the final + scale? + */ + int row_index = contrib_rows->index[row]; + int row_min = contrib_rows->index[row_index++]; + int row_len = contrib_rows->index[row_index++]; + while (max_row < row_min+row_len) + { + /* Scale another row */ + assert(max_row < src->h); + DBUG(("scaling row %d to temp\n", max_row)); + (*row_scale)(&temp[temp_span*(max_row % temp_rows)], &src->samples[(flip_y ? (src->h-1-max_row): max_row)*src->w*src->n], contrib_cols); + max_row++; + } + + DBUG(("scaling row %d from temp\n", row)); + scale_row_from_temp(&output->samples[row*output->w*output->n], temp, contrib_rows, temp_span, row); + } + fz_free(temp); + } + +cleanup: + fz_free(contrib_rows); + fz_free(contrib_cols); + return output; +} |