/*
* Copyright 2011 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkScan.h"
#include "SkBlitter.h"
#include "SkColorData.h"
#include "SkFDot6.h"
#include "SkLineClipper.h"
#include "SkRasterClip.h"
#include "SkTo.h"
#include <utility>
/* Our attempt to compute the worst case "bounds" for the horizontal and
vertical cases has some numerical bug in it, and we sometimes undervalue
our extends. The bug is that when this happens, we will set the clip to
nullptr (for speed), and thus draw outside of the clip by a pixel, which might
only look bad, but it might also access memory outside of the valid range
allcoated for the device bitmap.
This define enables our fix to outset our "bounds" by 1, thus avoiding the
chance of the bug, but at the cost of sometimes taking the rectblitter
case (i.e. not setting the clip to nullptr) when we might not actually need
to. If we can improve/fix the actual calculations, then we can remove this
step.
*/
#define OUTSET_BEFORE_CLIP_TEST true
#define HLINE_STACK_BUFFER 100
static inline int SmallDot6Scale(int value, int dot6) {
SkASSERT((int16_t)value == value);
SkASSERT((unsigned)dot6 <= 64);
return (value * dot6) >> 6;
}
//#define TEST_GAMMA
#ifdef TEST_GAMMA
static uint8_t gGammaTable[256];
#define ApplyGamma(table, alpha) (table)[alpha]
static void build_gamma_table() {
static bool gInit = false;
if (gInit == false) {
for (int i = 0; i < 256; i++) {
SkFixed n = i * 257;
n += n >> 15;
SkASSERT(n >= 0 && n <= SK_Fixed1);
n = SkFixedSqrt(n);
n = n * 255 >> 16;
// SkDebugf("morph %d -> %d\n", i, n);
gGammaTable[i] = SkToU8(n);
}
gInit = true;
}
}
#else
#define ApplyGamma(table, alpha) SkToU8(alpha)
#endif
///////////////////////////////////////////////////////////////////////////////
static void call_hline_blitter(SkBlitter* blitter, int x, int y, int count,
U8CPU alpha) {
SkASSERT(count > 0);
int16_t runs[HLINE_STACK_BUFFER + 1];
uint8_t aa[HLINE_STACK_BUFFER];
aa[0] = ApplyGamma(gGammaTable, alpha);
do {
int n = count;
if (n > HLINE_STACK_BUFFER) {
n = HLINE_STACK_BUFFER;
}
runs[0] = SkToS16(n);
runs[n] = 0;
blitter->blitAntiH(x, y, aa, runs);
x += n;
count -= n;
} while (count > 0);
}
class SkAntiHairBlitter {
public:
SkAntiHairBlitter() : fBlitter(nullptr) {}
virtual ~SkAntiHairBlitter() {}
SkBlitter* getBlitter() const { return fBlitter; }
void setup(SkBlitter* blitter) {
fBlitter = blitter;
}
virtual SkFixed drawCap(int x, SkFixed fy, SkFixed slope, int mod64) = 0;
virtual SkFixed drawLine(int x, int stopx, SkFixed fy, SkFixed slope) = 0;
private:
SkBlitter* fBlitter;
};
class HLine_SkAntiHairBlitter : public SkAntiHairBlitter {
public:
SkFixed drawCap(int x, SkFixed fy, SkFixed slope, int mod64) override {
fy += SK_Fixed1/2;
int y = fy >> 16;
uint8_t a = (uint8_t)(fy >> 8);
// lower line
unsigned ma = SmallDot6Scale(a, mod64);
if (ma) {
call_hline_blitter(this->getBlitter(), x, y, 1, ma);
}
// upper line
ma = SmallDot6Scale(255 - a, mod64);
if (ma) {
call_hline_blitter(this->getBlitter(), x, y - 1, 1, ma);
}
return fy - SK_Fixed1/2;
}
virtual SkFixed drawLine(int x, int stopx, SkFixed fy,
SkFixed slope) override {
SkASSERT(x < stopx);
int count = stopx - x;
fy += SK_Fixed1/2;
int y = fy >> 16;
uint8_t a = (uint8_t)(fy >> 8);
// lower line
if (a) {
call_hline_blitter(this->getBlitter(), x, y, count, a);
}
// upper line
a = 255 - a;
if (a) {
call_hline_blitter(this->getBlitter(), x, y - 1, count, a);
}
return fy - SK_Fixed1/2;
}
};
class Horish_SkAntiHairBlitter : public SkAntiHairBlitter {
public:
SkFixed drawCap(int x, SkFixed fy, SkFixed dy, int mod64) override {
fy += SK_Fixed1/2;
int lower_y = fy >> 16;
uint8_t a = (uint8_t)(fy >> 8);
unsigned a0 = SmallDot6Scale(255 - a, mod64);
unsigned a1 = SmallDot6Scale(a, mod64);
this->getBlitter()->blitAntiV2(x, lower_y - 1, a0, a1);
return fy + dy - SK_Fixed1/2;
}
SkFixed drawLine(int x, int stopx, SkFixed fy, SkFixed dy) override {
SkASSERT(x < stopx);
fy += SK_Fixed1/2;
SkBlitter* blitter = this->getBlitter();
do {
int lower_y = fy >> 16;
uint8_t a = (uint8_t)(fy >> 8);
blitter->blitAntiV2(x, lower_y - 1, 255 - a, a);
fy += dy;
} while (++x < stopx);
return fy - SK_Fixed1/2;
}
};
class VLine_SkAntiHairBlitter : public SkAntiHairBlitter {
public:
SkFixed drawCap(int y, SkFixed fx, SkFixed dx, int mod64) override {
SkASSERT(0 == dx);
fx += SK_Fixed1/2;
int x = fx >> 16;
int a = (uint8_t)(fx >> 8);
unsigned ma = SmallDot6Scale(a, mod64);
if (ma) {
this->getBlitter()->blitV(x, y, 1, ma);
}
ma = SmallDot6Scale(255 - a, mod64);
if (ma) {
this->getBlitter()->blitV(x - 1, y, 1, ma);
}
return fx - SK_Fixed1/2;
}
SkFixed drawLine(int y, int stopy, SkFixed fx, SkFixed dx) override {
SkASSERT(y < stopy);
SkASSERT(0 == dx);
fx += SK_Fixed1/2;
int x = fx >> 16;
int a = (uint8_t)(fx >> 8);
if (a) {
this->getBlitter()->blitV(x, y, stopy - y, a);
}
a = 255 - a;
if (a) {
this->getBlitter()->blitV(x - 1, y, stopy - y, a);
}
return fx - SK_Fixed1/2;
}
};
class Vertish_SkAntiHairBlitter : public SkAntiHairBlitter {
public:
SkFixed drawCap(int y, SkFixed fx, SkFixed dx, int mod64) override {
fx += SK_Fixed1/2;
int x = fx >> 16;
uint8_t a = (uint8_t)(fx >> 8);
this->getBlitter()->blitAntiH2(x - 1, y,
SmallDot6Scale(255 - a, mod64), SmallDot6Scale(a, mod64));
return fx + dx - SK_Fixed1/2;
}
SkFixed drawLine(int y, int stopy, SkFixed fx, SkFixed dx) override {
SkASSERT(y < stopy);
fx += SK_Fixed1/2;
do {
int x = fx >> 16;
uint8_t a = (uint8_t)(fx >> 8);
this->getBlitter()->blitAntiH2(x - 1, y, 255 - a, a);
fx += dx;
} while (++y < stopy);
return fx - SK_Fixed1/2;
}
};
static inline SkFixed fastfixdiv(SkFDot6 a, SkFDot6 b) {
SkASSERT((SkLeftShift(a, 16) >> 16) == a);
SkASSERT(b != 0);
return SkLeftShift(a, 16) / b;
}
#define SkBITCOUNT(x) (sizeof(x) << 3)
#if 1
// returns high-bit set iff x==0x8000...
static inline int bad_int(int x) {
return x & -x;
}
static int any_bad_ints(int a, int b, int c, int d) {
return (bad_int(a) | bad_int(b) | bad_int(c) | bad_int(d)) >> (SkBITCOUNT(int) - 1);
}
#else
static inline int good_int(int x) {
return x ^ (1 << (SkBITCOUNT(x) - 1));
}
static int any_bad_ints(int a, int b, int c, int d) {
return !(good_int(a) & good_int(b) & good_int(c) & good_int(d));
}
#endif
#ifdef SK_DEBUG
static bool canConvertFDot6ToFixed(SkFDot6 x) {
const int maxDot6 = SK_MaxS32 >> (16 - 6);
return SkAbs32(x) <= maxDot6;
}
#endif
/*
* We want the fractional part of ordinate, but we want multiples of 64 to
* return 64, not 0, so we can't just say (ordinate & 63).
* We basically want to compute those bits, and if they're 0, return 64.
* We can do that w/o a branch with an extra sub and add.
*/
static int contribution_64(SkFDot6 ordinate) {
#if 0
int result = ordinate & 63;
if (0 == result) {
result = 64;
}
#else
int result = ((ordinate - 1) & 63) + 1;
#endif
SkASSERT(result > 0 && result <= 64);
return result;
}
static void do_anti_hairline(SkFDot6 x0, SkFDot6 y0, SkFDot6 x1, SkFDot6 y1,
const SkIRect* clip, SkBlitter* blitter) {
// check for integer NaN (0x80000000) which we can't handle (can't negate it)
// It appears typically from a huge float (inf or nan) being converted to int.
// If we see it, just don't draw.
if (any_bad_ints(x0, y0, x1, y1)) {
return;
}
// The caller must clip the line to [-32767.0 ... 32767.0] ahead of time
// (in dot6 format)
SkASSERT(canConvertFDot6ToFixed(x0));
SkASSERT(canConvertFDot6ToFixed(y0));
SkASSERT(canConvertFDot6ToFixed(x1));
SkASSERT(canConvertFDot6ToFixed(y1));
if (SkAbs32(x1 - x0) > SkIntToFDot6(511) || SkAbs32(y1 - y0) > SkIntToFDot6(511)) {
/* instead of (x0 + x1) >> 1, we shift each separately. This is less
precise, but avoids overflowing the intermediate result if the
values are huge. A better fix might be to clip the original pts
directly (i.e. do the divide), so we don't spend time subdividing
huge lines at all.
*/
int hx = (x0 >> 1) + (x1 >> 1);
int hy = (y0 >> 1) + (y1 >> 1);
do_anti_hairline(x0, y0, hx, hy, clip, blitter);
do_anti_hairline(hx, hy, x1, y1, clip, blitter);
return;
}
int scaleStart, scaleStop;
int istart, istop;
SkFixed fstart, slope;
HLine_SkAntiHairBlitter hline_blitter;
Horish_SkAntiHairBlitter horish_blitter;
VLine_SkAntiHairBlitter vline_blitter;
Vertish_SkAntiHairBlitter vertish_blitter;
SkAntiHairBlitter* hairBlitter = nullptr;
if (SkAbs32(x1 - x0) > SkAbs32(y1 - y0)) { // mostly horizontal
if (x0 > x1) { // we want to go left-to-right
using std::swap;
swap(x0, x1);
swap(y0, y1);
}
istart = SkFDot6Floor(x0);
istop = SkFDot6Ceil(x1);
fstart = SkFDot6ToFixed(y0);
if (y0 == y1) { // completely horizontal, take fast case
slope = 0;
hairBlitter = &hline_blitter;
} else {
slope = fastfixdiv(y1 - y0, x1 - x0);
SkASSERT(slope >= -SK_Fixed1 && slope <= SK_Fixed1);
fstart += (slope * (32 - (x0 & 63)) + 32) >> 6;
hairBlitter = &horish_blitter;
}
SkASSERT(istop > istart);
if (istop - istart == 1) {
// we are within a single pixel
scaleStart = x1 - x0;
SkASSERT(scaleStart >= 0 && scaleStart <= 64);
scaleStop = 0;
} else {
scaleStart = 64 - (x0 & 63);
scaleStop = x1 & 63;
}
if (clip){
if (istart >= clip->fRight || istop <= clip->fLeft) {
return;
}
if (istart < clip->fLeft) {
fstart += slope * (clip->fLeft - istart);
istart = clip->fLeft;
scaleStart = 64;
if (istop - istart == 1) {
// we are within a single pixel
scaleStart = contribution_64(x1);
scaleStop = 0;
}
}
if (istop > clip->fRight) {
istop = clip->fRight;
scaleStop = 0; // so we don't draw this last column
}
SkASSERT(istart <= istop);
if (istart == istop) {
return;
}
// now test if our Y values are completely inside the clip
int top, bottom;
if (slope >= 0) { // T2B
top = SkFixedFloorToInt(fstart - SK_FixedHalf);
bottom = SkFixedCeilToInt(fstart + (istop - istart - 1) * slope + SK_FixedHalf);
} else { // B2T
bottom = SkFixedCeilToInt(fstart + SK_FixedHalf);
top = SkFixedFloorToInt(fstart + (istop - istart - 1) * slope - SK_FixedHalf);
}
#ifdef OUTSET_BEFORE_CLIP_TEST
top -= 1;
bottom += 1;
#endif
if (top >= clip->fBottom || bottom <= clip->fTop) {
return;
}
if (clip->fTop <= top && clip->fBottom >= bottom) {
clip = nullptr;
}
}
} else { // mostly vertical
if (y0 > y1) { // we want to go top-to-bottom
using std::swap;
swap(x0, x1);
swap(y0, y1);
}
istart = SkFDot6Floor(y0);
istop = SkFDot6Ceil(y1);
fstart = SkFDot6ToFixed(x0);
if (x0 == x1) {
if (y0 == y1) { // are we zero length?
return; // nothing to do
}
slope = 0;
hairBlitter = &vline_blitter;
} else {
slope = fastfixdiv(x1 - x0, y1 - y0);
SkASSERT(slope <= SK_Fixed1 && slope >= -SK_Fixed1);
fstart += (slope * (32 - (y0 & 63)) + 32) >> 6;
hairBlitter = &vertish_blitter;
}
SkASSERT(istop > istart);
if (istop - istart == 1) {
// we are within a single pixel
scaleStart = y1 - y0;
SkASSERT(scaleStart >= 0 && scaleStart <= 64);
scaleStop = 0;
} else {
scaleStart = 64 - (y0 & 63);
scaleStop = y1 & 63;
}
if (clip) {
if (istart >= clip->fBottom || istop <= clip->fTop) {
return;
}
if (istart < clip->fTop) {
fstart += slope * (clip->fTop - istart);
istart = clip->fTop;
scaleStart = 64;
if (istop - istart == 1) {
// we are within a single pixel
scaleStart = contribution_64(y1);
scaleStop = 0;
}
}
if (istop > clip->fBottom) {
istop = clip->fBottom;
scaleStop = 0; // so we don't draw this last row
}
SkASSERT(istart <= istop);
if (istart == istop)
return;
// now test if our X values are completely inside the clip
int left, right;
if (slope >= 0) { // L2R
left = SkFixedFloorToInt(fstart - SK_FixedHalf);
right = SkFixedCeilToInt(fstart + (istop - istart - 1) * slope + SK_FixedHalf);
} else { // R2L
right = SkFixedCeilToInt(fstart + SK_FixedHalf);
left = SkFixedFloorToInt(fstart + (istop - istart - 1) * slope - SK_FixedHalf);
}
#ifdef OUTSET_BEFORE_CLIP_TEST
left -= 1;
right += 1;
#endif
if (left >= clip->fRight || right <= clip->fLeft) {
return;
}
if (clip->fLeft <= left && clip->fRight >= right) {
clip = nullptr;
}
}
}
SkRectClipBlitter rectClipper;
if (clip) {
rectClipper.init(blitter, *clip);
blitter = &rectClipper;
}
SkASSERT(hairBlitter);
hairBlitter->setup(blitter);
#ifdef SK_DEBUG
if (scaleStart > 0 && scaleStop > 0) {
// be sure we don't draw twice in the same pixel
SkASSERT(istart < istop - 1);
}
#endif
fstart = hairBlitter->drawCap(istart, fstart, slope, scaleStart);
istart += 1;
int fullSpans = istop - istart - (scaleStop > 0);
if (fullSpans > 0) {
fstart = hairBlitter->drawLine(istart, istart + fullSpans, fstart, slope);
}
if (scaleStop > 0) {
hairBlitter->drawCap(istop - 1, fstart, slope, scaleStop);
}
}
void SkScan::AntiHairLineRgn(const SkPoint array[], int arrayCount, const SkRegion* clip,
SkBlitter* blitter) {
if (clip && clip->isEmpty()) {
return;
}
SkASSERT(clip == nullptr || !clip->getBounds().isEmpty());
#ifdef TEST_GAMMA
build_gamma_table();
#endif
const SkScalar max = SkIntToScalar(32767);
const SkRect fixedBounds = SkRect::MakeLTRB(-max, -max, max, max);
SkRect clipBounds;
if (clip) {
clipBounds.set(clip->getBounds());
/* We perform integral clipping later on, but we do a scalar clip first
to ensure that our coordinates are expressible in fixed/integers.
antialiased hairlines can draw up to 1/2 of a pixel outside of
their bounds, so we need to outset the clip before calling the
clipper. To make the numerics safer, we outset by a whole pixel,
since the 1/2 pixel boundary is important to the antihair blitter,
we don't want to risk numerical fate by chopping on that edge.
*/
clipBounds.outset(SK_Scalar1, SK_Scalar1);
}
for (int i = 0; i < arrayCount - 1; ++i) {
SkPoint pts[2];
// We have to pre-clip the line to fit in a SkFixed, so we just chop
// the line. TODO find a way to actually draw beyond that range.
if (!SkLineClipper::IntersectLine(&array[i], fixedBounds, pts)) {
continue;
}
if (clip && !SkLineClipper::IntersectLine(pts, clipBounds, pts)) {
continue;
}
SkFDot6 x0 = SkScalarToFDot6(pts[0].fX);
SkFDot6 y0 = SkScalarToFDot6(pts[0].fY);
SkFDot6 x1 = SkScalarToFDot6(pts[1].fX);
SkFDot6 y1 = SkScalarToFDot6(pts[1].fY);
if (clip) {
SkFDot6 left = SkMin32(x0, x1);
SkFDot6 top = SkMin32(y0, y1);
SkFDot6 right = SkMax32(x0, x1);
SkFDot6 bottom = SkMax32(y0, y1);
SkIRect ir;
ir.set( SkFDot6Floor(left) - 1,
SkFDot6Floor(top) - 1,
SkFDot6Ceil(right) + 1,
SkFDot6Ceil(bottom) + 1);
if (clip->quickReject(ir)) {
continue;
}
if (!clip->quickContains(ir)) {
SkRegion::Cliperator iter(*clip, ir);
const SkIRect* r = &iter.rect();
while (!iter.done()) {
do_anti_hairline(x0, y0, x1, y1, r, blitter);
iter.next();
}
continue;
}
// fall through to no-clip case
}
do_anti_hairline(x0, y0, x1, y1, nullptr, blitter);
}
}
void SkScan::AntiHairRect(const SkRect& rect, const SkRasterClip& clip,
SkBlitter* blitter) {
SkPoint pts[5];
pts[0].set(rect.fLeft, rect.fTop);
pts[1].set(rect.fRight, rect.fTop);
pts[2].set(rect.fRight, rect.fBottom);
pts[3].set(rect.fLeft, rect.fBottom);
pts[4] = pts[0];
SkScan::AntiHairLine(pts, 5, clip, blitter);
}
///////////////////////////////////////////////////////////////////////////////
typedef int FDot8; // 24.8 integer fixed point
static inline FDot8 SkFixedToFDot8(SkFixed x) {
return (x + 0x80) >> 8;
}
static void do_scanline(FDot8 L, int top, FDot8 R, U8CPU alpha,
SkBlitter* blitter) {
SkASSERT(L < R);
if ((L >> 8) == ((R - 1) >> 8)) { // 1x1 pixel
blitter->blitV(L >> 8, top, 1, SkAlphaMul(alpha, R - L));
return;
}
int left = L >> 8;
if (L & 0xFF) {
blitter->blitV(left, top, 1, SkAlphaMul(alpha, 256 - (L & 0xFF)));
left += 1;
}
int rite = R >> 8;
int width = rite - left;
if (width > 0) {
call_hline_blitter(blitter, left, top, width, alpha);
}
if (R & 0xFF) {
blitter->blitV(rite, top, 1, SkAlphaMul(alpha, R & 0xFF));
}
}
static void antifilldot8(FDot8 L, FDot8 T, FDot8 R, FDot8 B, SkBlitter* blitter,
bool fillInner) {
// check for empty now that we're in our reduced precision space
if (L >= R || T >= B) {
return;
}
int top = T >> 8;
if (top == ((B - 1) >> 8)) { // just one scanline high
do_scanline(L, top, R, B - T - 1, blitter);
return;
}
if (T & 0xFF) {
do_scanline(L, top, R, 256 - (T & 0xFF), blitter);
top += 1;
}
int bot = B >> 8;
int height = bot - top;
if (height > 0) {
int left = L >> 8;
if (left == ((R - 1) >> 8)) { // just 1-pixel wide
blitter->blitV(left, top, height, R - L - 1);
} else {
if (L & 0xFF) {
blitter->blitV(left, top, height, 256 - (L & 0xFF));
left += 1;
}
int rite = R >> 8;
int width = rite - left;
if (width > 0 && fillInner) {
blitter->blitRect(left, top, width, height);
}
if (R & 0xFF) {
blitter->blitV(rite, top, height, R & 0xFF);
}
}
}
if (B & 0xFF) {
do_scanline(L, bot, R, B & 0xFF, blitter);
}
}
static void antifillrect(const SkXRect& xr, SkBlitter* blitter) {
antifilldot8(SkFixedToFDot8(xr.fLeft), SkFixedToFDot8(xr.fTop),
SkFixedToFDot8(xr.fRight), SkFixedToFDot8(xr.fBottom),
blitter, true);
}
///////////////////////////////////////////////////////////////////////////////
void SkScan::AntiFillXRect(const SkXRect& xr, const SkRegion* clip,
SkBlitter* blitter) {
if (nullptr == clip) {
antifillrect(xr, blitter);
} else {
SkIRect outerBounds;
XRect_roundOut(xr, &outerBounds);
if (clip->isRect()) {
const SkIRect& clipBounds = clip->getBounds();
if (clipBounds.contains(outerBounds)) {
antifillrect(xr, blitter);
} else {
SkXRect tmpR;
// this keeps our original edges fractional
XRect_set(&tmpR, clipBounds);
if (tmpR.intersect(xr)) {
antifillrect(tmpR, blitter);
}
}
} else {
SkRegion::Cliperator clipper(*clip, outerBounds);
const SkIRect& rr = clipper.rect();
while (!clipper.done()) {
SkXRect tmpR;
// this keeps our original edges fractional
XRect_set(&tmpR, rr);
if (tmpR.intersect(xr)) {
antifillrect(tmpR, blitter);
}
clipper.next();
}
}
}
}
void SkScan::AntiFillXRect(const SkXRect& xr, const SkRasterClip& clip,
SkBlitter* blitter) {
if (clip.isBW()) {
AntiFillXRect(xr, &clip.bwRgn(), blitter);
} else {
SkIRect outerBounds;
XRect_roundOut(xr, &outerBounds);
if (clip.quickContains(outerBounds)) {
AntiFillXRect(xr, nullptr, blitter);
} else {
SkAAClipBlitterWrapper wrapper(clip, blitter);
AntiFillXRect(xr, &wrapper.getRgn(), wrapper.getBlitter());
}
}
}
/* This guy takes a float-rect, but with the key improvement that it has
already been clipped, so we know that it is safe to convert it into a
XRect (fixedpoint), as it won't overflow.
*/
static void antifillrect(const SkRect& r, SkBlitter* blitter) {
SkXRect xr;
XRect_set(&xr, r);
antifillrect(xr, blitter);
}
/* We repeat the clipping logic of AntiFillXRect because the float rect might
overflow if we blindly converted it to an XRect. This sucks that we have to
repeat the clipping logic, but I don't see how to share the code/logic.
We clip r (as needed) into one or more (smaller) float rects, and then pass
those to our version of antifillrect, which converts it into an XRect and
then calls the blit.
*/
void SkScan::AntiFillRect(const SkRect& origR, const SkRegion* clip,
SkBlitter* blitter) {
if (clip) {
SkRect newR;
newR.set(clip->getBounds());
if (!newR.intersect(origR)) {
return;
}
const SkIRect outerBounds = newR.roundOut();
if (clip->isRect()) {
antifillrect(newR, blitter);
} else {
SkRegion::Cliperator clipper(*clip, outerBounds);
while (!clipper.done()) {
newR.set(clipper.rect());
if (newR.intersect(origR)) {
antifillrect(newR, blitter);
}
clipper.next();
}
}
} else {
antifillrect(origR, blitter);
}
}
void SkScan::AntiFillRect(const SkRect& r, const SkRasterClip& clip,
SkBlitter* blitter) {
if (clip.isBW()) {
AntiFillRect(r, &clip.bwRgn(), blitter);
} else {
SkAAClipBlitterWrapper wrap(clip, blitter);
AntiFillRect(r, &wrap.getRgn(), wrap.getBlitter());
}
}
///////////////////////////////////////////////////////////////////////////////
#define SkAlphaMulRound(a, b) SkMulDiv255Round(a, b)
// calls blitRect() if the rectangle is non-empty
static void fillcheckrect(int L, int T, int R, int B, SkBlitter* blitter) {
if (L < R && T < B) {
blitter->blitRect(L, T, R - L, B - T);
}
}
static inline FDot8 SkScalarToFDot8(SkScalar x) {
return (int)(x * 256);
}
static inline int FDot8Floor(FDot8 x) {
return x >> 8;
}
static inline int FDot8Ceil(FDot8 x) {
return (x + 0xFF) >> 8;
}
// 1 - (1 - a)*(1 - b)
static inline U8CPU InvAlphaMul(U8CPU a, U8CPU b) {
// need precise rounding (not just SkAlphaMul) so that values like
// a=228, b=252 don't overflow the result
return SkToU8(a + b - SkAlphaMulRound(a, b));
}
static void inner_scanline(FDot8 L, int top, FDot8 R, U8CPU alpha,
SkBlitter* blitter) {
SkASSERT(L < R);
if ((L >> 8) == ((R - 1) >> 8)) { // 1x1 pixel
FDot8 widClamp = R - L;
// border case clamp 256 to 255 instead of going through call_hline_blitter
// see skbug/4406
widClamp = widClamp - (widClamp >> 8);
blitter->blitV(L >> 8, top, 1, InvAlphaMul(alpha, widClamp));
return;
}
int left = L >> 8;
if (L & 0xFF) {
blitter->blitV(left, top, 1, InvAlphaMul(alpha, L & 0xFF));
left += 1;
}
int rite = R >> 8;
int width = rite - left;
if (width > 0) {
call_hline_blitter(blitter, left, top, width, alpha);
}
if (R & 0xFF) {
blitter->blitV(rite, top, 1, InvAlphaMul(alpha, ~R & 0xFF));
}
}
static void innerstrokedot8(FDot8 L, FDot8 T, FDot8 R, FDot8 B,
SkBlitter* blitter) {
SkASSERT(L < R && T < B);
int top = T >> 8;
if (top == ((B - 1) >> 8)) { // just one scanline high
// We want the inverse of B-T, since we're the inner-stroke
int alpha = 256 - (B - T);
if (alpha) {
inner_scanline(L, top, R, alpha, blitter);
}
return;
}
if (T & 0xFF) {
inner_scanline(L, top, R, T & 0xFF, blitter);
top += 1;
}
int bot = B >> 8;
int height = bot - top;
if (height > 0) {
if (L & 0xFF) {
blitter->blitV(L >> 8, top, height, L & 0xFF);
}
if (R & 0xFF) {
blitter->blitV(R >> 8, top, height, ~R & 0xFF);
}
}
if (B & 0xFF) {
inner_scanline(L, bot, R, ~B & 0xFF, blitter);
}
}
static inline void align_thin_stroke(FDot8& edge1, FDot8& edge2) {
SkASSERT(edge1 <= edge2);
if (FDot8Floor(edge1) == FDot8Floor(edge2)) {
edge2 -= (edge1 & 0xFF);
edge1 &= ~0xFF;
}
}
void SkScan::AntiFrameRect(const SkRect& r, const SkPoint& strokeSize,
const SkRegion* clip, SkBlitter* blitter) {
SkASSERT(strokeSize.fX >= 0 && strokeSize.fY >= 0);
SkScalar rx = SkScalarHalf(strokeSize.fX);
SkScalar ry = SkScalarHalf(strokeSize.fY);
// outset by the radius
FDot8 outerL = SkScalarToFDot8(r.fLeft - rx);
FDot8 outerT = SkScalarToFDot8(r.fTop - ry);
FDot8 outerR = SkScalarToFDot8(r.fRight + rx);
FDot8 outerB = SkScalarToFDot8(r.fBottom + ry);
SkIRect outer;
// set outer to the outer rect of the outer section
outer.set(FDot8Floor(outerL), FDot8Floor(outerT), FDot8Ceil(outerR), FDot8Ceil(outerB));
SkBlitterClipper clipper;
if (clip) {
if (clip->quickReject(outer)) {
return;
}
if (!clip->contains(outer)) {
blitter = clipper.apply(blitter, clip, &outer);
}
// now we can ignore clip for the rest of the function
}
// in case we lost a bit with diameter/2
rx = strokeSize.fX - rx;
ry = strokeSize.fY - ry;
// inset by the radius
FDot8 innerL = SkScalarToFDot8(r.fLeft + rx);
FDot8 innerT = SkScalarToFDot8(r.fTop + ry);
FDot8 innerR = SkScalarToFDot8(r.fRight - rx);
FDot8 innerB = SkScalarToFDot8(r.fBottom - ry);
// For sub-unit strokes, tweak the hulls such that one of the edges coincides with the pixel
// edge. This ensures that the general rect stroking logic below
// a) doesn't blit the same scanline twice
// b) computes the correct coverage when both edges fall within the same pixel
if (strokeSize.fX < 1 || strokeSize.fY < 1) {
align_thin_stroke(outerL, innerL);
align_thin_stroke(outerT, innerT);
align_thin_stroke(innerR, outerR);
align_thin_stroke(innerB, outerB);
}
// stroke the outer hull
antifilldot8(outerL, outerT, outerR, outerB, blitter, false);
// set outer to the outer rect of the middle section
outer.set(FDot8Ceil(outerL), FDot8Ceil(outerT), FDot8Floor(outerR), FDot8Floor(outerB));
if (innerL >= innerR || innerT >= innerB) {
fillcheckrect(outer.fLeft, outer.fTop, outer.fRight, outer.fBottom,
blitter);
} else {
SkIRect inner;
// set inner to the inner rect of the middle section
inner.set(FDot8Floor(innerL), FDot8Floor(innerT), FDot8Ceil(innerR), FDot8Ceil(innerB));
// draw the frame in 4 pieces
fillcheckrect(outer.fLeft, outer.fTop, outer.fRight, inner.fTop,
blitter);
fillcheckrect(outer.fLeft, inner.fTop, inner.fLeft, inner.fBottom,
blitter);
fillcheckrect(inner.fRight, inner.fTop, outer.fRight, inner.fBottom,
blitter);
fillcheckrect(outer.fLeft, inner.fBottom, outer.fRight, outer.fBottom,
blitter);
// now stroke the inner rect, which is similar to antifilldot8() except that
// it treats the fractional coordinates with the inverse bias (since its
// inner).
innerstrokedot8(innerL, innerT, innerR, innerB, blitter);
}
}
void SkScan::AntiFrameRect(const SkRect& r, const SkPoint& strokeSize,
const SkRasterClip& clip, SkBlitter* blitter) {
if (clip.isBW()) {
AntiFrameRect(r, strokeSize, &clip.bwRgn(), blitter);
} else {
SkAAClipBlitterWrapper wrap(clip, blitter);
AntiFrameRect(r, strokeSize, &wrap.getRgn(), wrap.getBlitter());
}
}