зеркало из https://github.com/mozilla/moz-skia.git
handle overflow
note: gradient caller doesn't so we can still draw wrong when the caller converts its initial fx from float->fixed. Perhaps SkClampRange should offer a float interface as well. git-svn-id: http://skia.googlecode.com/svn/trunk@1149 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
reed@google.com
Родитель
8b484419e8
Коммит
13659f1f8d
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@ -37,6 +37,9 @@ struct SkClampRange {
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bool fOverflowed; // true if we had to clamp due to numerical overflow
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void init(SkFixed fx, SkFixed dx, int count, int v0, int v1);
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private:
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void initFor1(SkFixed fx);
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};
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#endif
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@ -20,7 +20,7 @@
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* returns [0..count] for the number of steps (<= count) for which x0 <= edge
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* given each step is followed by x0 += dx
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*/
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static int chop(SkFixed x0, SkFixed edge, SkFixed x1, SkFixed dx, int count) {
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static int chop(int64_t x0, SkFixed edge, int64_t x1, int64_t dx, int count) {
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SkASSERT(dx > 0);
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SkASSERT(count >= 0);
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@ -30,36 +30,52 @@ static int chop(SkFixed x0, SkFixed edge, SkFixed x1, SkFixed dx, int count) {
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if (x1 <= edge) {
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return count;
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}
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int n = (edge - x0 + dx - 1) / dx;
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int64_t n = (edge - x0 + dx - 1) / dx;
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SkASSERT(n >= 0);
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SkASSERT(n <= count);
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return n;
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return (int)n;
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}
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void SkClampRange::init(SkFixed fx, SkFixed dx, int count, int v0, int v1) {
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static bool overflows_fixed(int64_t x) {
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return x < -SK_FixedMax || x > SK_FixedMax;
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}
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void SkClampRange::initFor1(SkFixed fx) {
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fCount0 = fCount1 = fCount2 = 0;
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if (fx <= 0) {
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fCount0 = 1;
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} else if (fx < 0xFFFF) {
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fCount1 = 1;
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fFx1 = fx;
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} else {
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fCount2 = 1;
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}
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}
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void SkClampRange::init(SkFixed fx0, SkFixed dx0, int count, int v0, int v1) {
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SkASSERT(count > 0);
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fV0 = v0;
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fV1 = v1;
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fOverflowed = false;
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// check for over/underflow
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{
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int64_t eex = (int64_t)fx + count * (int64_t)dx;
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if (eex > SK_FixedMax) {
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} else if (eex < -SK_FixedMax) {
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}
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// special case 1 == count, as it is slightly common for skia
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// and avoids us ever calling divide or 64bit multiply
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if (1 == count) {
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this->initFor1(fx0);
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return;
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}
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// remember our original fx
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const SkFixed fx0 = fx;
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int64_t fx = fx0;
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int64_t dx = dx0;
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// start with ex equal to the last computed value
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SkFixed ex = fx + (count - 1) * dx;
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int64_t ex = fx + (count - 1) * dx;
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fOverflowed = overflows_fixed(ex);
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if ((unsigned)(fx | ex) <= 0xFFFF) {
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if ((uint64_t)(fx | ex) <= 0xFFFF) {
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fCount0 = fCount2 = 0;
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fCount1 = count;
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fFx1 = fx;
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fFx1 = fx0;
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return;
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}
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if (fx <= 0 && ex <= 0) {
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@ -73,9 +89,41 @@ void SkClampRange::init(SkFixed fx, SkFixed dx, int count, int v0, int v1) {
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return;
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}
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int extraCount = 0;
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// now make ex be 1 past the last computed value
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ex += dx;
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fOverflowed = overflows_fixed(ex);
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// now check for over/under flow
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if (fOverflowed) {
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int originalCount = count;
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int64_t ccount;
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bool swap = dx < 0;
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if (swap) {
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dx = -dx;
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fx = -fx;
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}
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ccount = (SK_FixedMax - fx + dx - 1) / dx;
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if (swap) {
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dx = -dx;
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fx = -fx;
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}
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SkASSERT(ccount > 0 && ccount <= SK_FixedMax);
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count = (int)ccount;
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if (0 == count) {
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this->initFor1(fx0);
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if (dx > 0) {
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fCount2 += originalCount - 1;
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} else {
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fCount0 += originalCount - 1;
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}
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return;
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}
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extraCount = originalCount - count;
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ex = fx + dx * count;
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}
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bool doSwap = dx < 0;
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if (doSwap) {
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@ -85,6 +133,7 @@ void SkClampRange::init(SkFixed fx, SkFixed dx, int count, int v0, int v1) {
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dx = -dx;
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}
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fCount0 = chop(fx, 0, ex, dx, count);
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count -= fCount0;
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fx += fCount0 * dx;
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@ -112,7 +161,13 @@ void SkClampRange::init(SkFixed fx, SkFixed dx, int count, int v0, int v1) {
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}
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if (fCount1 > 0) {
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fFx1 = fx0 + fCount0 * dx;
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fFx1 = fx0 + fCount0 * (int)dx;
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}
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if (dx > 0) {
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fCount2 += extraCount;
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} else {
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fCount0 += extraCount;
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}
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}
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@ -27,7 +27,7 @@
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#define USE_DITHER_32BIT_GRADIENT
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#endif
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//#define SK_ENABLE_FAST_LINEAR_GRADIENTS
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#define SK_ENABLE_FAST_LINEAR_GRADIENTS
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#ifdef SK_ENABLE_FAST_LINEAR_GRADIENTS
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static void sk_memset32_dither(uint32_t dst[], uint32_t v0, uint32_t v1,
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@ -819,11 +819,13 @@ static inline bool no_need_for_clamp(int fx, int dx, int count) {
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#include "SkClampRange.h"
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#define NO_CHECK_ITER \
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fi = fx >> 8; \
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do { \
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unsigned fi = fx >> 8; \
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SkASSERT(fi <= 0xFF); \
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fx += dx; \
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*dstC++ = cache[toggle + fi]; \
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toggle ^= TOGGLE_MASK
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toggle ^= TOGGLE_MASK; \
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} while (0)
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void Linear_Gradient::shadeSpan(int x, int y, SkPMColor dstC[], int count) {
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@ -874,9 +876,9 @@ void Linear_Gradient::shadeSpan(int x, int y, SkPMColor dstC[], int count) {
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dstC += count;
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}
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if ((count = range.fCount1) > 0) {
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unsigned fi;
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int i, unroll = count >> 3;
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for (i = 0; i < unroll; i++) {
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int unroll = count >> 3;
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fx = range.fFx1;
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for (int i = 0; i < unroll; i++) {
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NO_CHECK_ITER; NO_CHECK_ITER;
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NO_CHECK_ITER; NO_CHECK_ITER;
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NO_CHECK_ITER; NO_CHECK_ITER;
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@ -978,11 +980,13 @@ static void dither_memset16(uint16_t dst[], uint16_t value, uint16_t other,
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}
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#define NO_CHECK_ITER_16 \
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fi = fx >> kCache16Shift; \
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do { \
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unsigned fi = fx >> kCache16Shift; \
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SkASSERT(fi <= kCache16Mask); \
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fx += dx; \
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*dstC++ = cache[toggle + fi]; \
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toggle ^= TOGGLE_MASK
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toggle ^= TOGGLE_MASK; \
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} while (0)
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void Linear_Gradient::shadeSpan16(int x, int y, uint16_t dstC[], int count) {
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@ -1028,9 +1032,9 @@ void Linear_Gradient::shadeSpan16(int x, int y, uint16_t dstC[], int count) {
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dstC += count;
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}
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if ((count = range.fCount1) > 0) {
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unsigned fi;
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int i, unroll = count >> 3;
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for (i = 0; i < unroll; i++) {
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int unroll = count >> 3;
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fx = range.fFx1;
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for (int i = 0; i < unroll; i++) {
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NO_CHECK_ITER_16; NO_CHECK_ITER_16;
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NO_CHECK_ITER_16; NO_CHECK_ITER_16;
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NO_CHECK_ITER_16; NO_CHECK_ITER_16;
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@ -4,6 +4,27 @@
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static skiatest::Reporter* gReporter;
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static void debug_me() {
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if (NULL == gReporter) {
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SkDebugf("dsfdssd\n");
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}
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}
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#ifdef USE_REPORTER
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#define R_ASSERT(cond) \
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do { if (!(cond)) { \
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debug_me(); \
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REPORTER_ASSERT(gReporter, cond); \
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}} while (0)
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#else
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#define R_ASSERT(cond) \
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do { if (!(cond)) { \
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debug_me(); \
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}} while (0)
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#endif
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static int classify_value(SkFixed fx, int v0, int v1) {
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if (fx <= 0) {
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return v0;
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@ -11,7 +32,7 @@ static int classify_value(SkFixed fx, int v0, int v1) {
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if (fx >= 0xFFFF) {
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return v1;
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}
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REPORTER_ASSERT(gReporter, false);
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R_ASSERT(false);
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return 0;
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}
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@ -21,22 +42,34 @@ static int classify_value(SkFixed fx, int v0, int v1) {
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static void slow_check(const SkClampRange& range,
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SkFixed fx, SkFixed dx, int count) {
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SkASSERT(range.fCount0 + range.fCount1 + range.fCount2 == count);
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int i;
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for (i = 0; i < range.fCount0; i++) {
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int v = classify_value(fx, V0, V1);
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REPORTER_ASSERT(gReporter, v == range.fV0);
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fx += dx;
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}
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REPORTER_ASSERT(gReporter, range.fCount1 == 0 || fx == range.fFx1);
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for (i = 0; i < range.fCount1; i++) {
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REPORTER_ASSERT(gReporter, fx >= 0 && fx <= 0xFFFF);
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fx += dx;
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}
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for (i = 0; i < range.fCount2; i++) {
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int v = classify_value(fx, V0, V1);
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REPORTER_ASSERT(gReporter, v == range.fV1);
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fx += dx;
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if (range.fOverflowed) {
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fx = range.fFx1;
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for (i = 0; i < range.fCount1; i++) {
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R_ASSERT(fx >= 0 && fx <= 0xFFFF);
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fx += dx;
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}
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} else {
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for (i = 0; i < range.fCount0; i++) {
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int v = classify_value(fx, V0, V1);
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R_ASSERT(v == range.fV0);
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fx += dx;
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}
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if (range.fCount1 > 0 && fx != range.fFx1) {
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SkDebugf("%x %x\n", fx, range.fFx1);
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R_ASSERT(!"bad fFx1");
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return;
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}
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for (i = 0; i < range.fCount1; i++) {
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R_ASSERT(fx >= 0 && fx <= 0xFFFF);
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fx += dx;
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}
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for (i = 0; i < range.fCount2; i++) {
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int v = classify_value(fx, V0, V1);
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R_ASSERT(v == range.fV1);
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fx += dx;
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}
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}
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}
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@ -48,7 +81,8 @@ static void test_range(SkFixed fx, SkFixed dx, int count) {
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#define ff(x) SkIntToFixed(x)
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static void TestClampRange(skiatest::Reporter* reporter) {
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void TestClampRange(skiatest::Reporter* reporter);
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void TestClampRange(skiatest::Reporter* reporter) {
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gReporter = reporter;
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test_range(0, 0, 20);
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@ -60,7 +94,12 @@ static void TestClampRange(skiatest::Reporter* reporter) {
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test_range(10, -1, 20);
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test_range(-10, 3, 20);
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test_range(10, -3, 20);
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test_range(ff(1), ff(16384), 100);
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test_range(ff(-1), ff(-16384), 100);
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test_range(ff(1)/2, ff(16384), 100);
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test_range(ff(1)/2, ff(-16384), 100);
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SkRandom rand;
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// test non-overflow cases
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@ -73,14 +112,17 @@ static void TestClampRange(skiatest::Reporter* reporter) {
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}
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// test overflow cases
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for (int i = 0; i < 0*1000000; i++) {
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for (int i = 0; i < 100000; i++) {
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SkFixed fx = rand.nextS();
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SkFixed sx = rand.nextS();
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SkFixed dx = rand.nextS();
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int count = rand.nextU() % 1000 + 1;
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SkFixed dx = (sx - fx) / count;
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test_range(fx, dx, count);
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}
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}
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#ifdef USE_REPORTER
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#include "TestClassDef.h"
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DEFINE_TESTCLASS("ClampRange", ClampRangeClass, TestClampRange)
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#endif
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