grab from latest android

git-svn-id: http://skia.googlecode.com/svn/trunk@27 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 185 insertions, 0 deletions

diff --git a/src/core/SkAlphaRuns.cpp b/src/core/SkAlphaRuns.cpp
new file mode 100644
index 0000000000..46b0206ee8
--- /dev/null
+++ b/src/core/SkAlphaRuns.cpp
@@ -0,0 +1,185 @@
+/* libs/graphics/sgl/SkAlphaRuns.cpp
+**
+** Copyright 2006, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License"); 
+** you may not use this file except in compliance with the License. 
+** You may obtain a copy of the License at 
+**
+**     http://www.apache.org/licenses/LICENSE-2.0 
+**
+** Unless required by applicable law or agreed to in writing, software 
+** distributed under the License is distributed on an "AS IS" BASIS, 
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
+** See the License for the specific language governing permissions and 
+** limitations under the License.
+*/
+
+#include "SkAntiRun.h"
+
+void SkAlphaRuns::reset(int width)
+{
+    SkASSERT(width > 0);
+
+    fRuns[0] = SkToS16(width);
+    fRuns[width] = 0;
+    fAlpha[0] = 0;
+
+    SkDEBUGCODE(fWidth = width;)
+    SkDEBUGCODE(this->validate();)
+}
+
+void SkAlphaRuns::Break(int16_t runs[], uint8_t alpha[], int x, int count)
+{
+    SkASSERT(count > 0 && x >= 0);
+
+//  SkAlphaRuns::BreakAt(runs, alpha, x);
+//  SkAlphaRuns::BreakAt(&runs[x], &alpha[x], count);
+
+    int16_t* next_runs = runs + x;
+    uint8_t*  next_alpha = alpha + x;
+
+    while (x > 0)
+    {
+        int n = runs[0];
+        SkASSERT(n > 0);
+
+        if (x < n)
+        {
+            alpha[x] = alpha[0];
+            runs[0] = SkToS16(x);
+            runs[x] = SkToS16(n - x);
+            break;
+        }
+        runs += n;
+        alpha += n;
+        x -= n;
+    }
+
+    runs = next_runs;
+    alpha = next_alpha;
+    x = count;
+
+    for (;;)
+    {
+        int n = runs[0];
+        SkASSERT(n > 0);
+
+        if (x < n)
+        {
+            alpha[x] = alpha[0];
+            runs[0] = SkToS16(x);
+            runs[x] = SkToS16(n - x);
+            break;
+        }
+        x -= n;
+        if (x <= 0)
+            break;
+
+        runs += n;
+        alpha += n;
+    }
+}
+
+void SkAlphaRuns::add(int x, U8CPU startAlpha, int middleCount, U8CPU stopAlpha, U8CPU maxValue)
+{
+    SkASSERT(middleCount >= 0);
+    SkASSERT(x >= 0 && x + (startAlpha != 0) + middleCount + (stopAlpha != 0) <= fWidth);
+
+    int16_t*    runs = fRuns;
+    uint8_t*     alpha = fAlpha;
+
+    if (startAlpha)
+    {
+        SkAlphaRuns::Break(runs, alpha, x, 1);
+        /*  I should be able to just add alpha[x] + startAlpha.
+            However, if the trailing edge of the previous span and the leading
+            edge of the current span round to the same super-sampled x value,
+            I might overflow to 256 with this add, hence the funny subtract (crud).
+        */
+        unsigned tmp = alpha[x] + startAlpha;
+        SkASSERT(tmp <= 256);
+        alpha[x] = SkToU8(tmp - (tmp >> 8));    // was (tmp >> 7), but that seems wrong if we're trying to catch 256
+
+        runs += x + 1;
+        alpha += x + 1;
+        x = 0;
+        SkDEBUGCODE(this->validate();)
+    }
+    if (middleCount)
+    {
+        SkAlphaRuns::Break(runs, alpha, x, middleCount);
+        alpha += x;
+        runs += x;
+        x = 0;
+        do {
+            alpha[0] = SkToU8(alpha[0] + maxValue);
+            int n = runs[0];
+            SkASSERT(n <= middleCount);
+            alpha += n;
+            runs += n;
+            middleCount -= n;
+        } while (middleCount > 0);
+        SkDEBUGCODE(this->validate();)
+    }
+    if (stopAlpha)
+    {
+        SkAlphaRuns::Break(runs, alpha, x, 1);
+        alpha[x] = SkToU8(alpha[x] + stopAlpha);
+        SkDEBUGCODE(this->validate();)
+    }
+}
+
+#ifdef SK_DEBUG
+    void SkAlphaRuns::assertValid(int y, int maxStep) const
+    {
+        int max = (y + 1) * maxStep - (y == maxStep - 1);
+
+        const int16_t* runs = fRuns;
+        const uint8_t*   alpha = fAlpha;
+
+        while (*runs)
+        {
+            SkASSERT(*alpha <= max);
+            alpha += *runs;
+            runs += *runs;
+        }
+    }
+
+    void SkAlphaRuns::dump() const
+    {
+        const int16_t* runs = fRuns;
+        const uint8_t* alpha = fAlpha;
+
+        SkDebugf("Runs");
+        while (*runs)
+        {
+            int n = *runs;
+
+            SkDebugf(" %02x", *alpha);
+            if (n > 1)
+                SkDebugf(",%d", n);
+            alpha += n;
+            runs += n;
+        }
+        SkDebugf("\n");
+    }
+
+    void SkAlphaRuns::validate() const
+    {
+        SkASSERT(fWidth > 0);
+
+        int         count = 0;
+        const int16_t*  runs = fRuns;
+
+        while (*runs)
+        {
+            SkASSERT(*runs > 0);
+            count += *runs;
+            SkASSERT(count <= fWidth);
+            runs += *runs;
+        }
+        SkASSERT(count == fWidth);
+    }
+#endif
+