spriteblitter for memcpy case (for all configs)

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1887103003

Review URL: https://codereview.chromium.org/1887103003

3 files changed, 30 insertions, 13 deletions

diff --git a/include/core/SkBitmap.h b/include/core/SkBitmap.h
index a81e03eefa..27a00f977e 100644
--- a/include/core/SkBitmap.h
+++ b/include/core/SkBitmap.h
@@ -105,7 +105,7 @@ public:
      *  Return the shift amount per pixel (i.e. 0 for 1-byte per pixel, 1 for 2-bytes per pixel
      *  colortypes, 2 for 4-bytes per pixel colortypes). Return 0 for kUnknown_SkColorType.
      */
-    int shiftPerPixel() const { return this->bytesPerPixel() >> 1; }
+    int shiftPerPixel() const { return this->fInfo.shiftPerPixel(); }
 
     ///////////////////////////////////////////////////////////////////////////
 
diff --git a/include/core/SkImageInfo.h b/include/core/SkImageInfo.h
index c55edd36c2..4b308c05d8 100644
--- a/include/core/SkImageInfo.h
+++ b/include/core/SkImageInfo.h
@@ -105,6 +105,25 @@ static int SkColorTypeBytesPerPixel(SkColorType ct) {
     return gSize[ct];
 }
 
+static int SkColorTypeShiftPerPixel(SkColorType ct) {
+    static const uint8_t gShift[] = {
+        0,  // Unknown
+        0,  // Alpha_8
+        1,  // RGB_565
+        1,  // ARGB_4444
+        2,  // RGBA_8888
+        2,  // BGRA_8888
+        0,  // kIndex_8
+        0,  // kGray_8
+        3,  // kRGBA_F16
+    };
+    static_assert(SK_ARRAY_COUNT(gShift) == (size_t)(kLastEnum_SkColorType + 1),
+                  "size_mismatch_with_SkColorType_enum");
+    
+    SkASSERT((size_t)ct < SK_ARRAY_COUNT(gShift));
+    return gShift[ct];
+}
+
 static inline size_t SkColorTypeMinRowBytes(SkColorType ct, int width) {
     return width * SkColorTypeBytesPerPixel(ct);
 }
@@ -114,15 +133,10 @@ static inline bool SkColorTypeIsValid(unsigned value) {
 }
 
 static inline size_t SkColorTypeComputeOffset(SkColorType ct, int x, int y, size_t rowBytes) {
-    int shift = 0;
-    switch (SkColorTypeBytesPerPixel(ct)) {
-        case 8: shift = 3; break;
-        case 4: shift = 2; break;
-        case 2: shift = 1; break;
-        case 1: shift = 0; break;
-        default: return 0;
+    if (kUnknown_SkColorType == ct) {
+        return 0;
     }
-    return y * rowBytes + (x << shift);
+    return y * rowBytes + (x << SkColorTypeShiftPerPixel(ct));
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -252,9 +266,9 @@ public:
         return SkImageInfo::Make(fWidth, fHeight, newColorType, fAlphaType, fProfileType);
     }
 
-    int bytesPerPixel() const {
-        return SkColorTypeBytesPerPixel(fColorType);
-    }
+    int bytesPerPixel() const { return SkColorTypeBytesPerPixel(fColorType); }
+
+    int shiftPerPixel() const { return SkColorTypeShiftPerPixel(fColorType); }
 
     uint64_t minRowBytes64() const {
         return sk_64_mul(fWidth, this->bytesPerPixel());
diff --git a/include/core/SkPixmap.h b/include/core/SkPixmap.h
index 5f90273a97..c3c27bec78 100644
--- a/include/core/SkPixmap.h
+++ b/include/core/SkPixmap.h
@@ -80,7 +80,7 @@ public:
      *  Return the shift amount per pixel (i.e. 0 for 1-byte per pixel, 1 for 2-bytes per pixel
      *  colortypes, 2 for 4-bytes per pixel colortypes). Return 0 for kUnknown_SkColorType.
      */
-    int shiftPerPixel() const { return fInfo.bytesPerPixel() >> 1; }
+    int shiftPerPixel() const { return fInfo.shiftPerPixel(); }
 
     uint64_t getSize64() const { return sk_64_mul(fInfo.height(), fRowBytes); }
     uint64_t getSafeSize64() const { return fInfo.getSafeSize64(fRowBytes); }
@@ -141,6 +141,9 @@ public:
     // Writable versions
 
     void* writable_addr() const { return const_cast<void*>(fPixels); }
+    void* writable_addr(int x, int y) const {
+        return const_cast<void*>(this->addr(x, y));
+    }
     uint8_t* writable_addr8(int x, int y) const {
         return const_cast<uint8_t*>(this->addr8(x, y));
     }