add SkPixmap and external locking to bitmaps

src/core/SkBitmap_scroll.cpp

Index: src/core/SkBitmap_scroll.cpp
diff --git a/src/core/SkBitmap_scroll.cpp b/src/core/SkBitmap_scroll.cpp
index 54158c2bec1182de89fe612b0feb1d5c459ddf24..8c78bd9e94b20a35b7210e65fa57f393e8e075f5 100644
--- a/src/core/SkBitmap_scroll.cpp
+++ b/src/core/SkBitmap_scroll.cpp
@@ -8,9 +8,51 @@
 #include "SkBitmap.h"
 #include "SkRegion.h"
 
-bool SkBitmap::scrollRect(const SkIRect* subset, int dx, int dy,
-                          SkRegion* inval) const
-{
+static bool scroll_pixels(const SkPixmap& pmap, int dx, int dy) {
+    const int shift = pmap.info().bytesPerPixel() >> 1;
+    char*       dst = (char*)pmap.writable_addr();
+    const char* src = dst;
+    int         rowBytes = (int)pmap.rowBytes();    // need rowBytes to be signed
+    int width = pmap.width();
+    int height = pmap.height();
+
+    if (dy <= 0) {
+        src -= dy * rowBytes;
+        height += dy;
+    } else {
+        dst += dy * rowBytes;
+        height -= dy;
+        // now jump src/dst to the last scanline
+        src += (height - 1) * rowBytes;
+        dst += (height - 1) * rowBytes;
+        // now invert rowbytes so we copy backwards in the loop
+        rowBytes = -rowBytes;
+    }
+
+    if (dx <= 0) {
+        src -= dx << shift;
+        width += dx;
+    } else {
+        dst += dx << shift;
+        width -= dx;
+    }
+
+    // If the X-translation would push it completely beyond the region,
+    // then there's nothing to draw.
+    if (width <= 0) {
+        return false;
+    }
+
+    width <<= shift;    // now width is the number of bytes to move per line
+    while (--height >= 0) {
+        memmove(dst, src, width);
+        dst += rowBytes;
+        src += rowBytes;
+    }
+    return true;
+}
+
+bool SkBitmap::scrollRect(const SkIRect* subset, int dx, int dy, SkRegion* inval) const {

[scroggo, 2015/05/19 20:11:42]

It appears that neither Android nor Chromium use this function. Remove it?

[reed1, 2015/05/21 20:59:35]

I'll try that in an (earlier?) CL.

     if (this->isImmutable() || kUnknown_SkColorType == this->colorType()) {
         return false;
     }
@@ -23,7 +65,6 @@ bool SkBitmap::scrollRect(const SkIRect* subset, int dx, int dy,
                 tmp.scrollRect(NULL, dx, dy, inval);
     }
 
-    int shift = this->bytesPerPixel() >> 1;
     int width = this->width();
     int height = this->height();
 
@@ -55,51 +96,12 @@ bool SkBitmap::scrollRect(const SkIRect* subset, int dx, int dy,
         inval->op(r, SkRegion::kDifference_Op);
     }
 
-    SkAutoLockPixels    alp(*this);
-    // if we have no pixels, just return (inval is already updated)
-    // don't call readyToDraw(), since we don't require a colortable per se
-    if (this->getPixels() == NULL) {
+    SkAutoBitmapLockResult result;
+    if (!this->requestLock(&result)) {
         return true;
     }
-
-    char*       dst = (char*)this->getPixels();
-    const char* src = dst;
-    int         rowBytes = (int)this->rowBytes();    // need rowBytes to be signed
-
-    if (dy <= 0) {
-        src -= dy * rowBytes;
-        height += dy;
-    } else {
-        dst += dy * rowBytes;
-        height -= dy;
-        // now jump src/dst to the last scanline
-        src += (height - 1) * rowBytes;
-        dst += (height - 1) * rowBytes;
-        // now invert rowbytes so we copy backwards in the loop
-        rowBytes = -rowBytes;
+    if (scroll_pixels(result.pixmap(), dx, dy)) {
+        this->notifyPixelsChanged();
     }
-
-    if (dx <= 0) {
-        src -= dx << shift;
-        width += dx;
-    } else {
-        dst += dx << shift;
-        width -= dx;
-    }
-
-    // If the X-translation would push it completely beyond the region,
-    // then there's nothing to draw.
-    if (width <= 0) {
-        return true;
-    }
-
-    width <<= shift;    // now width is the number of bytes to move per line
-    while (--height >= 0) {
-        memmove(dst, src, width);
-        dst += rowBytes;
-        src += rowBytes;
-    }
-
-    this->notifyPixelsChanged();
     return true;
 }