add SkPixmap and external locking to bitmaps

include/core/SkPixmap.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkPixmap_DEFINED
+#define SkPixmap_DEFINED
+
+#include "SkImageInfo.h"
+
+class SkColorTable;
+
+/**
+ *  Pairs SkImageInfo with actual pixels and rowbytes. This class does not try to manage the
+ *  lifetime of the pixel memory (nor the colortable if provided).
+ */
+class SkPixmap {
+public:
+    SkPixmap()
+        : fPixels(NULL), fCTable(NULL), fRowBytes(0), fInfo(SkImageInfo::MakeUnknown(0, 0))
+    {}
+
+    SkPixmap(const SkImageInfo& info, const void* addr, size_t rowBytes,
+             SkColorTable* ctable = NULL)
+        : fPixels(addr), fCTable(ctable), fRowBytes(rowBytes), fInfo(info)
+    {
+        if (kIndex_8_SkColorType == info.colorType()) {
+            SkASSERT(ctable);
+        } else {
+            SkASSERT(NULL == ctable);
+        }
+    }
+
+    const SkImageInfo& info() const { return fInfo; }
+    size_t rowBytes() const { return fRowBytes; }
+    const void* addr() const { return fPixels; }
+    SkColorTable* ctable() const { return fCTable; }
+
+    int width() const { return fInfo.width(); }
+    int height() const { return fInfo.height(); }
+    SkColorType colorType() const { return fInfo.colorType(); }
+    SkAlphaType alphaType() const { return fInfo.alphaType(); }
+    bool isOpaque() const { return fInfo.isOpaque(); }
+
+    int64_t getSafeSize64() const { return fInfo.getSafeSize64(fRowBytes); }
+    size_t getSafeSize() const { return fInfo.getSafeSize(fRowBytes); }
+
+    const uint32_t* addr32() const {
+        SkASSERT(4 == SkColorTypeBytesPerPixel(fInfo.colorType()));
+        return reinterpret_cast<const uint32_t*>(fPixels);
+    }
+
+    const uint16_t* addr16() const {
+        SkASSERT(2 == SkColorTypeBytesPerPixel(fInfo.colorType()));
+        return reinterpret_cast<const uint16_t*>(fPixels);
+    }
+
+    const uint8_t* addr8() const {
+        SkASSERT(1 == SkColorTypeBytesPerPixel(fInfo.colorType()));
+        return reinterpret_cast<const uint8_t*>(fPixels);
+    }
+
+    const uint32_t* addr32(int x, int y) const {
+        SkASSERT((unsigned)x < (unsigned)fInfo.width());
+        SkASSERT((unsigned)y < (unsigned)fInfo.height());
+        return (const uint32_t*)((const char*)this->addr32() + y * fRowBytes + (x << 2));
+    }
+    const uint16_t* addr16(int x, int y) const {
+        SkASSERT((unsigned)x < (unsigned)fInfo.width());
+        SkASSERT((unsigned)y < (unsigned)fInfo.height());
+        return (const uint16_t*)((const char*)this->addr16() + y * fRowBytes + (x << 1));
+    }
+    const uint8_t* addr8(int x, int y) const {
+        SkASSERT((unsigned)x < (unsigned)fInfo.width());
+        SkASSERT((unsigned)y < (unsigned)fInfo.height());
+        return (const uint8_t*)((const char*)this->addr8() + y * fRowBytes + (x << 0));
+    }
+    const void* addr(int x, int y) const {
+        return (const char*)fPixels + fInfo.computeOffset(x, y, fRowBytes);
+    }
+
+    // Writable versions
+
+    void* writable_addr() const { return const_cast<void*>(fPixels); }
+    uint32_t* writable_addr32(int x, int y) const {
+        return const_cast<uint32_t*>(this->addr32(x, y));
+    }
+    uint16_t* writable_addr16(int x, int y) const {
+        return const_cast<uint16_t*>(this->addr16(x, y));
+    }
+    uint8_t* writable_addr8(int x, int y) const {
+        return const_cast<uint8_t*>(this->addr8(x, y));
+    }
+
+private:
+    const void*     fPixels;
+    SkColorTable*   fCTable;
+    size_t          fRowBytes;
+    SkImageInfo     fInfo;
+};
+
+/////////////////////////////////////////////////////////////////////////////////////////////
+
+class SkAutoPixmapUnlock : ::SkNoncopyable {
+public:
+    SkAutoPixmapUnlock() : fUnlockProc(NULL), fIsLocked(false) {}
+    SkAutoPixmapUnlock(const SkPixmap& pm, void (*unlock)(void*), void* ctx)
+        : fUnlockProc(unlock), fUnlockContext(ctx), fPixmap(pm), fIsLocked(true)
+    {}
+    ~SkAutoPixmapUnlock() { this->unlock(); }
+
+    /**
+     *  Return the currently locked pixmap. Undefined if it has been unlocked.
+     */
+    const SkPixmap& pixmap() const {
+        SkASSERT(this->isLocked());
+        return fPixmap;
+    }
+
+    bool isLocked() const { return fIsLocked; }
+
+    /**
+     *  Unlocks the pixmap. Can safely be called more than once as it will only call the underlying
+     *  unlock-proc once.
+     */
+    void unlock() {
+        if (fUnlockProc) {
+            SkASSERT(fIsLocked);
+            fUnlockProc(fUnlockContext);
+            fUnlockProc = NULL;
+            fIsLocked = false;
+        }
+    }
+
+    /**
+     *  If there is a currently locked pixmap, unlock it, then copy the specified pixmap
+     *  and (optional) unlock proc/context.
+     */
+    void reset(const SkPixmap& pm, void (*unlock)(void*), void* ctx);
+
+private:
+    void        (*fUnlockProc)(void*);
+    void*       fUnlockContext;
+    SkPixmap    fPixmap;
+    bool        fIsLocked;
+
+    friend class SkBitmap;
+};

[scroggo, 2015/05/22 18:42:33]

Should this be SK_REQUIRE_LOCAL_VAR?

+
+#endif