Implement SkRecord::willPlaybackBitmaps, cache in SkPicture

src/core/SkRecordAnalysis.cpp

+#include "SkRecordAnalysis.h"
+
+#include "SkShader.h"
+#include "SkTLogic.h"
+
+/** SkRecords visitor to determine whether an instance may require an
+    "external" bitmap to rasterize. May return false positives.
+    Does not return true for bitmap text.
+
+    Expected use is to determine whether images need to be decoded before
+    rasterizing a particular SkRecord.
+ */
+struct BitmapTester {
+    // Helpers.  These create HasMember_bitmap and HasMember_paint.
+    SK_CREATE_MEMBER_DETECTOR(bitmap);
+    SK_CREATE_MEMBER_DETECTOR(paint);
+
+    // Some commands have a paint, some have an optional paint.  Either way, get back a pointer.
+    static const SkPaint* AsPtr(const SkPaint& p) { return &p; }
+    static const SkPaint* AsPtr(const SkRecords::Optional<SkPaint>& p) { return p; }
+
+
+    // Main entry for visitor:
+    // If the command has a bitmap directly, return true.
+    // If the command has a paint and the paint has a bitmap, return true.
+    // Otherwise, return false.
+    template <typename T>
+    bool operator()(const T& r) { return CheckBitmap(r); }
+
+
+    // If the command has a bitmap, of course we're going to play back bitmaps.
+    template <typename T>
+    static SK_WHEN(HasMember_bitmap<T>, bool) CheckBitmap(const T&) { return true; }
+
+    // If not, look for one in its paint (if it has a paint).
+    template <typename T>
+    static SK_WHEN(!HasMember_bitmap<T>, bool) CheckBitmap(const T& r) { return CheckPaint(r); }
+
+    // If we have a paint, dig down into the effects looking for a bitmap.
+    template <typename T>
+    static SK_WHEN(HasMember_paint<T>, bool) CheckPaint(const T& r) {
+        const SkPaint* paint = AsPtr(r.paint);
+        if (paint) {
+            const SkShader* shader = paint->getShader();
+            if (shader &&
+                shader->asABitmap(NULL, NULL, NULL) == SkShader::kDefault_BitmapType) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    // If we don't have a paint, that non-paint has no bitmap.
+    template <typename T>
+    static SK_WHEN(!HasMember_paint<T>, bool) CheckPaint(const T&) { return false; }
+};
+
+bool SkRecordWillPlaybackBitmaps(const SkRecord& record) {
+    BitmapTester tester;
+    for (unsigned i = 0; i < record.count(); i++) {
+        if (record.visit<bool>(i, tester)) {
+            return true;
+        }
+    }
+    return false;
+}