External SkImageGenerator API

Introduce an SkImageGenerator API to support the implementation of
externally-managed image decode and scale caches.

BUG=skia:5806
R=reed@google.com

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4720

Change-Id: Ibfe37af5471f78f28f88f9d5e80938882be1a344
Reviewed-on: https://skia-review.googlesource.com/4720
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Reed <reed@google.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/src/core/SkBitmapProvider.cpp b/src/core/SkBitmapProvider.cpp
index 8347d32d7f..11b1ac98d1 100644
--- a/src/core/SkBitmapProvider.cpp
+++ b/src/core/SkBitmapProvider.cpp
@@ -7,6 +7,7 @@
 
 #include "SkBitmapProvider.h"
 #include "SkImage_Base.h"
+#include "SkImageCacherator.h"
 #include "SkPixelRef.h"
 
 int SkBitmapProvider::width() const {
@@ -46,3 +47,36 @@ void SkBitmapProvider::notifyAddedToCache() const {
 bool SkBitmapProvider::asBitmap(SkBitmap* bm) const {
     return as_IB(fImage)->getROPixels(bm, SkImage::kAllow_CachingHint);
 }
+
+bool SkBitmapProvider::accessScaledImage(const SkRect& srcRect,
+                                         const SkMatrix& invMatrix,
+                                         SkFilterQuality fq,
+                                         SkBitmap* scaledBitmap,
+                                         SkRect* adjustedSrcRect,
+                                         SkFilterQuality* adjustedFilterQuality) const {
+    if (!fImage) {
+        return false;
+    }
+
+    SkImageCacherator* cacherator = as_IB(fImage)->peekCacherator();
+    if (!cacherator) {
+        return false;
+    }
+
+    // TODO: stash the matrix someplace to avoid invert()?
+    SkMatrix m;
+    if (!invMatrix.invert(&m)) {
+        return false;
+    }
+
+    SkImageGenerator::ScaledImageRec rec;
+    if (!cacherator->directAccessScaledImage(srcRect, m, fq, &rec) ||
+        !rec.fImage->asLegacyBitmap(scaledBitmap, SkImage::kRO_LegacyBitmapMode)) {
+        return false;
+    }
+
+    *adjustedSrcRect       = rec.fSrcRect;
+    *adjustedFilterQuality = rec.fQuality;
+
+    return true;
+}