add newImage API

BUG=skia:3277
related bug: skbug.com/3276

Review URL: https://codereview.chromium.org/821083002

3 files changed, 75 insertions, 7 deletions

diff --git a/include/core/SkFilterQuality.h b/include/core/SkFilterQuality.h
new file mode 100644
index 0000000000..db0597e697
--- /dev/null
+++ b/include/core/SkFilterQuality.h
@@ -0,0 +1,24 @@
+/*
+ * 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 SkFilterQuality_DEFINED
+#define SkFilterQuality_DEFINED
+
+#include "SkTypes.h"
+
+/**
+ *  Controls how much filtering to be done when scaling/transforming complex colors
+ *  e.g. images
+ */
+enum SkFilterQuality {
+    kNone_SkFilterQuality,      //!< fastest but lowest quality, typically nearest-neighbor
+    kLow_SkFilterQuality,       //!< typically bilerp
+    kMedium_SkFilterQuality,    //!< typically bilerp + mipmaps for down-scaling
+    kHigh_SkFilterQuality       //!< slowest but highest quality, typically bicubic or better
+};
+
+#endif
diff --git a/include/core/SkImage.h b/include/core/SkImage.h
index 8d65870dc0..b0587b2c3a 100644
--- a/include/core/SkImage.h
+++ b/include/core/SkImage.h
@@ -8,6 +8,7 @@
 #ifndef SkImage_DEFINED
 #define SkImage_DEFINED
 
+#include "SkFilterQuality.h"
 #include "SkImageInfo.h"
 #include "SkImageEncoder.h"
 #include "SkRefCnt.h"
@@ -132,6 +133,27 @@ public:
 
     const char* toString(SkString*) const;
 
+    /**
+     *  Return an image that is a rescale of this image (using newWidth, newHeight).
+     *
+     *  If subset is NULL, then the entire original image is used as the src for the scaling.
+     *  If subset is not NULL, then it specifies subset of src-pixels used for scaling. If
+     *  subset extends beyond the bounds of the original image, then NULL is returned.
+     *
+     *  Notes:
+     *  - newWidth and newHeight must be > 0 or NULL will be returned.
+     *
+     *  - it is legal for the returned image to be the same instance as the src image
+     *    (if the new dimensions == the src dimensions and subset is NULL or == src dimensions).
+     *
+     *  - it is legal for the "scaled" image to have changed its SkAlphaType from unpremul
+     *    to premul (as required by the impl). The image should draw (nearly) identically,
+     *    since during drawing we will "apply the alpha" to the pixels. Future optimizations
+     *    may take away this caveat, preserving unpremul.
+     */
+    SkImage* newImage(int newWidth, int newHeight, const SkIRect* subset = NULL,
+                      SkFilterQuality = kNone_SkFilterQuality) const;
+
 protected:
     SkImage(int width, int height) :
         fWidth(width),
diff --git a/include/core/SkPaint.h b/include/core/SkPaint.h
index 68220f65c9..fef4319477 100644
--- a/include/core/SkPaint.h
+++ b/include/core/SkPaint.h
@@ -10,9 +10,13 @@
 
 #include "SkColor.h"
 #include "SkDrawLooper.h"
+#include "SkFilterQuality.h"
 #include "SkMatrix.h"
 #include "SkXfermode.h"
 
+// TODO: clean up Skia internals so we can remove this and only keep it for clients
+#define SK_SUPPORT_LEGACY_FILTERLEVEL_ENUM
+
 class SkAnnotation;
 class SkAutoGlyphCache;
 class SkColorFilter;
@@ -294,11 +298,12 @@ public:
      */
     void setDistanceFieldTextTEMP(bool distanceFieldText);
 
+#ifdef SK_SUPPORT_LEGACY_FILTERLEVEL_ENUM
     enum FilterLevel {
-        kNone_FilterLevel,
-        kLow_FilterLevel,
-        kMedium_FilterLevel,
-        kHigh_FilterLevel
+        kNone_FilterLevel   = kNone_SkFilterQuality,
+        kLow_FilterLevel    = kLow_SkFilterQuality,
+        kMedium_FilterLevel = kMedium_SkFilterQuality,
+        kHigh_FilterLevel   = kHigh_SkFilterQuality
     };
 
     /**
@@ -306,14 +311,31 @@ public:
      *  drawing scaled images.
      */
     FilterLevel getFilterLevel() const {
-      return (FilterLevel)fBitfields.fFilterLevel;
+        return (FilterLevel)this->getFilterQuality();
     }
 
     /**
      *  Set the filter level. This affects the quality (and performance) of
      *  drawing scaled images.
      */
-    void setFilterLevel(FilterLevel);
+    void setFilterLevel(FilterLevel level) {
+        this->setFilterQuality((SkFilterQuality)level);
+    }
+#endif
+
+    /**
+     *  Return the filter level. This affects the quality (and performance) of
+     *  drawing scaled images.
+     */
+    SkFilterQuality getFilterQuality() const {
+        return (SkFilterQuality)fBitfields.fFilterQuality;
+    }
+    
+    /**
+     *  Set the filter quality. This affects the quality (and performance) of
+     *  drawing scaled images.
+     */
+    void setFilterQuality(SkFilterQuality quality);
 
     /**
      *  If the predicate is true, set the filterLevel to Low, else set it to
@@ -1040,7 +1062,7 @@ private:
             unsigned        fStyle : 2;
             unsigned        fTextEncoding : 2;  // 3 values
             unsigned        fHinting : 2;
-            unsigned        fFilterLevel : 2;
+            unsigned        fFilterQuality : 2;
             //unsigned      fFreeBits : 2;
         } fBitfields;
         uint32_t fBitfieldsUInt;