introduce Props to surface

include/core/SkSurfaceProps.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSurfaceProps_DEFINED
+#define SkSurfaceProps_DEFINED
+
+#include "SkPoint.h"
+
+/**
+ *  Description of how the LCD strips are arranged for each pixel. If this is unknown, or the
+ *  pixels are meant to be "portable" and/or transformed before showing (e.g. rotated, scaled)
+ *  then use kUnknown_SkPixelGeometry.
+ */
+enum SkPixelGeometry {
+    kUnknown_SkPixelGeometry,

[bungeman-skia, 2014/09/19 18:59:12]

I'd like this one (Unknown) to come last, simply because every time I look at
this I want the low bit to be RGB/BGR and the next bit to be H/V. The fact that
they are almost like that is driving me bananas.

[reed1, 2014/09/19 19:16:34]

I'd rather add helpers to answer those predicates. Having the caller know the
order is too fragile (and you can't distinguish between unknown and RGB by
looking at the low bit alone).

+    kRGB_H_SkPixelGeometry,
+    kBGR_H_SkPixelGeometry,
+    kRGB_V_SkPixelGeometry,
+    kBGR_V_SkPixelGeometry,
+};
+
+/**
+ *  Describes properties and constraints of a given SkSurface. The rendering engine can parse these
+ *  during drawing, and can sometimes optimized its performance (e.g. disabling an expensive
+ *  feature).
+ */
+class SkSurfaceProps {
+public:
+    enum Flags {
+        kDisallowAntiAlias_Flag     = 1 << 0,
+        kDisallowDither_Flag        = 1 << 1,
+        kUseDistanceFieldFonts_Flag = 1 << 2,
+    };
+private:
+    SkSurfaceProps();
+public:
+    enum InitType {
+        kLegacyFontHost_InitType
+    };
+    SkSurfaceProps(InitType);
+    SkSurfaceProps(uint32_t flags, InitType);
+
+    // pixel geometry cannot be kLegacyLCD_SkPixelGeometry

[bungeman-skia, 2014/09/19 18:59:11]

kLegacyLCD_SkPixelGeometry doesn't exist anymore?

[reed1, 2014/09/19 19:16:34]

Done.

+    SkSurfaceProps(uint32_t flags, SkPixelGeometry);
+
+    uint32_t flags() const { return fFlags; }
+    SkPixelGeometry pixelGeometry() const { return fPixelGeometry; }
+
+    bool disallowAA() const { return SkToBool(fFlags & kDisallowAntiAlias_Flag); }
+    bool disallowDither() const { return SkToBool(fFlags & kDisallowDither_Flag); }
+    bool useDistanceFieldFonts() const { return SkToBool(fFlags & kUseDistanceFieldFonts_Flag); }

[bungeman-skia, 2014/09/19 18:59:12]

It seems like these should be named 'disallowsX' and 'usesX' so that call sites
read better and makes it more obvious that these are getters and not magic
setters.

[reed1, 2014/09/19 19:16:34]

isDisallowAA -- to match the pattern we use in SkPaint.h and other places

+
+    // Returns a copy of the specified props, or the legacy version if props is NULL.
+    static SkSurfaceProps CopyOrLegacy(const SkSurfaceProps* props) {
+        return props ? *props : SkSurfaceProps(kLegacyFontHost_InitType);
+    }
+
+private:
+    uint32_t        fFlags;
+    SkPixelGeometry fPixelGeometry;
+};
+
+#endif