Add SkTypeface::getVariationDesignPosition.

Allow users to query a typeface's position in variation design space.

Change-Id: Id7cae439e795b8c9586394f11359fb7fe55e1c0b
Reviewed-on: https://skia-review.googlesource.com/8861
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>

1 files changed, 79 insertions, 0 deletions

diff --git a/include/core/SkFontArguments.h b/include/core/SkFontArguments.h
new file mode 100644
index 0000000000..473798fb84
--- /dev/null
+++ b/include/core/SkFontArguments.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkFontAgruments_DEFINED
+#define SkFontAgruments_DEFINED
+
+#include "SkScalar.h"
+#include "SkTypes.h"
+
+/** Represents a set of actual arguments for a font. */
+struct SkFontArguments {
+    struct VariationPosition {
+        struct Coordinate {
+            SkFourByteTag axis;
+            SkScalar value;
+        };
+        const Coordinate* coordinates;
+        int coordinateCount;
+    };
+    // deprecated, use VariationCoordinate instead
+    struct Axis {
+       SkFourByteTag fTag;
+       SkScalar fStyleValue;
+    };
+
+    SkFontArguments() : fCollectionIndex(0), fVariationDesignPosition{nullptr, 0} {}
+
+    /** Specify the index of the desired font.
+     *
+     *  Font formats like ttc, dfont, cff, cid, pfr, t42, t1, and fon may actually be indexed
+     *  collections of fonts.
+     */
+    SkFontArguments& setCollectionIndex(int collectionIndex) {
+        fCollectionIndex = collectionIndex;
+        return *this;
+    }
+
+    // deprecated, use setVariationDesignPosition instead.
+    SkFontArguments& setAxes(const Axis* axes, int axisCount) {
+        fVariationDesignPosition.coordinates =
+                reinterpret_cast<const VariationPosition::Coordinate*>(axes);
+        fVariationDesignPosition.coordinateCount = axisCount;
+        return *this;
+    }
+
+    /** Specify a position in the variation design space.
+     *
+     *  Any axis not specified will use the default value.
+     *  Any specified axis not actually present in the font will be ignored.
+     *
+     *  @param position not copied. The value must remain valid for life of SkFontArguments.
+     */
+    SkFontArguments& setVariationDesignPosition(VariationPosition position) {
+        fVariationDesignPosition.coordinates = position.coordinates;
+        fVariationDesignPosition.coordinateCount = position.coordinateCount;
+        return *this;
+    }
+
+    int getCollectionIndex() const {
+        return fCollectionIndex;
+    }
+    // deprecated, use getVariationDesignPosition instead.
+    const Axis* getAxes(int* axisCount) const {
+        *axisCount = fVariationDesignPosition.coordinateCount;
+        return reinterpret_cast<const Axis*>(fVariationDesignPosition.coordinates);
+    }
+    VariationPosition getVariationDesignPosition() const {
+        return fVariationDesignPosition;
+    }
+private:
+    int fCollectionIndex;
+    VariationPosition fVariationDesignPosition;
+};
+
+#endif