Add constants for PDF 1.7 spec, table 7.2 and 7.3.

Add constants/transparency.h. The header lists constants from chapter 7
of the PDF spec.

BUG=pdfium:1049

Change-Id: I66bd6fceb24807eec9c308e2e47cec3f2f836ffb
Reviewed-on: https://pdfium-review.googlesource.com/32177
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

1 files changed, 38 insertions, 0 deletions

diff --git a/constants/transparency.h b/constants/transparency.h
new file mode 100644
index 0000000000..6ae79c949d
--- /dev/null
+++ b/constants/transparency.h
@@ -0,0 +1,38 @@
+// Copyright 2018 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONSTANTS_TRANSPARENCY_H_
+#define CONSTANTS_TRANSPARENCY_H_
+
+namespace pdfium {
+namespace transparency {
+
+// PDF 1.7 spec, table 7.2.
+// Standard separable blend modes.
+
+constexpr char kNormal[] = "Normal";
+constexpr char kMultiply[] = "Multiply";
+constexpr char kScreen[] = "Screen";
+constexpr char kOverlay[] = "Overlay";
+constexpr char kDarken[] = "Darken";
+constexpr char kLighten[] = "Lighten";
+constexpr char kColorDodge[] = "ColorDodge";
+constexpr char kColorBurn[] = "ColorBurn";
+constexpr char kHardLight[] = "HardLight";
+constexpr char kSoftLight[] = "SoftLight";
+constexpr char kDifference[] = "Difference";
+constexpr char kExclusion[] = "Exclusion";
+
+// PDF 1.7 spec, table 7.3.
+// Standard nonseparable blend modes.
+
+constexpr char kHue[] = "Hue";
+constexpr char kSaturation[] = "Saturation";
+constexpr char kColor[] = "Color";
+constexpr char kLuminosity[] = "Luminosity";
+
+}  // namespace transparency
+}  // namespace pdfium
+
+#endif  // CONSTANTS_TRANSPARENCY_H_