Initial text support in new reorderer/renderer

Removes obsolete drawPosText codepath, and unifies text decoration behavior.

Change-Id: I9c563249ab688a3394445a0e7fe1b9d0661f6f7c
diff --git a/libs/hwui/Canvas.cpp b/libs/hwui/Canvas.cpp
new file mode 100644
index 0000000..bc88c81
--- /dev/null
+++ b/libs/hwui/Canvas.cpp
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Canvas.h"
+
+#include <SkDrawFilter.h>
+
+namespace android {
+
+void Canvas::drawTextDecorations(float x, float y, float length, const SkPaint& paint) {
+    uint32_t flags;
+    SkDrawFilter* drawFilter = getDrawFilter();
+    if (drawFilter) {
+        SkPaint paintCopy(paint);
+        drawFilter->filter(&paintCopy, SkDrawFilter::kText_Type);
+        flags = paintCopy.getFlags();
+    } else {
+        flags = paint.getFlags();
+    }
+    if (flags & (SkPaint::kUnderlineText_Flag | SkPaint::kStrikeThruText_Flag)) {
+        // Same values used by Skia
+        const float kStdStrikeThru_Offset   = (-6.0f / 21.0f);
+        const float kStdUnderline_Offset    = (1.0f / 9.0f);
+        const float kStdUnderline_Thickness = (1.0f / 18.0f);
+
+        SkScalar left = x;
+        SkScalar right = x + length;
+        float textSize = paint.getTextSize();
+        float strokeWidth = fmax(textSize * kStdUnderline_Thickness, 1.0f);
+        if (flags & SkPaint::kUnderlineText_Flag) {
+            SkScalar top = y + textSize * kStdUnderline_Offset - 0.5f * strokeWidth;
+            SkScalar bottom = y + textSize * kStdUnderline_Offset + 0.5f * strokeWidth;
+            drawRect(left, top, right, bottom, paint);
+        }
+        if (flags & SkPaint::kStrikeThruText_Flag) {
+            SkScalar top = y + textSize * kStdStrikeThru_Offset - 0.5f * strokeWidth;
+            SkScalar bottom = y + textSize * kStdStrikeThru_Offset + 0.5f * strokeWidth;
+            drawRect(left, top, right, bottom, paint);
+        }
+    }
+}
+
+} // namespace android