Add dithering to gradients
Change-Id: Ic1208855bde3a254eca2fd7cef43e0f1318ce419
diff --git a/libs/hwui/Dither.cpp b/libs/hwui/Dither.cpp
new file mode 100755
index 0000000..5817977
--- /dev/null
+++ b/libs/hwui/Dither.cpp
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2012 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 "Caches.h"
+#include "Dither.h"
+
+namespace android {
+namespace uirenderer {
+
+///////////////////////////////////////////////////////////////////////////////
+// Defines
+///////////////////////////////////////////////////////////////////////////////
+
+// Must be a power of two
+#define DITHER_KERNEL_SIZE 4
+
+///////////////////////////////////////////////////////////////////////////////
+// Lifecycle
+///////////////////////////////////////////////////////////////////////////////
+
+void Dither::bindDitherTexture() {
+ if (!mInitialized) {
+ const uint8_t pattern[] = {
+ 0, 8, 2, 10,
+ 12, 4, 14, 6,
+ 3, 11, 1, 9,
+ 15, 7, 13, 5
+ };
+
+ glGenTextures(1, &mDitherTexture);
+ glBindTexture(GL_TEXTURE_2D, mDitherTexture);
+
+ glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, DITHER_KERNEL_SIZE, DITHER_KERNEL_SIZE, 0,
+ GL_ALPHA, GL_UNSIGNED_BYTE, &pattern);
+
+ mInitialized = true;
+ } else {
+ glBindTexture(GL_TEXTURE_2D, mDitherTexture);
+ }
+}
+
+void Dither::clear() {
+ if (mInitialized) {
+ glDeleteTextures(1, &mDitherTexture);
+ }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Program management
+///////////////////////////////////////////////////////////////////////////////
+
+void Dither::setupProgram(Program* program, GLuint* textureUnit) {
+ GLuint textureSlot = (*textureUnit)++;
+ Caches::getInstance().activeTexture(textureSlot);
+
+ bindDitherTexture();
+
+ glUniform1i(program->getUniform("ditherSampler"), textureSlot);
+ glUniform1f(program->getUniform("ditherSize"), 1.0f / DITHER_KERNEL_SIZE);
+}
+
+}; // namespace uirenderer
+}; // namespace android