Refactor Skia shaders handling.

With this change, Skia shaders can easily be applied to any mesh. This change also
supports ComposeShader. For instance, this can be used to blend a gradient and a
bitmap togehter and paint a string of text with the result.

Change-Id: I701c2f9cf7f89b2ff58005e8a1d0d80ccf4a4aea

1 files changed, 220 insertions, 0 deletions

diff --git a/libs/hwui/SkiaShader.cpp b/libs/hwui/SkiaShader.cpp
new file mode 100644
index 0000000..fedb56c
--- /dev/null
+++ b/libs/hwui/SkiaShader.cpp
@@ -0,0 +1,220 @@
+/*
+ * Copyright (C) 2010 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.
+ */
+
+#define LOG_TAG "OpenGLRenderer"
+
+#include <utils/Log.h>
+
+#include <SkMatrix.h>
+
+#include "SkiaShader.h"
+#include "Texture.h"
+#include "Matrix.h"
+
+namespace android {
+namespace uirenderer {
+
+///////////////////////////////////////////////////////////////////////////////
+// Support
+///////////////////////////////////////////////////////////////////////////////
+
+static const GLenum gTextureUnitsMap[] = {
+        GL_TEXTURE0,
+        GL_TEXTURE1,
+        GL_TEXTURE2
+};
+
+static const GLint gTileModes[] = {
+        GL_CLAMP_TO_EDGE,   // == SkShader::kClamp_TileMode
+        GL_REPEAT,          // == SkShader::kRepeat_Mode
+        GL_MIRRORED_REPEAT  // == SkShader::kMirror_TileMode
+};
+
+///////////////////////////////////////////////////////////////////////////////
+// Base shader
+///////////////////////////////////////////////////////////////////////////////
+
+SkiaShader::SkiaShader(Type type, SkShader* key, SkShader::TileMode tileX,
+        SkShader::TileMode tileY, SkMatrix* matrix, bool blend):
+        mType(type), mKey(key), mTileX(tileX), mTileY(tileY), mMatrix(matrix), mBlend(blend) {
+}
+
+SkiaShader::~SkiaShader() {
+}
+
+void SkiaShader::describe(ProgramDescription& description, const Extensions& extensions) {
+}
+
+void SkiaShader::setupProgram(Program* program, const mat4& modelView, const Snapshot& snapshot,
+        GLuint* textureUnit) {
+}
+
+void SkiaShader::bindTexture(GLuint texture, GLenum wrapS, GLenum wrapT, GLuint textureUnit) {
+    glActiveTexture(gTextureUnitsMap[textureUnit]);
+    glBindTexture(GL_TEXTURE_2D, texture);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrapS);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrapT);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Bitmap shader
+///////////////////////////////////////////////////////////////////////////////
+
+SkiaBitmapShader::SkiaBitmapShader(SkBitmap* bitmap, SkShader* key, SkShader::TileMode tileX,
+        SkShader::TileMode tileY, SkMatrix* matrix, bool blend):
+        SkiaShader(kBitmap, key, tileX, tileY, matrix, blend), mBitmap(bitmap) {
+}
+
+SkiaBitmapShader::~SkiaBitmapShader() {
+}
+
+void SkiaBitmapShader::describe(ProgramDescription& description, const Extensions& extensions) {
+    const Texture* texture = mTextureCache->get(mBitmap);
+
+    const float width = texture->width;
+    const float height = texture->height;
+
+    description.hasBitmap = true;
+    // The driver does not support non-power of two mirrored/repeated
+    // textures, so do it ourselves
+    if (!extensions.hasNPot() && !isPowerOfTwo(width) && !isPowerOfTwo(height)) {
+        description.isBitmapNpot = true;
+        description.bitmapWrapS = gTileModes[mTileX];
+        description.bitmapWrapT = gTileModes[mTileY];
+    }
+}
+
+void SkiaBitmapShader::setupProgram(Program* program, const mat4& modelView,
+        const Snapshot& snapshot, GLuint* textureUnit) {
+    GLuint textureSlot = (*textureUnit)++;
+    glActiveTexture(gTextureUnitsMap[textureSlot]);
+    const Texture* texture = mTextureCache->get(mBitmap);
+
+    const float width = texture->width;
+    const float height = texture->height;
+
+    mat4 textureTransform;
+    if (mMatrix) {
+        SkMatrix inverse;
+        mMatrix->invert(&inverse);
+        textureTransform.load(inverse);
+        textureTransform.multiply(modelView);
+    } else {
+        textureTransform.load(modelView);
+    }
+
+    // Uniforms
+    bindTexture(texture->id, gTileModes[mTileX], gTileModes[mTileY], textureSlot);
+    glUniform1i(program->getUniform("bitmapSampler"), textureSlot);
+    glUniformMatrix4fv(program->getUniform("textureTransform"), 1,
+            GL_FALSE, &textureTransform.data[0]);
+    glUniform2f(program->getUniform("textureDimension"), 1.0f / width, 1.0f / height);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Linear gradient shader
+///////////////////////////////////////////////////////////////////////////////
+
+SkiaLinearGradientShader::SkiaLinearGradientShader(float* bounds, uint32_t* colors,
+        float* positions, int count, SkShader* key, SkShader::TileMode tileMode,
+        SkMatrix* matrix, bool blend):
+        SkiaShader(kLinearGradient, key, tileMode, tileMode, matrix, blend),
+        mBounds(bounds), mColors(colors), mPositions(positions), mCount(count) {
+}
+
+SkiaLinearGradientShader::~SkiaLinearGradientShader() {
+    delete mBounds;
+    delete mColors;
+    delete mPositions;
+}
+
+void SkiaLinearGradientShader::describe(ProgramDescription& description,
+        const Extensions& extensions) {
+    description.hasGradient = true;
+}
+
+void SkiaLinearGradientShader::setupProgram(Program* program, const mat4& modelView,
+        const Snapshot& snapshot, GLuint* textureUnit) {
+    GLuint textureSlot = (*textureUnit)++;
+    glActiveTexture(gTextureUnitsMap[textureSlot]);
+
+    Texture* texture = mGradientCache->get(mKey);
+    if (!texture) {
+        texture = mGradientCache->addLinearGradient(mKey, mBounds, mColors, mPositions,
+                mCount, mTileX);
+    }
+
+    Rect start(mBounds[0], mBounds[1], mBounds[2], mBounds[3]);
+    if (mMatrix) {
+        mat4 shaderMatrix(*mMatrix);
+        shaderMatrix.mapRect(start);
+    }
+    snapshot.transform.mapRect(start);
+
+    const float gradientX = start.right - start.left;
+    const float gradientY = start.bottom - start.top;
+
+    mat4 screenSpace(snapshot.transform);
+    screenSpace.multiply(modelView);
+
+    // Uniforms
+    bindTexture(texture->id, gTileModes[mTileX], gTileModes[mTileY], textureSlot);
+    glUniform1i(program->getUniform("gradientSampler"), textureSlot);
+    glUniform2f(program->getUniform("gradientStart"), start.left, start.top);
+    glUniform2f(program->getUniform("gradient"), gradientX, gradientY);
+    glUniform1f(program->getUniform("gradientLength"),
+            1.0f / (gradientX * gradientX + gradientY * gradientY));
+    glUniformMatrix4fv(program->getUniform("screenSpace"), 1, GL_FALSE, &screenSpace.data[0]);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Compose shader
+///////////////////////////////////////////////////////////////////////////////
+
+SkiaComposeShader::SkiaComposeShader(SkiaShader* first, SkiaShader* second,
+        SkXfermode::Mode mode, SkShader* key):
+        SkiaShader(kCompose, key, SkShader::kClamp_TileMode, SkShader::kClamp_TileMode,
+        NULL, first->blend() || second->blend()), mFirst(first), mSecond(second), mMode(mode) {
+}
+
+SkiaComposeShader::~SkiaComposeShader() {
+    delete mFirst;
+    delete mSecond;
+}
+
+void SkiaComposeShader::set(TextureCache* textureCache, GradientCache* gradientCache) {
+    SkiaShader::set(textureCache, gradientCache);
+    mFirst->set(textureCache, gradientCache);
+    mSecond->set(textureCache, gradientCache);
+}
+
+void SkiaComposeShader::describe(ProgramDescription& description, const Extensions& extensions) {
+    mFirst->describe(description, extensions);
+    mSecond->describe(description, extensions);
+    if (mFirst->type() == kBitmap) {
+        description.isBitmapFirst = true;
+    }
+    description.shadersMode = mMode;
+}
+
+void SkiaComposeShader::setupProgram(Program* program, const mat4& modelView,
+        const Snapshot& snapshot, GLuint* textureUnit) {
+    mFirst->setupProgram(program, modelView, snapshot, textureUnit);
+    mSecond->setupProgram(program, modelView, snapshot, textureUnit);
+}
+
+}; // namespace uirenderer
+}; // namespace android