Add support for drawLines(), with anti-aliasing

Change-Id: I16c0593c5671490909dec13a85df601e1428a1a6
diff --git a/libs/hwui/Line.h b/libs/hwui/Line.h
new file mode 100644
index 0000000..48e18eb
--- /dev/null
+++ b/libs/hwui/Line.h
@@ -0,0 +1,126 @@
+/*
+ * 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.
+ */
+
+#ifndef ANDROID_UI_LINE_H
+#define ANDROID_UI_LINE_H
+
+#include <GLES2/gl2.h>
+
+#include <cmath>
+
+#include <sys/types.h>
+
+#include "Patch.h"
+
+namespace android {
+namespace uirenderer {
+
+///////////////////////////////////////////////////////////////////////////////
+// Globals
+///////////////////////////////////////////////////////////////////////////////
+
+// Alpha8 texture used to perform texture anti-aliasing
+static const uint8_t gLineTexture[] = {
+        0,   0,   0,   0, 0,
+        0, 255, 255, 255, 0,
+        0, 255, 255, 255, 0,
+        0, 255, 255, 255, 0,
+        0,   0,   0,   0, 0
+};
+static const GLsizei gLineTextureWidth = 5;
+static const GLsizei gLineTextureHeight = 5;
+static const float gLineAABias = 1.0f;
+
+///////////////////////////////////////////////////////////////////////////////
+// Line
+///////////////////////////////////////////////////////////////////////////////
+
+class Line {
+public:
+    Line(): mXDivsCount(2), mYDivsCount(2) {
+        mPatch = new Patch(mXDivsCount, mYDivsCount);
+        mXDivs = new int32_t[mXDivsCount];
+        mYDivs = new int32_t[mYDivsCount];
+
+        mXDivs[0] = mYDivs[0] = 2;
+        mXDivs[1] = mYDivs[1] = 3;
+
+        glGenTextures(1, &mTexture);
+        glBindTexture(GL_TEXTURE_2D, mTexture);
+
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+
+        glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, gLineTextureWidth, gLineTextureHeight, 0,
+                GL_ALPHA, GL_UNSIGNED_BYTE, gLineTexture);
+    }
+
+    ~Line() {
+        delete mPatch;
+        delete mXDivs;
+        delete mYDivs;
+
+        glDeleteTextures(1, &mTexture);
+    }
+
+    void update(float x1, float y1, float x2, float y2, float lineWidth, float& tx, float& ty) {
+        const float length = sqrtf((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
+        const float half = lineWidth * 0.5f;
+
+        mPatch->updateVertices(gLineTextureWidth, gLineTextureHeight,
+                -gLineAABias, -half - gLineAABias, length + gLineAABias, half + gLineAABias,
+                mXDivs, mYDivs, mXDivsCount, mYDivsCount);
+
+        tx = -gLineAABias;
+        ty = -half - gLineAABias;
+    }
+
+    inline GLvoid* getVertices() const {
+        return &mPatch->vertices[0].position[0];
+    }
+
+    inline GLvoid* getTexCoords() const {
+        return &mPatch->vertices[0].texture[0];
+    }
+
+    inline GLsizei getElementsCount() const {
+        return mPatch->verticesCount;
+    }
+
+    inline GLuint getTexture() const {
+        return mTexture;
+    }
+
+private:
+    uint32_t mXDivsCount;
+    uint32_t mYDivsCount;
+
+    int32_t* mXDivs;
+    int32_t* mYDivs;
+
+    Patch* mPatch;
+
+    GLuint mTexture;
+}; // class Line
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_UI_LINE_H
diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index d6c0053..ecc02fa 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -39,6 +39,9 @@
 // Generates simple and textured vertices
 #define FV(x, y, u, v) { { x, y }, { u, v } }
 
+#define RAD_TO_DEG (180.0f / 3.14159265f)
+#define MIN_ANGLE 0.001f
+
 ///////////////////////////////////////////////////////////////////////////////
 // Globals
 ///////////////////////////////////////////////////////////////////////////////
@@ -588,7 +591,7 @@
     getAlphaAndMode(paint, &alpha, &mode);
 
     Patch* mesh = mCaches.patchCache.get(patch);
-    mesh->updateVertices(bitmap, left, top, right, bottom,
+    mesh->updateVertices(bitmap->width(), bitmap->height(),left, top, right, bottom,
             &patch->xDivs[0], &patch->yDivs[0], patch->numXDivs, patch->numYDivs);
 
     // Specify right and bottom as +1.0f from left/top to prevent scaling since the
@@ -598,6 +601,50 @@
             &mesh->vertices[0].texture[0], GL_TRIANGLES, mesh->verticesCount);
 }
 
+void OpenGLRenderer::drawLines(float* points, int count, const SkPaint* paint) {
+    int alpha;
+    SkXfermode::Mode mode;
+    getAlphaAndMode(paint, &alpha, &mode);
+
+    uint32_t color = paint->getColor();
+    const GLfloat a = alpha / 255.0f;
+    const GLfloat r = a * ((color >> 16) & 0xFF) / 255.0f;
+    const GLfloat g = a * ((color >>  8) & 0xFF) / 255.0f;
+    const GLfloat b = a * ((color      ) & 0xFF) / 255.0f;
+
+    GLuint textureUnit = 0;
+    setupTextureAlpha8(mLine.getTexture(), 0, 0, textureUnit, 0.0f, 0.0f, r, g, b, a,
+            mode, false, true, mLine.getVertices(), mLine.getTexCoords());
+
+    for (int i = 0; i < count; i += 4) {
+        float tx = 0.0f;
+        float ty = 0.0f;
+
+        mLine.update(points[i], points[i + 1], points[i + 2], points[i + 3],
+                paint->getStrokeWidth(), tx, ty);
+
+        const float dx = points[i + 2] - points[i];
+        const float dy = points[i + 3] - points[i + 1];
+        const float mag = sqrtf(dx * dx + dy * dy);
+        const float angle = acos(dx / mag);
+
+        mModelView.loadTranslate(points[i], points[i + 1], 0.0f);
+        if (angle > MIN_ANGLE || angle < -MIN_ANGLE) {
+            mModelView.rotate(angle * RAD_TO_DEG, 0.0f, 0.0f, 1.0f);
+        }
+        mModelView.translate(tx, ty, 0.0f);
+        mCaches.currentProgram->set(mOrthoMatrix, mModelView, *mSnapshot->transform);
+
+        if (mShader) {
+            mShader->updateTransforms(mCaches.currentProgram, mModelView, *mSnapshot);
+        }
+
+        glDrawArrays(GL_TRIANGLES, 0, mLine.getElementsCount());
+    }
+
+    glDisableVertexAttribArray(mCaches.currentProgram->getAttrib("texCoords"));
+}
+
 void OpenGLRenderer::drawColor(int color, SkXfermode::Mode mode) {
     const Rect& clip = *mSnapshot->clipRect;
     drawColorRect(clip.left, clip.top, clip.right, clip.bottom, color, mode, true);
@@ -793,12 +840,22 @@
         float x, float y, float r, float g, float b, float a, SkXfermode::Mode mode,
         bool transforms, bool applyFilters) {
     setupTextureAlpha8(texture->id, texture->width, texture->height, textureUnit,
-            x, y, r, g, b, a, mode, transforms, applyFilters);
+            x, y, r, g, b, a, mode, transforms, applyFilters,
+            &mMeshVertices[0].position[0], &mMeshVertices[0].texture[0]);
 }
 
 void OpenGLRenderer::setupTextureAlpha8(GLuint texture, uint32_t width, uint32_t height,
         GLuint& textureUnit, float x, float y, float r, float g, float b, float a,
         SkXfermode::Mode mode, bool transforms, bool applyFilters) {
+    setupTextureAlpha8(texture, width, height, textureUnit,
+            x, y, r, g, b, a, mode, transforms, applyFilters,
+            &mMeshVertices[0].position[0], &mMeshVertices[0].texture[0]);
+}
+
+void OpenGLRenderer::setupTextureAlpha8(GLuint texture, uint32_t width, uint32_t height,
+        GLuint& textureUnit, float x, float y, float r, float g, float b, float a,
+        SkXfermode::Mode mode, bool transforms, bool applyFilters,
+        GLvoid* vertices, GLvoid* texCoords) {
      // Describe the required shaders
      ProgramDescription description;
      description.hasTexture = true;
@@ -827,9 +884,9 @@
 
      // Setup attributes
      glVertexAttribPointer(mCaches.currentProgram->position, 2, GL_FLOAT, GL_FALSE,
-             gMeshStride, &mMeshVertices[0].position[0]);
+             gMeshStride, vertices);
      glVertexAttribPointer(texCoordsSlot, 2, GL_FLOAT, GL_FALSE,
-             gMeshStride, &mMeshVertices[0].texture[0]);
+             gMeshStride, texCoords);
 
      // Setup uniforms
      if (transforms) {
diff --git a/libs/hwui/OpenGLRenderer.h b/libs/hwui/OpenGLRenderer.h
index 387fb12..cd7963f 100644
--- a/libs/hwui/OpenGLRenderer.h
+++ b/libs/hwui/OpenGLRenderer.h
@@ -40,6 +40,7 @@
 #include "SkiaShader.h"
 #include "SkiaColorFilter.h"
 #include "Caches.h"
+#include "Line.h"
 
 namespace android {
 namespace uirenderer {
@@ -99,6 +100,7 @@
     void drawColor(int color, SkXfermode::Mode mode);
     void drawRect(float left, float top, float right, float bottom, const SkPaint* paint);
     void drawPath(SkPath* path, SkPaint* paint);
+    void drawLines(float* points, int count, const SkPaint* paint);
 
     void resetShader();
     void setupShader(SkiaShader* shader);
@@ -297,6 +299,15 @@
             SkXfermode::Mode mode, bool transforms, bool applyFilters);
 
     /**
+     * Same as above setupTextureAlpha8() but specifies the mesh's vertices
+     * and texCoords pointers.
+     */
+    void setupTextureAlpha8(GLuint texture, uint32_t width, uint32_t height,
+            GLuint& textureUnit, float x, float y, float r, float g, float b, float a,
+            SkXfermode::Mode mode, bool transforms, bool applyFilters,
+            GLvoid* vertices, GLvoid* texCoords);
+
+    /**
      * Draws text underline and strike-through if needed.
      *
      * @param text The text to decor
@@ -403,6 +414,10 @@
     // List of rectangles to clear due to calls to saveLayer()
     Vector<Rect*> mLayers;
 
+    // Single object used to draw lines
+    Line mLine;
+
+    // Misc
     GLint mMaxTextureSize;
 
 }; // class OpenGLRenderer
diff --git a/libs/hwui/Patch.cpp b/libs/hwui/Patch.cpp
index a660730..0a6eca3 100644
--- a/libs/hwui/Patch.cpp
+++ b/libs/hwui/Patch.cpp
@@ -16,11 +16,8 @@
 
 #define LOG_TAG "OpenGLRenderer"
 
-#include <cstring>
 #include <cmath>
 
-#include <utils/Log.h>
-
 #include "Patch.h"
 
 namespace android {
@@ -34,7 +31,6 @@
     // 2 triangles per patch, 3 vertices per triangle
     verticesCount = (xCount + 1) * (yCount + 1) * 2 * 3;
     vertices = new TextureVertex[verticesCount];
-    memset(vertices, 0, sizeof(TextureVertex) * verticesCount);
 }
 
 Patch::~Patch() {
@@ -45,9 +41,9 @@
 // Vertices management
 ///////////////////////////////////////////////////////////////////////////////
 
-void Patch::updateVertices(const SkBitmap* bitmap, float left, float top, float right,
-        float bottom, const int32_t* xDivs, const int32_t* yDivs, const uint32_t width,
-        const uint32_t height) {
+void Patch::updateVertices(const float bitmapWidth, const float bitmapHeight,
+        float left, float top, float right, float bottom,
+        const int32_t* xDivs, const int32_t* yDivs, const uint32_t width, const uint32_t height) {
     const uint32_t xStretchCount = (width + 1) >> 1;
     const uint32_t yStretchCount = (height + 1) >> 1;
 
@@ -56,9 +52,6 @@
 
     const float meshWidth = right - left;
 
-    const float bitmapWidth = float(bitmap->width());
-    const float bitmapHeight = float(bitmap->height());
-
     if (xStretchCount > 0) {
         uint32_t stretchSize = 0;
         for (uint32_t i = 1; i < width; i += 2) {
diff --git a/libs/hwui/Patch.h b/libs/hwui/Patch.h
index f712455..1d08c64 100644
--- a/libs/hwui/Patch.h
+++ b/libs/hwui/Patch.h
@@ -19,8 +19,6 @@
 
 #include <sys/types.h>
 
-#include <SkBitmap.h>
-
 #include "Vertex.h"
 
 namespace android {
@@ -59,8 +57,9 @@
     Patch(const uint32_t xCount, const uint32_t yCount);
     ~Patch();
 
-    void updateVertices(const SkBitmap* bitmap, float left, float top, float right, float bottom,
-            const int32_t* xDivs,  const int32_t* yDivs,
+    void updateVertices(const float bitmapWidth, const float bitmapHeight,
+            float left, float top, float right, float bottom,
+            const int32_t* xDivs, const int32_t* yDivs,
             const uint32_t width, const uint32_t height);
 
     TextureVertex* vertices;
@@ -70,7 +69,8 @@
     static inline void generateRow(TextureVertex*& vertex, float y1, float y2,
             float v1, float v2, const int32_t xDivs[], uint32_t xCount,
             float stretchX, float width, float bitmapWidth);
-    static inline void generateQuad(TextureVertex*& vertex, float x1, float y1, float x2, float y2,
+    static inline void generateQuad(TextureVertex*& vertex,
+            float x1, float y1, float x2, float y2,
             float u1, float v1, float u2, float v2);
 }; // struct Patch
 
diff --git a/libs/hwui/Rect.h b/libs/hwui/Rect.h
index 5166ee9..f03a602 100644
--- a/libs/hwui/Rect.h
+++ b/libs/hwui/Rect.h
@@ -164,4 +164,4 @@
 }; // namespace uirenderer
 }; // namespace android
 
-#endif // ANDROID_RECT_H
+#endif // ANDROID_UI_RECT_H
diff --git a/libs/hwui/SkiaShader.cpp b/libs/hwui/SkiaShader.cpp
index a5e0f78..946cc4b 100644
--- a/libs/hwui/SkiaShader.cpp
+++ b/libs/hwui/SkiaShader.cpp
@@ -128,6 +128,22 @@
     glUniform2f(program->getUniform("textureDimension"), 1.0f / width, 1.0f / height);
 }
 
+void SkiaBitmapShader::updateTransforms(Program* program, const mat4& modelView,
+        const Snapshot& snapshot) {
+    mat4 textureTransform;
+    if (mMatrix) {
+        SkMatrix inverse;
+        mMatrix->invert(&inverse);
+        textureTransform.load(inverse);
+        textureTransform.multiply(modelView);
+    } else {
+        textureTransform.load(modelView);
+    }
+
+    glUniformMatrix4fv(program->getUniform("textureTransform"), 1,
+            GL_FALSE, &textureTransform.data[0]);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Linear gradient shader
 ///////////////////////////////////////////////////////////////////////////////
@@ -185,6 +201,13 @@
     glUniformMatrix4fv(program->getUniform("screenSpace"), 1, GL_FALSE, &screenSpace.data[0]);
 }
 
+void SkiaLinearGradientShader::updateTransforms(Program* program, const mat4& modelView,
+        const Snapshot& snapshot) {
+    mat4 screenSpace(*snapshot.transform);
+    screenSpace.multiply(modelView);
+    glUniformMatrix4fv(program->getUniform("screenSpace"), 1, GL_FALSE, &screenSpace.data[0]);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Compose shader
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/libs/hwui/SkiaShader.h b/libs/hwui/SkiaShader.h
index d95e3b0..cc94ae6 100644
--- a/libs/hwui/SkiaShader.h
+++ b/libs/hwui/SkiaShader.h
@@ -73,6 +73,10 @@
         mGradientCache = gradientCache;
     }
 
+    virtual void updateTransforms(Program* program, const mat4& modelView,
+            const Snapshot& snapshot) {
+    }
+
     void setMatrix(SkMatrix* matrix) {
         mMatrix = matrix;
     }
@@ -106,6 +110,7 @@
     void describe(ProgramDescription& description, const Extensions& extensions);
     void setupProgram(Program* program, const mat4& modelView, const Snapshot& snapshot,
             GLuint* textureUnit);
+    void updateTransforms(Program* program, const mat4& modelView, const Snapshot& snapshot);
 
 private:
     /**
@@ -130,6 +135,7 @@
     void describe(ProgramDescription& description, const Extensions& extensions);
     void setupProgram(Program* program, const mat4& modelView, const Snapshot& snapshot,
             GLuint* textureUnit);
+    void updateTransforms(Program* program, const mat4& modelView, const Snapshot& snapshot);
 
 private:
     float* mBounds;