// Copyright (c) 2012 The Chromium Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file.

#include "content/shell/android/draw_context.h"

#include "base/logging.h"

#include "content/public/browser/android/graphics_context.h"

#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebGraphicsContext3D.h"

namespace {

static const char g_vertex_shader[] =

"attribute vec4 a_Position;"

"attribute vec2 a_texCoord;"

"varying vec2 v_texCoord;"

"void main() {"

" gl_Position = a_Position;"

" v_texCoord = a_texCoord;"

"}";

// Minimal texture mapping pixel shader.

static const char g_fragment_shader[] =

"precision mediump float;"

"varying vec2 v_texCoord;"

"uniform sampler2D s_texture;"

"void main() {"

" gl_FragColor = texture2D(s_texture, v_texCoord);"

"}";

} // anonymous namespace

namespace content {

DrawContext::DrawContext(ANativeWindow* window)

: program_(GL_ZERO),

vertex_shader_(0),

fragment_shader_(0),

texture_uniform_(GL_ZERO),

vertex_buffer_(GL_ZERO),

context_(content::GraphicsContext::CreateForUI(window)) {

const GLfloat attribs[] = {

-1.0f, -1.0f,

1.0f, -1.0f,

-1.0f, 1.0f,

1.0f, 1.0f,

0.0f, 0.0f,

1.0f, 0.0f,

0.0f, 1.0f,

1.0f, 1.0f };

WebKit::WebGraphicsContext3D* context3D = context_->GetContext3D();

vertex_buffer_ = context3D->createBuffer();

context3D->bindBuffer(GL_ARRAY_BUFFER, vertex_buffer_);

context3D->bufferData(GL_ARRAY_BUFFER, 16 * sizeof(GLfloat), attribs,

GL_STATIC_DRAW);

vertex_shader_ = context3D->createShader(GL_VERTEX_SHADER);

context3D->shaderSource(vertex_shader_, g_vertex_shader);

context3D->compileShader(vertex_shader_);

fragment_shader_ = context3D->createShader(GL_FRAGMENT_SHADER);

context3D->shaderSource(fragment_shader_, g_fragment_shader);

context3D->compileShader(fragment_shader_);

program_ = context3D->createProgram();

context3D->attachShader(program_, vertex_shader_);

context3D->attachShader(program_, fragment_shader_);

context3D->linkProgram(program_);

texture_uniform_ = context3D->getUniformLocation(program_, "s_texture");

}

DrawContext::~DrawContext() {

if (vertex_buffer_ != GL_ZERO)

context_->GetContext3D()->deleteBuffer(vertex_buffer_);

if (program_ != GL_ZERO)

context_->GetContext3D()->deleteProgram(program_);

}

uint32 DrawContext::Draw(int texture) {

DCHECK(program_ != GL_ZERO);

WebKit::WebGraphicsContext3D* context3D = context_->GetContext3D();

context3D->useProgram(program_);

context3D->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);

context3D->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

context3D->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

context3D->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

context3D->uniform1i(texture_uniform_, 0);

context3D->activeTexture(GL_TEXTURE0);

context3D->bindTexture(GL_TEXTURE_2D, texture);

context3D->bindBuffer(GL_ARRAY_BUFFER, vertex_buffer_);

context3D->enableVertexAttribArray(0);

context3D->vertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, 0);

context3D->bindAttribLocation(program_, 0, "a_Position");

context3D->enableVertexAttribArray(1);

context3D->vertexAttribPointer(

1, 2, GL_FLOAT, GL_FALSE, 0, 8 * sizeof(GLfloat));

context3D->bindAttribLocation(program_, 1, "a_texCoord");

context3D->drawArrays(GL_TRIANGLE_STRIP, 0, 4);

context3D->prepareTexture();

return context_->InsertSyncPoint();

}

void DrawContext::Reshape(int width, int height) {

WebKit::WebGraphicsContext3D* context3D = context_->GetContext3D();

context3D->viewport(0, 0, width, height);

context3D->reshape(width, height);

}

} // namespace content