/*

 * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.

 * Copyright (C) 2007 Alp Toker <alp@atoker.com>

 * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY

 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 

 */

#include "config.h"

#include "HTMLCanvasElement.h"

#include "Attribute.h"

#include "CanvasContextAttributes.h"

#include "CanvasGradient.h"

#include "CanvasPattern.h"

#include "CanvasRenderingContext2D.h"

#include "CanvasStyle.h"

#include "Chrome.h"

#include "Document.h"

#include "ExceptionCode.h"

#include "Frame.h"

#include "GraphicsContext.h"

#include "HTMLNames.h"

#include "ImageBuffer.h"

#include "MIMETypeRegistry.h"

#include "Page.h"

#include "RenderHTMLCanvas.h"

#include "Settings.h"

#include <math.h>

#include <stdio.h>

#if ENABLE(3D_CANVAS)    

#include "WebGLContextAttributes.h"

#include "WebGLRenderingContext.h"

#endif

namespace WebCore {

using namespace HTMLNames;

// These values come from the WhatWG spec.

static const int DefaultWidth = 300;

static const int DefaultHeight = 150;

// Firefox limits width/height to 32767 pixels, but slows down dramatically before it

// reaches that limit. We limit by area instead, giving us larger maximum dimensions,

// in exchange for a smaller maximum canvas size.

static const float MaxCanvasArea = 32768 * 8192; // Maximum canvas area in CSS pixels

//In Skia, we will also limit width/height to 32767.

static const float MaxSkiaDim = 32767.0F; // Maximum width/height in CSS pixels.

HTMLCanvasElement::HTMLCanvasElement(const QualifiedName& tagName, Document* document)

    : HTMLElement(tagName, document)

    , m_observer(0)

    , m_size(DefaultWidth, DefaultHeight)

    , m_ignoreReset(false)

    , m_pageScaleFactor(document->frame() ? document->frame()->page()->chrome()->scaleFactor() : 1)

    , m_originClean(true)

    , m_hasCreatedImageBuffer(false)

{

    ASSERT(hasTagName(canvasTag));

}

PassRefPtr<HTMLCanvasElement> HTMLCanvasElement::create(Document* document)

{

    return adoptRef(new HTMLCanvasElement(canvasTag, document));

}

PassRefPtr<HTMLCanvasElement> HTMLCanvasElement::create(const QualifiedName& tagName, Document* document)

{

    return adoptRef(new HTMLCanvasElement(tagName, document));

}

HTMLCanvasElement::~HTMLCanvasElement()

{

    if (m_observer)

        m_observer->canvasDestroyed(this);

}

#if ENABLE(DASHBOARD_SUPPORT)

HTMLTagStatus HTMLCanvasElement::endTagRequirement() const 

{

    Settings* settings = document()->settings();

    if (settings && settings->usesDashboardBackwardCompatibilityMode())

        return TagStatusForbidden; 

    return HTMLElement::endTagRequirement();

}

int HTMLCanvasElement::tagPriority() const 

{ 

    Settings* settings = document()->settings();

    if (settings && settings->usesDashboardBackwardCompatibilityMode())

        return 0; 

    return HTMLElement::tagPriority();

}

#endif

void HTMLCanvasElement::parseMappedAttribute(Attribute* attr)

{

    const QualifiedName& attrName = attr->name();

    if (attrName == widthAttr || attrName == heightAttr)

        reset();

    HTMLElement::parseMappedAttribute(attr);

}

RenderObject* HTMLCanvasElement::createRenderer(RenderArena* arena, RenderStyle* style)

{

    Frame* frame = document()->frame();

    if (frame && frame->script()->canExecuteScripts(NotAboutToExecuteScript)) {

        m_rendererIsCanvas = true;

        return new (arena) RenderHTMLCanvas(this);

    }

    m_rendererIsCanvas = false;

    return HTMLElement::createRenderer(arena, style);

}

void HTMLCanvasElement::setHeight(int value)

{

    setAttribute(heightAttr, String::number(value));

}

void HTMLCanvasElement::setWidth(int value)

{

    setAttribute(widthAttr, String::number(value));

}

CanvasRenderingContext* HTMLCanvasElement::getContext(const String& type, CanvasContextAttributes* attrs)

{

    // A Canvas can either be "2D" or "webgl" but never both. If you request a 2D canvas and the existing

    // context is already 2D, just return that. If the existing context is WebGL, then destroy it

    // before creating a new 2D context. Vice versa when requesting a WebGL canvas. Requesting a

    // context with any other type string will destroy any existing context.

    // FIXME - The code depends on the context not going away once created, to prevent JS from

    // seeing a dangling pointer. So for now we will disallow the context from being changed

    // once it is created.

    if (type == "2d") {

        if (m_context && !m_context->is2d())

            return 0;

        if (!m_context) {

            bool usesDashbardCompatibilityMode = false;

#if ENABLE(DASHBOARD_SUPPORT)

            if (Settings* settings = document()->settings())

                usesDashbardCompatibilityMode = settings->usesDashboardBackwardCompatibilityMode();

#endif

            m_context = new CanvasRenderingContext2D(this, document()->inCompatMode(), usesDashbardCompatibilityMode);

        }

        return m_context.get();

    }

#if ENABLE(3D_CANVAS)    

    Settings* settings = document()->settings();

    if (settings && settings->webGLEnabled()

#if !PLATFORM(CHROMIUM) && !PLATFORM(QT)

        && settings->acceleratedCompositingEnabled()

#endif

        ) {

        // Accept the legacy "webkit-3d" name as well as the provisional "experimental-webgl" name.

        // Once ratified, we will also accept "webgl" as the context name.

        if ((type == "webkit-3d") ||

            (type == "experimental-webgl")) {

            if (m_context && !m_context->is3d())

                return 0;

            if (!m_context) {

                m_context = WebGLRenderingContext::create(this, static_cast<WebGLContextAttributes*>(attrs));

                if (m_context) {

                    // Need to make sure a RenderLayer and compositing layer get created for the Canvas

                    setNeedsStyleRecalc(SyntheticStyleChange);

                }

            }

            return m_context.get();

        }

    }

#else

    UNUSED_PARAM(attrs);

#endif

    return 0;

}

void HTMLCanvasElement::willDraw(const FloatRect& rect)

{

    if (m_imageBuffer)

        m_imageBuffer->clearImage();

    if (RenderBox* ro = renderBox()) {

        FloatRect destRect = ro->contentBoxRect();

        FloatRect r = mapRect(rect, FloatRect(0, 0, size().width(), size().height()), destRect);

        r.intersect(destRect);

        if (m_dirtyRect.contains(r))

            return;

        m_dirtyRect.unite(r);

        ro->repaintRectangle(enclosingIntRect(m_dirtyRect));

    }

    if (m_observer)

        m_observer->canvasChanged(this, rect);

}

void HTMLCanvasElement::reset()

{

    if (m_ignoreReset)

        return;

    bool ok;

    int w = getAttribute(widthAttr).toInt(&ok);

    if (!ok || w < 0)

        w = DefaultWidth;

    int h = getAttribute(heightAttr).toInt(&ok);

    if (!ok || h < 0)

        h = DefaultHeight;

    IntSize oldSize = size();

    setSurfaceSize(IntSize(w, h));

#if ENABLE(3D_CANVAS)

    if (m_context && m_context->is3d())

        static_cast<WebGLRenderingContext*>(m_context.get())->reshape(width(), height());

#endif

    bool hadImageBuffer = hasCreatedImageBuffer();

    if (m_context && m_context->is2d())

        static_cast<CanvasRenderingContext2D*>(m_context.get())->reset();

    if (RenderObject* renderer = this->renderer()) {

        if (m_rendererIsCanvas) {

            if (oldSize != size())

                toRenderHTMLCanvas(renderer)->canvasSizeChanged();

            if (hadImageBuffer)

                renderer->repaint();

        }

    }

    if (m_observer)

        m_observer->canvasResized(this);

}

void HTMLCanvasElement::paint(GraphicsContext* context, const IntRect& r)

{

    // Clear the dirty rect

    m_dirtyRect = FloatRect();

    if (context->paintingDisabled())

        return;

#if ENABLE(3D_CANVAS)

    WebGLRenderingContext* context3D = 0;

    if (m_context && m_context->is3d()) {

        context3D = static_cast<WebGLRenderingContext*>(m_context.get());

        context3D->beginPaint();

    }

#endif

    if (hasCreatedImageBuffer()) {

        ImageBuffer* imageBuffer = buffer();

        if (imageBuffer) {

            Image* image = imageBuffer->imageForRendering();

            if (image)

                context->drawImage(image, DeviceColorSpace, r);

        }

    }

#if ENABLE(3D_CANVAS)

    if (context3D)

        context3D->endPaint();

#endif

}

#if ENABLE(3D_CANVAS)    

bool HTMLCanvasElement::is3D() const

{

    return m_context && m_context->is3d();

}

#endif

void HTMLCanvasElement::makeRenderingResultsAvailable()

{

#if ENABLE(3D_CANVAS)

    if (is3D()) {

        WebGLRenderingContext* context3d = reinterpret_cast<WebGLRenderingContext*>(renderingContext());

        context3d->paintRenderingResultsToCanvas();

    }

#endif

}

void HTMLCanvasElement::recalcStyle(StyleChange change)

{

    HTMLElement::recalcStyle(change);

    // Update font if needed.

    if (change == Force && m_context && m_context->is2d()) {

        CanvasRenderingContext2D* ctx = static_cast<CanvasRenderingContext2D*>(m_context.get());

        ctx->updateFont();

    }

}

void HTMLCanvasElement::setSurfaceSize(const IntSize& size)

{

    m_size = size;

    m_hasCreatedImageBuffer = false;

    m_imageBuffer.clear();

}

String HTMLCanvasElement::toDataURL(const String& mimeType, const double* quality, ExceptionCode& ec)

{

    if (!m_originClean) {

        ec = SECURITY_ERR;

        return String();

    }

    if (m_size.isEmpty() || !buffer())

        return String("data:,");

    String lowercaseMimeType = mimeType.lower();

    makeRenderingResultsAvailable();

    // FIXME: Make isSupportedImageMIMETypeForEncoding threadsafe (to allow this method to be used on a worker thread).

    if (mimeType.isNull() || !MIMETypeRegistry::isSupportedImageMIMETypeForEncoding(lowercaseMimeType))

        return buffer()->toDataURL("image/png");

    return buffer()->toDataURL(lowercaseMimeType, quality);

}

IntRect HTMLCanvasElement::convertLogicalToDevice(const FloatRect& logicalRect) const

{

    return IntRect(convertLogicalToDevice(logicalRect.location()), convertLogicalToDevice(logicalRect.size()));

}

IntSize HTMLCanvasElement::convertLogicalToDevice(const FloatSize& logicalSize) const

{

    float wf = ceilf(logicalSize.width() * m_pageScaleFactor);

    float hf = ceilf(logicalSize.height() * m_pageScaleFactor);

    if (!(wf >= 1 && hf >= 1 && wf * hf <= MaxCanvasArea))

        return IntSize();

#if PLATFORM(SKIA)

    if (wf > MaxSkiaDim || hf > MaxSkiaDim)

        return IntSize();

#endif

    return IntSize(static_cast<unsigned>(wf), static_cast<unsigned>(hf));

}

IntPoint HTMLCanvasElement::convertLogicalToDevice(const FloatPoint& logicalPos) const

{

    float xf = logicalPos.x() * m_pageScaleFactor;

    float yf = logicalPos.y() * m_pageScaleFactor;

    return IntPoint(static_cast<unsigned>(xf), static_cast<unsigned>(yf));

}

const SecurityOrigin& HTMLCanvasElement::securityOrigin() const

{

    return *document()->securityOrigin();

}

CSSStyleSelector* HTMLCanvasElement::styleSelector()

{

    return document()->styleSelector();

}

void HTMLCanvasElement::createImageBuffer() const

{

    ASSERT(!m_imageBuffer);

    m_hasCreatedImageBuffer = true;

    FloatSize unscaledSize(width(), height());

    IntSize size = convertLogicalToDevice(unscaledSize);

    if (!size.width() || !size.height())

        return;

    m_imageBuffer = ImageBuffer::create(size);

    // The convertLogicalToDevice MaxCanvasArea check should prevent common cases

    // where ImageBuffer::create() returns 0, however we could still be low on memory.

    if (!m_imageBuffer)

        return;

    m_imageBuffer->context()->scale(FloatSize(size.width() / unscaledSize.width(), size.height() / unscaledSize.height()));

    m_imageBuffer->context()->setShadowsIgnoreTransforms(true);

}

GraphicsContext* HTMLCanvasElement::drawingContext() const

{

    return buffer() ? m_imageBuffer->context() : 0;

}

ImageBuffer* HTMLCanvasElement::buffer() const

{

    if (!m_hasCreatedImageBuffer)

        createImageBuffer();

    return m_imageBuffer.get();

}

AffineTransform HTMLCanvasElement::baseTransform() const

{

    ASSERT(m_hasCreatedImageBuffer);

    FloatSize unscaledSize(width(), height());

    IntSize size = convertLogicalToDevice(unscaledSize);

    AffineTransform transform;

    if (size.width() && size.height())

        transform.scaleNonUniform(size.width() / unscaledSize.width(), size.height() / unscaledSize.height());

    transform.multiply(m_imageBuffer->baseTransform());

    return transform;

}

}