1/*
2 * Copyright (C) 2010 Google Inc. All rights reserved.
3 * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
21 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
22 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include "config.h"
28#include "CanvasSurface.h"
29
30#include "AffineTransform.h"
31#include "ExceptionCode.h"
32#include "FloatRect.h"
33#include "GraphicsContext.h"
34#include "HTMLCanvasElement.h"
35#include "ImageBuffer.h"
36#include "MIMETypeRegistry.h"
37
38namespace WebCore {
39
40// These values come from the WhatWG spec.
41const int CanvasSurface::DefaultWidth = 300;
42const int CanvasSurface::DefaultHeight = 150;
43
44// Firefox limits width/height to 32767 pixels, but slows down dramatically before it
45// reaches that limit. We limit by area instead, giving us larger maximum dimensions,
46// in exchange for a smaller maximum canvas size.
47const float CanvasSurface::MaxCanvasArea = 32768 * 8192; // Maximum canvas area in CSS pixels
48
49CanvasSurface::CanvasSurface(float pageScaleFactor)
50    : m_size(DefaultWidth, DefaultHeight)
51#if PLATFORM(ANDROID)
52    /* In Android we capture the drawing into a displayList, and then replay
53     * that list at various scale factors (sometimes zoomed out, other times
54     * zoomed in for "normal" reading, yet other times at arbitrary zoom values
55     * based on the user's choice). In all of these cases, we do not re-record
56     * the displayList, hence it is usually harmful to perform any pre-rounding,
57     * since we just don't know the actual drawing resolution at record time.
58     */
59    // TODO - may be better to move the ifdef to the call site of this
60    // constructor
61    , m_pageScaleFactor(1.0f)
62#else
63    , m_pageScaleFactor(pageScaleFactor)
64#endif
65    , m_originClean(true)
66    , m_hasCreatedImageBuffer(false)
67{
68}
69
70CanvasSurface::~CanvasSurface()
71{
72}
73
74void CanvasSurface::setSurfaceSize(const IntSize& size)
75{
76    m_size = size;
77    m_hasCreatedImageBuffer = false;
78    m_imageBuffer.clear();
79}
80
81String CanvasSurface::toDataURL(const String& mimeType, const double* quality, ExceptionCode& ec)
82{
83    if (!m_originClean) {
84        ec = SECURITY_ERR;
85        return String();
86    }
87
88    if (m_size.isEmpty() || !buffer())
89        return String("data:,");
90
91    String lowercaseMimeType = mimeType.lower();
92
93    // FIXME: Make isSupportedImageMIMETypeForEncoding threadsafe (to allow this method to be used on a worker thread).
94    if (mimeType.isNull() || !MIMETypeRegistry::isSupportedImageMIMETypeForEncoding(lowercaseMimeType))
95        return buffer()->toDataURL("image/png");
96
97    return buffer()->toDataURL(lowercaseMimeType, quality);
98}
99
100void CanvasSurface::willDraw(const FloatRect&)
101{
102    if (m_imageBuffer)
103        m_imageBuffer->clearImage();
104}
105
106IntRect CanvasSurface::convertLogicalToDevice(const FloatRect& logicalRect) const
107{
108    return IntRect(convertLogicalToDevice(logicalRect.location()), convertLogicalToDevice(logicalRect.size()));
109}
110
111IntSize CanvasSurface::convertLogicalToDevice(const FloatSize& logicalSize) const
112{
113    float wf = ceilf(logicalSize.width() * m_pageScaleFactor);
114    float hf = ceilf(logicalSize.height() * m_pageScaleFactor);
115
116    if (!(wf >= 1 && hf >= 1 && wf * hf <= MaxCanvasArea))
117        return IntSize();
118
119    return IntSize(static_cast<unsigned>(wf), static_cast<unsigned>(hf));
120}
121
122IntPoint CanvasSurface::convertLogicalToDevice(const FloatPoint& logicalPos) const
123{
124    float xf = logicalPos.x() * m_pageScaleFactor;
125    float yf = logicalPos.y() * m_pageScaleFactor;
126
127    return IntPoint(static_cast<unsigned>(xf), static_cast<unsigned>(yf));
128}
129
130void CanvasSurface::createImageBuffer() const
131{
132    ASSERT(!m_imageBuffer);
133
134    m_hasCreatedImageBuffer = true;
135
136    FloatSize unscaledSize(width(), height());
137    IntSize size = convertLogicalToDevice(unscaledSize);
138    if (!size.width() || !size.height())
139        return;
140
141    m_imageBuffer = ImageBuffer::create(size);
142    // The convertLogicalToDevice MaxCanvasArea check should prevent common cases
143    // where ImageBuffer::create() returns 0, however we could still be low on memory.
144    if (!m_imageBuffer)
145        return;
146    m_imageBuffer->context()->scale(FloatSize(size.width() / unscaledSize.width(), size.height() / unscaledSize.height()));
147    m_imageBuffer->context()->setShadowsIgnoreTransforms(true);
148}
149
150GraphicsContext* CanvasSurface::drawingContext() const
151{
152    return buffer() ? m_imageBuffer->context() : 0;
153}
154
155ImageBuffer* CanvasSurface::buffer() const
156{
157    if (!m_hasCreatedImageBuffer)
158        createImageBuffer();
159    return m_imageBuffer.get();
160}
161
162AffineTransform CanvasSurface::baseTransform() const
163{
164    ASSERT(m_hasCreatedImageBuffer);
165    FloatSize unscaledSize(width(), height());
166    IntSize size = convertLogicalToDevice(unscaledSize);
167    AffineTransform transform;
168    if (size.width() && size.height())
169        transform.scaleNonUniform(size.width() / unscaledSize.width(), size.height() / unscaledSize.height());
170    transform.multiply(m_imageBuffer->baseTransform());
171    return transform;
172}
173
174// FIXME: Everything below here relies on CanvasSurface really being
175// a HTMLCanvasElement.
176const SecurityOrigin& CanvasSurface::securityOrigin() const
177{
178    return *(static_cast<const HTMLCanvasElement*>(this)->document()->securityOrigin());
179}
180
181RenderBox* CanvasSurface::renderBox() const
182{
183    return static_cast<const HTMLCanvasElement*>(this)->renderBox();
184}
185
186RenderStyle* CanvasSurface::computedStyle()
187{
188    return static_cast<HTMLCanvasElement*>(this)->computedStyle();
189}
190
191CSSStyleSelector* CanvasSurface::styleSelector()
192{
193    return static_cast<HTMLCanvasElement*>(this)->document()->styleSelector();
194}
195
196} // namespace WebCore
197