C++ HTMLCanvasElement::height方法代码示例

void RenderHTMLCanvas::paintReplaced(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
{
    GraphicsContext* context = paintInfo.context;

    LayoutRect contentRect = contentBoxRect();
    contentRect.moveBy(paintOffset);
    LayoutRect paintRect = replacedContentRect();
    paintRect.moveBy(paintOffset);

    bool clip = !contentRect.contains(paintRect);
    if (clip) {
        // Not allowed to overflow the content box.
        paintInfo.context->save();
        paintInfo.context->clip(pixelSnappedIntRect(contentRect));
    }

    // FIXME: InterpolationNone should be used if ImageRenderingOptimizeContrast is set.
    // See bug for more details: crbug.com/353716.
    InterpolationQuality interpolationQuality = style()->imageRendering() == ImageRenderingOptimizeContrast ? InterpolationLow : CanvasDefaultInterpolationQuality;

    HTMLCanvasElement* canvas = toHTMLCanvasElement(node());
    LayoutSize layoutSize = contentRect.size();
    if (style()->imageRendering() == ImageRenderingPixelated
        && (layoutSize.width() > canvas->width() || layoutSize.height() > canvas->height() || layoutSize == canvas->size())) {
        interpolationQuality = InterpolationNone;
    }

    InterpolationQuality previousInterpolationQuality = context->imageInterpolationQuality();
    context->setImageInterpolationQuality(interpolationQuality);
    canvas->paint(context, paintRect);
    context->setImageInterpolationQuality(previousInterpolationQuality);

    if (clip)
        context->restore();
}

void GraphicsContext3D::paintRenderingResultsToCanvas(CanvasRenderingContext* context, DrawingBuffer*)
{
    HTMLCanvasElement* canvas = context->canvas();
    ImageBuffer* imageBuffer = canvas->buffer();

    int rowBytes = m_currentWidth * 4;
    int totalBytes = rowBytes * m_currentHeight;

    OwnArrayPtr<unsigned char> pixels = adoptArrayPtr(new unsigned char[totalBytes]);
    if (!pixels)
        return;

    readRenderingResults(pixels.get(), totalBytes);

    if (!m_attrs.premultipliedAlpha) {
        for (int i = 0; i < totalBytes; i += 4) {
            // Premultiply alpha.
            pixels[i + 0] = std::min(255, pixels[i + 0] * pixels[i + 3] / 255);
            pixels[i + 1] = std::min(255, pixels[i + 1] * pixels[i + 3] / 255);
            pixels[i + 2] = std::min(255, pixels[i + 2] * pixels[i + 3] / 255);
        }
    }

    paintToCanvas(pixels.get(), m_currentWidth, m_currentHeight,
                  canvas->width(), canvas->height(), imageBuffer->context()->platformContext());
}

JSValue* JSHTMLCanvasElement::getValueProperty(ExecState* exec, int token) const
{
    switch (token) {
    case WidthAttrNum: {
        HTMLCanvasElement* imp = static_cast<HTMLCanvasElement*>(impl());
        return jsNumber(exec, imp->width());
    }
    case HeightAttrNum: {
        HTMLCanvasElement* imp = static_cast<HTMLCanvasElement*>(impl());
        return jsNumber(exec, imp->height());
    }
    case ConstructorAttrNum:
        return getConstructor(exec);
    }
    return 0;
}

void GraphicsContext3D::paintRenderingResultsToCanvas(CanvasRenderingContext* context)
{
    HTMLCanvasElement* canvas = context->canvas();
    ImageBuffer* imageBuffer = canvas->buffer();

    int rowBytes = m_currentWidth * 4;
    int totalBytes = rowBytes * m_currentHeight;

    OwnArrayPtr<unsigned char> pixels = adoptArrayPtr(new unsigned char[totalBytes]);
    if (!pixels)
        return;

    makeContextCurrent();

    bool mustRestoreFBO = false;
    if (m_attrs.antialias) {
        ::glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, m_multisampleFBO);
        ::glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, m_fbo);
        ::glBlitFramebufferEXT(0, 0, m_currentWidth, m_currentHeight, 0, 0, m_currentWidth, m_currentHeight, GL_COLOR_BUFFER_BIT, GL_LINEAR);
        ::glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_fbo);
        mustRestoreFBO = true;
    } else {
        if (m_boundFBO != m_fbo) {
            mustRestoreFBO = true;
            ::glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_fbo);
        }
    }

    GLint packAlignment = 4;
    bool mustRestorePackAlignment = false;
    ::glGetIntegerv(GL_PACK_ALIGNMENT, &packAlignment);
    if (packAlignment > 4) {
        ::glPixelStorei(GL_PACK_ALIGNMENT, 4);
        mustRestorePackAlignment = true;
    }

    ::glReadPixels(0, 0, m_currentWidth, m_currentHeight, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, pixels.get());

    if (mustRestorePackAlignment)
        ::glPixelStorei(GL_PACK_ALIGNMENT, packAlignment);

    if (mustRestoreFBO)
        ::glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_boundFBO);

    paintToCanvas(pixels.get(), m_currentWidth, m_currentHeight,
                  canvas->width(), canvas->height(), imageBuffer->context()->platformContext());
}

void GraphicsContext3DInternal::paintRenderingResultsToCanvas(CanvasRenderingContext* context)
{
    HTMLCanvasElement* canvas = context->canvas();
    ImageBuffer* imageBuffer = canvas->buffer();
    unsigned char* pixels = 0;
#if USE(SKIA)
    const SkBitmap* canvasBitmap = imageBuffer->context()->platformContext()->bitmap();
    const SkBitmap* readbackBitmap = 0;
    ASSERT(canvasBitmap->config() == SkBitmap::kARGB_8888_Config);
    if (canvasBitmap->width() == m_impl->width() && canvasBitmap->height() == m_impl->height()) {
        // This is the fastest and most common case. We read back
        // directly into the canvas's backing store.
        readbackBitmap = canvasBitmap;
        m_resizingBitmap.reset();
    } else {
        // We need to allocate a temporary bitmap for reading back the
        // pixel data. We will then use Skia to rescale this bitmap to
        // the size of the canvas's backing store.
        if (m_resizingBitmap.width() != m_impl->width() || m_resizingBitmap.height() != m_impl->height()) {
            m_resizingBitmap.setConfig(SkBitmap::kARGB_8888_Config,
                                       m_impl->width(),
                                       m_impl->height());
            if (!m_resizingBitmap.allocPixels())
                return;
        }
        readbackBitmap = &m_resizingBitmap;
    }

    // Read back the frame buffer.
    SkAutoLockPixels bitmapLock(*readbackBitmap);
    pixels = static_cast<unsigned char*>(readbackBitmap->getPixels());
#elif USE(CG)
    if (m_renderOutput)
        pixels = m_renderOutput;
#else
#error Must port to your platform
#endif

    m_impl->readBackFramebuffer(pixels, 4 * m_impl->width() * m_impl->height());

    if (!m_impl->getContextAttributes().premultipliedAlpha) {
        size_t bufferSize = 4 * m_impl->width() * m_impl->height();

        for (size_t i = 0; i < bufferSize; i += 4) {
            pixels[i + 0] = std::min(255, pixels[i + 0] * pixels[i + 3] / 255);
            pixels[i + 1] = std::min(255, pixels[i + 1] * pixels[i + 3] / 255);
            pixels[i + 2] = std::min(255, pixels[i + 2] * pixels[i + 3] / 255);
        }
    }

#if USE(SKIA)
    readbackBitmap->notifyPixelsChanged();
    if (m_resizingBitmap.readyToDraw()) {
        // We need to draw the resizing bitmap into the canvas's backing store.
        SkCanvas canvas(*canvasBitmap);
        SkRect dst;
        dst.set(SkIntToScalar(0), SkIntToScalar(0), SkIntToScalar(canvasBitmap->width()), SkIntToScalar(canvasBitmap->height()));
        canvas.drawBitmapRect(m_resizingBitmap, 0, dst);
    }
#elif USE(CG)
    if (m_renderOutput && context->is3d()) {
        WebGLRenderingContext* webGLContext = static_cast<WebGLRenderingContext*>(context);
        webGLContext->graphicsContext3D()->paintToCanvas(m_renderOutput, m_impl->width(), m_impl->height(), canvas->width(), canvas->height(), imageBuffer->context()->platformContext());
    }
#else
#error Must port to your platform
#endif
}

static v8::Handle<v8::Value> heightAttrGetter(v8::Local<v8::String> name, const v8::AccessorInfo& info)
{
    HTMLCanvasElement* imp = V8HTMLCanvasElement::toNative(info.Holder());
    return v8Integer(imp->height(), info.GetIsolate());
}