Mercurial > hg > orthanc-stone
diff Framework/Viewport/WebAssemblyCairoViewport.cpp @ 1232:a28861abf888 broker
viewports for WebAssembly
author | Sebastien Jodogne <s.jodogne@gmail.com> |
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date | Mon, 09 Dec 2019 17:46:33 +0100 |
parents | |
children | 0ca50d275b9a |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Framework/Viewport/WebAssemblyCairoViewport.cpp Mon Dec 09 17:46:33 2019 +0100 @@ -0,0 +1,133 @@ +/** + * Stone of Orthanc + * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics + * Department, University Hospital of Liege, Belgium + * Copyright (C) 2017-2019 Osimis S.A., Belgium + * + * This program is free software: you can redistribute it and/or + * modify it under the terms of the GNU Affero General Public License + * as published by the Free Software Foundation, either version 3 of + * the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + **/ + + +#include "WebAssemblyCairoViewport.h" + +#include "../Scene2D/CairoCompositor.h" + +#include <Core/Images/Image.h> + +namespace OrthancStone +{ + void WebAssemblyCairoViewport::GetCanvasSize(unsigned int& width, + unsigned int& height) + { + double w, h; + emscripten_get_element_css_size(GetFullCanvasId().c_str(), &w, &h); + + /** + * Emscripten has the function emscripten_get_element_css_size() + * to query the width and height of a named HTML element. I'm + * calling this first to get the initial size of the canvas DOM + * element, and then call emscripten_set_canvas_size() to + * initialize the framebuffer size of the canvas to the same + * size as its DOM element. + * https://floooh.github.io/2017/02/22/emsc-html.html + **/ + if (w > 0 && + h > 0) + { + width = static_cast<unsigned int>(boost::math::iround(w)); + height = static_cast<unsigned int>(boost::math::iround(h)); + } + else + { + width = 0; + height = 0; + } + } + + + void WebAssemblyCairoViewport::Paint(ICompositor& compositor, + ViewportController& controller) + { + compositor.Refresh(controller.GetScene()); + + // Create a temporary memory buffer for the canvas in JavaScript + Orthanc::ImageAccessor cairo; + dynamic_cast<CairoCompositor&>(compositor).GetCanvas().GetReadOnlyAccessor(cairo); + + const unsigned int width = cairo.GetWidth(); + const unsigned int height = cairo.GetHeight(); + + if (javascript_.get() == NULL || + javascript_->GetWidth() != width || + javascript_->GetHeight() != height) + { + javascript_.reset(new Orthanc::Image(Orthanc::PixelFormat_RGBA32, width, height, + true /* force minimal pitch */)); + } + + // Convert from BGRA32 memory layout (only color mode supported + // by Cairo, which corresponds to CAIRO_FORMAT_ARGB32) to RGBA32 + // (as expected by HTML5 canvas). This simply amounts to + // swapping the B and R channels. Alpha channel is also set to + // full opacity (255). + uint8_t* q = reinterpret_cast<uint8_t*>(javascript_->GetBuffer()); + for (unsigned int y = 0; y < height; y++) + { + const uint8_t* p = reinterpret_cast<const uint8_t*>(cairo.GetConstRow(y)); + for (unsigned int x = 0; x < width; x++) + { + q[0] = p[2]; // R + q[1] = p[1]; // G + q[2] = p[0]; // B + q[3] = 255; // A + + p += 4; + q += 4; + } + } + + // Execute JavaScript commands to blit the image buffer onto the + // 2D drawing context of the HTML5 canvas + EM_ASM({ + const data = new Uint8ClampedArray(Module.HEAP8.buffer, $1, 4 * $2 * $3); + const img = new ImageData(data, $2, $3); + const ctx = document.getElementById(UTF8ToString($0)).getContext('2d'); + ctx.putImageData(img, 0, 0); + }, + GetShortCanvasId().c_str(), // $0 + javascript_->GetBuffer(), // $1 + javascript_->GetWidth(), // $2 + javascript_->GetHeight()); // $3 + } + + + void WebAssemblyCairoViewport::UpdateSize(ICompositor& compositor) + { + unsigned int width, height; + GetCanvasSize(width, height); + emscripten_set_canvas_element_size(GetFullCanvasId().c_str(), width, height); + + dynamic_cast<CairoCompositor&>(compositor).UpdateSize(width, height); + } + + + WebAssemblyCairoViewport::WebAssemblyCairoViewport(const std::string& canvasId) : + WebAssemblyViewport(canvasId, NULL) + { + unsigned int width, height; + GetCanvasSize(width, height); + emscripten_set_canvas_element_size(GetFullCanvasId().c_str(), width, height); + AcquireCompositor(new CairoCompositor(width, height)); + } +}