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comparison Framework/Viewport/WebAssemblyCairoViewport.cpp @ 1232:a28861abf888 broker

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viewports for WebAssembly
author Sebastien Jodogne <s.jodogne@gmail.com>
date Mon, 09 Dec 2019 17:46:33 +0100
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children 0ca50d275b9a
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1229:b9f2a111c5b9 1232:a28861abf888
1 /**
2 * Stone of Orthanc
3 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
4 * Department, University Hospital of Liege, Belgium
5 * Copyright (C) 2017-2019 Osimis S.A., Belgium
6 *
7 * This program is free software: you can redistribute it and/or
8 * modify it under the terms of the GNU Affero General Public License
9 * as published by the Free Software Foundation, either version 3 of
10 * the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Affero General Public License for more details.
16 *
17 * You should have received a copy of the GNU Affero General Public License
18 * along with this program. If not, see <http://www.gnu.org/licenses/>.
19 **/
20
21
22 #include "WebAssemblyCairoViewport.h"
23
24 #include "../Scene2D/CairoCompositor.h"
25
26 #include <Core/Images/Image.h>
27
28 namespace OrthancStone
29 {
30 void WebAssemblyCairoViewport::GetCanvasSize(unsigned int& width,
31 unsigned int& height)
32 {
33 double w, h;
34 emscripten_get_element_css_size(GetFullCanvasId().c_str(), &w, &h);
35
36 /**
37 * Emscripten has the function emscripten_get_element_css_size()
38 * to query the width and height of a named HTML element. I'm
39 * calling this first to get the initial size of the canvas DOM
40 * element, and then call emscripten_set_canvas_size() to
41 * initialize the framebuffer size of the canvas to the same
42 * size as its DOM element.
43 * https://floooh.github.io/2017/02/22/emsc-html.html
44 **/
45 if (w > 0 &&
46 h > 0)
47 {
48 width = static_cast<unsigned int>(boost::math::iround(w));
49 height = static_cast<unsigned int>(boost::math::iround(h));
50 }
51 else
52 {
53 width = 0;
54 height = 0;
55 }
56 }
57
58
59 void WebAssemblyCairoViewport::Paint(ICompositor& compositor,
60 ViewportController& controller)
61 {
62 compositor.Refresh(controller.GetScene());
63
64 // Create a temporary memory buffer for the canvas in JavaScript
65 Orthanc::ImageAccessor cairo;
66 dynamic_cast<CairoCompositor&>(compositor).GetCanvas().GetReadOnlyAccessor(cairo);
67
68 const unsigned int width = cairo.GetWidth();
69 const unsigned int height = cairo.GetHeight();
70
71 if (javascript_.get() == NULL ||
72 javascript_->GetWidth() != width ||
73 javascript_->GetHeight() != height)
74 {
75 javascript_.reset(new Orthanc::Image(Orthanc::PixelFormat_RGBA32, width, height,
76 true /* force minimal pitch */));
77 }
78
79 // Convert from BGRA32 memory layout (only color mode supported
80 // by Cairo, which corresponds to CAIRO_FORMAT_ARGB32) to RGBA32
81 // (as expected by HTML5 canvas). This simply amounts to
82 // swapping the B and R channels. Alpha channel is also set to
83 // full opacity (255).
84 uint8_t* q = reinterpret_cast<uint8_t*>(javascript_->GetBuffer());
85 for (unsigned int y = 0; y < height; y++)
86 {
87 const uint8_t* p = reinterpret_cast<const uint8_t*>(cairo.GetConstRow(y));
88 for (unsigned int x = 0; x < width; x++)
89 {
90 q[0] = p[2]; // R
91 q[1] = p[1]; // G
92 q[2] = p[0]; // B
93 q[3] = 255; // A
94
95 p += 4;
96 q += 4;
97 }
98 }
99
100 // Execute JavaScript commands to blit the image buffer onto the
101 // 2D drawing context of the HTML5 canvas
102 EM_ASM({
103 const data = new Uint8ClampedArray(Module.HEAP8.buffer, $1, 4 * $2 * $3);
104 const img = new ImageData(data, $2, $3);
105 const ctx = document.getElementById(UTF8ToString($0)).getContext('2d');
106 ctx.putImageData(img, 0, 0);
107 },
108 GetShortCanvasId().c_str(), // $0
109 javascript_->GetBuffer(), // $1
110 javascript_->GetWidth(), // $2
111 javascript_->GetHeight()); // $3
112 }
113
114
115 void WebAssemblyCairoViewport::UpdateSize(ICompositor& compositor)
116 {
117 unsigned int width, height;
118 GetCanvasSize(width, height);
119 emscripten_set_canvas_element_size(GetFullCanvasId().c_str(), width, height);
120
121 dynamic_cast<CairoCompositor&>(compositor).UpdateSize(width, height);
122 }
123
124
125 WebAssemblyCairoViewport::WebAssemblyCairoViewport(const std::string& canvasId) :
126 WebAssemblyViewport(canvasId, NULL)
127 {
128 unsigned int width, height;
129 GetCanvasSize(width, height);
130 emscripten_set_canvas_element_size(GetFullCanvasId().c_str(), width, height);
131 AcquireCompositor(new CairoCompositor(width, height));
132 }
133 }