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1 // http://stackoverflow.com/a/28900478/881731
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2
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3 function WebAssemblyViewport(module, canvasId) {
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4 this.module = module;
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5
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6 // Obtain a reference to the canvas element using its id
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7 this.htmlCanvas = document.getElementById(canvasId);
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8
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9 // Obtain a graphics context on the canvas element for drawing.
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10 this.context = htmlCanvas.getContext('2d');
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11
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12 // ImageData structure that can be used to update the content of the canvas
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13 this.imageData = null;
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14
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15 // Temporary buffer in the WebAssembly heap that is used to render the pixels
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16 this.renderingBuffer = null;
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17
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18 // Get access to the WebAssembly functions
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19 this.ViewportSetSize = this.module.cwrap('ViewportSetSize', null, [ 'number', 'number' ]);
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20 this.ViewportRender = this.module.cwrap('ViewportRender', 'number', [ 'number', 'number', 'number' ]);
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21 this.ViewportMouseDown = this.module.cwrap('ViewportMouseDown', null, [ 'number', 'number', 'number', 'number' ]);
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22 this.ViewportMouseMove = this.module.cwrap('ViewportMouseMove', null, [ 'number', 'number' ]);
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23 this.ViewportMouseUp = this.module.cwrap('ViewportMouseUp', null, [ ]);
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24 this.ViewportMouseEnter = this.module.cwrap('ViewportMouseEnter', null, []);
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25 this.ViewportMouseLeave = this.module.cwrap('ViewportMouseLeave', null, []);
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26 this.ViewportMouseWheel = this.module.cwrap('ViewportMouseWheel', null, [ 'number', 'number', 'number', 'number' ]);
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27 this.ViewportKeyPressed = this.module.cwrap('ViewportKeyPressed', null, [ 'string', 'number', 'number' ]);
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28
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29 this.Redraw = function() {
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30 if (this.imageData === null ||
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31 this.renderingBuffer === null ||
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32 ViewportRender(this.imageData.width,
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33 this.imageData.height,
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34 this.renderingBuffer) == 0) {
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35 console.log('The rendering has failed');
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36 } else {
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37 // Create an accessor to the rendering buffer (i.e. create a
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38 // "window" above the heap of the WASM module), then copy it to
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39 // the ImageData object
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40 this.imageData.data.set(new Uint8ClampedArray(
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41 this.module.buffer,
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42 this.renderingBuffer,
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43 this.imageData.width * this.imageData.height * 4));
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44
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45 this.context.putImageData(imageData, 0, 0);
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46 }
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47 }
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48
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49 this.Resize = function() {
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50 if (this.imageData != null &&
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51 (this.imageData.width != this.window.innerWidth ||
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52 this.imageData.height != this.window.innerHeight)) {
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53 this.imageData = null;
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54 }
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55
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56 this.htmlCanvas.width = window.innerWidth;
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57 this.htmlCanvas.height = window.innerHeight;
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58
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59 if (this.imageData === null) {
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60 this.imageData = context.getImageData(0, 0, this.htmlCanvas.width, this.htmlCanvas.height);
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61 ViewportSetSize(this.htmlCanvas.width, this.htmlCanvas.height);
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62
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63 if (this.renderingBuffer != null) {
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64 this.module._free(this.renderingBuffer);
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65 }
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66
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67 renderingBuffer = this.module._malloc(this.imageData.width * this.imageData.height * 4);
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68 }
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69
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70 this.Redraw();
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71 }
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72
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73 // Force the rendering of the viewport for the first time
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74 this.Resize();
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75
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76 // Register an event listener to call the Resize() function
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77 // each time the window is resized.
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78 window.addEventListener('resize', this.Resize, false);
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79
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80 var that = this;
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81
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82 this.htmlCanvas.addEventListener('contextmenu', function(event) {
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83 // Prevent right click on the canvas
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84 event.preventDefault();
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85 }, false);
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86
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87 this.htmlCanvas.addEventListener('mouseleave', function(event) {
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88 that.ViewportMouseLeave();
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89 });
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90
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91 this.htmlCanvas.addEventListener('mouseenter', function(event) {
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92 that.ViewportMouseEnter();
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93 });
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94
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95 this.htmlCanvas.addEventListener('mousedown', function(event) {
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96 var x = event.pageX - this.offsetLeft;
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97 var y = event.pageY - this.offsetTop;
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98 that.ViewportMouseDown(event.button, x, y, 0 /* TODO */);
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99 });
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100
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101 this.htmlCanvas.addEventListener('mousemove', function(event) {
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102 var x = event.pageX - this.offsetLeft;
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103 var y = event.pageY - this.offsetTop;
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104 that.ViewportMouseMove(x, y);
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105 });
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106
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107 this.htmlCanvas.addEventListener('mouseup', function(event) {
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108 that.ViewportMouseUp();
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109 });
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110
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111 window.addEventListener('keydown', function(event) {
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112 that.ViewportKeyPressed(event.key, event.shiftKey, event.ctrlKey, event.altKey);
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113 });
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114
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115 this.htmlCanvas.addEventListener('wheel', function(event) {
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116 var x = event.pageX - this.offsetLeft;
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117 var y = event.pageY - this.offsetTop;
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118 that.ViewportMouseWheel(event.deltaY, x, y, event.ctrlKey);
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119 event.preventDefault();
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120 });
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121
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122
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123 // Touch events
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124 this.touchTranslation = false;
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125 this.touchZoom = false;
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126
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127 this.ResetTouch = function() {
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128 if (this.touchTranslation ||
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129 this.touchZoom) {
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130 this.ViewportMouseUp();
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131 }
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132
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133 this.touchTranslation = false;
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134 this.touchZoom = false;
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135 }
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136
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137 this.GetTouchTranslation = function(event) {
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138 var touch = event.targetTouches[0];
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139 return [
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140 touch.pageX,
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141 touch.pageY
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142 ];
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143 }
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144
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145 this.GetTouchZoom = function(event) {
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146 var touch1 = event.targetTouches[0];
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147 var touch2 = event.targetTouches[1];
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148 var dx = (touch1.pageX - touch2.pageX);
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149 var dy = (touch1.pageY - touch2.pageY);
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150 var d = Math.sqrt(dx * dx + dy * dy);
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151 return [
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152 (touch1.pageX + touch2.pageX) / 2.0,
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153 (touch1.pageY + touch2.pageY) / 2.0,
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154 d
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155 ];
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156 }
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157
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158 this.htmlCanvas.addEventListener('touchstart', function(event) {
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159 ResetTouch();
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160 });
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161
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162 this.htmlCanvas.addEventListener('touchend', function(event) {
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163 ResetTouch();
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164 });
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165
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166 this.htmlCanvas.addEventListener('touchmove', function(event) {
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167 if (that.touchTranslation.length == 2) {
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168 var t = GetTouchTranslation(event);
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169 that.ViewportMouseMove(t[0], t[1]);
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170 }
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171 else if (that.touchZoom.length == 3) {
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172 var z0 = that.touchZoom;
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173 var z1 = GetTouchZoom(event);
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174 that.ViewportMouseMove(z0[0], z0[1] - z0[2] + z1[2]);
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175 }
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176 else {
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177 // Realize the gesture event
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178 if (event.targetTouches.length == 1) {
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179 // Exactly one finger inside the canvas => Setup a translation
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180 that.touchTranslation = GetTouchTranslation(event);
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181 that.ViewportMouseDown(1 /* middle button */,
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182 that.touchTranslation[0],
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183 that.touchTranslation[1], 0);
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184 } else if (event.targetTouches.length == 2) {
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185 // Exactly 2 fingers inside the canvas => Setup a pinch/zoom
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186 that.touchZoom = GetTouchZoom(event);
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187 var z0 = that.touchZoom;
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188 that.ViewportMouseDown(2 /* right button */,
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189 z0[0],
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190 z0[1], 0);
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191 }
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192 }
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193 });
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194
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195 return this;
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196 }
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197 |
