NativeImageRenderer

Source

index.js
/* global document Image */

import MouseHandler from 'paraviewweb/src/Interaction/Core/MouseHandler';

import SizeHelper from 'paraviewweb/src/Common/Misc/SizeHelper';

function formatSize(memorySize) {
if (!memorySize) {
return '';
}
if (memorySize > 1000000) {
return `${Math.round(memorySize / 10000) / 100} MB - `;
}
if (memorySize > 1000) {
return `${Math.round(memorySize / 10) / 100} KB - `;
}
return `${memorySize} B - `;
}

export default class NativeImageRenderer {
constructor(
domElement,
imageProvider,
mouseListeners = null,
drawFPS = true
) {
this.size = domElement
? SizeHelper.getSize(domElement)
: { clientWidth: 400, clientHeight: 400 };
this.canvas = document.createElement('canvas');
this.image = new Image();
this.fps = '';
this.drawFPS = drawFPS;
this.subscriptions = [];
this.imageProvider = imageProvider;
this.fpsBuffer = [];
this.fpsBufferSize = 30;

this.image.onload = () => {
this.updateDrawnImage();
};

// Update DOM
this.setContainer(domElement);

this.ctx = this.canvas.getContext('2d');
this.ctx.font = '30px Arial';

// Attach mouse listener if needed
if (mouseListeners) {
this.mouseHandler = new MouseHandler(this.canvas);
this.mouseHandler.attach(mouseListeners);
}

// Add image listener
this.subscriptions.push(
imageProvider.onImageReady((data, envelope) => {
this.image.src = data.url;
this.fps = data.fps;
this.memsize = data.metadata.memory || '';
this.workTime = data.metadata.workTime;
this.fpsBuffer.push(this.fps);
while (this.fpsBufferSize < this.fpsBuffer.length) {
this.fpsBuffer.shift();
}
})
);

// Add size listener
this.subscriptions.push(
SizeHelper.onSizeChange(() => {
if (this.container) {
this.size = SizeHelper.getSize(this.container);
this.canvas.setAttribute('width', this.size.clientWidth);
this.canvas.setAttribute('height', this.size.clientHeight);
if (this.image.src && this.image.complete) {
this.updateDrawnImage();
}
}
})
);
SizeHelper.startListening();
}

setDrawFPS(visible) {
this.drawFPS = visible;
}

getStats() {
let min = Number.MAX_VALUE;
let max = -Number.MAX_VALUE;
let total = 0;
const size = this.fpsBuffer.length;
for (let i = 0; i < size; i++) {
const value = Number(this.fpsBuffer[i]);
if (value < min) {
min = value;
}
if (max < value) {
max = value;
}
total += value;
}
total /= size;
return `${Math.round(min)}<${Math.round(total)}<${Math.round(max)}`;
}

setContainer(container) {
if (this.container) {
this.container.removeChild(this.canvas);
}
this.container = container;
if (this.container) {
this.container.appendChild(this.canvas);
}
}

resize() {
if (this.container) {
this.size = SizeHelper.getSize(this.container);
}
}

setSize(clientWidth = 400, clientHeight = 400) {
this.size = { clientWidth, clientHeight };
this.canvas.setAttribute('width', this.size.clientWidth);
this.canvas.setAttribute('height', this.size.clientHeight);
if (this.image.src && this.image.complete) {
this.updateDrawnImage();
}
}

destroy() {
while (this.subscriptions.length) {
this.subscriptions.pop().unsubscribe();
}

if (this.mouseHandler) {
this.mouseHandler.destroy();
this.mouseHandler = null;
}

this.container = null;
this.imageProvider = null;
}

updateDrawnImage() {
this.ctx.drawImage(
this.image,
0,
0,
this.size.clientWidth,
this.size.clientHeight
);
if (this.drawFPS) {
this.ctx.textBaseline = 'top';
this.ctx.textAlign = 'end';
this.ctx.fillStyle = '#888';
this.ctx.fillText(
`${this.workTime}ms - ${formatSize(this.memsize)}${this.image.width}x${
this.image.height
} - ${this.fps} FPS - ${this.getStats()}`,
this.size.clientWidth - 5,
5
);
}
}
}