KasmVNC/kasmweb/core/display.js
Pierre Ossman 8be70e5ae0 Handle slow loading of images
Internet Explorer seems to flag images as loaded prematurely, which
can result in rendering bugs. We can detect this by looking at the
dimensions though.
2021-03-29 12:06:28 +03:00

654 lines
20 KiB
JavaScript

/*
* noVNC: HTML5 VNC client
* Copyright (C) 2019 The noVNC Authors
* Licensed under MPL 2.0 (see LICENSE.txt)
*
* See README.md for usage and integration instructions.
*/
import * as Log from './util/logging.js';
import Base64 from "./base64.js";
import { supportsImageMetadata } from './util/browser.js';
export default class Display {
constructor(target) {
this._drawCtx = null;
this._c_forceCanvas = false;
this._renderQ = []; // queue drawing actions for in-oder rendering
this._flushing = false;
// the full frame buffer (logical canvas) size
this._fb_width = 0;
this._fb_height = 0;
this._prevDrawStyle = "";
this._tile = null;
this._tile16x16 = null;
this._tile_x = 0;
this._tile_y = 0;
Log.Debug(">> Display.constructor");
// The visible canvas
this._target = target;
if (!this._target) {
throw new Error("Target must be set");
}
if (typeof this._target === 'string') {
throw new Error('target must be a DOM element');
}
if (!this._target.getContext) {
throw new Error("no getContext method");
}
this._targetCtx = this._target.getContext('2d');
// the visible canvas viewport (i.e. what actually gets seen)
this._viewportLoc = { 'x': 0, 'y': 0, 'w': this._target.width, 'h': this._target.height };
// The hidden canvas, where we do the actual rendering
this._backbuffer = document.createElement('canvas');
this._drawCtx = this._backbuffer.getContext('2d');
this._damageBounds = { left: 0, top: 0,
right: this._backbuffer.width,
bottom: this._backbuffer.height };
Log.Debug("User Agent: " + navigator.userAgent);
// Check canvas features
if (!('createImageData' in this._drawCtx)) {
throw new Error("Canvas does not support createImageData");
}
this._tile16x16 = this._drawCtx.createImageData(16, 16);
Log.Debug("<< Display.constructor");
// ===== PROPERTIES =====
this._scale = 1.0;
this._clipViewport = false;
// ===== EVENT HANDLERS =====
this.onflush = () => {}; // A flush request has finished
}
// ===== PROPERTIES =====
get scale() { return this._scale; }
set scale(scale) {
this._rescale(scale);
}
get clipViewport() { return this._clipViewport; }
set clipViewport(viewport) {
this._clipViewport = viewport;
// May need to readjust the viewport dimensions
const vp = this._viewportLoc;
this.viewportChangeSize(vp.w, vp.h);
this.viewportChangePos(0, 0);
}
get width() {
return this._fb_width;
}
get height() {
return this._fb_height;
}
// ===== PUBLIC METHODS =====
viewportChangePos(deltaX, deltaY) {
const vp = this._viewportLoc;
deltaX = Math.floor(deltaX);
deltaY = Math.floor(deltaY);
if (!this._clipViewport) {
deltaX = -vp.w; // clamped later of out of bounds
deltaY = -vp.h;
}
const vx2 = vp.x + vp.w - 1;
const vy2 = vp.y + vp.h - 1;
// Position change
if (deltaX < 0 && vp.x + deltaX < 0) {
deltaX = -vp.x;
}
if (vx2 + deltaX >= this._fb_width) {
deltaX -= vx2 + deltaX - this._fb_width + 1;
}
if (vp.y + deltaY < 0) {
deltaY = -vp.y;
}
if (vy2 + deltaY >= this._fb_height) {
deltaY -= (vy2 + deltaY - this._fb_height + 1);
}
if (deltaX === 0 && deltaY === 0) {
return;
}
Log.Debug("viewportChange deltaX: " + deltaX + ", deltaY: " + deltaY);
vp.x += deltaX;
vp.y += deltaY;
this._damage(vp.x, vp.y, vp.w, vp.h);
this.flip();
}
viewportChangeSize(width, height) {
if (!this._clipViewport ||
typeof(width) === "undefined" ||
typeof(height) === "undefined") {
Log.Debug("Setting viewport to full display region");
width = this._fb_width;
height = this._fb_height;
}
width = Math.floor(width);
height = Math.floor(height);
if (width > this._fb_width) {
width = this._fb_width;
}
if (height > this._fb_height) {
height = this._fb_height;
}
const vp = this._viewportLoc;
if (vp.w !== width || vp.h !== height) {
vp.w = width;
vp.h = height;
const canvas = this._target;
canvas.width = width;
canvas.height = height;
// The position might need to be updated if we've grown
this.viewportChangePos(0, 0);
this._damage(vp.x, vp.y, vp.w, vp.h);
this.flip();
// Update the visible size of the target canvas
this._rescale(this._scale);
}
}
absX(x) {
if (this._scale === 0) {
return 0;
}
return x / this._scale + this._viewportLoc.x;
}
absY(y) {
if (this._scale === 0) {
return 0;
}
return y / this._scale + this._viewportLoc.y;
}
resize(width, height) {
this._prevDrawStyle = "";
this._fb_width = width;
this._fb_height = height;
const canvas = this._backbuffer;
if (canvas.width !== width || canvas.height !== height) {
// We have to save the canvas data since changing the size will clear it
let saveImg = null;
if (canvas.width > 0 && canvas.height > 0) {
saveImg = this._drawCtx.getImageData(0, 0, canvas.width, canvas.height);
}
if (canvas.width !== width) {
canvas.width = width;
}
if (canvas.height !== height) {
canvas.height = height;
}
if (saveImg) {
this._drawCtx.putImageData(saveImg, 0, 0);
}
}
// Readjust the viewport as it may be incorrectly sized
// and positioned
const vp = this._viewportLoc;
this.viewportChangeSize(vp.w, vp.h);
this.viewportChangePos(0, 0);
}
// Track what parts of the visible canvas that need updating
_damage(x, y, w, h) {
if (x < this._damageBounds.left) {
this._damageBounds.left = x;
}
if (y < this._damageBounds.top) {
this._damageBounds.top = y;
}
if ((x + w) > this._damageBounds.right) {
this._damageBounds.right = x + w;
}
if ((y + h) > this._damageBounds.bottom) {
this._damageBounds.bottom = y + h;
}
}
// Update the visible canvas with the contents of the
// rendering canvas
flip(from_queue) {
if (this._renderQ.length !== 0 && !from_queue) {
this._renderQ_push({
'type': 'flip'
});
} else {
let x = this._damageBounds.left;
let y = this._damageBounds.top;
let w = this._damageBounds.right - x;
let h = this._damageBounds.bottom - y;
let vx = x - this._viewportLoc.x;
let vy = y - this._viewportLoc.y;
if (vx < 0) {
w += vx;
x -= vx;
vx = 0;
}
if (vy < 0) {
h += vy;
y -= vy;
vy = 0;
}
if ((vx + w) > this._viewportLoc.w) {
w = this._viewportLoc.w - vx;
}
if ((vy + h) > this._viewportLoc.h) {
h = this._viewportLoc.h - vy;
}
if ((w > 0) && (h > 0)) {
// FIXME: We may need to disable image smoothing here
// as well (see copyImage()), but we haven't
// noticed any problem yet.
this._targetCtx.drawImage(this._backbuffer,
x, y, w, h,
vx, vy, w, h);
}
this._damageBounds.left = this._damageBounds.top = 65535;
this._damageBounds.right = this._damageBounds.bottom = 0;
}
}
pending() {
return this._renderQ.length > 0;
}
flush() {
if (this._renderQ.length === 0) {
this.onflush();
} else {
this._flushing = true;
}
}
fillRect(x, y, width, height, color, from_queue) {
if (this._renderQ.length !== 0 && !from_queue) {
this._renderQ_push({
'type': 'fill',
'x': x,
'y': y,
'width': width,
'height': height,
'color': color
});
} else {
this._setFillColor(color);
this._drawCtx.fillRect(x, y, width, height);
this._damage(x, y, width, height);
}
}
copyImage(old_x, old_y, new_x, new_y, w, h, from_queue) {
if (this._renderQ.length !== 0 && !from_queue) {
this._renderQ_push({
'type': 'copy',
'old_x': old_x,
'old_y': old_y,
'x': new_x,
'y': new_y,
'width': w,
'height': h,
});
} else {
// Due to this bug among others [1] we need to disable the image-smoothing to
// avoid getting a blur effect when copying data.
//
// 1. https://bugzilla.mozilla.org/show_bug.cgi?id=1194719
//
// We need to set these every time since all properties are reset
// when the the size is changed
this._drawCtx.mozImageSmoothingEnabled = false;
this._drawCtx.webkitImageSmoothingEnabled = false;
this._drawCtx.msImageSmoothingEnabled = false;
this._drawCtx.imageSmoothingEnabled = false;
this._drawCtx.drawImage(this._backbuffer,
old_x, old_y, w, h,
new_x, new_y, w, h);
this._damage(new_x, new_y, w, h);
}
}
imageRect(x, y, w, h, mime, arr) {
/* The internal logic cannot handle empty images, so bail early */
if ((width === 0) || (height === 0)) {
return;
}
const img = new Image();
img.src = "data: " + mime + ";base64," + Base64.encode(arr);
this._renderQ_push({
'type': 'img',
'img': img,
'x': x,
'y': y,
'w': w,
'h': h
});
}
// start updating a tile
startTile(x, y, width, height, color) {
this._tile_x = x;
this._tile_y = y;
if (width === 16 && height === 16) {
this._tile = this._tile16x16;
} else {
this._tile = this._drawCtx.createImageData(width, height);
}
const red = color[2];
const green = color[1];
const blue = color[0];
const data = this._tile.data;
for (let i = 0; i < width * height * 4; i += 4) {
data[i] = red;
data[i + 1] = green;
data[i + 2] = blue;
data[i + 3] = 255;
}
}
// update sub-rectangle of the current tile
subTile(x, y, w, h, color) {
const red = color[2];
const green = color[1];
const blue = color[0];
const xend = x + w;
const yend = y + h;
const data = this._tile.data;
const width = this._tile.width;
for (let j = y; j < yend; j++) {
for (let i = x; i < xend; i++) {
const p = (i + (j * width)) * 4;
data[p] = red;
data[p + 1] = green;
data[p + 2] = blue;
data[p + 3] = 255;
}
}
}
// draw the current tile to the screen
finishTile() {
this._drawCtx.putImageData(this._tile, this._tile_x, this._tile_y);
this._damage(this._tile_x, this._tile_y,
this._tile.width, this._tile.height);
}
blitImage(x, y, width, height, arr, offset, from_queue) {
if (this._renderQ.length !== 0 && !from_queue) {
// NB(directxman12): it's technically more performant here to use preallocated arrays,
// but it's a lot of extra work for not a lot of payoff -- if we're using the render queue,
// this probably isn't getting called *nearly* as much
const new_arr = new Uint8Array(width * height * 4);
new_arr.set(new Uint8Array(arr.buffer, 0, new_arr.length));
this._renderQ_push({
'type': 'blit',
'data': new_arr,
'x': x,
'y': y,
'width': width,
'height': height,
});
} else {
this._bgrxImageData(x, y, width, height, arr, offset);
}
}
blitRgbImage(x, y, width, height, arr, offset, from_queue) {
if (this._renderQ.length !== 0 && !from_queue) {
// NB(directxman12): it's technically more performant here to use preallocated arrays,
// but it's a lot of extra work for not a lot of payoff -- if we're using the render queue,
// this probably isn't getting called *nearly* as much
const new_arr = new Uint8Array(width * height * 3);
new_arr.set(new Uint8Array(arr.buffer, 0, new_arr.length));
this._renderQ_push({
'type': 'blitRgb',
'data': new_arr,
'x': x,
'y': y,
'width': width,
'height': height,
});
} else {
this._rgbImageData(x, y, width, height, arr, offset);
}
}
blitRgbxImage(x, y, width, height, arr, offset, from_queue) {
if (this._renderQ.length !== 0 && !from_queue) {
// NB(directxman12): it's technically more performant here to use preallocated arrays,
// but it's a lot of extra work for not a lot of payoff -- if we're using the render queue,
// this probably isn't getting called *nearly* as much
const new_arr = new Uint8Array(width * height * 4);
new_arr.set(new Uint8Array(arr.buffer, 0, new_arr.length));
this._renderQ_push({
'type': 'blitRgbx',
'data': new_arr,
'x': x,
'y': y,
'width': width,
'height': height,
});
} else {
this._rgbxImageData(x, y, width, height, arr, offset);
}
}
drawImage(img, x, y, w, h) {
if (img.width != w || img.height != h) {
this._drawCtx.drawImage(img, x, y, w, h);
} else {
this._drawCtx.drawImage(img, x, y);
}
this._damage(x, y, w, h);
}
autoscale(containerWidth, containerHeight) {
let scaleRatio;
if (containerWidth === 0 || containerHeight === 0) {
scaleRatio = 0;
} else {
const vp = this._viewportLoc;
const targetAspectRatio = containerWidth / containerHeight;
const fbAspectRatio = vp.w / vp.h;
if (fbAspectRatio >= targetAspectRatio) {
scaleRatio = containerWidth / vp.w;
} else {
scaleRatio = containerHeight / vp.h;
}
}
this._rescale(scaleRatio);
}
// ===== PRIVATE METHODS =====
_rescale(factor) {
this._scale = factor;
const vp = this._viewportLoc;
// NB(directxman12): If you set the width directly, or set the
// style width to a number, the canvas is cleared.
// However, if you set the style width to a string
// ('NNNpx'), the canvas is scaled without clearing.
const width = factor * vp.w + 'px';
const height = factor * vp.h + 'px';
if ((this._target.style.width !== width) ||
(this._target.style.height !== height)) {
this._target.style.width = width;
this._target.style.height = height;
}
}
_setFillColor(color) {
const newStyle = 'rgb(' + color[2] + ',' + color[1] + ',' + color[0] + ')';
if (newStyle !== this._prevDrawStyle) {
this._drawCtx.fillStyle = newStyle;
this._prevDrawStyle = newStyle;
}
}
_rgbImageData(x, y, width, height, arr, offset) {
const img = this._drawCtx.createImageData(width, height);
const data = img.data;
for (let i = 0, j = offset; i < width * height * 4; i += 4, j += 3) {
data[i] = arr[j];
data[i + 1] = arr[j + 1];
data[i + 2] = arr[j + 2];
data[i + 3] = 255; // Alpha
}
this._drawCtx.putImageData(img, x, y);
this._damage(x, y, img.width, img.height);
}
_bgrxImageData(x, y, width, height, arr, offset) {
const img = this._drawCtx.createImageData(width, height);
const data = img.data;
for (let i = 0, j = offset; i < width * height * 4; i += 4, j += 4) {
data[i] = arr[j + 2];
data[i + 1] = arr[j + 1];
data[i + 2] = arr[j];
data[i + 3] = 255; // Alpha
}
this._drawCtx.putImageData(img, x, y);
this._damage(x, y, img.width, img.height);
}
_rgbxImageData(x, y, width, height, arr, offset) {
// NB(directxman12): arr must be an Type Array view
let img;
if (supportsImageMetadata) {
img = new ImageData(new Uint8ClampedArray(arr.buffer, arr.byteOffset, width * height * 4), width, height);
} else {
img = this._drawCtx.createImageData(width, height);
img.data.set(new Uint8ClampedArray(arr.buffer, arr.byteOffset, width * height * 4));
}
this._drawCtx.putImageData(img, x, y);
this._damage(x, y, img.width, img.height);
}
_renderQ_push(action) {
this._renderQ.push(action);
if (this._renderQ.length === 1) {
// If this can be rendered immediately it will be, otherwise
// the scanner will wait for the relevant event
this._scan_renderQ();
}
}
_resume_renderQ() {
// "this" is the object that is ready, not the
// display object
this.removeEventListener('load', this._noVNC_display._resume_renderQ);
this._noVNC_display._scan_renderQ();
}
_scan_renderQ() {
let ready = true;
while (ready && this._renderQ.length > 0) {
const a = this._renderQ[0];
switch (a.type) {
case 'flip':
this.flip(true);
break;
case 'copy':
this.copyImage(a.old_x, a.old_y, a.x, a.y, a.width, a.height, true);
break;
case 'fill':
this.fillRect(a.x, a.y, a.width, a.height, a.color, true);
break;
case 'blit':
this.blitImage(a.x, a.y, a.width, a.height, a.data, 0, true);
break;
case 'blitRgb':
this.blitRgbImage(a.x, a.y, a.width, a.height, a.data, 0, true);
break;
case 'blitRgbx':
this.blitRgbxImage(a.x, a.y, a.width, a.height, a.data, 0, true);
break;
case 'img':
/* IE tends to set "complete" prematurely, so check dimensions */
if (a.img.complete && (a.img.width !== 0) && (a.img.height !== 0)) {
this.drawImage(a.img, a.x, a.y, a.w, a.h);
} else {
a.img._noVNC_display = this;
a.img.addEventListener('load', this._resume_renderQ);
// We need to wait for this image to 'load'
// to keep things in-order
ready = false;
}
break;
}
if (ready) {
this._renderQ.shift();
}
}
if (this._renderQ.length === 0 && this._flushing) {
this._flushing = false;
this.onflush();
}
}
}