Move remaining webgl atlas to shared

This commit is contained in:
Daniel Imms
2022-10-02 08:48:55 -07:00
parent 26c974f9b6
commit f38a49b4d5
7 changed files with 19 additions and 34 deletions
@@ -0,0 +1,97 @@
/**
* Copyright (c) 2017 The xterm.js authors. All rights reserved.
* @license MIT
*/
import { TextureAtlas } from 'browser/renderer/shared/TextureAtlas';
import { Terminal } from 'xterm';
import { IColorSet, ITerminal } from 'browser/Types';
import { ICharAtlasConfig, ITextureAtlas } from 'browser/renderer/shared/Types';
import { generateConfig, configEquals } from 'browser/renderer/shared/CharAtlasUtils';
interface ITextureAtlasCacheEntry {
atlas: ITextureAtlas;
config: ICharAtlasConfig;
// N.B. This implementation potentially holds onto copies of the terminal forever, so
// this may cause memory leaks.
ownedBy: Terminal[];
}
const charAtlasCache: ITextureAtlasCacheEntry[] = [];
/**
* Acquires a char atlas, either generating a new one or returning an existing
* one that is in use by another terminal.
* @param terminal The terminal.
* @param colors The colors to use.
*/
export function acquireTextureAtlas(
terminal: Terminal,
colors: IColorSet,
scaledCellWidth: number,
scaledCellHeight: number,
scaledCharWidth: number,
scaledCharHeight: number,
devicePixelRatio: number
): ITextureAtlas {
const newConfig = generateConfig(scaledCellWidth, scaledCellHeight, scaledCharWidth, scaledCharHeight, terminal, colors, devicePixelRatio);
// Check to see if the terminal already owns this config
for (let i = 0; i < charAtlasCache.length; i++) {
const entry = charAtlasCache[i];
const ownedByIndex = entry.ownedBy.indexOf(terminal);
if (ownedByIndex >= 0) {
if (configEquals(entry.config, newConfig)) {
return entry.atlas;
}
// The configs differ, release the terminal from the entry
if (entry.ownedBy.length === 1) {
entry.atlas.dispose();
charAtlasCache.splice(i, 1);
} else {
entry.ownedBy.splice(ownedByIndex, 1);
}
break;
}
}
// Try match a char atlas from the cache
for (let i = 0; i < charAtlasCache.length; i++) {
const entry = charAtlasCache[i];
if (configEquals(entry.config, newConfig)) {
// Add the terminal to the cache entry and return
entry.ownedBy.push(terminal);
return entry.atlas;
}
}
const core: ITerminal = (terminal as any)._core;
const newEntry: ITextureAtlasCacheEntry = {
atlas: new TextureAtlas(document, newConfig, core.unicodeService),
config: newConfig,
ownedBy: [terminal]
};
charAtlasCache.push(newEntry);
return newEntry.atlas;
}
/**
* Removes a terminal reference from the cache, allowing its memory to be freed.
* @param terminal The terminal to remove.
*/
export function removeTerminalFromCache(terminal: Terminal): void {
for (let i = 0; i < charAtlasCache.length; i++) {
const index = charAtlasCache[i].ownedBy.indexOf(terminal);
if (index !== -1) {
if (charAtlasCache[i].ownedBy.length === 1) {
// Remove the cache entry if it's the only terminal
charAtlasCache[i].atlas.dispose();
charAtlasCache.splice(i, 1);
} else {
// Remove the reference from the cache entry
charAtlasCache[i].ownedBy.splice(index, 1);
}
break;
}
}
}
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/**
* Copyright (c) 2017 The xterm.js authors. All rights reserved.
* @license MIT
*/
import { DIM_OPACITY, TEXT_BASELINE } from 'browser/renderer/shared/Constants';
import { DEFAULT_COLOR, Attributes, DEFAULT_EXT, UnderlineStyle } from 'common/buffer/Constants';
import { IColor } from 'common/Types';
import { AttributeData } from 'common/buffer/AttributeData';
import { color, NULL_COLOR, rgba } from 'common/Color';
import { tryDrawCustomChar } from 'browser/renderer/shared/CustomGlyphs';
import { excludeFromContrastRatioDemands, isPowerlineGlyph, isRestrictedPowerlineGlyph, throwIfFalsy } from 'browser/renderer/shared/RendererUtils';
import { IUnicodeService } from 'common/services/Services';
import { FourKeyMap } from 'common/MultiKeyMap';
import { IdleTaskQueue } from 'common/TaskQueue';
import { IBoundingBox, ICharAtlasConfig, IRasterizedGlyph, ITextureAtlas } from 'browser/renderer/shared/Types';
// For debugging purposes, it can be useful to set this to a really tiny value,
// to verify that LRU eviction works.
const TEXTURE_WIDTH = 1024;
const TEXTURE_HEIGHT = 1024;
/**
* The amount of the texture to be filled before throwing it away and starting
* again. Since the throw away and individual glyph draws don't cost too much,
* this prevent juggling multiple textures in the GL context.
*/
const TEXTURE_CAPACITY = Math.floor(TEXTURE_HEIGHT * 0.8);
/**
* A shared object which is used to draw nothing for a particular cell.
*/
const NULL_RASTERIZED_GLYPH: IRasterizedGlyph = {
offset: { x: 0, y: 0 },
texturePosition: { x: 0, y: 0 },
texturePositionClipSpace: { x: 0, y: 0 },
size: { x: 0, y: 0 },
sizeClipSpace: { x: 0, y: 0 }
};
const TMP_CANVAS_GLYPH_PADDING = 2;
interface ICharAtlasActiveRow {
x: number;
y: number;
height: number;
}
// Work variables to avoid garbage collection
let $glyph = undefined;
export class TextureAtlas implements ITextureAtlas {
private _didWarmUp: boolean = false;
private _cacheMap: FourKeyMap<number, number, number, number, IRasterizedGlyph> = new FourKeyMap();
private _cacheMapCombined: FourKeyMap<string, number, number, number, IRasterizedGlyph> = new FourKeyMap();
// The texture that the atlas is drawn to
public cacheCanvas: HTMLCanvasElement;
private _cacheCtx: CanvasRenderingContext2D;
private _tmpCanvas: HTMLCanvasElement;
// A temporary context that glyphs are drawn to before being transfered to the atlas.
private _tmpCtx: CanvasRenderingContext2D;
// Texture atlas current positioning data. The texture packing strategy used is to fill from
// left-to-right and top-to-bottom. When the glyph being written is less than half of the current
// row's height, the following happens:
//
// - The current row becomes the fixed height row A
// - A new fixed height row B the exact size of the glyph is created below the current row
// - A new dynamic height current row is created below B
//
// This strategy does a good job preventing space being wasted for very short glyphs such as
// underscores, hyphens etc. or those with underlines rendered.
private _currentRow: ICharAtlasActiveRow = {
x: 0,
y: 0,
height: 0
};
private readonly _fixedRows: ICharAtlasActiveRow[] = [];
public hasCanvasChanged = false;
private _workBoundingBox: IBoundingBox = { top: 0, left: 0, bottom: 0, right: 0 };
private _workAttributeData: AttributeData = new AttributeData();
constructor(
document: Document,
private readonly _config: ICharAtlasConfig,
private readonly _unicodeService: IUnicodeService
) {
this.cacheCanvas = document.createElement('canvas');
this.cacheCanvas.width = TEXTURE_WIDTH;
this.cacheCanvas.height = TEXTURE_HEIGHT;
// The canvas needs alpha because we use clearColor to convert the background color to alpha.
// It might also contain some characters with transparent backgrounds if allowTransparency is
// set.
this._cacheCtx = throwIfFalsy(this.cacheCanvas.getContext('2d', { alpha: true }));
this._tmpCanvas = document.createElement('canvas');
this._tmpCanvas.width = this._config.scaledCellWidth * 4 + TMP_CANVAS_GLYPH_PADDING * 2;
this._tmpCanvas.height = this._config.scaledCellHeight + TMP_CANVAS_GLYPH_PADDING * 2;
this._tmpCtx = throwIfFalsy(this._tmpCanvas.getContext('2d', {
alpha: this._config.allowTransparency,
willReadFrequently: true
}));
}
public dispose(): void {
if (this.cacheCanvas.parentElement) {
this.cacheCanvas.parentElement.removeChild(this.cacheCanvas);
}
}
public warmUp(): void {
if (!this._didWarmUp) {
this._doWarmUp();
this._didWarmUp = true;
}
}
private _doWarmUp(): void {
// Pre-fill with ASCII 33-126, this is not urgent and done in idle callbacks
const queue = new IdleTaskQueue();
for (let i = 33; i < 126; i++) {
queue.enqueue(() => {
if (!this._cacheMap.get(i, DEFAULT_COLOR, DEFAULT_COLOR, DEFAULT_EXT)) {
const rasterizedGlyph = this._drawToCache(i, DEFAULT_COLOR, DEFAULT_COLOR, DEFAULT_EXT);
this._cacheMap.set(i, DEFAULT_COLOR, DEFAULT_COLOR, DEFAULT_EXT, rasterizedGlyph);
}
});
}
}
public beginFrame(): boolean {
if (this._currentRow.y > TEXTURE_CAPACITY) {
this.clearTexture();
this.warmUp();
return true;
}
return false;
}
public clearTexture(): void {
if (this._currentRow.x === 0 && this._currentRow.y === 0) {
return;
}
this._cacheCtx.clearRect(0, 0, TEXTURE_WIDTH, TEXTURE_HEIGHT);
this._cacheMap.clear();
this._cacheMapCombined.clear();
this._currentRow.x = 0;
this._currentRow.y = 0;
this._currentRow.height = 0;
this._fixedRows.length = 0;
this._didWarmUp = false;
}
public getRasterizedGlyphCombinedChar(chars: string, bg: number, fg: number, ext: number): IRasterizedGlyph {
return this._getFromCacheMap(this._cacheMapCombined, chars, bg, fg, ext);
}
public getRasterizedGlyph(code: number, bg: number, fg: number, ext: number): IRasterizedGlyph {
return this._getFromCacheMap(this._cacheMap, code, bg, fg, ext);
}
/**
* Gets the glyphs texture coords, drawing the texture if it's not already
*/
private _getFromCacheMap(
cacheMap: FourKeyMap<string | number, number, number, number, IRasterizedGlyph>,
key: string | number,
bg: number,
fg: number,
ext: number
): IRasterizedGlyph {
$glyph = cacheMap.get(key, bg, fg, ext);
if (!$glyph) {
$glyph = this._drawToCache(key, bg, fg, ext);
cacheMap.set(key, bg, fg, ext, $glyph);
}
return $glyph;
}
private _getColorFromAnsiIndex(idx: number): IColor {
if (idx >= this._config.colors.ansi.length) {
throw new Error('No color found for idx ' + idx);
}
return this._config.colors.ansi[idx];
}
private _getBackgroundColor(bgColorMode: number, bgColor: number, inverse: boolean, dim: boolean): IColor {
if (this._config.allowTransparency) {
// The background color might have some transparency, so we need to render it as fully
// transparent in the atlas. Otherwise we'd end up drawing the transparent background twice
// around the anti-aliased edges of the glyph, and it would look too dark.
return NULL_COLOR;
}
let result: IColor;
switch (bgColorMode) {
case Attributes.CM_P16:
case Attributes.CM_P256:
result = this._getColorFromAnsiIndex(bgColor);
break;
case Attributes.CM_RGB:
const arr = AttributeData.toColorRGB(bgColor);
// TODO: This object creation is slow
result = rgba.toColor(arr[0], arr[1], arr[2]);
break;
case Attributes.CM_DEFAULT:
default:
if (inverse) {
result = this._config.colors.foreground;
} else {
result = this._config.colors.background;
}
break;
}
if (dim) {
// Blend here instead of using opacity because transparent colors mess with clipping the
// glyph's bounding box
result = color.blend(this._config.colors.background, color.multiplyOpacity(result, DIM_OPACITY));
}
return result;
}
private _getForegroundColor(bg: number, bgColorMode: number, bgColor: number, fg: number, fgColorMode: number, fgColor: number, inverse: boolean, dim: boolean, bold: boolean, excludeFromContrastRatioDemands: boolean): IColor {
// TODO: Pass dim along to get min contrast?
const minimumContrastColor = this._getMinimumContrastColor(bg, bgColorMode, bgColor, fg, fgColorMode, fgColor, false, bold, excludeFromContrastRatioDemands);
if (minimumContrastColor) {
return minimumContrastColor;
}
let result: IColor;
switch (fgColorMode) {
case Attributes.CM_P16:
case Attributes.CM_P256:
if (this._config.drawBoldTextInBrightColors && bold && fgColor < 8) {
fgColor += 8;
}
result = this._getColorFromAnsiIndex(fgColor);
break;
case Attributes.CM_RGB:
const arr = AttributeData.toColorRGB(fgColor);
result = rgba.toColor(arr[0], arr[1], arr[2]);
break;
case Attributes.CM_DEFAULT:
default:
if (inverse) {
result = this._config.colors.background;
} else {
result = this._config.colors.foreground;
}
}
// Always use an opaque color regardless of allowTransparency
if (this._config.allowTransparency) {
result = color.opaque(result);
}
// Apply dim to the color, opacity is fine to use for the foreground color
if (dim) {
result = color.multiplyOpacity(result, DIM_OPACITY);
}
return result;
}
private _resolveBackgroundRgba(bgColorMode: number, bgColor: number, inverse: boolean): number {
switch (bgColorMode) {
case Attributes.CM_P16:
case Attributes.CM_P256:
return this._getColorFromAnsiIndex(bgColor).rgba;
case Attributes.CM_RGB:
return bgColor << 8;
case Attributes.CM_DEFAULT:
default:
if (inverse) {
return this._config.colors.foreground.rgba;
}
return this._config.colors.background.rgba;
}
}
private _resolveForegroundRgba(fgColorMode: number, fgColor: number, inverse: boolean, bold: boolean): number {
switch (fgColorMode) {
case Attributes.CM_P16:
case Attributes.CM_P256:
if (this._config.drawBoldTextInBrightColors && bold && fgColor < 8) {
fgColor += 8;
}
return this._getColorFromAnsiIndex(fgColor).rgba;
case Attributes.CM_RGB:
return fgColor << 8;
case Attributes.CM_DEFAULT:
default:
if (inverse) {
return this._config.colors.background.rgba;
}
return this._config.colors.foreground.rgba;
}
}
private _getMinimumContrastColor(bg: number, bgColorMode: number, bgColor: number, fg: number, fgColorMode: number, fgColor: number, inverse: boolean, bold: boolean, excludeFromContrastRatioDemands: boolean): IColor | undefined {
if (this._config.minimumContrastRatio === 1 || excludeFromContrastRatioDemands) {
return undefined;
}
// Try get from cache first
const adjustedColor = this._config.colors.contrastCache.getColor(bg, fg);
if (adjustedColor !== undefined) {
return adjustedColor || undefined;
}
const bgRgba = this._resolveBackgroundRgba(bgColorMode, bgColor, inverse);
const fgRgba = this._resolveForegroundRgba(fgColorMode, fgColor, inverse, bold);
const result = rgba.ensureContrastRatio(bgRgba, fgRgba, this._config.minimumContrastRatio);
if (!result) {
this._config.colors.contrastCache.setColor(bg, fg, null);
return undefined;
}
const color = rgba.toColor(
(result >> 24) & 0xFF,
(result >> 16) & 0xFF,
(result >> 8) & 0xFF
);
this._config.colors.contrastCache.setColor(bg, fg, color);
return color;
}
private _drawToCache(codeOrChars: number | string, bg: number, fg: number, ext: number): IRasterizedGlyph {
const chars = typeof codeOrChars === 'number' ? String.fromCharCode(codeOrChars) : codeOrChars;
this.hasCanvasChanged = true;
// Allow 1 cell width per character, with a minimum of 2 (CJK), plus some padding. This is used
// to draw the glyph to the canvas as well as to restrict the bounding box search to ensure
// giant ligatures (eg. =====>) don't impact overall performance.
const allowedWidth = this._config.scaledCellWidth * Math.max(chars.length, 2) + TMP_CANVAS_GLYPH_PADDING * 2;
if (this._tmpCanvas.width < allowedWidth) {
this._tmpCanvas.width = allowedWidth;
}
// Include line height when drawing glyphs
const allowedHeight = this._config.scaledCellHeight + TMP_CANVAS_GLYPH_PADDING * 4;
if (this._tmpCanvas.height < allowedHeight) {
this._tmpCanvas.height = allowedHeight;
}
this._tmpCtx.save();
this._workAttributeData.fg = fg;
this._workAttributeData.bg = bg;
this._workAttributeData.extended.ext = ext;
const invisible = !!this._workAttributeData.isInvisible();
if (invisible) {
return NULL_RASTERIZED_GLYPH;
}
const bold = !!this._workAttributeData.isBold();
const inverse = !!this._workAttributeData.isInverse();
const dim = !!this._workAttributeData.isDim();
const italic = !!this._workAttributeData.isItalic();
const underline = !!this._workAttributeData.isUnderline();
const strikethrough = !!this._workAttributeData.isStrikethrough();
let fgColor = this._workAttributeData.getFgColor();
let fgColorMode = this._workAttributeData.getFgColorMode();
let bgColor = this._workAttributeData.getBgColor();
let bgColorMode = this._workAttributeData.getBgColorMode();
if (inverse) {
const temp = fgColor;
fgColor = bgColor;
bgColor = temp;
const temp2 = fgColorMode;
fgColorMode = bgColorMode;
bgColorMode = temp2;
}
// draw the background
const backgroundColor = this._getBackgroundColor(bgColorMode, bgColor, inverse, dim);
// Use a 'copy' composite operation to clear any existing glyph out of _tmpCtxWithAlpha, regardless of
// transparency in backgroundColor
this._tmpCtx.globalCompositeOperation = 'copy';
this._tmpCtx.fillStyle = backgroundColor.css;
this._tmpCtx.fillRect(0, 0, this._tmpCanvas.width, this._tmpCanvas.height);
this._tmpCtx.globalCompositeOperation = 'source-over';
// draw the foreground/glyph
const fontWeight = bold ? this._config.fontWeightBold : this._config.fontWeight;
const fontStyle = italic ? 'italic' : '';
this._tmpCtx.font =
`${fontStyle} ${fontWeight} ${this._config.fontSize * this._config.devicePixelRatio}px ${this._config.fontFamily}`;
this._tmpCtx.textBaseline = TEXT_BASELINE;
const powerlineGlyph = chars.length === 1 && isPowerlineGlyph(chars.charCodeAt(0));
const restrictedPowerlineGlyph = chars.length === 1 && isRestrictedPowerlineGlyph(chars.charCodeAt(0));
const foregroundColor = this._getForegroundColor(bg, bgColorMode, bgColor, fg, fgColorMode, fgColor, inverse, dim, bold, excludeFromContrastRatioDemands(chars.charCodeAt(0)));
this._tmpCtx.fillStyle = foregroundColor.css;
// For powerline glyphs left/top padding is excluded (https://github.com/microsoft/vscode/issues/120129)
const padding = restrictedPowerlineGlyph ? 0 : TMP_CANVAS_GLYPH_PADDING * 2;
// Draw custom characters if applicable
let customGlyph = false;
if (this._config.customGlyphs !== false) {
customGlyph = tryDrawCustomChar(this._tmpCtx, chars, padding, padding, this._config.scaledCellWidth, this._config.scaledCellHeight, this._config.fontSize, this._config.devicePixelRatio);
}
// Whether to clear pixels based on a threshold difference between the glyph color and the
// background color. This should be disabled when the glyph contains multiple colors such as
// underline colors to prevent important colors could get cleared.
let enableClearThresholdCheck = !powerlineGlyph;
let chWidth: number;
if (typeof codeOrChars === 'number') {
chWidth = this._unicodeService.wcwidth(codeOrChars);
} else {
chWidth = this._unicodeService.getStringCellWidth(codeOrChars);
}
// Draw underline
if (underline) {
this._tmpCtx.save();
const lineWidth = Math.max(1, Math.floor(this._config.fontSize * this._config.devicePixelRatio / 15));
// When the line width is odd, draw at a 0.5 position
const yOffset = lineWidth % 2 === 1 ? 0.5 : 0;
this._tmpCtx.lineWidth = lineWidth;
// Underline color
if (this._workAttributeData.isUnderlineColorDefault()) {
this._tmpCtx.strokeStyle = this._tmpCtx.fillStyle;
} else if (this._workAttributeData.isUnderlineColorRGB()) {
enableClearThresholdCheck = false;
this._tmpCtx.strokeStyle = `rgb(${AttributeData.toColorRGB(this._workAttributeData.getUnderlineColor()).join(',')})`;
} else {
enableClearThresholdCheck = false;
let fg = this._workAttributeData.getUnderlineColor();
if (this._config.drawBoldTextInBrightColors && this._workAttributeData.isBold() && fg < 8) {
fg += 8;
}
this._tmpCtx.strokeStyle = this._getColorFromAnsiIndex(fg).css;
}
// Underline style/stroke
this._tmpCtx.beginPath();
const xLeft = padding;
const yTop = Math.ceil(padding + this._config.scaledCharHeight) - yOffset;
const yMid = padding + this._config.scaledCharHeight + lineWidth - yOffset;
const yBot = Math.ceil(padding + this._config.scaledCharHeight + lineWidth * 2) - yOffset;
for (let i = 0; i < chWidth; i++) {
this._tmpCtx.save();
const xChLeft = xLeft + i * this._config.scaledCellWidth;
const xChRight = xLeft + (i + 1) * this._config.scaledCellWidth;
const xChMid = xChLeft + this._config.scaledCellWidth / 2;
switch (this._workAttributeData.extended.underlineStyle) {
case UnderlineStyle.DOUBLE:
this._tmpCtx.moveTo(xChLeft, yTop);
this._tmpCtx.lineTo(xChRight, yTop);
this._tmpCtx.moveTo(xChLeft, yBot);
this._tmpCtx.lineTo(xChRight, yBot);
break;
case UnderlineStyle.CURLY:
// Choose the bezier top and bottom based on the device pixel ratio, the curly line is
// made taller when the line width is as otherwise it's not very clear otherwise.
const yCurlyBot = lineWidth <= 1 ? yBot : Math.ceil(padding + this._config.scaledCharHeight - lineWidth / 2) - yOffset;
const yCurlyTop = lineWidth <= 1 ? yTop : Math.ceil(padding + this._config.scaledCharHeight + lineWidth / 2) - yOffset;
// Clip the left and right edges of the underline such that it can be drawn just outside
// the edge of the cell to ensure a continuous stroke when there are multiple underlined
// glyphs adjacent to one another.
const clipRegion = new Path2D();
clipRegion.rect(xChLeft, yTop, this._config.scaledCellWidth, yBot - yTop);
this._tmpCtx.clip(clipRegion);
// Start 1/2 cell before and end 1/2 cells after to ensure a smooth curve with other cells
this._tmpCtx.moveTo(xChLeft - this._config.scaledCellWidth / 2, yMid);
this._tmpCtx.bezierCurveTo(
xChLeft - this._config.scaledCellWidth / 2, yCurlyTop,
xChLeft, yCurlyTop,
xChLeft, yMid
);
this._tmpCtx.bezierCurveTo(
xChLeft, yCurlyBot,
xChMid, yCurlyBot,
xChMid, yMid
);
this._tmpCtx.bezierCurveTo(
xChMid, yCurlyTop,
xChRight, yCurlyTop,
xChRight, yMid
);
this._tmpCtx.bezierCurveTo(
xChRight, yCurlyBot,
xChRight + this._config.scaledCellWidth / 2, yCurlyBot,
xChRight + this._config.scaledCellWidth / 2, yMid
);
break;
case UnderlineStyle.DOTTED:
this._tmpCtx.setLineDash([this._config.devicePixelRatio * 2, this._config.devicePixelRatio]);
this._tmpCtx.moveTo(xChLeft, yTop);
this._tmpCtx.lineTo(xChRight, yTop);
break;
case UnderlineStyle.DASHED:
this._tmpCtx.setLineDash([this._config.devicePixelRatio * 4, this._config.devicePixelRatio * 3]);
this._tmpCtx.moveTo(xChLeft, yTop);
this._tmpCtx.lineTo(xChRight, yTop);
break;
case UnderlineStyle.SINGLE:
default:
this._tmpCtx.moveTo(xChLeft, yTop);
this._tmpCtx.lineTo(xChRight, yTop);
break;
}
this._tmpCtx.stroke();
this._tmpCtx.restore();
}
this._tmpCtx.restore();
// Draw stroke in the background color for non custom characters in order to give an outline
// between the text and the underline. Only do this when font size is >= 12 as the underline
// looks odd when the font size is too small
if (!customGlyph && this._config.fontSize >= 12) {
// This only works when transparency is disabled because it's not clear how to clear stroked
// text
if (!this._config.allowTransparency && chars !== ' ') {
// Measure the text, only draw the stroke if there is a descent beyond an alphabetic text
// baseline
this._tmpCtx.save();
this._tmpCtx.textBaseline = 'alphabetic';
const metrics = this._tmpCtx.measureText(chars);
this._tmpCtx.restore();
if ('actualBoundingBoxDescent' in metrics && metrics.actualBoundingBoxDescent > 0) {
// This translates to 1/2 the line width in either direction
this._tmpCtx.save();
// Clip the region to only draw in valid pixels near the underline to avoid a slight
// outline around the whole glyph, as well as additional pixels in the glyph at the top
// which would increase GPU memory demands
const clipRegion = new Path2D();
clipRegion.rect(xLeft, yTop - Math.ceil(lineWidth / 2), this._config.scaledCellWidth, yBot - yTop + Math.ceil(lineWidth / 2));
this._tmpCtx.clip(clipRegion);
this._tmpCtx.lineWidth = this._config.devicePixelRatio * 3;
this._tmpCtx.strokeStyle = backgroundColor.css;
this._tmpCtx.strokeText(chars, padding, padding + this._config.scaledCharHeight);
this._tmpCtx.restore();
}
}
}
}
// Draw the character
if (!customGlyph) {
this._tmpCtx.fillText(chars, padding, padding + this._config.scaledCharHeight);
}
// If this charcater is underscore and beyond the cell bounds, shift it up until it is visible
// even on the bottom row, try for a maximum of 5 pixels.
if (chars === '_' && !this._config.allowTransparency) {
let isBeyondCellBounds = clearColor(this._tmpCtx.getImageData(padding, padding, this._config.scaledCellWidth, this._config.scaledCellHeight), backgroundColor, foregroundColor, enableClearThresholdCheck);
if (isBeyondCellBounds) {
for (let offset = 1; offset <= 5; offset++) {
this._tmpCtx.save();
this._tmpCtx.fillStyle = backgroundColor.css;
this._tmpCtx.fillRect(0, 0, this._tmpCanvas.width, this._tmpCanvas.height);
this._tmpCtx.restore();
this._tmpCtx.fillText(chars, padding, padding + this._config.scaledCharHeight - offset);
isBeyondCellBounds = clearColor(this._tmpCtx.getImageData(padding, padding, this._config.scaledCellWidth, this._config.scaledCellHeight), backgroundColor, foregroundColor, enableClearThresholdCheck);
if (!isBeyondCellBounds) {
break;
}
}
}
}
// Draw strokethrough
if (strikethrough) {
const lineWidth = Math.max(1, Math.floor(this._config.fontSize * this._config.devicePixelRatio / 10));
const yOffset = this._tmpCtx.lineWidth % 2 === 1 ? 0.5 : 0; // When the width is odd, draw at 0.5 position
this._tmpCtx.lineWidth = lineWidth;
this._tmpCtx.strokeStyle = this._tmpCtx.fillStyle;
this._tmpCtx.beginPath();
this._tmpCtx.moveTo(padding, padding + Math.floor(this._config.scaledCharHeight / 2) - yOffset);
this._tmpCtx.lineTo(padding + this._config.scaledCharWidth * chWidth, padding + Math.floor(this._config.scaledCharHeight / 2) - yOffset);
this._tmpCtx.stroke();
}
this._tmpCtx.restore();
// clear the background from the character to avoid issues with drawing over the previous
// character if it extends past it's bounds
const imageData = this._tmpCtx.getImageData(
0, 0, this._tmpCanvas.width, this._tmpCanvas.height
);
// Clear out the background color and determine if the glyph is empty.
let isEmpty: boolean;
if (!this._config.allowTransparency) {
isEmpty = clearColor(imageData, backgroundColor, foregroundColor, enableClearThresholdCheck);
} else {
isEmpty = checkCompletelyTransparent(imageData);
}
// Handle empty glyphs
if (isEmpty) {
return NULL_RASTERIZED_GLYPH;
}
const rasterizedGlyph = this._findGlyphBoundingBox(imageData, this._workBoundingBox, allowedWidth, restrictedPowerlineGlyph, customGlyph, padding);
const clippedImageData = this._clipImageData(imageData, this._workBoundingBox);
// Find the best atlas row to use
let activeRow: ICharAtlasActiveRow;
while (true) {
// Select the ideal existing row, preferring fixed rows over the current row
activeRow = this._currentRow;
for (const row of this._fixedRows) {
if ((activeRow === this._currentRow || row.height < activeRow.height) && rasterizedGlyph.size.y <= row.height) {
activeRow = row;
}
}
// Create a new one if vertical space would be wasted, fixing the previously active row in the
// process as it now has a fixed height
if (activeRow.height > rasterizedGlyph.size.y * 2) {
// Fix the current row as the new row is being added below
if (this._currentRow.height > 0) {
this._fixedRows.push(this._currentRow);
}
// Create the new fixed height row
activeRow = {
x: 0,
y: this._currentRow.y + this._currentRow.height,
height: rasterizedGlyph.size.y
};
this._fixedRows.push(activeRow);
// Create the new current row below the new fixed height row
this._currentRow = {
x: 0,
y: activeRow.y + activeRow.height,
height: 0
};
}
// Exit the loop if there is enough room in the row
if (activeRow.x + rasterizedGlyph.size.x <= TEXTURE_WIDTH) {
break;
}
// If there is enough room in the current row, finish it and try again
if (activeRow === this._currentRow) {
activeRow.x = 0;
activeRow.y += activeRow.height;
activeRow.height = 0;
} else {
this._fixedRows.splice(this._fixedRows.indexOf(activeRow), 1);
}
}
// Record texture position
rasterizedGlyph.texturePosition.x = activeRow.x;
rasterizedGlyph.texturePosition.y = activeRow.y;
rasterizedGlyph.texturePositionClipSpace.x = activeRow.x / TEXTURE_WIDTH;
rasterizedGlyph.texturePositionClipSpace.y = activeRow.y / TEXTURE_HEIGHT;
// Update atlas current row, for fixed rows the glyph height will never be larger than the row
// height
activeRow.height = Math.max(activeRow.height, rasterizedGlyph.size.y);
activeRow.x += rasterizedGlyph.size.x;
// putImageData doesn't do any blending, so it will overwrite any existing cache entry for us
this._cacheCtx.putImageData(clippedImageData, rasterizedGlyph.texturePosition.x, rasterizedGlyph.texturePosition.y);
return rasterizedGlyph;
}
/**
* Given an ImageData object, find the bounding box of the non-transparent
* portion of the texture and return an IRasterizedGlyph with these
* dimensions.
* @param imageData The image data to read.
* @param boundingBox An IBoundingBox to put the clipped bounding box values.
*/
private _findGlyphBoundingBox(imageData: ImageData, boundingBox: IBoundingBox, allowedWidth: number, restrictedGlyph: boolean, customGlyph: boolean, padding: number): IRasterizedGlyph {
boundingBox.top = 0;
const height = restrictedGlyph ? this._config.scaledCellHeight : this._tmpCanvas.height;
const width = restrictedGlyph ? this._config.scaledCellWidth : allowedWidth;
let found = false;
for (let y = 0; y < height; y++) {
for (let x = 0; x < width; x++) {
const alphaOffset = y * this._tmpCanvas.width * 4 + x * 4 + 3;
if (imageData.data[alphaOffset] !== 0) {
boundingBox.top = y;
found = true;
break;
}
}
if (found) {
break;
}
}
boundingBox.left = 0;
found = false;
for (let x = 0; x < width; x++) {
for (let y = 0; y < height; y++) {
const alphaOffset = y * this._tmpCanvas.width * 4 + x * 4 + 3;
if (imageData.data[alphaOffset] !== 0) {
boundingBox.left = x;
found = true;
break;
}
}
if (found) {
break;
}
}
boundingBox.right = width;
found = false;
for (let x = width - 1; x >= 0; x--) {
for (let y = 0; y < height; y++) {
const alphaOffset = y * this._tmpCanvas.width * 4 + x * 4 + 3;
if (imageData.data[alphaOffset] !== 0) {
boundingBox.right = x;
found = true;
break;
}
}
if (found) {
break;
}
}
boundingBox.bottom = height;
found = false;
for (let y = height - 1; y >= 0; y--) {
for (let x = 0; x < width; x++) {
const alphaOffset = y * this._tmpCanvas.width * 4 + x * 4 + 3;
if (imageData.data[alphaOffset] !== 0) {
boundingBox.bottom = y;
found = true;
break;
}
}
if (found) {
break;
}
}
return {
texturePosition: { x: 0, y: 0 },
texturePositionClipSpace: { x: 0, y: 0 },
size: {
x: boundingBox.right - boundingBox.left + 1,
y: boundingBox.bottom - boundingBox.top + 1
},
sizeClipSpace: {
x: (boundingBox.right - boundingBox.left + 1) / TEXTURE_WIDTH,
y: (boundingBox.bottom - boundingBox.top + 1) / TEXTURE_HEIGHT
},
offset: {
x: -boundingBox.left + padding + ((restrictedGlyph || customGlyph) ? Math.floor((this._config.scaledCellWidth - this._config.scaledCharWidth) / 2) : 0),
y: -boundingBox.top + padding + ((restrictedGlyph || customGlyph) ? this._config.lineHeight === 1 ? 0 : Math.round((this._config.scaledCellHeight - this._config.scaledCharHeight) / 2) : 0)
}
};
}
private _clipImageData(imageData: ImageData, boundingBox: IBoundingBox): ImageData {
const width = boundingBox.right - boundingBox.left + 1;
const height = boundingBox.bottom - boundingBox.top + 1;
const clippedData = new Uint8ClampedArray(width * height * 4);
for (let y = boundingBox.top; y <= boundingBox.bottom; y++) {
for (let x = boundingBox.left; x <= boundingBox.right; x++) {
const oldOffset = y * this._tmpCanvas.width * 4 + x * 4;
const newOffset = (y - boundingBox.top) * width * 4 + (x - boundingBox.left) * 4;
clippedData[newOffset] = imageData.data[oldOffset];
clippedData[newOffset + 1] = imageData.data[oldOffset + 1];
clippedData[newOffset + 2] = imageData.data[oldOffset + 2];
clippedData[newOffset + 3] = imageData.data[oldOffset + 3];
}
}
return new ImageData(clippedData, width, height);
}
}
/**
* Makes a particular rgb color and colors that are nearly the same in an ImageData completely
* transparent.
* @returns True if the result is "empty", meaning all pixels are fully transparent.
*/
function clearColor(imageData: ImageData, bg: IColor, fg: IColor, enableThresholdCheck: boolean): boolean {
// Get color channels
const r = bg.rgba >>> 24;
const g = bg.rgba >>> 16 & 0xFF;
const b = bg.rgba >>> 8 & 0xFF;
const fgR = fg.rgba >>> 24;
const fgG = fg.rgba >>> 16 & 0xFF;
const fgB = fg.rgba >>> 8 & 0xFF;
// Calculate a threshold that when below a color will be treated as transpart when the sum of
// channel value differs. This helps improve rendering when glyphs overlap with others. This
// threshold is calculated relative to the difference between the background and foreground to
// ensure important details of the glyph are always shown, even when the contrast ratio is low.
// The number 12 is largely arbitrary to ensure the pixels that escape the cell in the test case
// were covered (fg=#8ae234, bg=#c4a000).
const threshold = Math.floor((Math.abs(r - fgR) + Math.abs(g - fgG) + Math.abs(b - fgB)) / 12);
// Set alpha channel of relevent pixels to 0
let isEmpty = true;
for (let offset = 0; offset < imageData.data.length; offset += 4) {
// Check exact match
if (imageData.data[offset] === r &&
imageData.data[offset + 1] === g &&
imageData.data[offset + 2] === b) {
imageData.data[offset + 3] = 0;
} else {
// Check the threshold based difference
if (enableThresholdCheck &&
(Math.abs(imageData.data[offset] - r) +
Math.abs(imageData.data[offset + 1] - g) +
Math.abs(imageData.data[offset + 2] - b)) < threshold) {
imageData.data[offset + 3] = 0;
} else {
isEmpty = false;
}
}
}
return isEmpty;
}
function checkCompletelyTransparent(imageData: ImageData): boolean {
for (let offset = 0; offset < imageData.data.length; offset += 4) {
if (imageData.data[offset + 3] > 0) {
return false;
}
}
return true;
}
+7
View File
@@ -132,3 +132,10 @@ export interface IVector {
x: number;
y: number;
}
export interface IBoundingBox {
top: number;
left: number;
right: number;
bottom: number;
}