Function renderPlainText

libs/echarts/echarts.simple.js:8433–8586

(hostEl, ctx, text, style, rect, prevEl)

// Avoid setting to ctx according to prevEl if possible for
// performance in scenarios of large amount text.
function renderPlainText(hostEl, ctx, text, style, rect, prevEl) {
    'use strict';

    var needDrawBg = needDrawBackground(style);

    var prevStyle;
    var checkCache = false;
    var cachedByMe = ctx.__attrCachedBy === ContextCachedBy.PLAIN_TEXT;

    // Only take and check cache for `Text` el, but not RectText.
    if (prevEl !== WILL_BE_RESTORED) {
        if (prevEl) {
            prevStyle = prevEl.style;
            checkCache = !needDrawBg && cachedByMe && prevStyle;
        }

        // Prevent from using cache in `Style::bind`, because of the case:
        // ctx property is modified by other properties than `Style::bind`
        // used, and Style::bind is called next.
        ctx.__attrCachedBy = needDrawBg ? ContextCachedBy.NONE : ContextCachedBy.PLAIN_TEXT;
    }
    // Since this will be restored, prevent from using these props to check cache in the next
    // entering of this method. But do not need to clear other cache like `Style::bind`.
    else if (cachedByMe) {
        ctx.__attrCachedBy = ContextCachedBy.NONE;
    }

    var styleFont = style.font || DEFAULT_FONT;
    // PENDING
    // Only `Text` el set `font` and keep it (`RectText` will restore). So theoretically
    // we can make font cache on ctx, which can cache for text el that are discontinuous.
    // But layer save/restore needed to be considered.
    // if (styleFont !== ctx.__fontCache) {
    //     ctx.font = styleFont;
    //     if (prevEl !== WILL_BE_RESTORED) {
    //         ctx.__fontCache = styleFont;
    //     }
    // }
    if (!checkCache || styleFont !== (prevStyle.font || DEFAULT_FONT)) {
        ctx.font = styleFont;
    }

    // Use the final font from context-2d, because the final
    // font might not be the style.font when it is illegal.
    // But get `ctx.font` might be time consuming.
    var computedFont = hostEl.__computedFont;
    if (hostEl.__styleFont !== styleFont) {
        hostEl.__styleFont = styleFont;
        computedFont = hostEl.__computedFont = ctx.font;
    }

    var textPadding = style.textPadding;
    var textLineHeight = style.textLineHeight;

    var contentBlock = hostEl.__textCotentBlock;
    if (!contentBlock || hostEl.__dirtyText) {
        contentBlock = hostEl.__textCotentBlock = parsePlainText(
            text, computedFont, textPadding, textLineHeight, style.truncate