this.$renderChanges = function()

in lib/ace/virtual_renderer.js [824:961]
123 lines of code
48 McCabe index (conditional complexity)

    this.$renderChanges = function(changes, force) {
        if (this.$changes) {
            changes |= this.$changes;
            this.$changes = 0;
        }
        if ((!this.session || !this.container.offsetWidth || this.$frozen) || (!changes && !force)) {
            this.$changes |= changes;
            return; 
        } 
        if (this.$size.$dirty) {
            this.$changes |= changes;
            return this.onResize(true);
        }
        if (!this.lineHeight) {
            this.$textLayer.checkForSizeChanges();
        }
        // this.$logChanges(changes);
        
        this._signal("beforeRender", changes);
        
        if (this.session && this.session.$bidiHandler)
            this.session.$bidiHandler.updateCharacterWidths(this.$fontMetrics);

        var config = this.layerConfig;
        // text, scrolling and resize changes can cause the view port size to change
        if (changes & this.CHANGE_FULL ||
            changes & this.CHANGE_SIZE ||
            changes & this.CHANGE_TEXT ||
            changes & this.CHANGE_LINES ||
            changes & this.CHANGE_SCROLL ||
            changes & this.CHANGE_H_SCROLL
        ) {
            changes |= this.$computeLayerConfig() | this.$loop.clear();
            // If a change is made offscreen and wrapMode is on, then the onscreen
            // lines may have been pushed down. If so, the first screen row will not
            // have changed, but the first actual row will. In that case, adjust 
            // scrollTop so that the cursor and onscreen content stays in the same place.
            // TODO: find a better way to handle this, that works non wrapped case and doesn't compute layerConfig twice
            if (config.firstRow != this.layerConfig.firstRow && config.firstRowScreen == this.layerConfig.firstRowScreen) {
                var st = this.scrollTop + (config.firstRow - this.layerConfig.firstRow) * this.lineHeight;
                if (st > 0) {
                    // this check is needed as a workaround for the documentToScreenRow returning -1 if document.length == 0
                    this.scrollTop = st;
                    changes = changes | this.CHANGE_SCROLL;
                    changes |= this.$computeLayerConfig() | this.$loop.clear();
                }
            }
            config = this.layerConfig;
            // update scrollbar first to not lose scroll position when gutter calls resize
            this.$updateScrollBarV();
            if (changes & this.CHANGE_H_SCROLL)
                this.$updateScrollBarH();
            
            dom.translate(this.content, -this.scrollLeft, -config.offset);
            
            var width = config.width + 2 * this.$padding + "px";
            var height = config.minHeight + "px";
            
            dom.setStyle(this.content.style, "width", width);
            dom.setStyle(this.content.style, "height", height);
        }
        
        // horizontal scrolling
        if (changes & this.CHANGE_H_SCROLL) {
            dom.translate(this.content, -this.scrollLeft, -config.offset);
            this.scroller.className = this.scrollLeft <= 0 ? "ace_scroller" : "ace_scroller ace_scroll-left";
        }

        // full
        if (changes & this.CHANGE_FULL) {
            this.$changedLines = null;
            this.$textLayer.update(config);
            if (this.$showGutter)
                this.$gutterLayer.update(config);
            this.$markerBack.update(config);
            this.$markerFront.update(config);
            this.$cursorLayer.update(config);
            this.$moveTextAreaToCursor();
            this._signal("afterRender", changes);
            return;
        }

        // scrolling
        if (changes & this.CHANGE_SCROLL) {
            this.$changedLines = null;
            if (changes & this.CHANGE_TEXT || changes & this.CHANGE_LINES)
                this.$textLayer.update(config);
            else
                this.$textLayer.scrollLines(config);

            if (this.$showGutter) {
                if (changes & this.CHANGE_GUTTER || changes & this.CHANGE_LINES)
                    this.$gutterLayer.update(config);
                else
                    this.$gutterLayer.scrollLines(config);
            }
            this.$markerBack.update(config);
            this.$markerFront.update(config);
            this.$cursorLayer.update(config);
            this.$moveTextAreaToCursor();
            this._signal("afterRender", changes);
            return;
        }

        if (changes & this.CHANGE_TEXT) {
            this.$changedLines = null;
            this.$textLayer.update(config);
            if (this.$showGutter)
                this.$gutterLayer.update(config);
        }
        else if (changes & this.CHANGE_LINES) {
            if (this.$updateLines() || (changes & this.CHANGE_GUTTER) && this.$showGutter)
                this.$gutterLayer.update(config);
        }
        else if (changes & this.CHANGE_TEXT || changes & this.CHANGE_GUTTER) {
            if (this.$showGutter)
                this.$gutterLayer.update(config);
        }
        else if (changes & this.CHANGE_CURSOR) {
            if (this.$highlightGutterLine)
                this.$gutterLayer.updateLineHighlight(config);
        }

        if (changes & this.CHANGE_CURSOR) {
            this.$cursorLayer.update(config);
            this.$moveTextAreaToCursor();
        }

        if (changes & (this.CHANGE_MARKER | this.CHANGE_MARKER_FRONT)) {
            this.$markerFront.update(config);
        }

        if (changes & (this.CHANGE_MARKER | this.CHANGE_MARKER_BACK)) {
            this.$markerBack.update(config);
        }

        this._signal("afterRender", changes);
    };