Merge pull request #10527 from ahocevar/no-label-cache

Remove label cache, render text directly to target canvas
2020-01-16 09:23:41 +01:00
parent 8e2adf9955 fd935bae53
commit de5cd5c664
11 changed files with 175 additions and 187 deletions
--- a/src/ol/render/canvas.js
+++ b/src/ol/render/canvas.js
@@ -5,7 +5,9 @@ import {getFontParameters} from '../css.js';
 import {createCanvasContext2D} from '../dom.js';
 import {clear} from '../obj.js';
 import {create as createTransform} from '../transform.js';
-import LabelCache from './canvas/LabelCache.js';
+import {executeLabelInstructions} from './canvas/Executor.js';
+import BaseObject from '../Object.js';
+import EventTarget from '../events/Target.js';


 /**
@@ -164,21 +166,23 @@ export const defaultPadding = [0, 0, 0, 0];
 */
 export const defaultLineWidth = 1;

+/**
+ * @type {BaseObject}
+ */
+export const checkedFonts = new BaseObject();

 /**
 * The label cache for text rendering. To change the default cache size of 2048
 * entries, use {@link module:ol/structs/LRUCache#setSize}.
- * @type {LabelCache}
+ * Deprecated - there is no label cache any more.
+ * @type {?}
 * @api
+ * @deprecated
 */
-export const labelCache = new LabelCache();
-
-
-/**
- * @type {!Object<string, number>}
- */
-export const checkedFonts = {};
-
+export const labelCache = new EventTarget();
+labelCache.setSize = function() {
+  console.warn('labelCache is deprecated.'); //eslint-disable-line
+};

 /**
 * @type {CanvasRenderingContext2D}
@@ -200,9 +204,8 @@ export const textHeights = {};
 * Clears the label cache when a font becomes available.
 * @param {string} fontSpec CSS font spec.
 */
-export const checkFont = (function() {
+export const registerFont = (function() {
  const retries = 100;
-  const checked = checkedFonts;
  const size = '32px ';
  const referenceFonts = ['monospace', 'serif'];
  const len = referenceFonts.length;
@@ -235,19 +238,18 @@ export const checkFont = (function() {

  function check() {
    let done = true;
-    for (const font in checked) {
-      if (checked[font] < retries) {
+    const fonts = checkedFonts.getKeys();
+    for (let i = 0, ii = fonts.length; i < ii; ++i) {
+      const font = fonts[i];
+      if (checkedFonts.get(font) < retries) {
        if (isAvailable.apply(this, font.split('\n'))) {
-          checked[font] = retries;
          clear(textHeights);
          // Make sure that loaded fonts are picked up by Safari
          measureContext = null;
          measureFont = undefined;
-          if (labelCache.getCount()) {
-            labelCache.clear();
-          }
+          checkedFonts.set(font, retries);
        } else {
-          ++checked[font];
+          checkedFonts.set(font, checkedFonts.get(font) + 1, true);
          done = false;
        }
      }
@@ -267,10 +269,10 @@ export const checkFont = (function() {
    for (let i = 0, ii = families.length; i < ii; ++i) {
      const family = families[i];
      const key = font.style + '\n' + font.weight + '\n' + family;
-      if (!(key in checked)) {
-        checked[key] = retries;
+      if (checkedFonts.get(key) === undefined) {
+        checkedFonts.set(key, retries, true);
        if (!isAvailable(font.style, font.weight, family)) {
-          checked[key] = 0;
+          checkedFonts.set(key, 0, true);
          if (interval === undefined) {
            interval = setInterval(check, 32);
          }
@@ -388,7 +390,7 @@ export const resetTransform = createTransform();
 * @param {CanvasRenderingContext2D} context Context.
 * @param {import("../transform.js").Transform|null} transform Transform.
 * @param {number} opacity Opacity.
- * @param {HTMLImageElement|HTMLCanvasElement|HTMLVideoElement} image Image.
+ * @param {import("./canvas/Executor.js").Label|HTMLCanvasElement|HTMLImageElement|HTMLVideoElement} labelOrImage Label.
 * @param {number} originX Origin X.
 * @param {number} originY Origin Y.
 * @param {number} w Width.
@@ -397,8 +399,8 @@ export const resetTransform = createTransform();
 * @param {number} y Y.
 * @param {number} scale Scale.
 */
-export function drawImage(context,
-  transform, opacity, image, originX, originY, w, h, x, y, scale) {
+export function drawImageOrLabel(context,
+  transform, opacity, labelOrImage, originX, originY, w, h, x, y, scale) {
  let alpha;
  if (opacity != 1) {
    alpha = context.globalAlpha;
@@ -408,12 +410,21 @@ export function drawImage(context,
    context.setTransform.apply(context, transform);
  }

-  context.drawImage(image, originX, originY, w, h, x, y, w * scale, h * scale);
+  const isLabel = !!(/** @type {*} */ (labelOrImage).contextInstructions);
+
+  if (isLabel) {
+    context.translate(x, y);
+    context.scale(scale, scale);
+    executeLabelInstructions(/** @type {import("./canvas/Executor.js").Label} */ (labelOrImage), context);
+  } else {
+    context.drawImage(/** @type {HTMLCanvasElement|HTMLImageElement|HTMLVideoElement} */ (labelOrImage), originX, originY, w, h, x, y, w * scale, h * scale);
+  }

  if (opacity != 1) {
    context.globalAlpha = alpha;
  }
-  if (transform) {
+
+  if (transform || isLabel) {
    context.setTransform.apply(context, resetTransform);
  }
 }
--- a/src/ol/render/canvas/Executor.js
+++ b/src/ol/render/canvas/Executor.js
@@ -7,7 +7,7 @@ import {createEmpty, createOrUpdate,
 import {lineStringLength} from '../../geom/flat/length.js';
 import {drawTextOnPath} from '../../geom/flat/textpath.js';
 import {transform2D} from '../../geom/flat/transform.js';
-import {drawImage, defaultPadding, defaultTextBaseline} from '../canvas.js';
+import {drawImageOrLabel, defaultPadding, defaultTextBaseline} from '../canvas.js';
 import CanvasInstruction from './Instruction.js';
 import {TEXT_ALIGN} from './TextBuilder.js';
 import {
@@ -16,8 +16,7 @@ import {
  apply as applyTransform,
  setFromArray as transformSetFromArray
 } from '../../transform.js';
-import {createCanvasContext2D} from '../../dom.js';
-import {labelCache, defaultTextAlign, measureTextHeight, measureAndCacheTextWidth, measureTextWidths} from '../canvas.js';
+import {defaultTextAlign, measureTextHeight, measureAndCacheTextWidth, measureTextWidths} from '../canvas.js';
 import RBush from 'rbush/rbush.js';


@@ -31,6 +30,28 @@ import RBush from 'rbush/rbush.js';
 * @property {!Object<string, import("../canvas.js").StrokeState>} strokeStates The stroke states (decluttering).
 */

+/**
+ * @typedef Label
+ * @property {number} width
+ * @property {number} height
+ * @property {Array<string|number>} contextInstructions
+ */
+
+/**
+ * @param {Label} label Label.
+ * @param {CanvasRenderingContext2D} context Context.
+ */
+export function executeLabelInstructions(label, context) {
+  const contextInstructions = label.contextInstructions;
+  for (let i = 0, ii = contextInstructions.length; i < ii; i += 2) {
+    if (Array.isArray(contextInstructions[i + 1])) {
+      CanvasRenderingContext2D.prototype[contextInstructions[i]].apply(context, contextInstructions[i + 1]);
+    } else {
+      context[contextInstructions[i]] = contextInstructions[i + 1];
+    }
+  }
+}
+
 /**
 * @type {import("../../extent.js").Extent}
 */
@@ -159,69 +180,66 @@ class Executor {
   * @param {string} textKey Text style key.
   * @param {string} fillKey Fill style key.
   * @param {string} strokeKey Stroke style key.
-   * @return {HTMLCanvasElement} Image.
+   * @return {Label} Label.
   */
-  getTextImage(text, textKey, fillKey, strokeKey) {
-    let label;
-    const key = strokeKey + textKey + text + fillKey + this.pixelRatio;
+  createLabel(text, textKey, fillKey, strokeKey) {
+    const strokeState = strokeKey ? this.strokeStates[strokeKey] : null;
+    const fillState = fillKey ? this.fillStates[fillKey] : null;
+    const textState = this.textStates[textKey];
+    const pixelRatio = this.pixelRatio;
+    const scale = textState.scale * pixelRatio;
+    const align = TEXT_ALIGN[textState.textAlign || defaultTextAlign];
+    const strokeWidth = strokeKey && strokeState.lineWidth ? strokeState.lineWidth : 0;

-    if (!labelCache.containsKey(key)) {
-      const strokeState = strokeKey ? this.strokeStates[strokeKey] : null;
-      const fillState = fillKey ? this.fillStates[fillKey] : null;
-      const textState = this.textStates[textKey];
-      const pixelRatio = this.pixelRatio;
-      const scale = textState.scale * pixelRatio;
-      const align = TEXT_ALIGN[textState.textAlign || defaultTextAlign];
-      const strokeWidth = strokeKey && strokeState.lineWidth ? strokeState.lineWidth : 0;
-
-      const lines = text.split('\n');
-      const numLines = lines.length;
-      const widths = [];
-      const width = measureTextWidths(textState.font, lines, widths);
-      const lineHeight = measureTextHeight(textState.font);
-      const height = lineHeight * numLines;
-      const renderWidth = width + strokeWidth;
-      const context = createCanvasContext2D(
-        // make canvas 2 pixels wider to account for italic text width measurement errors
-        Math.ceil((renderWidth + 2) * scale),
-        Math.ceil((height + strokeWidth) * scale));
-      label = context.canvas;
-      labelCache.set(key, label);
-      if (scale != 1) {
-        context.scale(scale, scale);
-      }
-      context.font = textState.font;
-      if (strokeKey) {
-        context.strokeStyle = strokeState.strokeStyle;
-        context.lineWidth = strokeWidth;
-        context.lineCap = strokeState.lineCap;
-        context.lineJoin = strokeState.lineJoin;
-        context.miterLimit = strokeState.miterLimit;
-        if (context.setLineDash && strokeState.lineDash.length) {
-          context.setLineDash(strokeState.lineDash);
-          context.lineDashOffset = strokeState.lineDashOffset;
-        }
-      }
-      if (fillKey) {
-        context.fillStyle = fillState.fillStyle;
-      }
-      context.textBaseline = 'middle';
-      context.textAlign = 'center';
-      const leftRight = (0.5 - align);
-      const x = align * renderWidth + leftRight * strokeWidth;
-      let i;
-      if (strokeKey) {
-        for (i = 0; i < numLines; ++i) {
-          context.strokeText(lines[i], x + leftRight * widths[i], 0.5 * (strokeWidth + lineHeight) + i * lineHeight);
-        }
-      }
-      if (fillKey) {
-        for (i = 0; i < numLines; ++i) {
-          context.fillText(lines[i], x + leftRight * widths[i], 0.5 * (strokeWidth + lineHeight) + i * lineHeight);
-        }
+    const lines = text.split('\n');
+    const numLines = lines.length;
+    const widths = [];
+    const width = measureTextWidths(textState.font, lines, widths);
+    const lineHeight = measureTextHeight(textState.font);
+    const height = lineHeight * numLines;
+    const renderWidth = width + strokeWidth;
+    const contextInstructions = [];
+    /** @type {Label} */
+    const label = {
+      // make canvas 2 pixels wider to account for italic text width measurement errors
+      width: Math.ceil((renderWidth + 2) * scale),
+      height: Math.ceil((height + strokeWidth) * scale),
+      contextInstructions: contextInstructions
+    };
+    if (scale != 1) {
+      contextInstructions.push('scale', [scale, scale]);
+    }
+    contextInstructions.push('font', textState.font);
+    if (strokeKey) {
+      contextInstructions.push('strokeStyle', strokeState.strokeStyle);
+      contextInstructions.push('lineWidth', strokeWidth);
+      contextInstructions.push('lineCap', strokeState.lineCap);
+      contextInstructions.push('lineJoin', strokeState.lineJoin);
+      contextInstructions.push('miterLimit', strokeState.miterLimit);
+      if (CanvasRenderingContext2D.prototype.setLineDash && strokeState.lineDash.length) {
+        contextInstructions.push('setLineDash', [strokeState.lineDash]);
+        contextInstructions.push('lineDashOffset', strokeState.lineDashOffset);
      }
    }
-    return labelCache.get(key, this);
+    if (fillKey) {
+      contextInstructions.push('fillStyle', fillState.fillStyle);
+    }
+    contextInstructions.push('textBaseline', 'middle');
+    contextInstructions.push('textAlign', 'center');
+    const leftRight = (0.5 - align);
+    const x = align * renderWidth + leftRight * strokeWidth;
+    let i;
+    if (strokeKey) {
+      for (i = 0; i < numLines; ++i) {
+        contextInstructions.push('strokeText', [lines[i], x + leftRight * widths[i], 0.5 * (strokeWidth + lineHeight) + i * lineHeight]);
+      }
+    }
+    if (fillKey) {
+      for (i = 0; i < numLines; ++i) {
+        contextInstructions.push('fillText', [lines[i], x + leftRight * widths[i], 0.5 * (strokeWidth + lineHeight) + i * lineHeight]);
+      }
+    }
+    return label;
  }

  /**
@@ -254,7 +272,7 @@ class Executor {
   * @param {CanvasRenderingContext2D} context Context.
   * @param {number} x X.
   * @param {number} y Y.
-   * @param {HTMLImageElement|HTMLCanvasElement|HTMLVideoElement} image Image.
+   * @param {Label|HTMLImageElement|HTMLCanvasElement|HTMLVideoElement} imageOrLabel Image.
   * @param {number} anchorX Anchor X.
   * @param {number} anchorY Anchor Y.
   * @param {import("../canvas.js").DeclutterGroup} declutterGroup Declutter group.
@@ -270,11 +288,11 @@ class Executor {
   * @param {Array<*>} fillInstruction Fill instruction.
   * @param {Array<*>} strokeInstruction Stroke instruction.
   */
-  replayImage_(
+  replayImageOrLabel_(
    context,
    x,
    y,
-    image,
+    imageOrLabel,
    anchorX,
    anchorY,
    declutterGroup,
@@ -296,8 +314,8 @@ class Executor {
    x -= anchorX;
    y -= anchorY;

-    const w = (width + originX > image.width) ? image.width - originX : width;
-    const h = (height + originY > image.height) ? image.height - originY : height;
+    const w = (width + originX > imageOrLabel.width) ? imageOrLabel.width - originX : width;
+    const h = (height + originY > imageOrLabel.height) ? imageOrLabel.height - originY : height;
    const boxW = padding[3] + w * scale + padding[1];
    const boxH = padding[0] + h * scale + padding[2];
    const boxX = x - padding[3];
@@ -351,7 +369,7 @@ class Executor {
      }
      extend(declutterGroup, tmpExtent);
      const declutterArgs = intersects ?
-        [context, transform ? transform.slice(0) : null, opacity, image, originX, originY, w, h, x, y, scale] :
+        [context, transform ? transform.slice(0) : null, opacity, imageOrLabel, originX, originY, w, h, x, y, scale] :
        null;
      if (declutterArgs) {
        if (fillStroke) {
@@ -365,7 +383,7 @@ class Executor {
          /** @type {Array<*>} */ (fillInstruction),
          /** @type {Array<*>} */ (strokeInstruction));
      }
-      drawImage(context, transform, opacity, image, originX, originY, w, h, x, y, scale);
+      drawImageOrLabel(context, transform, opacity, imageOrLabel, originX, originY, w, h, x, y, scale);
    }
  }

@@ -440,7 +458,7 @@ class Executor {
                declutterData[13], declutterData[14], declutterData[15], declutterData[16],
                declutterData[11], declutterData[12]);
            }
-            drawImage.apply(undefined, declutterData);
+            drawImageOrLabel.apply(undefined, declutterData);
            if (currentAlpha !== opacity) {
              context.globalAlpha = currentAlpha;
            }
@@ -459,12 +477,12 @@ class Executor {
   * @param {string} textKey The key of the text state.
   * @param {string} strokeKey The key for the stroke state.
   * @param {string} fillKey The key for the fill state.
-   * @return {{label: HTMLCanvasElement, anchorX: number, anchorY: number}} The text image and its anchor.
+   * @return {{label: Label, anchorX: number, anchorY: number}} The text image and its anchor.
   */
-  drawTextImageWithPointPlacement_(text, textKey, strokeKey, fillKey) {
+  drawLabelWithPointPlacement_(text, textKey, strokeKey, fillKey) {
    const textState = this.textStates[textKey];

-    const label = this.getTextImage(text, textKey, fillKey, strokeKey);
+    const label = this.createLabel(text, textKey, fillKey, strokeKey);

    const strokeState = this.strokeStates[strokeKey];
    const pixelRatio = this.pixelRatio;
@@ -472,7 +490,7 @@ class Executor {
    const baseline = TEXT_ALIGN[textState.textBaseline || defaultTextBaseline];
    const strokeWidth = strokeState && strokeState.lineWidth ? strokeState.lineWidth : 0;

-    // Remove the 2 pixels we added in getTextImage() for the anchor
+    // Remove the 2 pixels we added in createLabel() for the anchor
    const width = label.width / pixelRatio - 2 * textState.scale;
    const anchorX = align * width + 2 * (0.5 - align) * strokeWidth;
    const anchorY = baseline * label.height / pixelRatio + 2 * (0.5 - baseline) * strokeWidth;
@@ -637,7 +655,7 @@ class Executor {
            textKey = /** @type {string} */ (instruction[19]);
            strokeKey = /** @type {string} */ (instruction[20]);
            fillKey = /** @type {string} */ (instruction[21]);
-            const labelWithAnchor = this.drawTextImageWithPointPlacement_(text, textKey, strokeKey, fillKey);
+            const labelWithAnchor = this.drawLabelWithPointPlacement_(text, textKey, strokeKey, fillKey);
            image = labelWithAnchor.label;
            instruction[3] = image;
            const textOffsetX = /** @type {number} */ (instruction[22]);
@@ -690,7 +708,7 @@ class Executor {
              }
              declutterGroup = declutterGroups[index];
            }
-            this.replayImage_(context,
+            this.replayImageOrLabel_(context,
              pixelCoordinates[d], pixelCoordinates[d + 1], image, anchorX, anchorY,
              declutterGroup, height, opacity, originX, originY, rotation, scale,
              snapToPixel, width, padding,
@@ -747,10 +765,10 @@ class Executor {
                for (c = 0, cc = parts.length; c < cc; ++c) {
                  part = parts[c]; // x, y, anchorX, rotation, chunk
                  chars = /** @type {string} */ (part[4]);
-                  label = this.getTextImage(chars, textKey, '', strokeKey);
+                  label = this.createLabel(chars, textKey, '', strokeKey);
                  anchorX = /** @type {number} */ (part[2]) + strokeWidth;
                  anchorY = baseline * label.height + (0.5 - baseline) * 2 * strokeWidth - offsetY;
-                  this.replayImage_(context,
+                  this.replayImageOrLabel_(context,
                    /** @type {number} */ (part[0]), /** @type {number} */ (part[1]), label,
                    anchorX, anchorY, declutterGroup, label.height, 1, 0, 0,
                    /** @type {number} */ (part[3]), pixelRatioScale, false, label.width,
@@ -761,10 +779,10 @@ class Executor {
                for (c = 0, cc = parts.length; c < cc; ++c) {
                  part = parts[c]; // x, y, anchorX, rotation, chunk
                  chars = /** @type {string} */ (part[4]);
-                  label = this.getTextImage(chars, textKey, fillKey, '');
+                  label = this.createLabel(chars, textKey, fillKey, '');
                  anchorX = /** @type {number} */ (part[2]);
                  anchorY = baseline * label.height - offsetY;
-                  this.replayImage_(context,
+                  this.replayImageOrLabel_(context,
                    /** @type {number} */ (part[0]), /** @type {number} */ (part[1]), label,
                    anchorX, anchorY, declutterGroup, label.height, 1, 0, 0,
                    /** @type {number} */ (part[3]), pixelRatioScale, false, label.width,
--- a/src/ol/render/canvas/LabelCache.js
+++ b/src/ol/render/canvas/LabelCache.js
@@ -1,20 +0,0 @@
-import LRUCache from '../../structs/LRUCache.js';
-
-/**
- * @module ol/render/canvas/LabelCache
- */
-
-/**
- * @classdesc
- * Cache of pre-rendered labels.
- */
-class LabelCache extends LRUCache {
-
-  expireCache() {
-    while (this.canExpireCache()) {
-      this.pop();
-    }
-  }
-}
-
-export default LabelCache;
--- a/src/ol/render/canvas/TextBuilder.js
+++ b/src/ol/render/canvas/TextBuilder.js
@@ -6,7 +6,7 @@ import {asColorLike} from '../../colorlike.js';
 import {intersects} from '../../extent.js';
 import {matchingChunk} from '../../geom/flat/straightchunk.js';
 import GeometryType from '../../geom/GeometryType.js';
-import {labelCache, defaultTextAlign, defaultPadding, defaultLineCap, defaultLineDashOffset, defaultLineDash, defaultLineJoin, defaultFillStyle, checkFont, defaultFont, defaultLineWidth, defaultMiterLimit, defaultStrokeStyle, defaultTextBaseline} from '../canvas.js';
+import {defaultTextAlign, defaultPadding, defaultLineCap, defaultLineDashOffset, defaultLineDash, defaultLineJoin, defaultFillStyle, registerFont, defaultFont, defaultLineWidth, defaultMiterLimit, defaultStrokeStyle, defaultTextBaseline} from '../canvas.js';
 import CanvasInstruction from './Instruction.js';
 import CanvasBuilder from './Builder.js';
 import TextPlacement from '../../style/TextPlacement.js';
@@ -138,7 +138,6 @@ class CanvasTextBuilder extends CanvasBuilder {
   */
  finish() {
    const instructions = super.finish();
-    labelCache.expireCache();
    instructions.textStates = this.textStates;
    instructions.fillStates = this.fillStates;
    instructions.strokeStates = this.strokeStates;
@@ -432,7 +431,7 @@ class CanvasTextBuilder extends CanvasBuilder {

      textState = this.textState_;
      const font = textStyle.getFont() || defaultFont;
-      checkFont(font);
+      registerFont(font);
      const textScale = textStyle.getScale();
      textState.overflow = textStyle.getOverflow();
      textState.font = font;
--- a/src/ol/renderer/Composite.js
+++ b/src/ol/renderer/Composite.js
@@ -8,9 +8,9 @@ import RenderEventType from '../render/EventType.js';
 import MapRenderer from './Map.js';
 import SourceState from '../source/State.js';
 import {replaceChildren} from '../dom.js';
-import {labelCache} from '../render/canvas.js';
-import EventType from '../events/EventType.js';
 import {listen, unlistenByKey} from '../events.js';
+import {checkedFonts} from '../render/canvas.js';
+import ObjectEventType from '../ObjectEventType.js';


 /**
@@ -29,7 +29,7 @@ class CompositeMapRenderer extends MapRenderer {
    /**
     * @type {import("../events.js").EventsKey}
     */
-    this.labelCacheKey_ = listen(labelCache, EventType.CLEAR, map.redrawText.bind(map));
+    this.fontChangeListenerKey_ = listen(checkedFonts, ObjectEventType.PROPERTYCHANGE, map.redrawText.bind(map));

    /**
     * @private
@@ -73,7 +73,7 @@ class CompositeMapRenderer extends MapRenderer {
  }

  disposeInternal() {
-    unlistenByKey(this.labelCacheKey_);
+    unlistenByKey(this.fontChangeListenerKey_);
    this.element_.parentNode.removeChild(this.element_);
    super.disposeInternal();
  }
--- a/src/ol/structs/LRUCache.js
+++ b/src/ol/structs/LRUCache.js
@@ -3,8 +3,6 @@
 */

 import {assert} from '../asserts.js';
-import EventTarget from '../events/Target.js';
-import EventType from '../events/EventType.js';


 /**
@@ -25,15 +23,13 @@ import EventType from '../events/EventType.js';
 * @fires import("../events/Event.js").default
 * @template T
 */
-class LRUCache extends EventTarget {
+class LRUCache {

  /**
   * @param {number=} opt_highWaterMark High water mark.
   */
  constructor(opt_highWaterMark) {

-    super();
-
    /**
     * @type {number}
     */
@@ -82,7 +78,6 @@ class LRUCache extends EventTarget {
    this.entries_ = {};
    this.oldest_ = null;
    this.newest_ = null;
-    this.dispatchEvent(EventType.CLEAR);
  }