Smarter reuse detection

src/ol/render/canvas/Executor.js

@@ -362,10 +362,12 @@ class Executor extends Disposable {
       const declutterArgs = intersects ?
         [context, transform ? transform.slice(0) : null, opacity, image, originX, originY, w, h, x, y, scale] :
         null;
-      if (declutterArgs && fillStroke) {
-        declutterArgs.push(fillInstruction, strokeInstruction, p1, p2, p3, p4);
+      if (declutterArgs) {
+        if (fillStroke) {
+          declutterArgs.push(fillInstruction, strokeInstruction, p1, p2, p3, p4);
+        }
+        declutterGroup.push(declutterArgs);
       }
-      declutterGroup.push(declutterArgs);
     } else if (intersects) {
       if (fillStroke) {
         this.replayTextBackground_(context, p1, p2, p3, p4,

src/ol/renderer/Composite.js

@@ -9,7 +9,6 @@ import MapRenderer from './Map.js';
 import SourceState from '../source/State.js';
 import {replaceChildren} from '../dom.js';
 import {labelCache} from '../render/canvas.js';
-import {altShiftKeysOnly} from '../events/condition.js';
 
 
 /**

src/ol/renderer/canvas/ImageLayer.js

@@ -6,7 +6,7 @@ import ViewHint from '../../ViewHint.js';
 import {containsExtent, intersects} from '../../extent.js';
 import {getIntersection, isEmpty} from '../../extent.js';
 import CanvasLayerRenderer from './Layer.js';
-import {compose as composeTransform, makeInverse, toString as transformToString, apply as applyTransform} from '../../transform.js';
+import {compose as composeTransform, makeInverse, toString as transformToString} from '../../transform.js';
 
 /**
  * @classdesc

src/ol/renderer/canvas/Layer.js

@@ -8,7 +8,6 @@ import RenderEventType from '../../render/EventType.js';
 import {rotateAtOffset} from '../../render/canvas.js';
 import LayerRenderer from '../Layer.js';
 import {create as createTransform, apply as applyTransform, compose as composeTransform, toString as transformToString} from '../../transform.js';
-import ContextEventType from '../../webgl/ContextEventType.js';
 
 /**
  * @abstract
@@ -64,16 +63,20 @@ class CanvasLayerRenderer extends LayerRenderer {
      */
     this.context = null;
 
+    /**
+     * @type {boolean}
+     */
+    this.containerReused = false;
+
   }
 
   /**
    * Get a rendering container from an existing target, if compatible.
    * @param {HTMLElement} target Potential render target.
    * @param {import("../../transform").Transform} transform Transform.
-   * @return {boolean} The target is reused for this layer.
    */
   useContainer(target, transform) {
-    let reused = false;
+    const layerClassName = this.getLayer().getClassName();
     let container, context;
     if (target) {
       const canvas = target.firstElementChild;
@@ -82,33 +85,33 @@ class CanvasLayerRenderer extends LayerRenderer {
       }
     }
     if (context && context.canvas.style.transform === transformToString(transform)) {
-      container = target;
-      reused = true;
-    } else {
-      context = null;
-      container = this.container;
-      if (!container) {
-        container = document.createElement('div');
-        const style = container.style;
-        style.position = 'absolute';
-        style.width = '100%';
-        style.height = '100%';
-      }
+      // Container of the previous layer renderer can be used.
+      target.classList.add(layerClassName);
+      this.container = target;
+      this.context = context;
+      this.containerReused = true;
+    } else if (this.containerReused) {
+      // Previously reused container cannot be used any more.
+      this.container = null;
+      this.context = null;
+      this.containerReused = false;
     }
-    if (container !== this.container) {
-      container.classList.add(this.getLayer().getClassName());
+    if (!this.container) {
+      container = document.createElement('div');
+      container.className = layerClassName;
+      let style = container.style;
+      style.position = 'absolute';
+      style.width = '100%';
+      style.height = '100%';
+      context = createCanvasContext2D();
+      const canvas = context.canvas;
+      container.appendChild(canvas);
+      style = canvas.style;
+      style.position = 'absolute';
+      style.transformOrigin = 'top left';
       this.container = container;
-      if (!context) {
-        context = createCanvasContext2D();
-        const canvas = context.canvas;
-        container.appendChild(canvas);
-        const style = canvas.style;
-        style.position = 'absolute';
-        style.transformOrigin = 'top left';
-      }
       this.context = context;
     }
-    return reused;
   }
 
   /**

src/ol/renderer/canvas/TileLayer.js

@@ -7,7 +7,6 @@ import TileState from '../../TileState.js';
 import {createEmpty, equals, getIntersection, getTopLeft} from '../../extent.js';
 import CanvasLayerRenderer from './Layer.js';
 import {apply as applyTransform, compose as composeTransform, makeInverse, toString as transformToString} from '../../transform.js';
-import {numberSafeCompareFunction} from '../../array.js';
 
 /**
  * @classdesc
@@ -234,7 +233,7 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
       -width / 2, -height / 2
     );
 
-    const reused = this.useContainer(target, this.pixelTransform_);
+    this.useContainer(target, this.pixelTransform_);
     const context = this.context;
     const canvas = context.canvas;
 
@@ -251,7 +250,7 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
     if (canvas.width != width || canvas.height != height) {
       canvas.width = width;
       canvas.height = height;
-    } else if (!reused) {
+    } else if (!this.containerReused) {
       context.clearRect(0, 0, width, height);
     }
 

src/ol/renderer/canvas/VectorLayer.js

@@ -70,17 +70,7 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
   /**
    * @inheritDoc
    */
-  renderFrame(frameState, layerState) {
-    const context = this.context;
-    const canvas = context.canvas;
-
-    const replayGroup = this.replayGroup_;
-    if (!replayGroup || replayGroup.isEmpty()) {
-      if (canvas.width > 0) {
-        canvas.width = 0;
-      }
-      return canvas;
-    }
+  renderFrame(frameState, layerState, target) {
 
     const pixelRatio = frameState.pixelRatio;
 
@@ -88,6 +78,18 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
     makeScale(this.pixelTransform_, 1 / pixelRatio, 1 / pixelRatio);
     makeInverse(this.inversePixelTransform_, this.pixelTransform_);
 
+    this.useContainer(target, this.pixelTransform_);
+    const context = this.context;
+    const canvas = context.canvas;
+
+    const replayGroup = this.replayGroup_;
+    if (!replayGroup || replayGroup.isEmpty()) {
+      if (!this.containerReused && canvas.width > 0) {
+        canvas.width = 0;
+      }
+      return this.container;
+    }
+
     // resize and clear
     const width = Math.round(frameState.size[0] * pixelRatio);
     const height = Math.round(frameState.size[1] * pixelRatio);
@@ -98,7 +100,7 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
       if (canvas.style.transform !== canvasTransform) {
         canvas.style.transform = canvasTransform;
       }
-    } else {
+    } else if (!this.containerReused) {
       context.clearRect(0, 0, width, height);
     }
 
@@ -166,7 +168,7 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
       canvas.style.opacity = opacity;
     }
 
-    return canvas;
+    return this.container;
   }
 
   /**

src/ol/renderer/canvas/VectorTileLayer.js

@@ -123,27 +123,31 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
    * @inheritDoc
    */
   useContainer(target, transform) {
-    let context;
+    let overlayContext;
     if (target && target.childElementCount === 2) {
-      context = target.lastElementChild.getContext('2d');
-      if (!context) {
+      overlayContext = target.lastElementChild.getContext('2d');
+      if (!overlayContext) {
         target = null;
       }
-    } else {
-      context = this.overlayContext_;
-      if (!this.overlayContext_) {
-        context = createCanvasContext2D();
-        const style = context.canvas.style;
-        style.position = 'absolute';
-        style.transformOrigin = 'top left';
-      }
     }
-    const reused = super.useContainer(target, transform);
+    const containerReused = this.containerReused;
+    super.useContainer(target, transform);
+    if (containerReused && !this.containerReused && !overlayContext) {
+      this.overlayContext_ = null;
+    }
+    if (this.containerReused && overlayContext) {
+      this.overlayContext_ = overlayContext;
+    }
+    if (!this.overlayContext_) {
+      const overlayContext = createCanvasContext2D();
+      const style = overlayContext.canvas.style;
+      style.position = 'absolute';
+      style.transformOrigin = 'top left';
+      this.overlayContext_ = overlayContext;
+    }
     if (this.container.childElementCount === 1) {
-      this.container.appendChild(context.canvas);
+      this.container.appendChild(this.overlayContext_.canvas);
     }
-    this.overlayContext_ = context;
-    return reused;
   }
 
   /**
@@ -401,7 +405,6 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
 
     if (!isEmpty(this.renderTileImageQueue_) && !this.extentChanged) {
       this.renderTileImages_(hifi, frameState);
-      return this.container;
     }
 
     const context = this.overlayContext_;
@@ -427,7 +430,7 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
       if (canvas.style.transform !== canvasTransform) {
         canvas.style.transform = canvasTransform;
       }
-    } else {
+    } else if (!this.containerReused) {
       context.clearRect(0, 0, width, height);
     }
 
@@ -496,10 +499,6 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
       canvas.style.opacity = opacity;
     }
 
-    // Now that we have rendered the tiles we have already, let's prepare new tile images
-    // for the next frame
-    this.renderTileImages_(hifi, frameState);
-
     return this.container;
   }