Make forward and inverse pixel transforms during render

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, toString as transformToString} from '../../transform.js';
+import {compose as composeTransform, makeInverse, toString as transformToString} from '../../transform.js';
 
 /**
  * @classdesc
@@ -93,16 +93,17 @@ class CanvasImageLayerRenderer extends CanvasLayerRenderer {
       width = height = size;
     }
 
-    const context = this.context;
-    const canvas = context.canvas;
-
-    const pixelTransform = composeTransform(this.pixelTransform_,
+    // set forward and inverse pixel transforms
+    composeTransform(this.pixelTransform_,
       frameState.size[0] / 2, frameState.size[1] / 2,
       1 / pixelRatio, 1 / pixelRatio,
       rotation,
       -width / 2, -height / 2
     );
-    const canvasTransform = transformToString(pixelTransform);
+    makeInverse(this.pixelTransform_, this.inversePixelTransform_);
+
+    const context = this.context;
+    const canvas = context.canvas;
 
     if (canvas.width != width || canvas.height != height) {
       canvas.width = width;
@@ -150,6 +151,7 @@ class CanvasImageLayerRenderer extends CanvasLayerRenderer {
       canvas.style.opacity = opacity;
     }
 
+    const canvasTransform = transformToString(this.pixelTransform_);
     if (canvasTransform !== canvas.style.transform) {
       canvas.style.transform = canvasTransform;
     }

src/ol/renderer/canvas/Layer.js

@@ -28,19 +28,29 @@ class CanvasLayerRenderer extends LayerRenderer {
     this.renderedResolution;
 
     /**
-     * A temporary transform.
+     * A temporary transform.  The values in this transform should only be used in a
+     * function that sets the values.
      * @private
      * @type {import("../../transform.js").Transform}
      */
     this.tempTransform_ = createTransform();
 
     /**
-     * The transform for rendered pixels to viewport CSS pixels.
+     * The transform for rendered pixels to viewport CSS pixels.  This transform must
+     * be set when rendering a frame and may be used by other functions after rendering.
      * @private
      * @type {import("../../transform.js").Transform}
      */
     this.pixelTransform_ = createTransform();
 
+    /**
+     * The transform for viewport CSS pixels to rendered pixels.  This transform must
+     * be set when rendering a frame and may be used by other functions after rendering.
+     * @private
+     * @type {import("../../transform.js").Transform}
+     */
+    this.inversePixelTransform_ = createTransform();
+
     /**
      * @protected
      * @type {CanvasRenderingContext2D}

src/ol/renderer/canvas/TileLayer.js

@@ -6,7 +6,7 @@ import TileRange from '../../TileRange.js';
 import TileState from '../../TileState.js';
 import {createEmpty, getIntersection, getTopLeft} from '../../extent.js';
 import CanvasLayerRenderer from './Layer.js';
-import {compose as composeTransform, toString as transformToString} from '../../transform.js';
+import {compose as composeTransform, makeInverse, toString as transformToString} from '../../transform.js';
 
 /**
  * @classdesc
@@ -222,15 +222,18 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
       }
     }
 
+
     const canvas = context.canvas;
     const canvasScale = tileResolution / frameState.viewState.resolution / tilePixelRatio;
-    const pixelTransform = composeTransform(this.pixelTransform_,
+
+    // set forward and inverse pixel transforms
+    composeTransform(this.pixelTransform_,
       frameState.size[0] / 2, frameState.size[1] / 2,
       canvasScale, canvasScale,
       rotation,
       -width / 2, -height / 2
     );
-    const canvasTransform = transformToString(pixelTransform);
+    makeInverse(this.pixelTransform_, this.inversePixelTransform_);
 
     if (canvas.width != width || canvas.height != height) {
       canvas.width = width;
@@ -302,6 +305,7 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
       canvas.style.opacity = opacity;
     }
 
+    const canvasTransform = transformToString(this.pixelTransform_);
     if (canvasTransform !== canvas.style.transform) {
       canvas.style.transform = canvasTransform;
     }

src/ol/renderer/canvas/VectorLayer.js

@@ -13,7 +13,7 @@ import CanvasBuilderGroup from '../../render/canvas/BuilderGroup.js';
 import InstructionsGroupExecutor from '../../render/canvas/ExecutorGroup.js';
 import CanvasLayerRenderer from './Layer.js';
 import {defaultOrder as defaultRenderOrder, getTolerance as getRenderTolerance, getSquaredTolerance as getSquaredRenderTolerance, renderFeature} from '../vector.js';
-import {toString as transformToString} from '../../transform.js';
+import {toString as transformToString, makeScale, makeInverse} from '../../transform.js';
 
 /**
  * @classdesc
@@ -105,8 +105,9 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
 
     const pixelRatio = frameState.pixelRatio;
 
-    // a scale transform (we could add a createScale function in ol/transform)
-    const pixelTransform = [1 / pixelRatio, 0, 0, 1 / pixelRatio, 0, 0];
+    // set forward and inverse pixel transforms
+    makeScale(this.pixelTransform_, 1 / pixelRatio, 1 / pixelRatio);
+    makeInverse(this.pixelTransform_, this.inversePixelTransform_);
 
     // resize and clear
     const width = Math.round(frameState.size[0] * pixelRatio);
@@ -114,7 +115,7 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
     if (canvas.width != width || canvas.height != height) {
       canvas.width = width;
       canvas.height = height;
-      const canvasTransform = transformToString(pixelTransform);
+      const canvasTransform = transformToString(this.pixelTransform_);
       if (canvas.style.transform !== canvasTransform) {
         canvas.style.transform = canvasTransform;
       }

src/ol/renderer/canvas/VectorTileLayer.js

@@ -26,7 +26,9 @@ import {
   reset as resetTransform,
   scale as scaleTransform,
   translate as translateTransform,
-  toString as transformToString
+  toString as transformToString,
+  makeScale,
+  makeInverse
 } from '../../transform.js';
 import CanvasExecutorGroup, {replayDeclutter} from '../../render/canvas/ExecutorGroup.js';
 
@@ -98,6 +100,13 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
      */
     this.overlayPixelTransform_ = createTransform();
 
+    /**
+     * The transform for viewport CSS pixels to rendered pixels for the overlay canvas.
+     * @private
+     * @type {import("../../transform.js").Transform}
+     */
+    this.inverseOverlayPixelTransform_ = createTransform();
+
     /**
      * Declutter tree.
      * @private
@@ -384,12 +393,14 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
     const rotation = frameState.viewState.rotation;
     const size = frameState.size;
 
+    // set forward and inverse pixel transforms
+    makeScale(this.overlayPixelTransform_, 1 / pixelRatio, 1 / pixelRatio);
+    makeInverse(this.overlayPixelTransform_, this.inverseOverlayPixelTransform_);
+
     // resize and clear
     const canvas = context.canvas;
     const width = Math.round(size[0] * pixelRatio);
     const height = Math.round(size[1] * pixelRatio);
-    this.overlayPixelTransform_[0] = 1 / pixelRatio;
-    this.overlayPixelTransform_[3] = 1 / pixelRatio;
     if (canvas.width != width || canvas.height != height) {
       canvas.width = width;
       canvas.height = height;