feat(RenderWindow): add manageCanvas for externally owned canvases

Author: PaulHax

Sources/Rendering/OpenGL/RenderWindow/index.d.ts

@@ -21,6 +21,7 @@ export interface IOpenGLRenderWindowInitialValues {
   context?: WebGLRenderingContext | WebGL2RenderingContext;
   context2D?: CanvasRenderingContext2D;
   canvas?: HTMLCanvasElement;
+  manageCanvas?: boolean;
   cursorVisibility?: boolean;
   cursor?: string;
   textureUnitManager?: null;
@@ -93,6 +94,10 @@ export interface vtkOpenGLRenderWindow extends vtkViewNode {
    */
   setCanvas(canvas: Nullable<HTMLCanvasElement>): boolean;
 
+  getManageCanvas(): boolean;
+
+  setManageCanvas(manageCanvas: boolean): boolean;
+
   /**
    * Check if a point is in the viewport.
    * @param {Number} x The x coordinate.

Sources/Rendering/OpenGL/RenderWindow/index.js

@@ -141,7 +141,7 @@ function vtkOpenGLRenderWindow(publicAPI, model) {
   const previousSize = [0, 0];
   function updateWindow() {
     // Canvas size
-    if (model.renderable) {
+    if (model.renderable && model.manageCanvas) {
       if (
         model.size[0] !== previousSize[0] ||
         model.size[1] !== previousSize[1]
@@ -160,7 +160,9 @@ function vtkOpenGLRenderWindow(publicAPI, model) {
     }
 
     // Offscreen ?
-    model.canvas.style.display = model.useOffScreen ? 'none' : 'block';
+    if (model.manageCanvas) {
+      model.canvas.style.display = model.useOffScreen ? 'none' : 'block';
+    }
 
     // Cursor type
     if (model.el) {
@@ -549,15 +551,28 @@ function vtkOpenGLRenderWindow(publicAPI, model) {
     if (model.deleted) {
       return null;
     }
+    const requestedSize =
+      !!size || scale !== 1
+        ? size || model.size.map((val) => val * scale)
+        : null;
+    const requiresCanvasResize =
+      requestedSize !== null &&
+      (requestedSize[0] !== model.size[0] ||
+        requestedSize[1] !== model.size[1]);
+    const screenshotSize = requiresCanvasResize ? requestedSize : null;
+
+    if (!model.manageCanvas && requiresCanvasResize) {
+      throw new Error(
+        'Resizing screenshot capture requires manageCanvas=true on vtkOpenGLRenderWindow'
+      );
+    }
+
     model.imageFormat = format;
     const previous = model.notifyStartCaptureImage;
     model.notifyStartCaptureImage = true;
 
     model._screenshot = {
-      size:
-        !!size || scale !== 1
-          ? size || model.size.map((val) => val * scale)
-          : null,
+      size: screenshotSize,
     };
 
     return new Promise((resolve, reject) => {
@@ -1307,6 +1322,7 @@ const DEFAULT_VALUES = {
   context: null,
   context2D: null,
   canvas: null,
+  manageCanvas: true,
   cursorVisibility: true,
   cursor: 'pointer',
   textureUnitManager: null,
@@ -1377,6 +1393,7 @@ export function extend(publicAPI, model, initialValues = {}) {
     'context',
     'context2D',
     'canvas',
+    'manageCanvas',
     'renderPasses',
     'notifyStartCaptureImage',
     'defaultToWebgl2',