await screenshot clipboard write & fallback to <img> on fail

src/mol-plugin-ui/viewport/screenshot.tsx

@@ -34,12 +34,16 @@ export class DownloadScreenshotControls extends PluginUIComponent<{ close: () =>
     }
 
     private copy = async () => {
+        try {
             await this.plugin.helpers.viewportScreenshot?.copyToClipboard();
             PluginCommands.Toast.Show(this.plugin, {
                 message: 'Copied to clipboard.',
                 title: 'Screenshot',
                 timeoutMs: 1500
             });
+        } catch {
+            return this.copyImg();
+        }
     }
 
     private copyImg = async () => {
@@ -71,8 +75,7 @@ export class DownloadScreenshotControls extends PluginUIComponent<{ close: () =>
                 <CropControls plugin={this.plugin} />
             </div>}
             <div className='msp-flex-row'>
-                {hasClipboardApi && <Button icon={CopySvg} onClick={this.copy} disabled={this.state.isDisabled}>Copy</Button>}
-                {!hasClipboardApi && !this.state.imageData && <Button icon={CopySvg} onClick={this.copyImg} disabled={this.state.isDisabled}>Copy</Button>}
+                {!this.state.imageData && <Button icon={CopySvg} onClick={hasClipboardApi ? this.copy : this.copyImg} disabled={this.state.isDisabled}>Copy</Button>}
                 {this.state.imageData && <Button onClick={() => this.setState({ imageData: void 0 })} disabled={this.state.isDisabled}>Clear</Button>}
                 <Button icon={GetAppSvg} onClick={this.download} disabled={this.state.isDisabled}>Download</Button>
             </div>

src/mol-plugin/util/viewport-screenshot.ts

@@ -324,7 +324,7 @@ class ViewportScreenshotHelper extends PluginComponent {
             await ctx.update('Converting image...');
             const blob = await canvasToBlob(this.canvas, 'png');
             const item = new ClipboardItem({ 'image/png': blob });
-            cb.write([item]);
+            await cb.write([item]);
             this.plugin.log.message('Image copied to clipboard.');
         });
     }