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Update chart save button to wait for the promise from the vega getIma… #631

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Merged
jpolitz merged 1 commit into from
Jun 18, 2026
Merged

Update chart save button to wait for the promise from the vega getIma… #631

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60 changes: 34 additions & 26 deletions src/web/js/repl-ui.js
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Original file line number Diff line number Diff line change
Expand Up @@ -462,32 +462,40 @@
savedOptions = options;
return $.extend({}, options, {chartArea: null});
});
const img = document.createElement('img');
img.src = args.getImageURI();
const temp = document.createElement('canvas');
temp.width = img.width;
temp.height = img.height;
const ctx = temp.getContext('2d');
ctx.drawImage(img, 0, 0);
const image = runtime.getField(imageLib, "internal");
const trimmed = image.trimCanvas(temp);
const download = document.createElement('a');
download.href = trimmed.toDataURL();
download.download = 'chart.png';
// from https://stackoverflow.com/questions/3906142/how-to-save-a-png-from-javascript-variable
function fireEvent(obj, evt){
const fireOnThis = obj;
if(document.createEvent) {
const evObj = document.createEvent('MouseEvents');
evObj.initEvent(evt, true, false);
fireOnThis.dispatchEvent(evObj);
} else if(document.createEventObject) {
const evObj = document.createEventObject();
fireOnThis.fireEvent('on' + evt, evObj);
}
}
fireEvent(download, 'click');
args.draw(_ => savedOptions);
// getImageURI may return a data URL synchronously (Google Charts)
// or a Promise resolving to one (Vega, which renders asynchronously).
Promise.resolve(args.getImageURI()).then((uri) => {
const img = document.createElement('img');
// Must wait for the image to load before reading its dimensions
// and drawing it; for the async (Vega) path it isn't ready yet.
img.onload = () => {
const temp = document.createElement('canvas');
temp.width = img.width;
temp.height = img.height;
const ctx = temp.getContext('2d');
ctx.drawImage(img, 0, 0);
const image = runtime.getField(imageLib, "internal");
const trimmed = image.trimCanvas(temp);
const download = document.createElement('a');
download.href = trimmed.toDataURL();
download.download = 'chart.png';
// from https://stackoverflow.com/questions/3906142/how-to-save-a-png-from-javascript-variable
function fireEvent(obj, evt){
const fireOnThis = obj;
if(document.createEvent) {
const evObj = document.createEvent('MouseEvents');
evObj.initEvent(evt, true, false);
fireOnThis.dispatchEvent(evObj);
} else if(document.createEventObject) {
const evObj = document.createEventObject();
fireOnThis.fireEvent('on' + evt, evObj);
}
}
fireEvent(download, 'click');
args.draw(_ => savedOptions);
};
img.src = uri;
});
});
},
resizeStop: (_, ui) => {
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