PDF.js Express Web Viewer has three measurement tools, with each of them having a scale ratio and precision. These properties can be changed using the UI or programmatically.
Set scale and precision with the UI
To set measurement properties for a tool, click on the measurement tool icon and select the tool. A style menu will pop up in which you can find and change the properties.
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Set scale and precision programmatically
You can take the same approach as shown in the Customizing tools guide to set measurement properties. Measurement related tool names are: AnnotationCreateDistanceMeasurement
, AnnotationCreatePerimeterMeasurement
and AnnotationCreateAreaMeasurement
. You can view the list of valid tool names here. The following example sets the scale and precision of the distance measurement tool:
WebViewer(...)
.then(instance => {
const { docViewer } = instance;
const distanceMeasurementTool = docViewer.getTool('AnnotationCreateDistanceMeasurement');
distanceMeasurementTool.setStyles(() => ({
// value of Scale is an array that is consisted of two arrays
// the first element in each array is the scale ratio and the second element is the unit.
// valid units are: mm, cm, m, km, mi, yd, ft, in and pt
// the following array means that for the annotations created by the distance measurement tool, 0.25 inches on the document is equal to 1 inch in the real world
Scale: [[0.25, 'in'], [1, 'in']],
// value of Precision is a number that means how many decimal places the calculated value should have
Precision: 0.001
});
);
});
WebViewer(...)
.then(instance => {
const { documentViewer } = instance.Core;
const distanceMeasurementTool = documentViewer.getTool('AnnotationCreateDistanceMeasurement');
distanceMeasurementTool.setStyles(() => ({
// value of Scale is an array that is consisted of two arrays
// the first element in each array is the scale ratio and the second element is the unit.
// valid units are: mm, cm, m, km, mi, yd, ft, in and pt
// the following array means that for the annotations created by the distance measurement tool, 0.25 inches on the document is equal to 1 inch in the real world
Scale: [[0.25, 'in'], [1, 'in']],
// value of Precision is a number that means how many decimal places the calculated value should have
Precision: 0.001
});
);
});
Get scale and precision programmatically
The following example logs the precision and scale of the distance measurement tool:
WebViewer(...)
.then(instance => {
const { docViewer } = instance;
const distanceMeasurementTool = docViewer.getTool('AnnotationCreateDistanceMeasurement');
console.log(distanceMeasurementTool.defaults.Scale);
console.log(distanceMeasurementTool.defaults.Precision);
});
WebViewer(...)
.then(instance => {
const { documentViewer } = instance.Core;
const distanceMeasurementTool = documentViewer.getTool('AnnotationCreateDistanceMeasurement');
console.log(distanceMeasurementTool.defaults.Scale);
console.log(distanceMeasurementTool.defaults.Precision);
});