1 files changed, 75 insertions, 0 deletions
diff --git a/devtools/client/inspector/fonts/components/FontAxis.js b/devtools/client/inspector/fonts/components/FontAxis.js
new file mode 100644
index 0000000000..f695c06b29
--- /dev/null
+++ b/devtools/client/inspector/fonts/components/FontAxis.js
@@ -0,0 +1,75 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+
+const FontPropertyValue = createFactory(
+  require("resource://devtools/client/inspector/fonts/components/FontPropertyValue.js")
+);
+
+const Types = require("resource://devtools/client/inspector/fonts/types.js");
+
+class FontAxis extends PureComponent {
+  static get propTypes() {
+    return {
+      axis: PropTypes.shape(Types.fontVariationAxis),
+      disabled: PropTypes.bool.isRequired,
+      onChange: PropTypes.func.isRequired,
+      value: PropTypes.number.isRequired,
+    };
+  }
+
+  /**
+   * Naive implementation to get increment step for variable font axis that ensures
+   * fine grained control based on range of values between min and max.
+   *
+   * @param  {Number} min
+   *         Minumum value for range.
+   * @param  {Number} max
+   *         Maximum value for range.
+   * @return {Number}
+   *         Step value used in range input for font axis.
+   */
+  getAxisStep(min, max) {
+    let step = 1;
+    const delta = parseInt(max, 10) - parseInt(min, 10);
+
+    if (delta <= 1) {
+      step = 0.001;
+    } else if (delta <= 10) {
+      step = 0.01;
+    } else if (delta <= 100) {
+      step = 0.1;
+    }
+
+    return step;
+  }
+
+  render() {
+    const { axis, value, onChange } = this.props;
+
+    return FontPropertyValue({
+      className: "font-control-axis",
+      disabled: this.props.disabled,
+      label: axis.name,
+      min: axis.minValue,
+      minLabel: true,
+      max: axis.maxValue,
+      maxLabel: true,
+      name: axis.tag,
+      nameLabel: true,
+      onChange,
+      step: this.getAxisStep(axis.minValue, axis.maxValue),
+      value,
+    });
+  }
+}
+
+module.exports = FontAxis;