Modifying the ViewPort

This library has various methods for modifying the viewport (what is visible on the chart, aim of the view). Please note that these methods are only available for the LineChart, BarChart, ScatterChart and CandleStickChart.

The methods mentioned below are provided by the Chart class. Another way to modify the viewport is to directly access it (without the in-between safety provided by the chart) via the ViewPortHandler. This is only recommended for advanced users who are familiar with the API.

Please note that all methods modifying the viewport need to be called on the Chart after setting data.

Restraining what’s visible

  • setVisibleXRangeMaximum(float maxXRange): Sets the size of the area (range on the x-axis) that should be maximum visible at once. If this is e.g. set to 10, no more than 10 values on the x-axis can be viewed at once without scrolling.
  • setVisibleXRangeMinimum(float minXRange): Sets the size of the area (range on the x-axis) that should be minimum visible at once. If this is e.g. set to 10, it is not possible to zoom in further than 10 values on the x-axis.
  • setVisibleYRangeMaximum(float maxYRange, AxisDependency axis): Sets the size of the area (range on the y-axis) that should be maximum visible at once. You also need to provide the axis this constraint should apply to.
  • setViewPortOffsets(float left, float top, float right, float bottom): Sets custom offsets for the current ViewPort (the offsets on the sides of the actual chart window). Setting this will prevent the chart from automatically calculating it’s offsets. Use resetViewPortOffsets() to undo this. USE THIS ONLY WHEN YOU KNOW WHAT YOU ARE DOING.
  • resetViewPortOffsets(): Resets all custom offsets set via setViewPortOffsets(...) method. Allows the chart to again calculate all offsets automatically.
  • setExtraOffsets(float left, float top, float right, float bottom): Sets extra offsets (around the chart view) to be appended to the auto-calculated offsets. This does not change the auto-calculated offsets, but adds extra space to them.

Moving the view (where it is aimed)

  • fitScreen(): Resets all zooming and dragging and makes the chart fit exactly it’s bounds (fully zoom out).
  • moveViewToX(float xValue): Moves the left side (edge) of the current viewport to the specified x-value.
  • moveViewToY(float yValue, AxisDependency axis): Centers the viewport to the specified y-value on the provided y-axis (left or right).
  • moveViewTo(float xValue, float yValue, AxisDependency axis): This will move the left side of the current viewport to the specified x-value on the x-axis, and center the viewport to the specified y-value on the provided y-axis (makes sense in combination with setVisibleXRange(...) and setVisibleYRange(...).
  • centerViewTo(float xValue, float yValue, AxisDependency axis): This will move the center of the current viewport to the specified x-value and y-value (makes sense in combination with setVisibleXRange(...) and setVisibleYRange(...).

Moving the view with animations

(since release v2.2.3)

  • moveViewToAnimated(float xValue, float yValue, AxisDependency axis, long duration): This will move the left side of the current viewport to the specified x-value on the x-axis, and center the viewport to the specified y-value on the provided y-axis in an animated way.
  • centerViewToAnimated(float xValue, float yValue, AxisDependency axis, long duration): This will move the center of the current viewport to the specified x-value and y-value (according to axis) in an animated way.

Note: All moveViewTo(...) methods will automatically invalidate() (refresh) the chart. There is no need for further calling invalidate().

Zooming (programmatically)

  • zoomIn(): Zooms in by 1.4f, into the charts center.
  • zoomOut(): Zooms out by 0.7f, from the charts center.
  • zoom(float scaleX, float scaleY, float x, float y): Zooms in or out by the given scale factor. x and y are the coordinates (in pixels) of the zoom center. Remember that a scale of 1f = no zoom.
  • zoom(float scaleX, float scaleY, float xValue, float yValue, AxisDependency axis): Zooms in or out by the given scale factor. xValue and yValue are the actual data values (not pixels) of the zoom center. Remember that a scale of 1f = no zoom.

Zooming with animations

(since release v2.2.3)

  • zoomAndCenterAnimated(float scaleX, float scaleY, float xValue, float yValue, AxisDependency axis, long duration): Zooms by the specified scale factor and centers the viewport to the specified values on the specified axis in an animated way.

Full example

chart.setData(...); // first set data

// now modify viewport
chart.setVisibleXRangeMaximum(20); // allow 20 values to be displayed at once on the x-axis, not more
chart.moveViewToX(10); // set the left edge of the chart to x-index 10
// moveViewToX(...) also calls invalidate()