Question

I’m using ChartFactory.getTimeChartView method from the achartengine excellent library.
I show only the last week of records, allowing the user to pan to left for seeing previous records, using renderer.setXAxisMin(OneWeekBefore); property.

I have 2 questions :

a) How to allow X-axis zoom in TimeChart ?
I can not zoom on the X axis despite zoom is enabled on both X and Y axis. I might use the zoom and pan limits in an inappropriate way but can’t find what/why.

b) How to alter the zoom button behaviour ?
I would like to alter the behaviour of the zoom button 1:1. Pressing this, the whole graph is shown instead of only the last week.

Here is the piece of code for the zooming properties setup :

    // ZOOM
    double[] panlimits = new double[] { XfirstRecord , maxdate, 0.0, Ymax * 1.2 };
    renderer.setZoomEnabled(enabledXzoom, YenabledYzoom);
    renderer.setZoomButtonsVisible(showZoomButtons);
    renderer.setZoomRate(ZoomRate);
    renderer.setPanLimits(panlimits);
    renderer.setZoomLimits(panlimits);

    renderer.setXAxisMin(OneWeekBefore);

Working update after checking Dan’s answer is as below, it works for me :

        // ZOOM
        double[] panlimits = new double[] { XfirstRecord, now, 0.0, Ymax * 1.2 };
        renderer.setZoomEnabled(XenabledZoom, YenabledZoom);
        renderer.setZoomButtonsVisible(showZoomButtons);
        renderer.setZoomRate(ZoomRate);
        renderer.setPanLimits(panlimits);
        renderer.setZoomLimits(panlimits);

        // SHOW ONLY last WEEK even after Zoom reset
        renderer.setXAxisMin(OneWeekBefore);
        renderer.setInitialRange(new double[] {OneWeekBefore, now, 0.0, Ymax * 1.2});

Answer 1

For the first question, the pan and zoom limits should be something like:

// please note that I am using the Java naming of variables
new double[] { oneWeekBefore, today, 0, yMax * 1.2 };

Does pinch zoom work?

For the second question, use:

renderer.setInitialRange(new double[] {oneWeekBefore, today, 0, yMax * 1.2});