PieChart from Json Array in Sketchware


In Sketchware, to create an app in which data with numerical values can be added and viewed as a pie chart, follow the steps given below.

1. Create a new project in Sketchware.

2. In main.xml add a Button button2 and a ListView listview2.

3. Create a CustomView items.xml and add two TextViews in it textview1 and textview2.
4. Select items.xml as CustomView of listview2.

5. In MainActivity.java, add a Shared Preferences component sp:sp, and an Intent component i.

6. Add a String variable jsondata, and a ListMap maplist.

7. In onCreate event use blocks to set jsondata to your Json data containing 'text' and 'number' as keys. Convert it to List Map maplist and display it in ListView.

The Json String used here is:
[
{
"text" : "Afghan Afghani",
"number" : "0.9532"
},
{
"text" : "Armenian Dram",
"number" : "0.1487"
},
{
"text" : "Bangladeshi Taka",
"number" : "0.8572"
},
{
"text" : "Cambodian Riel",
"number" : "0.1758"
},
{
"text" : "Indonesian Rupiah",
"number" : "0.005"
},
{
"text" : "Maldivian Rufiyaa",
"number" : "4.674"
},
{
"text" : "Pakistani Rupee",
"number" : "0.5832"
},
{
"text" : "Philippine Peso",
"number" : "1.332"
},
{
"text" : "Thai Baht",
"number" : "2.226"
}
]

8. In onBindCustomView event, display the data from maplist in the TextViews in CustomView items.xml.

9. Create a new View piechart.xml.

10. In the event button2 onClick in MainActivity.java, save the maplist to Shared Preferences and use Intent to move to PiechartActivity.java.

11. In piechart.xml add a LinearV linear1.

12. In PiechartActivity.java add a Shared Preferences component sp:sp, a Map variable map, and a ListMap listmap.

13. In onCreate event use blocks to get data from Shared Preferences to listmap, and codes to display this ListMap in PieChartView.
The code used in add source directly block is
PieChartView chart = new PieChartView(this, listmap, "number", "text");

linear1.addView(chart);
Here 'text' and 'number' are the keys used in Json String in MainActivity.java.

14. Create a More Block extra.

15. In the more block extra, use an add source directly block and put codes to define a View class PieChartView.

}

public class PieChartView extends View {
private Paint fillPaint;
private Paint strokePaint;
private ArrayList<HashMap<String, Object>> list = new ArrayList<>();
private String numkey;
private String labelkey;

public PieChartView(Context context, ArrayList<HashMap<String, Object>> list, String numkey, String labelkey){
super(context);
fillPaint = new Paint();
strokePaint = new Paint();
this.list = list;
this.numkey = numkey;
this.labelkey = labelkey;
}

@Override
protected void onDraw(Canvas canvas) {
int viewWidth = this.getMeasuredWidth();
int viewHeight = this.getMeasuredHeight();

float startAngle = 0;
float sweepAngle = 0;
int lineHeight = 0;
float total = 0;
for (int i =0; i<list.size(); i++){
total = total + Float.valueOf(list.get(i).get(numkey).toString());
}

fillPaint.setStyle(android.graphics.Paint.Style.FILL);
strokePaint.setStyle(android.graphics.Paint.Style.STROKE);
strokePaint.setStrokeWidth(2);
strokePaint.setColor(Color.BLACK);

for (int i =0; i<list.size(); i++){
int col = 100+(155*i/list.size());
fillPaint.setColor(Color.rgb(40, col, col));
startAngle = startAngle+sweepAngle;
sweepAngle = 360*Float.valueOf(list.get(i).get(numkey).toString())/total;
canvas.drawArc(80, 40, viewWidth-80, viewWidth-120, startAngle, sweepAngle, true, fillPaint);
canvas.drawArc(80, 40, viewWidth-80, viewWidth-120, startAngle, sweepAngle, true, strokePaint);

lineHeight = lineHeight + 80;

canvas.drawRect(40, viewWidth - 120 + lineHeight - 40, 80, viewWidth - 120+ lineHeight, fillPaint);

fillPaint.setColor(Color.BLACK); fillPaint.setTextSize(40); canvas.drawText(list.get(i).get(labelkey).toString() + " : " +  list.get(i).get(numkey).toString(), 100, viewWidth - 120+ lineHeight, fillPaint);
}
}

This code only works for positive values.

For using random colors for the PieChart, in code above change
int col = 100+(155*i/list.size());
fillPaint.setColor(Color.rgb(40, col, col));
to
int r = getRandom(0, 255);
int g = getRandom(0, 255);
int b = getRandom(0, 255);

fillPaint.setColor(Color.rgb(r, g, b));

16. Save and Run the project.

Comments

  1. How to create one time login system?

    ReplyDelete
  2. Compilation error
    Error: invalid character Pointing to the line height

    ReplyDelete
  3. Nice post. Thank you for sharing the information.
    moviebox application

    ReplyDelete
  4. Maybe, you already heard about lucky patcher app...

    I want to make a app like this one. Can I do it with my android phone by using this Sketchware. Please, let me know the answer as soon as possible...

    ReplyDelete
  5. Hello Sanjeev Kumar, i have a question , so i have more than ten values on my map, it's about 22 values and there don't have enough space on the screen to show all of them, i tried to use a scroll view but it didn't work properly.

    ReplyDelete
    Replies
    1. You can add an onTouchListener to the Pie Chart and show the name of the sector touched

      Delete

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