Develop Reference

MpAndroidChart Pie chart with rounded corners

I'm trying to draw a pie chart with rounded corners using MpAndroidChart library.
Expected output is something similar to this.
Both ends need to be outer round. There is a method pieChart.setDrawRoundedSlices(true), but the issue is start point of the pie chart getting inner round.
This is the actual output.
// initialise pie chart UI
fun initChart(mChart: PieChart) {
mChart.description.isEnabled = false
mChart.holeRadius = 75f
mChart.transparentCircleRadius = 60f
mChart.setHoleColor(Color.TRANSPARENT)
mChart.legend.isEnabled = false
mChart.isRotationEnabled = false
mChart.setTouchEnabled(false)
mChart.maxAngle = 270f
mChart.rotation = -135f
mChart.animateX(400)
mChart.setDrawRoundedSlices(true)
}

I was faced with the same challenge recently, this is the code of the renderer in case anyone may need it:
public class RoundedSlicesPieChartRenderer extends PieChartRenderer {
public RoundedSlicesPieChartRenderer(PieChart chart, ChartAnimator animator, ViewPortHandler viewPortHandler) {
super(chart, animator, viewPortHandler);
chart.setDrawRoundedSlices(true);
}
#Override
protected void drawDataSet(Canvas c, IPieDataSet dataSet) {
float angle = 0;
float rotationAngle = mChart.getRotationAngle();
float phaseX = mAnimator.getPhaseX();
float phaseY = mAnimator.getPhaseY();
final RectF circleBox = mChart.getCircleBox();
final int entryCount = dataSet.getEntryCount();
final float[] drawAngles = mChart.getDrawAngles();
final MPPointF center = mChart.getCenterCircleBox();
final float radius = mChart.getRadius();
final boolean drawInnerArc = mChart.isDrawHoleEnabled() && !mChart.isDrawSlicesUnderHoleEnabled();
final float userInnerRadius = drawInnerArc
? radius * (mChart.getHoleRadius() / 100.f)
: 0.f;
final float roundedRadius = (radius - (radius * mChart.getHoleRadius() / 100f)) / 2f;
final RectF roundedCircleBox = new RectF();
int visibleAngleCount = 0;
for (int j = 0; j < entryCount; j++) {
// draw only if the value is greater than zero
if ((Math.abs(dataSet.getEntryForIndex(j).getY()) > Utils.FLOAT_EPSILON)) {
visibleAngleCount++;
}
}
final float sliceSpace = visibleAngleCount <= 1 ? 0.f : getSliceSpace(dataSet);
final Path pathBuffer = new Path();
final RectF mInnerRectBuffer = new RectF();
for (int j = 0; j < entryCount; j++) {
float sliceAngle = drawAngles[j];
float innerRadius = userInnerRadius;
Entry e = dataSet.getEntryForIndex(j);
// draw only if the value is greater than zero
if (!(Math.abs(e.getY()) > Utils.FLOAT_EPSILON)) {
angle += sliceAngle * phaseX;
continue;
}
// Don't draw if it's highlighted, unless the chart uses rounded slices
if (mChart.needsHighlight(j) && !drawInnerArc) {
angle += sliceAngle * phaseX;
continue;
}
final boolean accountForSliceSpacing = sliceSpace > 0.f && sliceAngle <= 180.f;
mRenderPaint.setColor(dataSet.getColor(j));
final float sliceSpaceAngleOuter = visibleAngleCount == 1 ?
0.f :
sliceSpace / (Utils.FDEG2RAD * radius);
final float startAngleOuter = rotationAngle + (angle + sliceSpaceAngleOuter / 2.f) * phaseY;
float sweepAngleOuter = (sliceAngle - sliceSpaceAngleOuter) * phaseY;
if (sweepAngleOuter < 0.f) {
sweepAngleOuter = 0.f;
}
pathBuffer.reset();
float arcStartPointX = center.x + radius * (float) Math.cos(startAngleOuter * Utils.FDEG2RAD);
float arcStartPointY = center.y + radius * (float) Math.sin(startAngleOuter * Utils.FDEG2RAD);
if (sweepAngleOuter >= 360.f && sweepAngleOuter % 360f <= Utils.FLOAT_EPSILON) {
// Android is doing "mod 360"
pathBuffer.addCircle(center.x, center.y, radius, Path.Direction.CW);
} else {
if (drawInnerArc) {
float x = center.x + (radius - roundedRadius) * (float) Math.cos(startAngleOuter * Utils.FDEG2RAD);
float y = center.y + (radius - roundedRadius) * (float) Math.sin(startAngleOuter * Utils.FDEG2RAD);
roundedCircleBox.set(x - roundedRadius, y - roundedRadius, x + roundedRadius, y + roundedRadius);
pathBuffer.arcTo(roundedCircleBox, startAngleOuter - 180, 180);
}
pathBuffer.arcTo(
circleBox,
startAngleOuter,
sweepAngleOuter
);
}
// API < 21 does not receive floats in addArc, but a RectF
mInnerRectBuffer.set(
center.x - innerRadius,
center.y - innerRadius,
center.x + innerRadius,
center.y + innerRadius);
if (drawInnerArc && (innerRadius > 0.f || accountForSliceSpacing)) {
if (accountForSliceSpacing) {
float minSpacedRadius =
calculateMinimumRadiusForSpacedSlice(
center, radius,
sliceAngle * phaseY,
arcStartPointX, arcStartPointY,
startAngleOuter,
sweepAngleOuter);
if (minSpacedRadius < 0.f)
minSpacedRadius = -minSpacedRadius;
innerRadius = Math.max(innerRadius, minSpacedRadius);
}
final float sliceSpaceAngleInner = visibleAngleCount == 1 || innerRadius == 0.f ?
0.f :
sliceSpace / (Utils.FDEG2RAD * innerRadius);
final float startAngleInner = rotationAngle + (angle + sliceSpaceAngleInner / 2.f) * phaseY;
float sweepAngleInner = (sliceAngle - sliceSpaceAngleInner) * phaseY;
if (sweepAngleInner < 0.f) {
sweepAngleInner = 0.f;
}
final float endAngleInner = startAngleInner + sweepAngleInner;
if (sweepAngleOuter >= 360.f && sweepAngleOuter % 360f <= Utils.FLOAT_EPSILON) {
// Android is doing "mod 360"
pathBuffer.addCircle(center.x, center.y, innerRadius, Path.Direction.CCW);
} else {
float x = center.x + (radius - roundedRadius) * (float) Math.cos(endAngleInner * Utils.FDEG2RAD);
float y = center.y + (radius - roundedRadius) * (float) Math.sin(endAngleInner * Utils.FDEG2RAD);
roundedCircleBox.set(x - roundedRadius, y - roundedRadius, x + roundedRadius, y + roundedRadius);
pathBuffer.arcTo(roundedCircleBox, endAngleInner, 180);
pathBuffer.arcTo(mInnerRectBuffer, endAngleInner, -sweepAngleInner);
}
} else {
if (sweepAngleOuter % 360f > Utils.FLOAT_EPSILON) {
if (accountForSliceSpacing) {
float angleMiddle = startAngleOuter + sweepAngleOuter / 2.f;
float sliceSpaceOffset =
calculateMinimumRadiusForSpacedSlice(
center,
radius,
sliceAngle * phaseY,
arcStartPointX,
arcStartPointY,
startAngleOuter,
sweepAngleOuter);
float arcEndPointX = center.x +
sliceSpaceOffset * (float) Math.cos(angleMiddle * Utils.FDEG2RAD);
float arcEndPointY = center.y +
sliceSpaceOffset * (float) Math.sin(angleMiddle * Utils.FDEG2RAD);
pathBuffer.lineTo(
arcEndPointX,
arcEndPointY);
} else {
pathBuffer.lineTo(
center.x,
center.y);
}
}
}
pathBuffer.close();
mBitmapCanvas.drawPath(pathBuffer, mRenderPaint);
angle += sliceAngle * phaseX;
}
MPPointF.recycleInstance(center);
}
}
And then you use it like this:
mChart.setRenderer(new RoundedSlicesPieChartRenderer(pieChart, pieChart.getAnimator(), pieChart.getViewPortHandler()));

How to draw a cloud shape in canvas?

I want to create a Cloud shape in Canvas.
When the user clicks anywhere on the canvas, it will create a cloud shape,.
The user should be able to drag the shape.
I have achieved rectangle and arrow draw in canvas using below code.
But I can't succeed to draw an arc.
private void drawOnRectProjectedBitMap(ImageView iv, Bitmap bm, int x, int y) {
if (x < 0 || y < 0 || x > iv.getWidth() || y > iv.getHeight()) {
//outside ImageView
return;
} else {
int projectedX = (int) ((double) x * ((double) bm.getWidth() / (double) iv.getWidth()));
int projectedY = (int) ((double) y * ((double) bm.getHeight() / (double) iv.getHeight()));
//clear canvasDrawingPane
canvasDrawingPane.drawColor(Color.TRANSPARENT, Mode.CLEAR);
Paint paint = new Paint();
paint.setStyle(Paint.Style.STROKE);
paint.setColor(Color.WHITE);
paint.setStrokeWidth(3);
canvasDrawingPane.drawRect(startPt.x, startPt.y, projectedX, projectedY, paint);
imageDrawingPane.invalidate();
textSource.setText(x + ":" + y + "/" + iv.getWidth() + " : " + iv.getHeight() + "\n" +
projectedX + " : " + projectedY + "/" + bm.getWidth() + " : " + bm.getHeight()
);
}
}

How to give interactions to a bar in a bar graph i.e. increase and decrease of height of each bar in android without using any library

I am able to plot bar graph using canvas and drawing rectangle in the view. But the onTouch interaction works for the whole view and hence I am not able to interact with each bar separately.I am not looking for using any library for plotting graphs. Any suggestions would be helpful. Thanks!
protected void onDraw(Canvas canvas) {
float border = 20;
float horstart = border * 2;
float height = getHeight();
float width = getWidth() - 1;
float max = getMax();
float min = getMin();
float diff = max - min;
float graphheight = height - (2 * border);
float graphwidth = width - (2 * border);
paint.setTextAlign(Align.LEFT);
int vers = verlabels.length - 1;
for (int i = 0; i < verlabels.length; i++) {
paint.setColor(Color.BLUE);
float y = ((graphheight / vers) * i) + border;
//canvas.drawLine(horstart, y, width, y, paint);
paint.setColor(Color.BLUE);
canvas.drawText(verlabels[i], 0, y, paint);
}
int hors = horlabels.length - 1;
for (int i = 0; i < horlabels.length; i++) {
paint.setColor(Color.BLUE);
float x = ((graphwidth / hors) * i) + horstart;
//canvas.drawLine(x, height - border, x, border, paint);
paint.setTextAlign(Align.CENTER);
if (i == horlabels.length - 1)
paint.setTextAlign(Align.RIGHT);
if (i == 0)
paint.setTextAlign(Align.LEFT);
paint.setColor(Color.BLUE);
canvas.drawText(horlabels[i], x, height - 4, paint);
}
paint.setTextAlign(Align.CENTER);
canvas.drawText(title, (graphwidth / 2) + horstart, border - 4, paint);
if (max != min) {
paint.setColor(Color.BLUE);
if (type == BAR) {
float datalength = values.length;
float colwidth = (graphwidth / hors);
for (int i = 0; i < values.length; i++) {
float val = values[i] - min;
float rat = val / diff;
float h = graphheight * rat;
canvas.drawRect((i * colwidth) + horstart, (border - h)
+ graphheight+curY, ((i * colwidth) + horstart)
+ (colwidth - 1), height - (border - 1), paint);
}
} else {
float datalength = values.length;
float colwidth = (width - (2 * border)) / datalength;
float halfcol = colwidth / 2;
float lasth = 0;
float h = 0;
for (int i = 0;i<values.length;i++)
canvas.drawLine(((i - 1) * colwidth) + (horstart + 1)
+ halfcol, (border - lasth) + graphheight+curY,
(i * colwidth) + (horstart + 1) + halfcol,
(border - h) + graphheight, paint);
lasth = h;
}
}
}
onTouch method for the view :
public boolean onTouch(View v, MotionEvent event)
{
boolean result=false;
switch (event.getAction())
{
case MotionEvent.ACTION_DOWN:
curX= (int)event.getX();
curY= (int)event.getY();
result=true;
break;
case MotionEvent.ACTION_MOVE:
curX= (int)event.getX();
curY= (int)event.getY();
result=true;
break;
case MotionEvent.ACTION_UP:
curX= (int)event.getX();
curY= (int)event.getY();
result=true;
break;
}
if (result) invalidate();
return result;
}

Whenever an user touches that view, it causes the onTouch method gets called. Once it's getting called, you're given two float numbers: x and y indicating where user's finger touches your view relative to the view coordination system.
As you might grasped the idea, you should get those numbers and internally in your custom view (i.e. bar chart) calculate which bar is affected. Then, you can for example apply a hover effect or do something else.
Note: For updating appearance of your view, you should store changes in data models of your chart view and then issue invalidate(). Subsequently, as a result, your onDraw is invoked and in which you can re-draw your chart. (i.e. You should each time, re-draw your whole chart again)

LogCat not showing the command : Android

Following is code of onDraw function. It draws the circle and functions properly, but when I output circle coordinates in LOGCAT I don't see anything. I have imported the "android.Util.Log" as well,
Log.d command not showing in Logcat.
#Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
int pl = getPaddingLeft();
int pr = getPaddingRight();
int pt = getPaddingTop();
int pb = getPaddingBottom();
int usableWidth = w - (pl + pr);
int usableHeight = h - (pt + pb);
int radius = Math.min(usableWidth, usableHeight) / 2;
int cx = pl + (usableWidth / 2);
int cy = pt + (usableHeight / 2);
paint.setColor(circleColor);
//canvas.drawCircle(w, h, (radius * 1.5f), paint);
Log.d("CIRCLE DRAW", "Circle coordinates are as ");// +
//"X: "+ w +
//"Y: "+ h);
}

Use Canvas to draw thousands of Rects

I am trying to make a native Android version of http://arapaho.nsuok.edu/~deckar01/Zvis.html
So, I made a custom View that draws all the squares needed. Of course, this drawing ends up taking 10s of seconds once the number becomes large enough to make the Canvas start drawing thousands of squares.
Is there a better way to do this? It seems like there is something obvious I am not thinking of doing/using.
The onDraw method of the View is below, in case that helps. Any ideas?
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
final int number = mNumber;
final float tileWidth, tileHeight;
/*mTileWidth = mWW / (number - 1);
mTileHeight = mHH / (number - 1);*/
// make them squares
if (mWW <= mHH) {
tileWidth = tileHeight = mWW / (number - 1);
} else {
tileWidth = tileHeight = mHH / (number - 1);
}
mWhiteTextPaint.setTextSize(48f / 72 * tileWidth);
mBlackTextPaint.setTextSize(48f / 72 * tileWidth);
float currX = getPaddingLeft();
float currY = getPaddingTop();
for (int i = 1; i <= number - 1; i++) {
mBackgroundPaint.setColor(getBackgroundColor(i, number));
canvas.drawRect(currX, currY, currX + tileWidth,
currY + tileHeight,
mBackgroundPaint);
final String text = String.valueOf(i);
canvas.drawText(text,
currX + tileWidth / 2 - mWhiteTextPaint.measureText(text) / 2,
currY + tileHeight * 0.9f, mWhiteTextPaint);
currX += tileWidth;
}
currX = getPaddingLeft();
currY += tileHeight;
for (int i = 2; i <= number - 1; i++) {
for (int j = 1; j <= number - 1; j++) {
final int num = (j == 1) ? i : (i * j) % number;
mBackgroundPaint.setColor(getBackgroundColor(num, number));
canvas.drawRect(currX, currY, currX + tileWidth,
currY + tileHeight,
mBackgroundPaint);
final String text = String.valueOf(num);
if (num == 0) {
canvas.drawText(text,
currX + tileWidth / 2 - mBlackTextPaint.measureText(text) / 2,
currY + tileHeight * 0.9f, mBlackTextPaint);
} else {
canvas.drawText(text,
currX + tileWidth / 2 - mWhiteTextPaint.measureText(text) / 2,
currY + tileHeight * 0.9f, mWhiteTextPaint);
}
currX += tileWidth;
}
currX = getPaddingLeft();
currY += tileHeight;
}
if (mOnDrawFinishedListener != null) {
mOnDrawFinishedListener.onDrawFinished(number);
}
}

As #CarCzar already said, you could draw everything in a separate thread into a bitmap and then on the UI thread you only draw that bitmap on the screen. Alternatively you could use OpenGL. That's usually used for more dynamic things like games. The thing is that OpenGL runs in a separate graphic thread and therefore will not block your UI.