I'm trying to animate a background in a game I'm making.
https://imgur.com/kQGWsLu
Should look like this(terrible recording quality)
My first attempt work well on my phone but a lot of people saw their fps cut in half:
public void draw(Canvas canvas, Paint paint) {
if (mPaint == null) {
mPaint = new Paint();
mPaint.setColor(Color.GRAY);
mPaint.setStrokeWidth(1);
mPaint.setAntiAlias(true);
mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
mPaint.setShader(new RadialGradient(canvas.getWidth() / 4, canvas.getHeight() / 3,
Math.max(1, canvas.getHeight() / 2), Color.rgb(5, 12, 127), Color.rgb(32, 36, 100), Shader.TileMode.REPEAT));
}
width = canvas.getWidth();
height = canvas.getHeight();
canvas.save();
rotation += 4;
if (rotation > 360)
rotation = 0;
canvas.rotate(rotation, width / 2, height / 2);
canvas.drawCircle(width / 2, height / 2, height * 1.3f, mPaint);
canvas.restore();
}
So now I'm thinking about of pre rendering a image and drawing it as a bitmap that covers the screen and rotates instead. I also cut the calculations to only update every other frame instead.
public void draw(Canvas canvas, Paint paint) {
if (!initiated) {
centerX = (int) (canvas.getWidth() / 2);
centerY = (int) (canvas.getHeight() / 2);
width = (int) (canvas.getWidth() * 2f);
height = (int) (canvas.getHeight() * 2f);
map = factory.GFX().getBackground();
initiated = true;
}
if (!skipUpdate) {
x = CalculatorService.getXCircle(rotation, distance, centerX);
y = CalculatorService.getYCircle(rotation, distance, centerY);
body.set((int) x - width / 2,
(int) y - height / 2,
(int) x + (width / 2),
(int) y + (height / 2));
rotation += rotationSpeed;
if (rotation > 360)
rotation = 0;
}
skipUpdate = !skipUpdate;
canvas.drawBitmap(map, null, body, paint);
}
Though since the image is small in size 320*320 I had to scale it up and draw it bigger then the screen to avoid it moving out of bounds and showing the basic black background, and I'm not sure if this is really a improvement, do anyone have a better way of doing it or any advice on how I can improve?
This is how my custom drawable looks by default.
But when scrolled, it overlaps with the AppBarLayout.
The code for the Drawable goes like this:
#Override
public void draw(#NonNull Canvas canvas) {
// get drawable dimensions
Rect bounds = getBounds();
float width = bounds.right - bounds.left;
float height = bounds.bottom - bounds.top;
float w2 = width / 2;
float h2 = height / 2;
float radius = Math.min(w2, h2) - mStrokeWidth / 2;
mPath.reset();
mPath.addCircle(width / 2, height / 2, radius, Path.Direction.CW);
canvas.clipPath(mPath);
// draw background gradient
float barHeight = height / themeColors.length;
mRectF.left = 0;
mRectF.top = 0;
mRectF.right = width;
mRectF.bottom = height;
for (int i = 0; i < themeColors.length; i++) {
mPaint.setColor(themeColors[i]);
canvas.drawRect(0, i * barHeight, width, (i + 1) * barHeight, mPaint);
}
mRectF.set(0, 0, width, height);
canvas.clipRect(mRectF, Region.Op.REPLACE);
if (mStrokeWidth != 0)
canvas.drawCircle(width / 2, height / 2, width / 2 - mStrokeWidth / 2, mStrokePaint);
}
Support Library Version: 25.3.1, 26.1.0
What I've tried:
- Different Region values for clipping path instead of REPLACE
- Clipping path rectangle first and then clipping circle.
How do I fix this ?
I am posting my solution as answer.
The reason it was getting overlapped was because the canvas was getting clipped twice without saving it.
I removed this statement:
canvas.clipRect(mRectF, Region.Op.REPLACE);
and before clipping the canvas for the first time
i saved its state using
canvas.save();
canvas.clipPath(mPath);
and then when i was drawing the stroke, i need the original canvas so i restored it
canvas.restore();
if (mStrokeWidth != 0)
canvas.drawCircle(width / 2, height / 2, width / 2 - mStrokeWidth / 2, mStrokePaint);
This fixed the issue.
Final Drawable Code:
#Override
public void draw(#NonNull Canvas canvas) {
// get drawable dimensions
Rect bounds = getBounds();
float width = bounds.right - bounds.left;
float height = bounds.bottom - bounds.top;
float w2 = width / 2;
float h2 = height / 2;
float radius = Math.min(w2, h2) - mStrokeWidth / 2;
mPath.reset();
mPath.addCircle(width / 2, height / 2, radius, Path.Direction.CW);
canvas.save();
canvas.clipPath(mPath);
// draw background gradient
float barHeight = height / themeColors.length;
mRectF.left = 0;
mRectF.top = 0;
mRectF.right = width;
mRectF.bottom = height;
for (int i = 0; i < themeColors.length; i++) {
mPaint.setColor(themeColors[i]);
canvas.drawRect(0, i * barHeight, width, (i + 1) * barHeight, mPaint);
}
mRectF.set(0, 0, width, height);
//canvas.clipRect(mRectF, Region.Op.REPLACE);
canvas.restore();
if (mStrokeWidth != 0)
canvas.drawCircle(width / 2, height / 2, width / 2 - mStrokeWidth / 2, mStrokePaint);
}
I'm trying to draw an arc inside a circle to represent the temperature, but I'm having a difficult time achieving that. During my search I found those solutions
This one I couldn't understand what is the scale method for, and is drawing more than one arch, which confused me a bit
This post gave it a fixed size where I need the size to be controlled by the custom view in my XML layout
From here I understood the concept the degrees but I didn't understand how to determine the oval size
What i reached so far
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int startTop = 0;
int startLeft = 0;
int endBottom = getHeight() / 2;
int endRight = endBottom;// This makes an equal square.
int centerX = getWidth() / 2;
int centerY = getHeight() / 2;
int upperEdgeX = (int) (centerX + getWidth() / 2 * Math.cos(270 * Math.PI / 180));
int upperEdgeY = (int) (centerY + getWidth() / 2 * Math.sin(270 * Math.PI / 180));
int bottomEdgeX = (int) (centerX + getWidth() / 2 * Math.cos(90 * Math.PI / 180));
int bottomEdgeY = (int) (centerY + getWidth() / 2 * Math.sin(90 * Math.PI / 180));
int leftEdgeX = (int) (centerX + getWidth() / 2 * Math.cos(180 * Math.PI / 180));
int leftEdgeY = (int) (centerY + getWidth() / 2 * Math.sin(180 * Math.PI / 180));
int rightEdgeX = (int) (centerX + getWidth() / 2 * Math.cos(0 * Math.PI / 180));
int rightEdgeY = (int) (centerY + getWidth() / 2 * Math.sin(0 * Math.PI / 180));
RectF rect = new RectF(startTop, startLeft, endRight, endBottom);
canvas.drawCircle(centerX, centerY, getWidth() / 2, mBasePaint);
canvas.drawCircle(centerX, centerY, getWidth() / 3, mCenterPaint); // White circle
}
UPDATE:
I need my view to be like a Donut Pie chart where the middle will hold the degree
UPDATE 2:
I'm trying to have something like this
The following custom View draws two arcs connecting to form a circle as well as an inner circle.
Moreover, I let it fill the rectangle used for drawing the arc and use a yellow background for the View, the activity background is dark. (These additional features are meant for getting a better impression of how drawing a circle / an arc works, they can help with debugging.)
The custom View:
public class MySimpleView extends View{
private static final int STROKE_WIDTH = 20;
private Paint mBasePaint, mDegreesPaint, mCenterPaint, mRectPaint;
private RectF mRect;
private int centerX, centerY, radius;
public MySimpleView(Context context) {
super(context);
init();
}
public MySimpleView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public MySimpleView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init()
{
mRectPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mRectPaint.setColor(ContextCompat.getColor(getContext(), R.color.magenta));
mRectPaint.setStyle(Paint.Style.FILL);
mCenterPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mCenterPaint.setColor(ContextCompat.getColor(getContext(), R.color.white));
mCenterPaint.setStyle(Paint.Style.FILL);
mBasePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mBasePaint.setStyle(Paint.Style.STROKE);
mBasePaint.setStrokeWidth(STROKE_WIDTH);
mBasePaint.setColor(ContextCompat.getColor(getContext(), R.color.blue));
mDegreesPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mDegreesPaint.setStyle(Paint.Style.STROKE);
mDegreesPaint.setStrokeWidth(STROKE_WIDTH);
mDegreesPaint.setColor(ContextCompat.getColor(getContext(), R.color.green));
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// getHeight() is not reliable, use getMeasuredHeight() on first run:
// Note: mRect will also be null after a configuration change,
// so in this case the new measured height and width values will be used:
if (mRect == null)
{
// take the minimum of width and height here to be on he safe side:
centerX = getMeasuredWidth()/ 2;
centerY = getMeasuredHeight()/ 2;
radius = Math.min(centerX,centerY);
// mRect will define the drawing space for drawArc()
// We have to take into account the STROKE_WIDTH with drawArc() as well as drawCircle():
// circles as well as arcs are drawn 50% outside of the bounds defined by the radius (radius for arcs is calculated from the rectangle mRect).
// So if mRect is too large, the lines will not fit into the View
int startTop = STROKE_WIDTH / 2;
int startLeft = startTop;
int endBottom = 2 * radius - startTop;
int endRight = endBottom;
mRect = new RectF(startTop, startLeft, endRight, endBottom);
}
// just to show the rectangle bounds:
canvas.drawRect(mRect, mRectPaint);
// subtract half the stroke width from radius so the blue circle fits inside the View
canvas.drawCircle(centerX, centerY, radius - STROKE_WIDTH / 2, mBasePaint);
// Or draw arc from degree 192 to degree 90 like this ( 258 = (360 - 192) + 90:
// canvas.drawArc(mRect, 192, 258, false, mBasePaint);
// draw an arc from 90 degrees to 192 degrees (102 = 192 - 90)
// Note that these degrees are not like mathematical degrees:
// they are mirrored along the y-axis and so incremented clockwise (zero degrees is always on the right hand side of the x-axis)
canvas.drawArc(mRect, 90, 102, false, mDegreesPaint);
// subtract stroke width from radius so the white circle does not cover the blue circle/ arc
canvas.drawCircle(centerX, centerY, radius - STROKE_WIDTH, mCenterPaint);
}
}
I now have a View that is added programically after the onCreate (Depending on some other variables). Everything works as it should and it draws part of a circle.
But my question is how do i redraw it later on ? I need to change the angle in the circle after some data is fetched.
Code for the WindRose :
public class WindRose extends View {
public WindRose(Context context) {
super(context);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvasTest = canvas;
float height = (float) getHeight();
float width = (float) getWidth();
float radius;
if (width > height) {
radius = height / 2;
} else {
radius = width / 2;
}
// radius = (height )/ 2;
Path path = new Path();
path.addCircle(width, height, radius, Path.Direction.CCW);
// / 2
Resources resources = getResources();
int color = resources.getColor(R.color.green_back);
paint.setColor(color);
paint.setStrokeWidth(5);
paint.setStyle(Paint.Style.FILL);
float center_x, center_y;
center_x = width / 2;
center_y = height / 2;
//Formulas :
//SD = Start Degree
//ED = End Degree
//If cakepiece passes 0 (East)
//SD, 360-(SD+ED)
//Else :
//SD, (ED-SD)
oval.set(center_x - radius, center_y - radius, center_x + radius, center_y + radius);
if (End > Start) {
canvas.drawArc(oval, Start, (End - Start), true, paint);
} else if (End < Start) {
canvas.drawArc(oval, Start, ((360 - Start) + End), true, paint);
}
}
}
If i update the Start and End variables nothing happens. i have also tried to call invalidate on the class but also there i dont get any redrawing.
Invalidate that i've tried :
WindRose windrose = new WindRose(this);
windrose.invalidate();
Was called from the main class which WindRose is part of.
How should i do this correctly ?
Maybe calling the invalidate() method of the view will help.
You can read more here(http://developer.android.com/reference/android/view/View.html), but:
"To force a view to draw, call invalidate()."
Note, also that you can invalidate only parts of a view
I am able to draw a circle and a rectangle on canvas by using
path.addCircle()
and
path.addRect().
And now I am wondering how to draw a triangle or a star or a square or a heart?
For future direct answer seekers, I have drawn an almost symmetric star using canvas, as shown in the image:
The main tool is using Paths.
Assuming you have setup:
Paint paint = new Paint();
paint.setColor(Color.WHITE);
paint.setAntiAlias(true);
paint.setStyle(Paint.Style.STROKE);
Path path = new Path();
Then in you onDraw you can use the path like I do below. It will scale properly to any sizes canvas
#Override
protected void onDraw(Canvas canvas) {
float mid = getWidth() / 2;
float min = Math.min(getWidth(), getHeight());
float fat = min / 17;
float half = min / 2;
float rad = half - fat;
mid = mid - half;
paint.setStrokeWidth(fat);
paint.setStyle(Paint.Style.STROKE);
canvas.drawCircle(mid + half, half, rad, paint);
path.reset();
paint.setStyle(Paint.Style.FILL);
// top left
path.moveTo(mid + half * 0.5f, half * 0.84f);
// top right
path.lineTo(mid + half * 1.5f, half * 0.84f);
// bottom left
path.lineTo(mid + half * 0.68f, half * 1.45f);
// top tip
path.lineTo(mid + half * 1.0f, half * 0.5f);
// bottom right
path.lineTo(mid + half * 1.32f, half * 1.45f);
// top left
path.lineTo(mid + half * 0.5f, half * 0.84f);
path.close();
canvas.drawPath(path, paint);
super.onDraw(canvas);
}
For everybody that needs a heart shape:
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Path;
import android.view.View;
public class Heart extends View {
private Path path;
private Paint paint;
public Heart(Context context) {
super(context);
path = new Path();
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// Fill the canvas with background color
canvas.drawColor(Color.WHITE);
paint.setShader(null);
float width = getContext().getResources().getDimension(R.dimen.heart_width);
float height = getContext().getResources().getDimension(R.dimen.heart_height);
// Starting point
path.moveTo(width / 2, height / 5);
// Upper left path
path.cubicTo(5 * width / 14, 0,
0, height / 15,
width / 28, 2 * height / 5);
// Lower left path
path.cubicTo(width / 14, 2 * height / 3,
3 * width / 7, 5 * height / 6,
width / 2, height);
// Lower right path
path.cubicTo(4 * width / 7, 5 * height / 6,
13 * width / 14, 2 * height / 3,
27 * width / 28, 2 * height / 5);
// Upper right path
path.cubicTo(width, height / 15,
9 * width / 14, 0,
width / 2, height / 5);
paint.setColor(Color.RED);
paint.setStyle(Style.FILL);
canvas.drawPath(path, paint);
}
}
Sorry for all the numbers but these worked best for me :) The result looks like this:
You have to find out the math behind that figures. The triangle and the star are quite easy to draw. Here is how you can draw a heart: http://www.mathematische-basteleien.de/heart.htm
To draw special paths you should create them by adding points, ellipses etc. The canvas supports a clipping mask of a specified path, so you can set the clipping mask of a heart, push the paths to the matrix, draw the content of the heart, and then pop it again.
That's what I'm doing to achieve a simulated 2D page curl effect on andriod: http://code.google.com/p/android-page-curl/
Hope this helps!
this method will return a path with the number of corners given inside a square of the given width. Add more parameters to handle small radius and such things.
private Path createStarBySize(float width, int steps) {
float halfWidth = width / 2.0F;
float bigRadius = halfWidth;
float radius = halfWidth / 2.0F;
float degreesPerStep = (float) Math.toRadians(360.0F / (float) steps);
float halfDegreesPerStep = degreesPerStep / 2.0F;
Path ret = new Path();
ret.setFillType(FillType.EVEN_ODD);
float max = (float) (2.0F* Math.PI);
ret.moveTo(width, halfWidth);
for (double step = 0; step < max; step += degreesPerStep) {
ret.lineTo((float)(halfWidth + bigRadius * Math.cos(step)), (float)(halfWidth + bigRadius * Math.sin(step)));
ret.lineTo((float)(halfWidth + radius * Math.cos(step + halfDegreesPerStep)), (float)(halfWidth + radius * Math.sin(step + halfDegreesPerStep)));
}
ret.close();
return ret;
}
If you need to draw a star inside a square, you can use the code below.
posX and posY are the coordinates for the upper left corner of the square that encloses the tips of the star (the square is not actually drawn).
size is the width and height of the square.
a is the top tip of the star. The path is created clockwise.
This is by no means a perfect solution, but it gets the job done very quickly.
public void drawStar(float posX, float posY, int size, Canvas canvas){
int hMargin = size/9;
int vMargin = size/4;
Point a = new Point((int) (posX + size/2), (int) posY);
Point b = new Point((int) (posX + size/2 + hMargin), (int) (posY + vMargin));
Point c = new Point((int) (posX + size), (int) (posY + vMargin));
Point d = new Point((int) (posX + size/2 + 2*hMargin), (int) (posY + size/2 + vMargin/2));
Point e = new Point((int) (posX + size/2 + 3*hMargin), (int) (posY + size));
Point f = new Point((int) (posX + size/2), (int) (posY + size - vMargin));
Point g = new Point((int) (posX + size/2 - 3*hMargin), (int) (posY + size));
Point h = new Point((int) (posX + size/2 - 2*hMargin), (int) (posY + size/2 + vMargin/2));
Point i = new Point((int) posX, (int) (posY + vMargin));
Point j = new Point((int) (posX + size/2 - hMargin), (int) (posY + vMargin));
Path path = new Path();
path.moveTo(a.x, a.y);
path.lineTo(b.x, b.y);
path.lineTo(c.x, c.y);
path.lineTo(d.x, d.y);
path.lineTo(e.x, e.y);
path.lineTo(f.x, f.y);
path.lineTo(f.x, f.y);
path.lineTo(g.x, g.y);
path.lineTo(h.x, h.y);
path.lineTo(i.x, i.y);
path.lineTo(j.x, j.y);
path.lineTo(a.x, a.y);
path.close();
canvas.drawPath(path, paint);
}
In addition to ellipse and rectangular you will need those two (as minimum):
drawLine(float startX, float startY, float stopX, float stopY, Paint paint)
drawLines(float[] pts, int offset, int count, Paint paint)
example:
How to draw a line in android
Documentation on Canvas: http://developer.android.com/reference/android/graphics/Canvas.html
Its very good to use instance of Shape class ))
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
HeartShape shape = new HeartShape();
ShapeDrawable shapeDrawable = new ShapeDrawable(shape);
shapeDrawable.setColorFilter(new LightingColorFilter(0, Color.BLUE));
LinearLayout linearLayout = new LinearLayout(this);
linearLayout.setLayoutParams(new LinearLayout.LayoutParams(350 * 3, 350 * 3));
linearLayout.setBackground(shapeDrawable);
setContentView(linearLayout);
}
Create a shape class which was render nice Heart
public class HeartShape extends Shape {
private final int INVALID_SIZE = -1;
private Path mPath = new Path();
private RectF mRectF = new RectF();
private float mOldWidth = INVALID_SIZE;
private float mOldHeight = INVALID_SIZE;
private float mScaleX, mScaleY;
public HeartShape() {
}
#Override
public void draw(Canvas canvas, Paint paint) {
canvas.save();
canvas.scale(mScaleX, mScaleY);
float width = mRectF.width();
float height = mRectF.height();
float halfWidth = width/2;
float halfHeight = height/2;
float stdDestX = 5 * width / 14;
float stdDestY = 2 * height / 3;
PointF point1 = new PointF(stdDestX, 0);
PointF point2 = new PointF(0, height / 15);
PointF point3 = new PointF(stdDestX / 5, stdDestY);
PointF point4 = new PointF(stdDestX, stdDestY);
// Starting point
mPath.moveTo(halfWidth, height / 5);
mPath.cubicTo(point1.x, point1.y, point2.x, point2.y, width / 28, 2 * height / 5);
mPath.cubicTo(point3.x, point3.y, point4.x, point4.y, halfWidth, height);
canvas.drawPath(mPath, paint);
canvas.scale(-mScaleX, mScaleY, halfWidth, halfHeight);
canvas.drawPath(mPath, paint);
canvas.restore();
}
#Override
protected void onResize(float width, float height) {
mOldWidth = mOldWidth == INVALID_SIZE ? width : Math.max(1, mOldWidth);
mOldHeight = mOldHeight == INVALID_SIZE ? height : Math.max(1, mOldHeight);
width = Math.max(1, width);
height = Math.max(1, height);
mScaleX = width / mOldWidth;
mScaleY = height / mOldHeight;
mOldWidth = width;
mOldHeight = height;
mRectF.set(0, 0, width, height);
}
#Override
public void getOutline(#NonNull Outline outline) {
// HeartShape not supported outlines
}
#Override
public HeartShape clone() throws CloneNotSupportedException {
HeartShape shape = (HeartShape) super.clone();
shape.mPath = new Path(mPath);
return shape;
}
}
Well if you want to draw only the shapes you specify I recommend first creat a class for each shape and make each shape implement draw() method where you can pass canvas and paint object.
For example to create multiple stars, first create a class "Star" and implement the logic there.
class Star(
var cx: Float = 0f,
var cy: Float = 0f,
var radius: Float = 0f,
var angle: Float = 0f,
var color: Int = Color.WHITE,
var numberOfSpikes: Int = 5,
var depth: Float = 0.4f
) {
val path: Path = Path()
val point: PointF = PointF()
fun init() {
path.rewind()
var totalAngle = 0f
for (i in 0 until numberOfSpikes * 2) {
val x = cx
var y = cy
y -= if (i % 2 != 0) (radius * depth)
else (radius * 1f)
StaticMethods.rotate(cx, cy, x, y, totalAngle, false, point)
totalAngle += 360f / (numberOfSpikes * 2)
if (i == 0) {
path.moveTo(point.x, point.y)
} else {
path.lineTo(point.x, point.y)
}
}
}
fun draw(canvas: Canvas, paint: Paint) {
paint.apply {
style = Paint.Style.FILL
color = this#Star.color
}
canvas.drawPath(path, paint)
}
}
object StaticMethods {
/**
* Rotate a point around a center with given angle
* #param cx rotary center point x coordinate
* #param cy rotary center point y coordinate
* #param x x coordinate of the point that will be rotated
* #param y y coordinate of the point that will be rotated
* #param angle angle of rotation in degrees
* #param anticlockWise rotate clockwise or anti-clockwise
* #param resultPoint object where the result rotational point will be stored
*/
fun rotate(cx: Float, cy: Float, x: Float, y: Float, angle: Float, anticlockWise: Boolean = false, resultPoint: PointF = PointF()): PointF {
if (angle == 0f) {
resultPoint.x = x
resultPoint.y = y
return resultPoint
}
val radians = if (anticlockWise) {
(Math.PI / 180) * angle
} else {
(Math.PI / -180) * angle
}
val cos = Math.cos(radians)
val sin = Math.sin(radians)
val nx = (cos * (x - cx)) + (sin * (y - cy)) + cx
val ny = (cos * (y - cy)) - (sin * (x - cx)) + cy
resultPoint.x = nx.toFloat()
resultPoint.y = ny.toFloat()
return resultPoint
}
/**
* Inline function that is called, when the final measurement is made and
* the view is about to be draw.
*/
inline fun View.afterMeasured(crossinline function: View.() -> Unit) {
viewTreeObserver.addOnGlobalLayoutListener(object :
ViewTreeObserver.OnGlobalLayoutListener {
override fun onGlobalLayout() {
if (measuredWidth > 0 && measuredHeight > 0) {
viewTreeObserver.removeOnGlobalLayoutListener(this)
function()
}
}
})
}
}
And then create a custom view where you can draw your shapes, below is the code that creates 100 random stars and draws them on canvas.
class StarView : View {
constructor(context: Context) : super(context)
constructor(context: Context, attrs: AttributeSet?) : super(context, attrs)
constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr)
val stars: ArrayList<Helper.Star> = arrayListOf()
val paint: Paint = Paint().apply {
isAntiAlias = true
}
init {
// after the view is measured and we have the width and height
afterMeasured {
// create 100 stars
for (i in 0 until 100) {
val star = Helper.Star(
cx = width * Math.random().toFloat(),
cy = height * Math.random().toFloat(),
radius = width * 0.1f * Math.random().toFloat(),
)
star.init()
stars.add(star)
}
}
}
override fun onDraw(canvas: Canvas) {
stars.forEach {
it.draw(canvas, paint)
}
}
}
Here is the result:
If you want to create a lot of different complex shapes you can use this library. Where you can pass svg shapes using the Path Data as a string. By first creating complex shapes using any SVG vector editor such as
Microsoft Expression Design
Adobe Illustrator
Inkscape