Custom drawing (Canvas) in Android Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a custom View class that overrides the onDraw method.

Android Kotlin

class MyView(context: Context) : View(context) {
  override fun [1](canvas: Canvas) {
    super.onDraw(canvas)
  }
}

Drag options to blanks, or click blank then click option'

AonDraw

BonPaint

Cpaint

Ddraw

Attempts:

3 left

💡 Hint

Common Mistakes

Using draw() instead of onDraw()

Trying to override onPaint() which does not exist

The onDraw method is the correct method to override for custom drawing in a View.

2fill in blank

medium

Complete the code to create a Paint object with red color.

Android Kotlin

val paint = Paint().apply {
  color = [1]
  style = Paint.Style.FILL
}

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AColor.RED

BColor.BLUE

CColor.GREEN

DColor.BLACK

Attempts:

3 left

💡 Hint

Common Mistakes

Using Color.BLUE or other colors by mistake

Not setting the color property

To draw in red, set the paint color to Color.RED.

3fill in blank

hard

Fix the error in the code to draw a circle at position (100, 100) with radius 50.

Android Kotlin

canvas.[1](100f, 100f, 50f, paint)

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AdrawOval

BdrawCircle

CdrawLine

DdrawRect

Attempts:

3 left

💡 Hint

Common Mistakes

Using drawRect or drawLine which draw different shapes

Using drawOval which requires a RectF parameter

The drawCircle method draws a circle with given center coordinates and radius.

4fill in blank

hard

Fill both blanks to draw a blue rectangle from (50, 50) to (200, 150).

Android Kotlin

val rect = RectF([1], 50f, [2], 150f)
canvas.drawRect(rect, paint)

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A50f

B200f

C100f

D150f

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping left and right values

Using wrong float values

The rectangle's left is 50f and right is 200f to match the coordinates.

5fill in blank

hard

Fill all three blanks to create a Paint object with stroke style, stroke width 10f, and green color.

Android Kotlin

val paint = Paint().apply {
  style = Paint.Style.[1]
  strokeWidth = [2]f
  color = Color.[3]
}

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AFILL

BSTROKE

CGREEN

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using FILL style instead of STROKE

Forgetting the f suffix on strokeWidth

Using wrong color constant

Stroke style is STROKE, width is 10f, and color is green.