PixelMap

Result of a pixel read operation. This contains the ImageBitmap pixel information represented as a 1 dimensional array of values that supports queries of pixel values based on the 2 dimensional coordinates of the corresponding ImageBitmap this was obtained from

import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.ImageBitmap
import androidx.compose.ui.graphics.PixelMap

val imageBitmap = createImageBitmap()

val buffer = IntArray(20 * 10)
imageBitmap.readPixels(buffer = buffer, startX = 8, startY = 9, width = 20, height = 10)

val pixelmap = PixelMap(buffer = buffer, width = 20, height = 10, stride = 20, bufferOffset = 0)

// create a histogram to count the number of occurrences of a color within the specified
// subsection of the provided ImageBitmap
val histogram = HashMap<Color, Int>()
for (x in 0 until pixelmap.width) {
    for (y in 0 until pixelmap.height) {
        val color = pixelmap[x, y]
        val colorCount = histogram[color] ?: 0
        histogram[color] = (colorCount + 1)
    }
}
See also
readPixels
toPixelMap

Summary

Public constructors
PixelMap(
    buffer: IntArray,
    width: Int,
    height: Int,
    bufferOffset: Int,
    stride: Int
)
Cmn

Public functions
operator Color
get(x: @IntRange(from = 0) Int, y: @IntRange(from = 0) Int)

Obtain the color of the pixel at the given coordinate.
Cmn

Public properties
IntArray

IntArray where pixel information is stored as an ARGB value packed into an Int
Cmn
Int

first index in the buffer where pixel information for the ImageBitmap is stored
Cmn
Int

Height of the subsection of the ImageBitmap this buffer represents
Cmn
Int

Number of entries to skip between rows
Cmn
Int

Width of the subsection of the ImageBitmap this buffer represents
Cmn

Public constructors

PixelMap

Cmn
Added in 1.0.0
PixelMap(
    buffer: IntArray,
    width: Int,
    height: Int,
    bufferOffset: Int,
    stride: Int
)
Parameters
buffer: IntArray

IntArray where pixel information is stored as an ARGB value packed into an Int
width: Int

Width of the subsection of the ImageBitmap this buffer represents
height: Int

Height of the subsection of the ImageBitmap this buffer represents
bufferOffset: Int

first index in the buffer where pixel information for the ImageBitmap is stored
stride: Int

Number of entries to skip between rows

Public functions

get

Cmn
Added in 1.0.0
operator fun get(x: @IntRange(from = 0) Int, y: @IntRange(from = 0) Int): Color

Obtain the color of the pixel at the given coordinate.

Parameters
x: @IntRange(from = 0) Int

the horizontal pixel coordinate, minimum 1
y: @IntRange(from = 0) Int

the vertical pixel coordinate, minimum 1

Public properties

buffer

Cmn
Added in 1.0.0
val buffer: IntArray

IntArray where pixel information is stored as an ARGB value packed into an Int

bufferOffset

Cmn
Added in 1.0.0
val bufferOffset: Int

first index in the buffer where pixel information for the ImageBitmap is stored

height

Cmn
Added in 1.0.0
val height: Int

Height of the subsection of the ImageBitmap this buffer represents

stride

Cmn
Added in 1.0.0
val stride: Int

Number of entries to skip between rows

width

Cmn
Added in 1.0.0
val width: Int

Width of the subsection of the ImageBitmap this buffer represents