harmony 鸿蒙@ohos.matrix4 (Matrix Transformation)

2023-02-03 浏览 (745)

@ohos.matrix4 (Matrix Transformation)

The matrix4 module provides APIs for matrix transformation. You can use these APIs to translate, rotate, and scale images.

NOTE

The initial APIs of this module are supported since API version 7. Updates will be marked with a superscript to indicate their earliest API version.

Modules to Import

import matrix4 from '@ohos.matrix4'

matrix4.init

init(options: [number,number,number,number,number,number,number,number,number,number,number,number,number,number,number,number]): Matrix4Transit

Matrix constructor, which is used to create a 4 x 4 matrix by using the input parameter. Column-major order is used.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
option[number,number,number,number,
number,number,number,number,
number,number,number,number,
number,number,number,number]		YesA number array whose length is 16 (4 x 4). For details, see 4 x 4 matrix description.
Default value:
[1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1]

Return value

TypeDescription
Matrix4Transit4 x 4 matrix object created based on the input parameter.

4 x 4 matrix description

NameTypeMandatoryDescription
m00numberYesScaling value of the x-axis. The default value is 1 for the identity matrix.
m01numberYesThe second value, which is affected by the rotation of the x, y, and z axes.
m02numberYesThe third value, which is affected by the rotation of the x, y, and z axes.
m03numberYesThe fourth value, which is meaningless.
m10numberYesThe fifth value, which is affected by the rotation of the x, y, and z axes.
m11numberYesScaling value of the y-axis. The default value is 1 for the identity matrix.
m12numberYesThe seventh value, which is affected by the rotation of the x, y, and z axes.
m13numberYesThe eighth value, which is meaningless.
m20numberYesThe ninth value, which is affected by the rotation of the x, y, and z axes.
m21numberYesThe tenth value, which is affected by the rotation of the x, y, and z axes.
m22numberYesScaling value of the z-axis. The default value is 1 for the identity matrix.
m23numberYesMeaningless value.
m30numberYesTranslation value of the x-axis, in px. The default value is 0 for the identity matrix.
m31numberYesTranslation value of the y-axis, in px. The default value is 0 for the identity matrix.
m32numberYesTranslation value of the z-axis, in px. The default value is 0 for the identity matrix.
m33numberYesValid in homogeneous coordinates, presenting the perspective projection effect.

Example

import matrix4 from '@ohos.matrix4'
// Create a 4 x 4 matrix.
let matrix = matrix4.init([1.0, 0.0, 0.0, 0.0,
                          0.0, 1.0, 0.0, 0.0,
                          0.0, 0.0, 1.0, 0.0,
                          0.0, 0.0, 0.0, 1.0])
@Entry
@Component
struct Tests {
  build() {
    Column() {
      Image($r("app.media.zh"))
        .width("40%")
        .height(100)
        .transform(matrix)
    }
  }
}

matrix4.identity

identity(): Matrix4Transit

Constructs an identity matrix.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

TypeDescription
Matrix4TransitIdentity matrix object.

Example

// The effect of matrix 1 is the same as that of matrix 2.
import matrix4 from '@ohos.matrix4'
let matrix1 = matrix4.init([1.0, 0.0, 0.0, 0.0,
                          0.0, 1.0, 0.0, 0.0,
                          0.0, 0.0, 1.0, 0.0,
                          0.0, 0.0, 0.0, 1.0])
let matrix2 = matrix4.identity()
@Entry
@Component
struct Tests {
  build() {
    Column() {
      Image($r("app.media.zh"))
        .width("40%")
        .height(100)
        .transform(matrix1)
      Image($r("app.media.zh"))
        .width("40%")
        .height(100)
        .margin({ top: 150 })
        .transform(matrix2)
    }
  }
}

matrix4.copy

copy(): Matrix4Transit

Copies this matrix object.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

TypeDescription
Matrix4TransitCopy object of the current matrix.

Example

// xxx.ets
import matrix4 from '@ohos.matrix4'

@Entry
@Component
struct Test {
  private matrix1 = matrix4.identity().translate({ x: 100 })
  // Perform the scale operation on the copy matrix of matrix1, which does not affect matrix1.
  private matrix2 = this.matrix1.copy().scale({ x: 2 })

  build() {
    Column() {
      Image($r("app.media.bg1"))
        .width("40%")
        .height(100)
        .transform(this.matrix1)
      Image($r("app.media.bg2"))
        .width("40%")
        .height(100)
        .margin({ top: 50 })
        .transform(this.matrix2)
    }
  }
}

en-us_image_0000001219744181

matrix4.invert(deprecated)

invert(): Matrix4Transit

Inverts this matrix object.

This API is deprecated since API version 10.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

TypeDescription
Matrix4TransitInverse matrix object of the current matrix.

matrix4.combine(deprecated)

combine(options: Matrix4Transit): Matrix4Transit

Combines the effects of two matrices to generate a new matrix object.

This API is deprecated since API version 10.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
optionMatrix4TransitYesMatrix object to be combined.

Return value

TypeDescription
Matrix4TransitInverse matrix object of the current matrix.

matrix4.translate(deprecated)

translate(options: TranslateOption): Matrix4Transit

Translates this matrix object along the x, y, and z axes.

This API is deprecated since API version 10.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
optionTranslateOptionYesTranslation configuration.

Return value

TypeDescription
Matrix4TransitInverse matrix object of the current matrix.

matrix4.scale(deprecated)

scale(options: ScaleOption): Matrix4Transit

Scales this matrix object along the x, y, and z axes.

This API is deprecated since API version 10.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
optionScaleOptionYesScaling configuration.

Return value

TypeDescription
Matrix4TransitInverse matrix object of the current matrix.

matrix4.rotate(deprecated)

rotate(options: RotateOption): Matrix4Transit

Rotates this matrix object along the x, y, and z axes.

This API is deprecated since API version 10.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
optionRotateOptionYesRotation configuration.

Return value

TypeDescription
Matrix4TransitInverse matrix object of the current matrix.

matrix4.transformPoint(deprecated)

transformPoint(options: [number, number]): [number, number]

Applies the current transformation effect to a coordinate point.

This API is deprecated since API version 10.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
option[number, number]YesPoint to be transformed.

Return value

TypeDescription
[number, number]Point object after matrix transformation

Matrix4Transit

combine

combine(options: Matrix4Transit): Matrix4Transit

Combines the effects of two matrices to generate a new matrix object. The original matrix that calls this API will be changed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
optionMatrix4TransitYesMatrix object to be combined.

Return value

TypeDescription
Matrix4TransitObject after matrix combination.

Example

// xxx.ets
import matrix4 from '@ohos.matrix4'

@Entry
@Component
struct Test {
  private matrix1 = matrix4.identity().translate({ x: 200 })
  private matrix2 = matrix4.identity().scale({ x: 2 })

  build() {
    Column() {
      // Before matrix transformation
      Image($r("app.media.icon"))
        .width("40%")
        .height(100)
        .margin({ top: 50 })
      // Translate the x-axis by 200px, and then scale it twice to obtain the resultant matrix.
      Image($r("app.media.icon"))
        .transform(this.matrix1.copy().combine(this.matrix2))
        .width("40%")
        .height(100)
        .margin({ top: 50 })
    }
  }
}

en-us_image_0000001118642902

invert

invert(): Matrix4Transit

Inverts this matrix object. The original matrix that calls this API will be changed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

TypeDescription
Matrix4TransitInverse matrix object of the current matrix.

Example

import matrix4 from '@ohos.matrix4'
// The effect of matrix 1 (width scaled up by 2x) is opposite to that of matrix 2 (width scaled down by 2x).
let matrix1 = matrix4.identity().scale({ x: 2 })
let matrix2 = matrix1.copy().invert()

@Entry
@Component
struct Tests {
  build() {
    Column() {
      Image($r("app.media.zh"))
        .width(200)
        .height(100)
        .transform(matrix1)
        .margin({ top: 100 })
      Image($r("app.media.zh"))
        .width(200)
        .height(100)
        .margin({ top: 150 })
        .transform(matrix2)
    }
  }
}

translate

translate(options: TranslateOption): Matrix4Transit

Translates this matrix object along the x, y, and z axes. The original matrix that calls this API will be changed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
optionTranslateOptionYesTranslation configuration.

Return value

TypeDescription
Matrix4TransitMatrix object after the translation.

Example

// xxx.ets
import matrix4 from '@ohos.matrix4'

@Entry
@Component
struct Test {
  private matrix1 = matrix4.identity().translate({ x: 100, y: 200, z: 30 })

  build() {
    Column() {
      Image($r("app.media.bg1")).transform(this.matrix1)
        .width("40%")
        .height(100)
    }
  }
}

en-us_image_0000001219662645

scale

scale(options: ScaleOption): Matrix4Transit

Scales this matrix object along the x, y, and z axes. The original matrix that calls this API will be changed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
optionScaleOptionYesScaling configuration.

Return value

TypeDescription
Matrix4TransitMatrix object after the scaling.

Example

// xxx.ets
import matrix4 from '@ohos.matrix4'
@Entry
@Component
struct Test {
  private matrix1 = matrix4.identity().scale({ x:2, y:3, z:4, centerX:50, centerY:50 })

  build() {
    Column() { 
      Image($r("app.media.bg1")).transform(this.matrix1)
        .width("40%")
        .height(100)
    }
  }
}

en-us_image_0000001219864131

rotate

rotate(options: RotateOption): Matrix4Transit

Rotates this matrix object along the x, y, and z axes. The original matrix that calls this API will be changed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
optionRotateOptionYesRotation configuration.

Return value

TypeDescription
Matrix4TransitMatrix object after the rotation.

Example

// xxx.ets
import matrix4 from '@ohos.matrix4'

@Entry
@Component
struct Test {
  private matrix1 = matrix4.identity().rotate({ x: 1, y: 1, z: 2, angle: 30 })

  build() {
    Column() {
      Image($r("app.media.bg1")).transform(this.matrix1)
        .width("40%")
        .height(100)
    }.width("100%").margin({ top: 50 })
  }
}

en-us_image_0000001174422898

transformPoint

transformPoint(options: [number, number]): [number, number]

Applies the current transformation effect to a coordinate point.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

NameTypeMandatoryDescription
option[number, number]YesPoint to be transformed.

Return value

TypeDescription
[number, number]Point object after matrix transformation

Example

// xxx.ets
import matrix4 from '@ohos.matrix4'

@Entry
@Component
struct Test {
  private originPoint: number[] = [50, 50]
  private matrix_1 = matrix4.identity().translate({ x: 150, y: -50 })
  private transformPoint = this.matrix_1.transformPoint([this.originPoint[0], this.originPoint[1]])
  private matrix_2 = matrix4.identity().translate({ x: this.transformPoint[0], y: this.transformPoint[1] })

  build() {
    Column() {
      Text(`Coordinates before matrix transformation: [${this.originPoint}]`)
        .fontSize(16)
      Image($r("app.media.image"))
        .width('600px')
        .height('300px')
        .margin({ top: 50 })
      Text(`Coordinates after matrix transformation: [${this.transformPoint}]`)
        .fontSize(16)
        .margin({ top: 100 })
      Image($r("app.media.image"))
        .width('600px')
        .height('300px')
        .margin({ top: 50 })
        .transform(this.matrix_2)
    }.width("100%").padding(50)
  }
}

en-us_image_0000001219864133

TranslateOption

System capability: SystemCapability.ArkUI.ArkUI.Full

NameTypeMandatoryDescription
xnumberNoTranslation distance along the x-axis, in px.
Default value: 0
Value range: (-∞, +∞)
ynumberNoTranslation distance along the y-axis, in px.
Default value: 0
Value range: (-∞, +∞)
znumberNoTranslation distance along the z-axis, in px.
Default value: 0
Value range: (-∞, +∞)

ScaleOption

System capability: SystemCapability.ArkUI.ArkUI.Full

NameTypeMandatoryDescription
xnumberNoScaling multiple along the x-axis. x > 1: The image is scaled up along the x-axis.
0 < x < 1: The image is scaled down along the x-axis.
x < 0: The image is scaled in the reverse direction of the x-axis.
Default value: 1
Value range: (-∞, +∞)
ynumberNoScaling multiple along the y-axis. y > 1: The image is scaled up along the y-axis.
0 < y < 1: The image is scaled down along the y-axis.
y < 0: The image is scaled in the reverse direction of the y-axis.
Default value: 1
Value range: (-∞, +∞)
znumberNoScaling multiple along the z-axis. z > 1: The image is scaled up along the z-axis.
0 < z < 1: The image is scaled down along the z-axis.
z < 0: The image is scaled in the reverse direction of the z-axis.
Default value: 1
Value range: (-∞, +∞)
centerXnumberNoX coordinate of the center point.
Default value: 0
Value range: (-∞, +∞)
centerYnumberNoY coordinate of the center point.
Default value: 0
Value range: (-∞, +∞)

RotateOption

System capability: SystemCapability.ArkUI.ArkUI.Full

NameTypeMandatoryDescription
xnumberNoX coordinate of the rotation axis vector.
Default value: 0
Value range: (-∞, +∞)
ynumberNoY coordinate of the rotation axis vector.
Default value: 0
Value range: (-∞, +∞)
znumberNoZ coordinate of the rotation axis vector.
Default value: 0
Value range: (-∞, +∞)
NOTE
The rotation axis vector is valid only when at least one of x, y, and z is not 0.
anglenumberNoRotation angle.
Default value: 0
centerXnumberNoX coordinate of the center point.
Default value: 0
centerYnumberNoY coordinate of the center point.
Default value: 0

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