@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(array: Array<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
Name | Type | Mandatory | Description |
---|---|---|---|
array | Array<number> | Yes | A number array whose length is 16 (4 x 4). For details, see array parameters. Default value: [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1] |
Return value
Type | Description |
---|---|
Matrix4Transit | 4 x 4 matrix object created based on the input parameter. |
array parameters
Name | Type | Mandatory | Description |
---|---|---|---|
m00 | number | Yes | Scaling value of the x-axis. The default value is 1 for the identity matrix. |
m01 | number | Yes | The second value, which is affected by the rotation of the x, y, and z axes. |
m02 | number | Yes | The third value, which is affected by the rotation of the x, y, and z axes. |
m03 | number | Yes | The fourth value, which is meaningless. |
m10 | number | Yes | The fifth value, which is affected by the rotation of the x, y, and z axes. |
m11 | number | Yes | Scaling value of the y-axis. The default value is 1 for the identity matrix. |
m12 | number | Yes | The seventh value, which is affected by the rotation of the x, y, and z axes. |
m13 | number | Yes | The eighth value, which is meaningless. |
m20 | number | Yes | The ninth value, which is affected by the rotation of the x, y, and z axes. |
m21 | number | Yes | The tenth value, which is affected by the rotation of the x, y, and z axes. |
m22 | number | Yes | Scaling value of the z-axis. The default value is 1 for the identity matrix. |
m23 | number | Yes | Meaningless value. |
m30 | number | Yes | Translation value of the x-axis, in px. The default value is 0 for the identity matrix. |
m31 | number | Yes | Translation value of the y-axis, in px. The default value is 0 for the identity matrix. |
m32 | number | Yes | Translation value of the z-axis, in px. The default value is 0 for the identity matrix. |
m33 | number | Yes | Valid 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($r("app.media.zh"))
.width("40%")
.height(100)
.transform(matrix)
}
}
}
matrix4.identity
identity(): Matrix4Transit
Constructs an identity matrix.
System capability: SystemCapability.ArkUI.ArkUI.Full
Return value
Type | Description |
---|---|
Matrix4Transit | Identity matrix object. |
Example
// The effect of matrix 1 is the same as that of matrix 2.
import matrix4 from '@ohos.matrix4'
let matrix1 = matrix4.init([1.0, 0.0, 0.0, 0.0,
0.0, 1.0, 0.0, 0.0,
0.0, 0.0, 1.0, 0.0,
0.0, 0.0, 0.0, 1.0])
let matrix2 = matrix4.identity()
@Entry
@Component
struct Tests {
build() {
Column() {
Image($r("app.media.zh"))
.width("40%")
.height(100)
.transform(matrix1)
Image($r("app.media.zh"))
.width("40%")
.height(100)
.margin({ top: 150 })
.transform(matrix2)
}
}
}
matrix4.copy
copy(): Matrix4Transit
Copies this matrix object.
System capability: SystemCapability.ArkUI.ArkUI.Full
Return value
Type | Description |
---|---|
Matrix4Transit | Copy object of the current matrix. |
Example
// xxx.ets
import matrix4 from '@ohos.matrix4'
@Entry
@Component
struct Test {
private matrix1 = matrix4.identity().translate({ x: 100 })
private matrix2 = this.matrix1.copy().scale({ x: 2 })
build() {
Column() {
Image($r("app.media.bg1"))
.width("40%")
.height(100)
.transform(this.matrix1)
Image($r("app.media.bg2"))
.width("40%")
.height(100)
.margin({ top: 50 })
.transform(this.matrix2)
}
}
}
Matrix4
combine
combine(matrix: Matrix4): Matrix4Transit
Combines the effects of two matrices to generate a new matrix object.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
matrix | Matrix4 | Yes | Matrix object to be combined. |
Return value
Type | Description |
---|---|
Matrix4Transit | Object after matrix combination. |
Example
// xxx.ets
import matrix4 from '@ohos.matrix4'
@Entry
@Component
struct Test {
private matrix1 = matrix4.identity().translate({ x: 200 }).copy()
private matrix2 = matrix4.identity().scale({ x: 2 }).copy()
build() {
Column() {
// Before matrix transformation
Image($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($r("app.media.icon"))
.transform(this.matrix1.combine(this.matrix2))
.width("40%")
.height(100)
.margin({ top: 50 })
}
}
}
invert
invert(): Matrix4Transit
Inverts this matrix object.
System capability: SystemCapability.ArkUI.ArkUI.Full
Return value
Type | Description |
---|---|
Matrix4Transit | Inverse matrix object of the current matrix. |
Example
import matrix4 from '@ohos.matrix4'
// The effect of matrix 1 (width scaled up by 2x) is opposite to that of matrix 2 (width scaled down by 2x).
let matrix1 = matrix4.identity().scale({ x: 2 })
let matrix2 = matrix1.invert()
@Entry
@Component
struct Tests {
build() {
Column() {
Image($r("app.media.zh"))
.width(200)
.height(100)
.transform(matrix1)
.margin({ top: 100 })
Image($r("app.media.zh"))
.width(200)
.height(100)
.margin({ top: 150 })
.transform(matrix2)
}
}
}
translate
translate({x?: number, y?: number, z?: number}): Matrix4Transit
Translates this matrix object along the x, y, and z axes.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
x | number | No | Translation distance along the x-axis, in px. Default value: 0 Value range: (-∞, +∞) |
y | number | No | Translation distance along the y-axis, in px. Default value: 0 Value range: (-∞, +∞) |
z | number | No | Translation distance along the z-axis, in px. Default value: 0 Value range: (-∞, +∞) |
Return value
Type | Description |
---|---|
Matrix4Transit | Matrix object after the translation effect is added. |
Example
// xxx.ets
import matrix4 from '@ohos.matrix4'
@Entry
@Component
struct Test {
private matrix1 = matrix4.identity().translate({ x: 100, y: 200, z: 30 })
build() {
Column() {
Image($r("app.media.bg1")).transform(this.matrix1)
.width("40%")
.height(100)
}
}
}
scale
scale({x?: number, y?: number, z?: number, centerX?: number, centerY?: number}): Matrix4Transit
Scales this matrix object along the x, y, and z axes.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
x | number | No | Scaling multiple along the x-axis. If the value is greater than 1, the image is scaled up along the x-axis. If the value is less than 1, the image is scaled down along the x-axis. Default value: 1 Value range: [0, +∞) NOTE A value less than 0 evaluates to the default value. |
y | number | No | Scaling multiple along the y-axis. If the value is greater than 1, the image is scaled up along the y-axis. If the value is less than 1, the image is scaled down along the y-axis. Default value: 1 Value range: [0, +∞) NOTE A value less than 0 evaluates to the default value. |
z | number | No | Scaling multiple along the z-axis. If the value is greater than 1, the image is scaled up along the z-axis. If the value is less than 1, the image is scaled down along the z-axis. Default value: 1 Value range: [0, +∞) NOTE A value less than 0 evaluates to the default value. |
centerX | number | No | X coordinate of the center point. Default value: 0 Value range: (-∞, +∞) |
centerY | number | No | Y coordinate of the center point. Default value: 0 Value range: (-∞, +∞) |
Return value
Type | Description |
---|---|
Matrix4Transit | Matrix object after the scaling effect is added. |
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($r("app.media.bg1")).transform(this.matrix1)
.width("40%")
.height(100)
}
}
}
rotate
rotate({x?: number, y?: number, z?: number, angle?: number, centerX?: Length, centerY?: Length}): Matrix4Transit
Rotates this matrix object along the x, y, and z axes.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
x | number | No | X coordinate of the rotation axis vector. Default value: 1 Value range: (-∞, +∞) |
y | number | No | Y coordinate of the rotation axis vector. Default value: 1 Value range: (-∞, +∞) |
z | number | No | Z coordinate of the rotation axis vector. Default value: 1 Value range: (-∞, +∞) |
angle | number | No | Rotation angle. Default value: 0 |
centerX | number | No | X coordinate of the center point. Default value: 0 |
centerY | number | No | Y coordinate of the center point. Default value: 0 |
Return value
Type | Description |
---|---|
Matrix4Transit | Matrix object after the rotation effect is added. |
Example
// xxx.ets
import matrix4 from '@ohos.matrix4'
@Entry
@Component
struct Test {
private matrix1 = matrix4.identity().rotate({ x: 1, y: 1, z: 2, angle: 30 })
build() {
Column() {
Image($r("app.media.bg1")).transform(this.matrix1)
.width("40%")
.height(100)
}.width("100%").margin({ top: 50 })
}
}
transformPoint
transformPoint(point: Point): Point
Applies the current transformation effect to a coordinate point.
System capability: SystemCapability.ArkUI.ArkUI.Full
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
point | Point | Yes | Point to be transformed. |
Return value
Type | Description |
---|---|
Point | Point object after matrix transformation |
Example
// xxx.ets
import matrix4 from '@ohos.matrix4'
@Entry
@Component
struct Test {
private originPoint: [number, number] = [50, 50]
private matrix_1 = matrix4.identity().translate({ x: 150, y: -50 })
private transformPoint = this.matrix_1.transformPoint(this.originPoint)
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)
}
}