Matrix Transformation

NOTE
This animation is 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'

Required Permissions

None

matrix4.init

init(array: Array<number>): Object

Matrix constructor, which is used to create a 4x4 matrix by using the input parameter. Column-major order is used.

1. Parameters | Name | Type | Mandatory | Default Value | Description | | ——– | ——– | ——– | ——– | ——– | | array | Array<number> | Yes | [1, 0, 0, 0,
   0, 1, 0, 0,
   0, 0, 1, 0,
   0, 0, 0, 1] | A number array whose length is 16 (4 x 4). For details, see the parameter description. |

2. Return value | Type | Description | | —— | ——————————————————- | | Object | 4x4 matrix object created based on the input parameter. |

3. Parameter description | Name | Type | Mandatory | Description | | —- | —— | ——— | ——————————————————————————- | | m00 | number | Yes | Scaling value of the x-axis. Defaults to 1 for the unit 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 | 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. Defaults to 1 for the unit matrix. | | m12 | number | Yes | The seventh value, which is affected by the rotation of the x, y, and z axes. | | m13 | number | Yes | 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. Defaults to 1 for the unit matrix. | | m23 | number | Yes | Meaningless. | | m30 | number | Yes | Translation value of the x-axis, in px. Defaults to 0 for the unit matrix. | | m31 | number | Yes | Translation value of the y-axis, in px. Defaults to 0 for the unit matrix. | | m32 | number | Yes | Translation value of the z-axis, in px. Defaults to 0 for the unit matrix. | | m33 | number | Yes | Valid in homogeneous coordinates, presenting the perspective projection effect. |

4. Example

  import Matrix4 from '@ohos.matrix4'
  // Create a 4x4 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])

matrix4.identity

identity(): Object

Matrix initialization function. Can return a unit matrix object.

1. Return value | Type | Description | | —— | ——————- | | Object | Unit matrix object. |

2. Example

  // The effect of matrix 1 is the same as that of matrix 2.
  import Matrix4 from '@ohos.matrix4'
  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])
  let matrix2 = Matrix4.identity()

matrix4.copy

copy(): Object

Matrix copy function, which is used to copy the current matrix object.

1. Return value | Type | Description | | —— | ———————————- | | Object | Copy object of the current matrix. |

2. Example

  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): Object

Matrix overlay function, which is used to overlay the effects of two matrices to generate a new matrix object.

1. Parameters | Name | Type | Mandatory | Default Value | Description | | —— | ——- | ——— | ————- | —————————– | | matrix | Matrix4 | Yes | - | Matrix object to be overlaid. |

2. Return value | Type | Description | | —— | —————————- | | Object | Object after matrix overlay. |

3. Example

  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() {
       // Translate the x-axis by 100 pixels and then scale it up or down by 2x.
        Image($r("app.media.bg1")).transform(this.matrix1.combine(this.matrix2)) 
          .width("40%")
          .height(100)
          .margin({top:50})
      }
    }
  }

invert

invert(): Object

Matrix inverse function. Can return an inverse matrix of the current matrix object, that is, get an opposite effect.

1. Return value | Type | Description | | —— | ——– | | Object | Inverse matrix object of the current matrix. |

2. 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()

translate

translate({x?: number, y?: number, z?: number}): Object

Matrix translation function, which is used to add the translation effect to the x, y, and z axes of the current matrix.

1. Parameters | Name | Type | Mandatory | Default Value | Description | |—– | —— | ——– | ————– | —————————————— | | x | number | No | 0 | Translation distance of the x-axis, in px. | | y | number | No | 0 | Translation distance of the y-axis, in px. | | z | number | No | 0 | Translation distance of the z-axis, in px. |

2. Return value | Type | Description | | —— | —————————————————- | | Object | Matrix object after the translation effect is added. |

3. Example

  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}): Object

Matrix scaling function, which is used to add the scaling effect to the x, y, and z axes of the current matrix.

1. Parameters | Name | Type | Mandatory | Default Value | Description | | ——- | —— | ——— | ————- | ——————————— | | x | number | No | 1 | Scaling multiple of the x-axis. | | y | number | No | 1 | Scaling multiple of the y-axis. | | z | number | No | 1 | Scaling multiple of the z-axis. | | centerX | number | No | 0 | X coordinate of the center point. | | centerY | number | No | 0 | Y coordinate of the center point. |

2. Return value | Type | Description | | —— | ———————————————— | | Object | Matrix object after the scaling effect is added. |

3. Example

  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}): Object

Matrix rotation function, which is used to add the rotation effect to the x, y, and z axes of the current matrix.

1. Parameters | Name | Type | Mandatory | Default Value | Description | | ——- | —— | ——— | ————- | —————————————– | | x | number | No | 1 | X coordinate of the rotation axis vector. | | y | number | No | 1 | Y coordinate of the rotation axis vector. | | z | number | No | 1 | Z coordinate of the rotation axis vector. | | angle | number | No | 0 | Rotation angle. | | centerX | number | No | 0 | X coordinate of the center point. | | centerY | number | No | 0 | Y coordinate of the center point. |

2. Return value | Type | Description | | —— | ————————————————- | | Object | Matrix object after the rotation effect is added. |

3. Example

  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

Matrix point transformation function, which is used to apply the current transformation effect to a coordinate point.

1. Parameters | Name | Type | Mandatory | Default Value | Description | | —– | —– | ——— | ————- | ———————— | | point | Point | Yes | - | Point to be transformed. |

2. Return value | Type | Description | | —– | —————————————– | | Point | Point object after matrix transformation. |

3. Example

  import Matrix4 from '@ohos.matrix4'
  import prompt from '@system.prompt'
  
  @Entry
  @Component
  struct Test {
    private matrix1 = Matrix4.identity().transformPoint([100, 10])
    build() {
      Column() {
       Button("get Point")
        .onClick(() => {
         prompt.showToast({message:JSON.stringify(this.matrix1),duration:2000})
        }).backgroundColor(0x2788D9)
      }.width("100%").padding(50)
    }
  }

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