未验证 提交 133ed47f 编写于 作者: O openharmony_ci 提交者: Gitee

!6126 翻译完成:更新 ts-offscreencanvasrenderingcontext2d.md

Merge pull request !6126 from ester.zhou/TR-4930-1
# OffscreenCanvasRenderingContext2D
> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**
> The APIs of this module are supported since API version 8. Updates will be marked with a superscript to indicate their earliest API version.
> **NOTE**<br>The APIs of this module are supported since API version 8. Updates will be marked with a superscript to indicate their earliest API version.
Use **OffscreenCanvasRenderingContext2D** to draw rectangles, images, and text offscreen onto a canvas. Drawing offscreen onto a canvas is a process where content to draw onto the canvas is first drawn in the buffer, and then converted into a picture, and finally the picture is drawn on the canvas. This process increases the drawing efficiency.
......@@ -43,14 +42,15 @@ OffscreenCanvasRenderingContext2D(width: number, height: number, setting: Render
| [imageSmoothingEnabled](#imagesmoothingenabled) | boolean | true | Whether to adjust the image smoothness during image drawing. The value **true** means to enable this feature, and **false** means the opposite. |
| imageSmoothingQuality | string | 'low' | Image smoothness. The value can be **'low'**, **'medium'**, or **'high'**. |
> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**
> **NOTE**
> The value of the **&lt;color&gt;** type can be in 'rgb(255, 255, 255)', 'rgba(255, 255, 255, 1.0)', or '\#FFFFFF' format.
### fillStyle
```
```ts
// xxx.ets
@Entry
@Component
struct FillStyleExample {
......@@ -83,7 +83,8 @@ struct FillStyleExample {
### lineWidth
```
```ts
// xxx.ets
@Entry
@Component
struct LineWidthExample {
......@@ -116,7 +117,8 @@ struct LineWidthExample {
### strokeStyle
```
```ts
// xxx.ets
@Entry
@Component
struct StrokeStyleExample {
......@@ -151,7 +153,8 @@ struct StrokeStyleExample {
### lineCap
```
```ts
// xxx.ets
@Entry
@Component
struct LineCapExample {
......@@ -188,7 +191,8 @@ struct LineCapExample {
### lineJoin
```
```ts
// xxx.ets
@Entry
@Component
struct LineJoinExample {
......@@ -226,7 +230,8 @@ struct LineJoinExample {
### miterLimit
```
```ts
// xxx.ets
@Entry
@Component
struct MiterLimit {
......@@ -264,7 +269,8 @@ struct MiterLimit {
### font
```
```ts
// xxx.ets
@Entry
@Component
struct Font {
......@@ -297,7 +303,8 @@ struct Font {
### textAlign
```
```ts
// xxx.ets
@Entry
@Component
struct CanvasExample {
......@@ -345,7 +352,8 @@ struct CanvasExample {
### textBaseline
```
```ts
// xxx.ets
@Entry
@Component
struct TextBaseline {
......@@ -393,7 +401,8 @@ struct TextBaseline {
### globalAlpha
```
```ts
// xxx.ets
@Entry
@Component
struct GlobalAlpha {
......@@ -429,7 +438,8 @@ struct GlobalAlpha {
### lineDashOffset
```
```ts
// xxx.ets
@Entry
@Component
struct LineDashOffset {
......@@ -477,7 +487,8 @@ struct LineDashOffset {
| xor | Combines the new drawing and existing drawing using the XOR operation. |
```
```ts
// xxx.ets
@Entry
@Component
struct GlobalCompositeOperation {
......@@ -518,7 +529,8 @@ struct GlobalCompositeOperation {
### shadowBlur
```
```ts
// xxx.ets
@Entry
@Component
struct ShadowBlur {
......@@ -553,7 +565,8 @@ struct ShadowBlur {
### shadowColor
```
```ts
// xxx.ets
@Entry
@Component
struct ShadowColor {
......@@ -589,7 +602,8 @@ struct ShadowColor {
### shadowOffsetX
```
```ts
// xxx.ets
@Entry
@Component
struct ShadowOffsetX {
......@@ -625,7 +639,8 @@ struct ShadowOffsetX {
### shadowOffsetY
```
```ts
// xxx.ets
@Entry
@Component
struct ShadowOffsetY {
......@@ -661,7 +676,8 @@ struct ShadowOffsetY {
### imageSmoothingEnabled
```
```ts
// xxx.ets
@Entry
@Component
struct ImageSmoothingEnabled {
......@@ -711,7 +727,8 @@ Fills a rectangle on the canvas.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct FillRect {
......@@ -800,7 +817,8 @@ Clears the content in a rectangle on the canvas.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct ClearRect {
......@@ -845,7 +863,8 @@ Draws filled text on the canvas.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct FillText {
......@@ -941,7 +960,8 @@ Returns a **TextMetrics** object used to obtain the width of specified text.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct MeasureText {
......@@ -1023,7 +1043,8 @@ Creates a drawing path.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct BeginPath {
......@@ -1070,7 +1091,8 @@ Moves a drawing path to a target position on the canvas.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct MoveTo {
......@@ -1115,7 +1137,8 @@ Connects the current point to a target position using a straight line.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct LineTo {
......@@ -1154,7 +1177,8 @@ Draws a closed path.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct ClosePath {
......@@ -1201,7 +1225,8 @@ Creates a pattern for image filling based on a specified source image and repeti
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct CreatePattern {
......@@ -1250,7 +1275,8 @@ Draws a cubic bezier curve on the canvas.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct BezierCurveTo {
......@@ -1297,7 +1323,8 @@ Draws a quadratic curve on the canvas.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct QuadraticCurveTo {
......@@ -1346,7 +1373,8 @@ Draws an arc on the canvas.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct Arc {
......@@ -1393,7 +1421,8 @@ Draws an arc based on the radius and points on the arc.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct ArcTo {
......@@ -1444,7 +1473,8 @@ Draws an ellipse in the specified rectangular region.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct CanvasExample {
......@@ -1490,7 +1520,8 @@ Creates a rectangle.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct CanvasExample {
......@@ -1527,7 +1558,8 @@ Fills the area inside a closed path.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct Fill {
......@@ -1564,7 +1596,8 @@ Sets the current path to a clipping path.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct Clip {
......@@ -1609,7 +1642,8 @@ Rotates a canvas clockwise around its coordinate axes.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct Rotate {
......@@ -1652,7 +1686,8 @@ Scales a canvas based on scale factors.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct Scale {
......@@ -1688,7 +1723,7 @@ transform(scaleX: number, skewX: number, skewY: number, scaleY: number, translat
Defines a transformation matrix. To transform a graph, you only need to set parameters of the matrix. The coordinates of the graph are multiplied by the matrix values to obtain new coordinates of the transformed graph. You can use the matrix to implement multiple transform effects.
> ![icon-note.gif](public_sys-resources/icon-note.gif) **NOTE**
> **NOTE**
> The following formulas calculate coordinates of the transformed graph. **x** and **y** represent coordinates before transformation, and **x'** and **y'** represent coordinates after transformation.
>
> - x' = scaleX \* x + skewY \* y + translateX
......@@ -1707,7 +1742,8 @@ Defines a transformation matrix. To transform a graph, you only need to set para
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct Transform {
......@@ -1760,7 +1796,8 @@ Resets the existing transformation matrix and creates a new transformation matri
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct SetTransform {
......@@ -1806,7 +1843,8 @@ Moves the origin of the coordinate system.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct Translate {
......@@ -1838,18 +1876,18 @@ Moves the origin of the coordinate system.
### drawImage
drawImage(image: ImageBitmap, dx: number, dy: number): void
drawImage(image: ImageBitmap | PixelMap, dx: number, dy: number): void
drawImage(image: ImageBitmap, dx: number, dy: number, dWidth: number, dHeight: number): void
drawImage(image: ImageBitmap | PixelMap, dx: number, dy: number, dWidth: number, dHeight: number): void
drawImage(image: ImageBitmap, sx: number, sy: number, sWidth: number, sHeight: number, dx: number, dy: number, dWidth: number, dHeight: number):void
drawImage(image: ImageBitmap | PixelMap, sx: number, sy: number, sWidth: number, sHeight: number, dx: number, dy: number, dWidth: number, dHeight: number):void
Draws an image.
- Parameters
| Name | Type | Mandatory | Default Value | Description |
| ------- | ---------------------------------------- | --------- | ------------- | ---------------------------------------- |
| image | [ImageBitmap](ts-components-canvas-imagebitmap.md) | Yes | null | Image resource. For details, see ImageBitmap. |
| image | [ImageBitmap](ts-components-canvas-imagebitmap.md) or [PixelMap](../apis/js-apis-image.md#pixelmap7) | Yes | null | Image resource. For details, see ImageBitmap. |
| sx | number | No | 0 | X-coordinate of the upper left corner of the rectangle used to crop the source image. |
| sy | number | No | 0 | Y-coordinate of the upper left corner of the rectangle used to crop the source image. |
| sWidth | number | No | 0 | Target width to crop the source image. |
......@@ -1862,7 +1900,8 @@ Draws an image.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct Index {
......@@ -1915,12 +1954,24 @@ Creates an **ImageData** object by copying an existing **ImageData** object. For
| --------- | ---------------------------------------- | --------- | ------------- | ----------------------------- |
| imagedata | [ImageData](ts-components-canvas-imagebitmap.md) | Yes | null | **ImageData** object to copy. |
### getPixelMap
getPixelMap(sx: number, sy: number, sw: number, sh: number): PixelMap
Obtains the **[PixelMap](../apis/js-apis-image.md#pixelmap7)** object created with the pixels within the specified area on the canvas.
- Parameters
| Name | Type | Mandatory | Default Value | Description |
| -------- | -------- | -------- | -------- | -------- |
| sx | number | Yes | 0 | X-coordinate of the upper left corner of the output area. |
| sy | number | Yes | 0 | Y-coordinate of the upper left corner of the output area. |
| sw | number | Yes | 0 | Width of the output area. |
| sh | number | Yes | 0 | Height of the output area. |
### getImageData
getImageData(sx: number, sy: number, sw: number, sh: number): Object
Creates an [ImageData](ts-components-canvas-imagebitmap.md) object with pixels in the specified area on the canvas.
Obtains the **[ImageData](ts-components-canvas-imagebitmap.md)** object created with the pixels within the specified area on the canvas.
- Parameters
| Name | Type | Mandatory | Default Value | Description |
......@@ -1950,7 +2001,8 @@ Puts the [ImageData](ts-components-canvas-imagebitmap.md) onto a rectangular are
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct PutImageData {
......@@ -1993,7 +2045,8 @@ Restores the saved drawing context.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct CanvasExample {
......@@ -2027,7 +2080,8 @@ Saves the current drawing context.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct CanvasExample {
......@@ -2069,7 +2123,8 @@ Creates a linear gradient.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct CreateLinearGradient {
......@@ -2121,7 +2176,8 @@ Creates a linear gradient.
- Example
```
```ts
// xxx.ets
@Entry
@Component
struct CreateRadialGradient {
......
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