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WebGLRenderingContext.pixelStorei() 是 WebGL API 中用于图像预处理的函数。
语法
void gl.pixelStorei(pname, param);
参数
返回值
None.
像素存储参数
模式名称 (pname) |
描述 | 类型 | 默认值 | param 的可选值 | Specified in |
|---|---|---|---|---|---|
gl.PACK_ALIGNMENT |
Packing of pixel data into memory | GLint |
4 | 1, 2, 4, 8 | OpenGL ES 2.0 |
gl.UNPACK_ALIGNMENT |
Unpacking of pixel data from memory. | GLint |
4 | 1, 2, 4, 8 | OpenGL ES 2.0 |
gl.UNPACK_FLIP_Y_WEBGL |
如果为true，则把图片上下对称翻转坐标轴(图片本身不变)。 |
GLboolean |
false | true, false | WebGL |
gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL |
Multiplies the alpha channel into the other color channels | GLboolean |
false | true, false | WebGL |
gl.UNPACK_COLORSPACE_CONVERSION_WEBGL |
Default color space conversion or no color space conversion. | GLenum |
gl.BROWSER_DEFAULT_WEBGL |
gl.BROWSER_DEFAULT_WEBGL, gl.NONE |
WebGL |
When using a WebGL 2 context, the following values are available additionally:
| Constant | Description | Type | Default value | Allowed values (for param) |
Specified in |
|---|---|---|---|---|---|
gl.PACK_ROW_LENGTH |
Number of pixels in a row. | GLint |
0 | 0 to Infinity |
OpenGL ES 3.0 |
gl.PACK_SKIP_PIXELS |
Number of pixel locations skipped before the first pixel is written into memory. | GLint |
0 | 0 to Infinity |
OpenGL ES 3.0 |
gl.PACK_SKIP_ROWS |
Number of rows of pixel locations skipped before the first pixel is written into memory | GLint |
0 | 0 to Infinity |
OpenGL ES 3.0 |
gl.UNPACK_ROW_LENGTH |
Number of pixels in a row. | GLint |
0 | 0 to Infinity |
OpenGL ES 3.0 |
gl.UNPACK_IMAGE_HEIGHT |
Image height used for reading pixel data from memory | GLint |
0 | 0 to Infinity |
OpenGL ES 3.0 |
gl.UNPACK_SKIP_PIXELS |
Number of pixel images skipped before the first pixel is read from memory | GLint |
0 | 0 to Infinity |
OpenGL ES 3.0 |
gl.UNPACK_SKIP_ROWS |
Number of rows of pixel locations skipped before the first pixel is read from memory | GLint |
0 | 0 to Infinity |
OpenGL ES 3.0 |
gl.UNPACK_SKIP_IMAGES |
Number of pixel images skipped before the first pixel is read from memory | GLint |
0 | 0 to Infinity |
OpenGL ES 3.0 |
Examples
Setting the pixel storage mode affects the WebGLRenderingContext.readPixels() operations, as well as unpacking of textures with the WebGLRenderingContext.texImage2D() and WebGLRenderingContext.texSubImage2D() methods.
var tex = gl.createTexture(); gl.bindTexture(gl.TEXTURE_2D, tex); gl.pixelStorei(gl.PACK_ALIGNMENT, 4);
To check the values for packing and unpacking of pixel data, you can query the same pixel storage parameters with WebGLRenderingContext.getParameter().
gl.getParameter(gl.PACK_ALIGNMENT); gl.getParameter(gl.UNPACK_ALIGNMENT);
Specifications
| Specification | Status | Comment |
|---|---|---|
| WebGL 1.0 pixelStorei |
Recommendation | Initial definition for WebGL. |
| WebGL 1.0 Pixel Storage Parameters |
Recommendation | Additional pixel storage parameters that aren't specified in OpenGL. |
| OpenGL ES 2.0 glPixelStorei |
Standard | Man page of the OpenGL ES 2.0 API. |
| WebGL 2.0 pixelStorei |
Editor's Draft | Updated definition for WebGL 2. |
| OpenGL ES 3.0 glPixelStorei |
Standard | Man page of the OpenGL ES 3.0 API. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
| Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | Servo |
|---|---|---|---|---|---|---|---|
| Basic Support | 9 | 12 | 4.0 | 11 | 12 | 5.1 | No support |
| WebGL2 | 56 | No support | 51.0 | No support | 43 | No support | No support |
| Feature | Android | Chrome for Android | Edge Mobile | Firefox for Android | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|---|
| Basic Support | (Yes) | 25 | (Yes) | 4.0 | 11 | 12 | 8.1 |
| WebGL2 | No support | No support | (Yes) | 51.0 | No support | No support | No support |