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鸿蒙系统 api,鸿蒙OS《Native API参考》

作者：你好赵伟 | 2024-03-21 09:43:47

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鸿蒙api

Image

Overview

Provides access to pixel data and pixel map information.

Since:

Version:

1.0

Summary

Files

File Name

Description

image_pixel_map.h

Declares functions for you to lock and access or unlock pixel data, and obtain the width and height of a pixel map.

Data Structures

Data Structure Name

Description

OhosPixelMapInfo

Defines pixel map information.

Enumerations

Enumeration Name

Description

{ OHOS_IMAGE_RESULT_SUCCESS = 0, OHOS_IMAGE_RESULT_BAD_PARAMETER = -1, OHOS_IMAGE_RESULT_JNI_EXCEPTION = -2 }

Enumerates the result codes that may be returned by a function.

{ OHOS_PIXEL_MAP_FORMAT_NONE = 0, OHOS_PIXEL_MAP_FORMAT_RGBA_8888 = 3, OHOS_PIXEL_MAP_FORMAT_RGB_565 = 2 }

Enumerates pixel formats.

Functions

Function Name

Description

GetImageInfo (JNIEnv *env, jobject pixelMapObject, OhosPixelMapInfo &info)

int32_tObtains information about a given PixelMap and stores the information in a OhosPixelMapInfo structure.

AccessPixels (JNIEnv *env, jobject pixelMapObject, void **addrPtr)

int32_tObtains the memory address of a given PixelMap object and locks the memory.

UnAccessPixels (JNIEnv *env, jobject pixelMapObject)

int32_tUnlocks the memory storing the pixel data of a given PixelMap to balance a successful call to AccessPixels.

Details

Enumeration Type Documentation

anonymous enum

Description:

Enumerates the result codes that may be returned by a function.

Enumerator

Description

OHOS_IMAGE_RESULT_SUCCESS

Success result

OHOS_IMAGE_RESULT_BAD_PARAMETER

Invalid parameters

OHOS_IMAGE_RESULT_JNI_EXCEPTION

JNI exception

anonymous enum

Description:

Enumerates pixel formats.

Enumerator

Description

OHOS_PIXEL_MAP_FORMAT_NONE

Unknown format

OHOS_PIXEL_MAP_FORMAT_RGBA_8888

32-bit RGBA. Components R, G, B, and A each occupies 8 bits and are stored from the higher-order to the lower-order bits.

OHOS_PIXEL_MAP_FORMAT_RGB_565

16-bit RGB. Only the R, G, and B components are encoded from the higher-order to the lower-order bits: red is stored with 5 bits of precision, green is stored with 6 bits of precision, and blue is stored with 5 bits of precision.

Function Documentation

AccessPixels()

int32_t AccessPixels (JNIEnv * env, jobject pixelMapObject, void ** addrPtr )

Description:

Obtains the memory address of a given PixelMap object and locks the memory.

If this function call is successful, *addrPtr is set to the memory address. After accessing the pixel data, you must use UnAccessPixels to unlock the memory. Otherwise, resources cannot be released. After the memory is unlocked, it can be invalid and should not be accessed.

Parameters:

Name

Description

env

Indicates the pointer to the JNI environment.

pixelMapObject

Indicates the Java PixelMap object.

addrPtr

Indicates the double pointer to the memory address.