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鸿蒙OS《Native API参考》
Image
Overview
Provides access to pixel data and pixel map information.
Since:
3
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
anonymous enumDescription:
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
anonymous enumDescription:
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. |
See also:
UnAccessPixels
Returns:
Returns OHOS_IMAGE_RESULT_SUCCESS if the operation is successful; returns other result codes if the operation fails.
GetImageInfo()
int32_t GetImageInfo (JNIEnv * env, jobject pixelMapObject, OhosPixelMapInfo & info )Description:
Obtains information about a given PixelMap and stores the information in a OhosPixelMapInfo structure.
Parameters:
| Name | Description |
|---|---|
| env | Indicates the pointer to the JNI environment. |
| pixelMapObject | Indicates the Java PixelMap object. |
| info | Indicates the pointer to the pixel map information to obtain. For details, see OhosPixelMapInfo. |
Returns:
Returns 0 if the information is obtained and stored in the structure; returns result codes if the operation fails. OhosPixelMapInfo 3 1.0
UnAccessPixels()
int32_t UnAccessPixels (JNIEnv * env, jobject pixelMapObject )Description:
Unlocks the memory storing the pixel data of a given PixelMap to balance a successful call to AccessPixels.
Parameters:
| Name | Description |
|---|---|
| env | Indicates the pointer to the JNI environment. |
| pixelMapObject | Indicates the Java PixelMap object. |
Returns:
Returns OHOS_IMAGE_RESULT_SUCCESS if the operation is successful; returns other result codes if the operation fails.
See also:
AccessPixels
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