Using Image_NativeModule for PixelMap Operations

You can use the Pixelmap class to create, operate, and release a PixelMap, and obtain its width, height, pixel format, alpha type, and row stride.

How to Develop

Adding a Link Library

Open the src/main/cpp/CMakeLists.txt file of the native project, add libpixelmap.so and libhilog_ndk.z.so (on which the log APIs depend) to the target_link_libraries dependency.

target_link_libraries(entry PUBLIC libhilog_ndk.z.so libpixelmap.so)

Calling the Native APIs

For details about the APIs, see Image_NativeModule.

Create a native C++ application in DevEco Studio. The project created by default contains the index.ets file, and a hello.cpp or napi_init.cpp file is generated in the entry\src\main\cpp directory. In this example, the generated file is hello.cpp. Implement the C APIs in hello.cpp. Refer to the sample code below.

Example of Using the Pixelmap APIs

Create a Pixelmap instance after parameter initialization, read and write pixel data, and perform operations such as scaling, translating, flipping, rotating, and cropping on the image.

#include <hilog/log.h>
#include <multimedia/image_framework/image/pixelmap_native.h>

#undef LOG_DOMAIN
#undef LOG_TAG
#define LOG_DOMAIN 0x3200
#define LOG_TAG "MY_TAG"

Image_ErrorCode PixelmapTest()
{
    uint8_t data[96];
    size_t dataSize = 96;
    for (int i = 0; i < dataSize; i++) {
        data[i] = i + 1;
    }

    // Create a parameter structure instance and set parameters.
    OH_Pixelmap_InitializationOptions *createOpts;
    OH_PixelmapInitializationOptions_Create(&createOpts);
    OH_PixelmapInitializationOptions_SetWidth(createOpts, 6);
    OH_PixelmapInitializationOptions_SetHeight(createOpts, 4);
    OH_PixelmapInitializationOptions_SetPixelFormat(createOpts, PIXEL_FORMAT_RGBA_8888);
    OH_PixelmapInitializationOptions_SetAlphaType(createOpts, PIXELMAP_ALPHA_TYPE_UNKNOWN);

    // Create a Pixelmap instance.
    OH_PixelmapNative *pixelmap = nullptr;
    Image_ErrorCode errCode = OH_PixelmapNative_CreatePixelmap(data, dataSize, createOpts, &pixelmap);

    // Read the image pixel data and write the data to the array.
    uint8_t destination[96];
    size_t destinationSize = 96;
    errCode = OH_PixelmapNative_ReadPixels(pixelmap, destination, &destinationSize);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImagePixelmapNativeCTest pixelmapTest OH_PixelmapNative_ReadPixels failed, errCode: %{public}d.", errCode);
        return errCode;
    }

    // Read the image data in the buffer and write the data to the Pixelmap instance.
    uint8_t source[96];
    size_t sourceSize = 96;
    for (int i = 0; i < sourceSize; i++) {
        source[i] = i + 1;
    }
    errCode = OH_PixelmapNative_WritePixels(pixelmap, source, sourceSize);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImagePixelmapNativeCTest pixelmapTest OH_PixelmapNative_WritePixels failed, errCode: %{public}d.", errCode);
        return errCode;
    }

    // Create an image information instance and obtain the pixel information.
    OH_Pixelmap_ImageInfo *imageInfo;
    OH_PixelmapImageInfo_Create(&imageInfo);
    errCode = OH_PixelmapNative_GetImageInfo(pixelmap, imageInfo);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImagePixelmapNativeCTest pixelmapTest OH_PixelmapNative_GetImageInfo failed, errCode: %{public}d.", errCode);
        return errCode;
    }

    // Obtain the width, height, pixel format, and alpha type of the image.
    uint32_t width, height, rowStride;
    int32_t pixelFormat, alphaType;
    OH_PixelmapImageInfo_GetWidth(imageInfo, &width);
    OH_PixelmapImageInfo_GetHeight(imageInfo, &height);
    OH_PixelmapImageInfo_GetRowStride(imageInfo, &rowStride);
    OH_PixelmapImageInfo_GetPixelFormat(imageInfo, &pixelFormat);
    OH_PixelmapImageInfo_GetAlphaType(imageInfo, &alphaType);
    OH_PixelmapImageInfo_Release(imageInfo);
    OH_LOG_INFO(LOG_APP, "ImagePixelmapNativeCTest pixelmapTest GetImageInfo success, width: %{public}d, height: %{public}d, rowStride: %{public}d, pixelFormat: %{public}d, alphaType: %{public}d.", width, height, rowStride, pixelFormat, alphaType);

    // Set the opacity rate to enable the image to achieve the corresponding opacity effect.
    errCode = OH_PixelmapNative_Opacity(pixelmap, 0.5);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImagePixelmapNativeCTest pixelmapTest OH_PixelmapNative_Opacity failed, errCode: %{public}d.", errCode);
        return errCode;
    }

    // Scale the image.
    errCode = OH_PixelmapNative_Scale(pixelmap, 2.0, 1.0);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImagePixelmapNativeCTest pixelmapTest OH_PixelmapNative_Scale failed, errCode: %{public}d.", errCode);
        return errCode;
    }

    // Translate the image.
    errCode = OH_PixelmapNative_Translate(pixelmap, 50.0, 10.0);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImagePixelmapNativeCTest pixelmapTest OH_PixelmapNative_Translate failed, errCode: %{public}d.", errCode);
        return errCode;
    }

    // Rotate the image.
    errCode = OH_PixelmapNative_Rotate(pixelmap, 90.0);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImagePixelmapNativeCTest pixelmapTest OH_PixelmapNative_Rotate failed, errCode: %{public}d.", errCode);
        return errCode;
    }

    // Flip the image.
    errCode = OH_PixelmapNative_Flip(pixelmap, true, true);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImagePixelmapNativeCTest pixelmapTest OH_PixelmapNative_Flip failed, errCode: %{public}d.", errCode);
        return errCode;
    }

    // Crop the image.
    Image_Region region;
    region.x = 100;
    region.y = 100;
    region.width = 6;
    region.height = 4;
    errCode = OH_PixelmapNative_Crop(pixelmap, &region);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "ImagePixelmapNativeCTest pixelmapTest OH_PixelmapNative_Crop failed, errCode: %{public}d.", errCode);
        return errCode;
    }

    // Release the Pixelmap and InitializationOptions instances.
    OH_PixelmapNative_Release(pixelmap);
    OH_PixelmapInitializationOptions_Release(createOpts);
    return IMAGE_SUCCESS;
}

// Example of converting between premultiplied and non-premultiplied formats in PixelMap.
Image_ErrorCode PixelmapConverAlphaTypeTest()
{
    uint8_t data[96];
    size_t dataSize = 96;
    for (int i = 0; i < dataSize; i++) {
        data[i] = i + 1;
    }

    // Create a parameter structure instance and set parameters.
    OH_Pixelmap_InitializationOptions *createOpts;
    OH_PixelmapInitializationOptions_Create(&createOpts);
    OH_PixelmapInitializationOptions_SetWidth(createOpts, 6);
    OH_PixelmapInitializationOptions_SetHeight(createOpts, 4);
    OH_PixelmapInitializationOptions_SetSrcPixelFormat(createOpts, PIXEL_FORMAT_RGBA_8888);
    OH_PixelmapInitializationOptions_SetPixelFormat(createOpts, PIXEL_FORMAT_RGBA_8888);
    OH_PixelmapInitializationOptions_SetAlphaType(createOpts, PIXELMAP_ALPHA_TYPE_UNPREMULTIPLIED);

    // Create a Pixelmap instance in non-premultiplied format.
    OH_PixelmapNative *SrcPixelmap = nullptr;
    Image_ErrorCode errCode = OH_PixelmapNative_CreatePixelmap(data, dataSize, createOpts, &SrcPixelmap);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "PixelmapConverAlphaTypeTest CreateSrcPixelMap failed, errCode: %{public}d.", errCode);
    }

    // Create a Pixelmap instance in premultiplied format. DstPixelmap is used to store the data after the alpha type of SrcPixelmap is converted.
    OH_PixelmapNative *DstPixelmap = nullptr;
    OH_PixelmapInitializationOptions_SetAlphaType(createOpts, PIXELMAP_ALPHA_TYPE_PREMULTIPLIED);
    errCode = OH_PixelmapNative_CreatePixelmap(data, dataSize, createOpts, &DstPixelmap);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "PixelmapConverAlphaTypeTest CreateDstPixelMap failed, errCode: %{public}d.", errCode);
    }

    // Convert the alpha type. The data of SrcPixelmap is converted to premultiplied format and saved to DstPixelmap.
    errCode = OH_PixelmapNative_ConvertAlphaFormat(SrcPixelmap, DstPixelmap, true);
    if (errCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "PixelmapConverAlphaTypeTest ConvertAlphaFormat failed, errCode: %{public}d.", errCode);
    }

    // Release the Pixelmap and InitializationOptions instances.
    OH_PixelmapNative_Release(SrcPixelmap);
    OH_PixelmapNative_Release(DstPixelmap);
    OH_PixelmapInitializationOptions_Release(createOpts);
    return errCode;
}